The Mitragyna speciosa (kratom) alkaloid mitragynine: Analysis of adrenergic α2 receptor activity in vitro and in vivo.

Mitragynine, an alkaloid present in the leaves of Mitragyna speciosa (kratom), has a complex pharmacology that includes low efficacy agonism at µ-opioid receptors (MORs). This study examined the activity of mitragynine at adrenergic α2 receptors (Aα2Rs) in vitro and in vivo. Mitragynine displaced a radiolabeled Aα2R antagonist ([3H]RX821002) from human Aα2ARs in vitro with lower affinity (Ki = 1260 nM) than the agonists (-)-epinephrine (Ki = 263 nM) or lofexidine (Ki = 7.42 nM). Mitragynine did not significantly stimulate [35S]GTPγS binding at Aα2ARs in vitro, but in rats trained to discriminate 32 mg/kg mitragynine from vehicle (intraperitoneally administered; i.p.), mitragynine exerted an Aα2R agonist-like effect. Both α2R antagonists (atipamezole and yohimbine) and MOR antagonists (naloxone and naltrexone) produced rightward shifts in mitragynine discrimination dose-effect function and Aα2R agonists lofexidine and clonidine produced leftward shifts. In the mitragynine trained rats, Aα2R agonists also produced leftward shifts in discrimination dose-effect functions for morphine and fentanyl. In a separate rat cohort trained to discriminate 3.2 mg/kg i.p. morphine from vehicle, naltrexone produced a rightward shift, but neither an Aα2R agonist or antagonist affected morphine discrimination. In a hypothermia assay, both lofexidine and clonidine produced marked effects antagonized by yohimbine. Mitragynine did not produce hypothermia. Together, these data demonstrate that mitragynine acts in vivo like an Aα2R agonist, although its failure to induce hypothermia or stimulate [35S]GTPγS binding in vitro, suggests that mitragynine maybe a low efficacy Aα2R agonist.

Potentially Inappropriate Use of Opioids in the Management of Migraine in Colombia.

RESEARCH OBJECTIVE: To identify the frequency of opioid use in a group of patients diagnosed with migraine in Colombia. METHODS: Study of a retrospective cohort of patients with a diagnosis of migraine and a first prescription of antimigraine drugs from emergency services and a priority outpatient clinic. Sociodemographic, clinical, and pharmacological variables were identified; a 12-month follow-up was carried out to identify the use of a new opioid. RESULTS: A total of 6309 patients with a diagnosis of migraine were identified, with a mean age of 35.5 ± 12.3 years, of which 81.3% were women. Nonsteroidal anti-inflammatory drugs (51.1%) were the most frequently prescribed medications, followed by ergotamine + caffeine (31.3%), acetaminophen (15.05%), and acetaminophen + codeine (14.4%). At the time of the index, 1300 (20.6%) patients received some opioid. During the follow-up, a total of 1437 (22.8%) patients received a new opioid, of which 31.8% belonged to the group that received an initial opioid and 20.4% to the group that did not receive one, which was statistically significant (OR:1.81; 95%CI:1.58-2.07; p < 0.001). CONCLUSIONS: The frequent use of opioids in the management of migraines is potentially inappropriate and can lead to problems of tolerance, abuse and dependence. This combined with the low prescription of triptans, offers an opportunity for improvements in medical practice.

Treatment patterns of antidiabetic and kidney protective therapies among patients with type 2 diabetes mellitus and chronic kidney disease in Colombia. The KDICO descriptive study.

BACKGROUND: Type 2 diabetes mellitus is one of the most common causes of chronic kidney disease (CKD) worldwide and prevalence of 1.75 per 100 inhabitants in Colombia. The aim of this study was to describe the treatment patterns of a group of patients with type 2 diabetes mellitus and CKD in an outpatient setting from Colombia. METHODS: A cross-sectional study in adult patients with type 2 diabetes mellitus and CKD identified in the Audifarma S.A. administrative healthcare database between April 2019 and March 2020 was performed. Sociodemographic, clinical and pharmacological variables were considered and analyzed. RESULTS: A total of 14,722 patients with type 2 diabetes mellitus and CKD were identified, predominantly male (51%), with a mean age of 74.7 years. The most common treatment patterns of type 2 diabetes mellitus included the use of metformin monotherapy (20.5%), followed by the combination of metformin + dipeptidyl peptidase-4 inhibitor (13.4%). Regarding the use of drugs with nephroprotective properties, the most prescribed treatments were angiotensin receptor blockers (67.2%), angiotensin converting enzyme inhibitors (15.8%), sodium glucose cotransporter 2 inhibitors (SGLT2i) (17.0%) and glucagon-like peptide-1 analogs (GLP1a) (5.2%). CONCLUSION: In Colombia, the majority of patients with type 2 diabetes mellitus and CKD identified in this study were treated with antidiabetic and protective medications to ensure adequate metabolic, cardiovascular, and renal control. The management of type 2 diabetes mellitus and CKD may be improved if the beneficial properties of new groups of antidiabetics (SGLT2i, GLP1a), as well as novel mineralocorticoid receptor antagonists, are considered.

Pharmacokinetic and Pharmacodynamic Consequences of Cytochrome P450 3A Inhibition on Mitragynine Metabolism in Rats.

Mitragynine, an opioidergic alkaloid present in Mitragyna speciosa (kratom), is metabolized by cytochrome P450 3A (CYP3A) to 7-hydroxymitragynine, a more potent opioid receptor agonist. The extent to which conversion to 7-hydroxymitragynine mediates the in vivo effects of mitragynine is unclear. The current study examined how CYP3A inhibition (ketoconazole) modifies the pharmacokinetics of mitragynine in rat liver microsomes in vitro. The study further examined how ketoconazole modifies the discriminative stimulus and antinociceptive effects of mitragynine in rats. Ketoconazole [30 mg/kg, oral gavage (o.g.)] increased systemic exposure to mitragynine (13.3 mg/kg, o.g.) by 120% and 7-hydroxymitragynine exposure by 130%. The unexpected increase in exposure to 7-hydroxymitragynine suggested that ketoconazole inhibits metabolism of both mitragynine and 7-hydroxymitragynine, a finding confirmed in rat liver microsomes. In rats discriminating 3.2 mg/kg morphine from vehicle under a fixed-ratio schedule of food delivery, ketoconazole pretreatment increased the potency of both mitragynine (4.7-fold) and 7-hydroxymitragynine (9.7-fold). Ketoconazole did not affect morphine's potency. Ketoconazole increased the antinociceptive potency of 7-hydroxymitragynine by 4.1-fold. Mitragynine (up to 56 mg/kg, i.p.) lacked antinociceptive effects both in the presence and absence of ketoconazole. These results suggest that both mitragynine and 7-hydroxymitragynine are cleared via CYP3A and that 7-hydroxymitragynine is formed as a metabolite of mitragynine by other routes. These results have implications for kratom use in combination with numerous medications and citrus juices that inhibit CYP3A. SIGNIFICANCE STATEMENT: Mitragynine is an abundant kratom alkaloid that exhibits low efficacy at the µ-opioid receptor (MOR). Its metabolite, 7-hydroxymitragynine, is also an MOR agonist but with higher affinity and efficacy than mitragynine. Our results in rats demonstrate that cytochrome P450 3A (CYP3A) inhibition can increase the systematic exposure of both mitragynine and 7-hydroxymitragynine and their potency to produce MOR-mediated behavioral effects. These data highlight potential interactions between kratom and CYP3A inhibitors, which include numerous medications and citrus juices.

Treatment patterns in fibromyalgia including the use of opioids.

OBJECTIVE: Opioids (except for tramadol) have not been shown to be effective in patients with fibromyalgia, but they can increase the risk of adverse drug reactions. The aim was to determine the treatment patterns of a group of patients with fibromyalgia and to identify the factors associated with the use of opioids in Colombia. METHODS: This was a cross-sectional study of a group of patients with fibromyalgia from a pain clinic in Colombia. Sociodemographic, clinical and pharmacological variables were identified. Descriptive, bivariate, and multivariate analyses were performed. RESULTS: A total of 559 patients were analysed, 88.6% of whom were women, and the mean age was 53.4 ± 12.6 years. A total of 40.6% received nonpharmacological management, and the majority were treated with acetaminophen (96.1%) and pregabalin (62.8%). A total of 69.6% received opioids, the most common of which was hydrocodone (36.3%). The average morphine equivalent milligrammes was 36.9 ± 91.2 (range: 2.3-750 mg), and 43.8% had intermediate/high doses. Being male (OR: 3.12; 95% CI: 1.40-6.91), having arterial hypertension (OR: 1.67; 95% CI: 1.04-2.69), obesity (OR: 2.23; 95% CI: 1.18-4.24), degenerative disease of vertebral discs (OR: 2.32; 95% CI: 1.10-4.88) and comedication with gabapentinoids (OR: 1.75; 95% CI: 1,15-2.65) were associated with a higher probability of receiving opioids, while patients treated with muscle relaxants had a lower risk of opioid treatment (OR: 0.64; 95% CI: 0.41-0.98). CONCLUSIONS: A significant proportion of patients were treated with opioids, the most common of which was hydrocodone, which goes against the recommendations of clinical practice guidelines.

Interactive Effects of µ-Opioid and Adrenergic-α 2 Receptor Agonists in Rats: Pharmacological Investigation of the Primary Kratom Alkaloid Mitragynine and Its Metabolite 7-Hydroxymitragynine.

The primary kratom alkaloid mitragynine is proposed to act through multiple mechanisms, including actions at µ-opioid receptors (MORs) and adrenergic-α 2 receptors (Aα 2Rs), as well as conversion in vivo to a MOR agonist metabolite (i.e., 7-hydroxymitragynine). Aα 2R and MOR agonists can produce antinociceptive synergism. Here, contributions of both receptors to produce mitragynine-related effects were assessed by measuring receptor binding in cell membranes and, in rats, pharmacological behavioral effect antagonism studies. Mitragynine displayed binding affinity at both receptors, whereas 7-hydroxymitragynine only displayed MOR binding affinity. Compounds were tested for their capacity to decrease food-maintained responding and rectal temperature and to produce antinociception in a hotplate test. Prototypical MOR agonists and 7-hydroxymitragynine, but not mitragynine, produced antinociception. MOR agonist and 7-hydroxymitragynine rate-deceasing and antinociceptive effects were antagonized by the opioid antagonist naltrexone but not by the Aα 2R antagonist yohimbine. Hypothermia only resulted from reference Aα 2R agonists. The rate-deceasing and hypothermic effects of reference Aα 2R agonists were antagonized by yohimbine but not naltrexone. Neither naltrexone nor yohimbine antagonized the rate-decreasing effects of mitragynine. Mitragynine and 7-hydroxymitragynine increased the potency of the antinociceptive effects of Aα 2R but not MOR reference agonists. Only mitragynine produced hypothermic effects. Isobolographic analyses for the rate-decreasing effects of the reference Aα 2R and MOR agonists were also conducted. These results suggest mitragynine and 7-hydroxymitragynine may produce antinociceptive synergism with Aα 2R and MOR agonists. When combined with Aα 2R agonists, mitragynine could also produce hypothermic synergism. SIGNIFICANCE STATEMENT: Mitragynine is proposed to target the µ-opioid receptor (MOR) and adrenergic-α2 receptor (Aα2R) and to produce behavioral effects through conversion to its MOR agonist metabolite 7-hydroxymitragynine. Isobolographic analyses indicated supra-additivity in some dose ratio combinations. This study suggests mitragynine and 7-hydroxymitragynine may produce antinociceptive synergism with Aα2R and MOR agonists. When combined with Aα2R agonists, mitragynine could also produce hypothermic synergism.

The Lack of Contribution of 7-Hydroxymitragynine to the Antinociceptive Effects of Mitragynine in Mice: A Pharmacokinetic and Pharmacodynamic Study.

Kratom (Mitragyna speciosa), a Southeast Asian tree, has been used for centuries in pain relief and mitigation of opium withdrawal symptoms. Mitragynine (MTG), the major kratom alkaloid, is being investigated for its potential to provide analgesia without the deleterious effects associated with typical opioids. Concerns have been raised regarding the active metabolite of MTG, 7-hydroxymitragynine (7HMG), which has higher affinity and efficacy at µ-opioid receptors than MTG. Here we investigated the hotplate antinociception, pharmacokinetics, and tissue distribution of MTG and 7HMG at equianalgesic oral doses in male and female C57BL/6 mice to determine the extent to which 7HMG metabolized from MTG accounts for the antinociceptive effects of MTG and investigate any sex differences. The mechanism of action was examined by performing studies with the opioid receptor antagonist naltrexone. A population pharmacokinetic/pharmacodynamic model was developed to predict the behavioral effects after administration of various doses of MTG and 7HMG. When administered alone, 7HMG was 2.8-fold more potent than MTG to produce antinociception. At equivalent effective doses of MTG and 7HMG, there was a marked difference in the maximum brain concentration of 7HMG achieved, i.e., 11-fold lower as a metabolite of MTG. The brain concentration of 7HMG observed 4 hours post administration, producing an analgesic effect <10%, was still 1.5-fold higher than the maximum concentration of 7HMG as a metabolite of MTG. These results provide strong evidence that 7HMG has a negligible role in the antinociceptive effects of MTG in mice. SIGNIFICANCE STATEMENT: Mitragynine (MTG) is being investigated for its potential to aid in pain relief, opioid withdrawal syndrome, and opioid use disorder. The active metabolite of MTG, 7-hydroxymitragynine (7HMG), has been shown to have abuse potential and has been implicated in the opioid-like analgesic effect after MTG administration. The results of this study suggest a lack of involvement of 7HMG in the antinociceptive effects of MTG in mice.

Activity of Mitragyna speciosa ("Kratom") Alkaloids at Serotonin Receptors.

Kratom alkaloids have mostly been evaluated for their opioid activity but less at other targets that could contribute to their physiological effects. Here, we investigated the in vitro and in vivo activity of kratom alkaloids at serotonin receptors (5-HTRs). Paynantheine and speciogynine exhibited high affinity for 5-HT1ARs and 5-HT2BRs, unlike the principal kratom alkaloid mitragynine. Both alkaloids produced antinociceptive properties in rats via an opioid receptor-independent mechanism, and neither activated 5-HT2BRs in vitro. Paynantheine, speciogynine, and mitragynine induced lower lip retraction and antinociception in rats, effects blocked by a selective 5-HT1AR antagonist. In vitro functional assays revealed that the in vivo 5-HT1AR agonistic effects may be due to the metabolites 9-O-desmethylspeciogynine and 9-O-desmethylpaynantheine and not the parent compounds. Both metabolites did not activate 5-HT2BR, suggesting low inherent risk of causing valvulopathy. The 5-HT1AR agonism by kratom alkaloids may contribute to the mood-enhancing effects associated with kratom use.

The use of hypercapnic conditions to assess opioid-induced respiratory depression in rats.

INTRODUCTION: Whole-body plethysmography (WBP) in unrestrained, non-anesthetized rodents is a preclinical method to assess the respiratory depressant effects of opioids, the leading cause of opioid overdose death in humans. However, low baseline respiration rates under normocapnic conditions (i.e., "floor" effect) can render the measurement of respiratory decreases challenging. We assessed hypercapnia-induced increases in respiration as a strategy to assess opioid-induced decreases in respiration in rats. METHODS: WBP was used to assess respiration frequency, tidal volume and minute volume in the presence of normocapnic and hypercapnic (8% CO2) conditions in rats during the rat diurnal period of the light cycle. The mu-opioid receptor agonist fentanyl was administered intravenously, and the hot plate test was used to assess acute antinociception. RESULTS AND DISCUSSION: Hypercapnia-induced increases in respiratory parameters (frequency, minute volume, and tidal volume) were decreased by fentanyl at doses that did not decrease the same parameters under the normocapnic conditions. These findings show that hypercapnia increases sensitivity to respiratory depressant effects of fentanyl, as compared with assessments during the rat diurnal period when activity and breathing rate are generally low, i.e., there is a floor effect. The current approach is highly sensitive to opioid-induced respiratory depression, and therefore provides a useful method for assessment in a pre-clinical setting.

Exploring the Chemistry of Alkaloids from Malaysian Mitragyna speciosa (Kratom) and the Role of Oxindoles on Human Opioid Receptors.

Ten indole and oxindole alkaloids (1-10) were isolated from the freshly collected leaves of Malaysian Mitragyna speciosa (Kratom). The chemical structures of these compounds were established on the basis of extensive 1D and 2D NMR and HRMS data analysis. The spectroscopic data of mitragynine oxindole B (4) are reported herein for the first time. The spatial configuration of mitragynine oxindole B (4) was confirmed by single-crystal X-ray diffraction. Simultaneous quantification of the isolated alkaloids in the M. speciosa leaf specimens collected from different locations in the northern region of Peninsular Malaysia was also performed using UPLC-MS/MS. The oxindole alkaloids (1-4) and the indole alkaloid (10) were assessed for binding affinity at opioid receptors. Corynoxine (1) showed high binding affinity to µ-opioid receptors with a Ki value of 16.4 nM. Further, corynoxine (1) was 1.8-fold more potent than morphine in rats subjected to a nociceptive hot plate assay. These findings have important implications for evaluating the combined effects of the minor oxindole alkaloids in the overall therapeutic activity of M. speciosa.

Pharmacological Comparison of Mitragynine and 7-Hydroxymitragynine: In Vitro Affinity and Efficacy for µ-Opioid Receptor and Opioid-Like Behavioral Effects in Rats.

Relationships between µ-opioid receptor (MOR) efficacy and effects of mitragynine and 7-hydroxymitragynine are not fully established. We assessed in vitro binding affinity and efficacy and discriminative stimulus effects together with antinociception in rats. The binding affinities of mitragynine and 7-hydroxymitragynine at MOR (Ki values 77.9 and 709 nM, respectively) were higher than their binding affinities at κ-opioid receptor (KOR) or δ-opioid receptor (DOR). [35S]guanosine 5'-O-[γ-thio]triphosphate stimulation at MOR demonstrated that mitragynine was an antagonist, whereas 7-hydroxymitragynine was a partial agonist (Emax = 41.3%). In separate groups of rats discriminating either morphine (3.2 mg/kg) or mitragynine (32 mg/kg), mitragynine produced a maximum of 72.3% morphine-lever responding, and morphine produced a maximum of 65.4% mitragynine-lever responding. Other MOR agonists produced high percentages of drug-lever responding in the morphine and mitragynine discrimination assays: 7-hydroxymitragynine (99.7% and 98.1%, respectively), fentanyl (99.7% and 80.1%, respectively), buprenorphine (99.8% and 79.4%, respectively), and nalbuphine (99.4% and 98.3%, respectively). In the morphine and mitragynine discrimination assays, the KOR agonist U69,593 produced maximums of 72.3% and 22.3%, respectively, and the DOR agonist SNC 80 produced maximums of 34.3% and 23.0%, respectively. 7-Hydroxymitragynine produced antinociception; mitragynine did not. Naltrexone antagonized all of the effects of morphine and 7-hydroxymitragynine; naltrexone antagonized the discriminative stimulus effects of mitragynine but not its rate-decreasing effects. Mitragynine increased the potency of the morphine discrimination yet decreased morphine antinociception. Here we illustrate striking differences in MOR efficacy, with mitragynine having less than 7-hydroxymitragynine. SIGNIFICANCE STATEMENT: At human µ-opioid receptor (MOR) in vitro, mitragynine has low affinity and is an antagonist, whereas 7-hydroxymitragynine has 9-fold higher affinity than mitragynine and is an MOR partial agonist. In rats, intraperitoneal mitragynine exhibits a complex pharmacology including MOR agonism; 7-hydroxymitragynine has higher MOR potency and efficacy than mitragynine. These results are consistent with 7-hydroxymitragynine being a highly selective MOR agonist and with mitragynine having a complex pharmacology that combines low efficacy MOR agonism with activity at nonopioid receptors.

Investigation of the Adrenergic and Opioid Binding Affinities, Metabolic Stability, Plasma Protein Binding Properties, and Functional Effects of Selected Indole-Based Kratom Alkaloids.

Selected indole-based kratom alkaloids were evaluated for their opioid and adrenergic receptor binding and functional effects, in vivo antinociceptive effects, plasma protein binding, and metabolic stability. Mitragynine, the major alkaloid in Mitragyna speciosa (kratom), had higher affinity at opioid receptors than at adrenergic receptors while the vice versa was observed for corynantheidine. The observed polypharmacology of kratom alkaloids may support its utilization to treat opioid use disorder and withdrawal.

Profilaxis combinada con inmunoglobulina intravenosa y plasmaféresis en pacientes altamente sensibilizados, receptores de trasplante renal o combinado hígado-riñón: experiencia en un centro médico colombiano / Combined prophylaxis with intravenous immunoglobulin and plasmapheresis in highly sensitized patients, recipients of kidney or combined liver-kidney transplant: experience in a Colombian medical center

El trasplante renal constituye la mejor opción de tratamiento para los pacientes con enfermedad renal crónica terminal. La supervivencia del injerto es de gran importancia y puede ser afectada por factores inmunológicos o no inmunológicos; esto unido al número de pacientes en las listas de espera, hace necesario definir estrategias de manejo que permitan tener mejores resultados a largo plazo. Objetivo. Determinar las características clínicas y humorales, y los desenlaces en receptores de trasplante renal o combinado hígado-riñón, altamente sensibilizados, que recibieron profilaxis combinada con inmunoglobulina intravenosa y plasmaféresis en el Hospital San Vicente Fundación, en Colombia. Materiales y métodos. Se realizó un estudio retrospectivo, observacional, descriptivo, que incluyó los pacientes trasplantados entre el 4 de julio de 2010 y el 19 de abril de 2017. Como variables se incluyeron, entre otras, la etiología de la enfermedad renal crónica, el tipo de terapia recibida, y el tiempo en lista de espera en días. Como desenlace se evaluó la presencia de rechazo, el tipo de rechazo, la pérdida del injerto, las complicaciones y la muerte. Resultados. Del total de 25 pacientes, el 100% recibió inmunoglobulina intravenosa y el 84% plasmaféresis. El 12% presentó rechazo del injerto, todos de tipo humoral, y el 20% perdió el injerto. Discusión. A pesar de la gran variedad de protocolos propuestos en la literatura, en esta población especial no se ha establecido un protocolo óptimo de inmunosupresión. El protocolo en nuestra pequeña cohorte no tuvo un impacto negativo en el porcentaje de infecciones postrasplante ni en la pérdida del injerto renal, pero sí redujo el tiempo en las listas de espera; por lo tanto, se requieren estudios adicionales para confirmar los hallazgos encontrados en este estudio

Kidney transplantation is the best treatment option for patients with terminal chronic kidney disease, regardless of the etiology, making graft survival an important feature, which may be affected by immunological or non-immunological factors. This, added to the increasing number of patients on waiting lists, makes it necessary to define management strategies for these patients that allow better long-term results. Objectives. To determine the clinical, humoral and outcome characteristics in highly sensitized recipients of kidney and simultaneous kidneyliver transplant who received combined prophylaxis with intravenous immunoglobulin and plasmapheresis therapy in a Colombian medical center. Materials and methods. A retrospective, observational, descriptive study was carried out that included the transplanted patients between July 4, 2010 and April 19, 2017. Variables included the etiology of chronic kidney disease, the type of therapy received, and waiting time in days, among others. As outcomes, the presence of rejection, type of rejection, graft loss, complications and death were evaluated. Results. From a total of 25 patients, 100% received intravenous immunoglobulin and 84% plasmapheresis. Twelve percent presented graft rejection, all humoral, and 20% lost the graft. Discussion. Despite the great variety of protocols proposed in the literature, an optimal immunosuppression protocol has not been established for this particular population. The protocol in our small cohort did not have a negative impact on the percentage of post-transplant infections nor in the loss of the renal graft, but it did reduce waiting time; therefore, additional studies are required to confirm the findings in this study

The Effects of Morphine, Baclofen, and Buspirone Alone and in Combination on Schedule-Controlled Responding and Hot Plate Antinociception in Rats.

Better therapeutic options are needed for pain. Baclofen, buspirone, and morphine are characterized as having analgesic properties. However, little is known about potential interactions between analgesic effects of these drugs when combined. Furthermore, it is not known if the magnitude of these potential interactions will be similar for all drug effects. Thus, we tested the effects of these drugs alone and in combination for their capacity to produce thermal antinociception and to decrease food-maintained responding. Four male and four female Sprague-Dawley rats responded for food under a fixed-ratio 10 schedule; afterward they were immediately placed on a 52°C hot plate. Morphine, baclofen, and buspirone were examined alone and in 1:1 combinations, based upon ED50 values. Morphine and baclofen effects were evaluated with the opioid antagonist naltrexone and the GABAB antagonist (3-Aminopropyl)(diethoxymethyl)phosphinic acid (CGP35348), respectively. Morphine, baclofen, and buspirone dose dependently decreased operant responding, with the calculated ED50 values being 7.09, 3.42, and 0.57 mg/kg, respectively. The respective antinociception ED50 values were 16.15, 8.75, and 2.20 mg/kg. Analysis of 1:1 combinations showed the effects of morphine plus baclofen to decrease schedule-controlled responding and to produce thermal antinociception were synergistic. Effects of morphine plus buspirone and baclofen plus buspirone to decrease schedule-controlled responding were additive. Effects of the two combinations to produce thermal antinociception were synergistic. Naltrexone and CGP35348 antagonized the effects of morphine and baclofen, respectively. Synergistic antinociceptive effects, in conjunction with additive effects on food-maintained responding, highlight the therapeutic utility of opioid and non-opioid drug combinations.

The effects of mitragynine and morphine on schedule-controlled responding and antinociception in rats.

RATIONALE: Mitragyna speciosa (kratom) may hold promise as both an analgesic and treatment for opioid use disorder. Mitragynine, its primary alkaloid constituent, is an opioid receptor ligand. However, the extent to which the in vivo effects of mitragynine are mediated by opioid receptors, or whether mitragynine interacts with other opioid agonists, is not fully established. OBJECTIVES: The effects of mitragynine and the prototypical opioid agonist morphine were compared for their capacity to decrease operant responding for food delivery, and to increase response latency to a thermal stimulus. METHODS: Male and female Sprague-Dawley rats responded under a multiple cycle fixed ratio 10 schedule of food delivery and were tested on a hot plate (52 °C) immediately after each cycle. Morphine and mitragynine were administered alone, in combination with each other, and in combination with the opioid antagonist naltrexone. RESULTS: Morphine and mitragynine dose-dependently decreased schedule-controlled responding; the ED50 values were 7.3 and 31.5 mg/kg, respectively. Both drugs increased thermal antinociception; the ED50 value for morphine was 18.3. Further, doses of naltrexone that antagonized morphine did not antagonize mitragynine. Mitragynine (17.8 mg/kg) did not alter the rate-decreasing or antinociceptive effects of morphine. CONCLUSIONS: The antinociceptive effects of mitragynine and morphine occur at doses larger than those that disrupt learned behavior. Opioid receptors do not appear to mediate the disruptive effects of mitragynine on learned behavior. Mitragynine had lesser antinociceptive effects than morphine, and these did not appear to be mediated by opioid receptors. The pharmacology of mitragynine includes a substantial non-opioid mechanism.

When to Cheat: Modeling Dynamics of Paternity and Promiscuity in Socially Monogamous Prairie Voles (Microtus ochrogaster).

In many socially monogamous species, individuals form long-term pair bonds and males mate guard females. Such behavior is thought to help secure intra-pair fertilizations, the result of intra-pair copulations (IPCs), and ensure paternity. However, socially monogamous males are also often opportunistic and seek additional mating opportunities with other females, leaving their partner unguarded. The success associated with a male's decision to seek more mates over guarding his partner might be impacted by the activity of other males, specifically the proportion of other males leaving their territories to seek extra-pair copulations (EPCs). The amount of EPC-seeking males can impact the likelihood of a given male encountering an unguarded paired female, but also of being cuckolded (losing IPCs). It remains unclear under which conditions it is optimal to stay and guard or seek EPCs. Using field data from socially monogamous prairie voles (Microtus ochrogaster) to generate parameters, we used optimal performance modeling (Monte Carlo simulations) to ask when is it most reproductively advantageous for a bonded male to seek EPCs, despite the risk of losing IPCs. We defined three types of males: exclusive mating bonded males (true residents), non-exclusive mating bonded residents (roving residents), and unpaired males (wanderers). We first modeled the success of an individual male living in a context that incorporated only true and roving residents. We next added wandering males to this model. Finally, we considered the effects of including wandering males and unpaired females in our model. For all contexts, we found that as EPC-seeking in the population increases, the potential reproductive benefit for seeking EPCs increasingly outpaces the rate of cuckolding. In other words, we observe a shift in optimal strategy from true residents to rovers among paired males. Our models also demonstrate that reproductive fitness is likely to remain constant, despite the shift toward obtaining success via EPCs over IPCs. Our results show the dynamic nature of reproductive decision-making, and demonstrate that alternative reproductive decisions yield subtle but important differences despite appearing as balanced strategies.

Application of the principal-component analysis in the evaluation of three grass varieties / Aplicación del análisis por componentes principales en la evaluación de tres variedades de pasto / Aplicação da análise de componentes principais na avaliação de três variedades de capim

Objective: demonstrate how to use the principal-component analysis to reduce dimensionality in assessing three varieties of Ryegrass (Lolium sp. L.), namely, tetraploid hybrid (Foster), annual diploid (Southern Star), and annual tetraploid (Beefbuilder). Both the statistical properties and programming using the SAS statistical package are also highlighted. Results: The variables that defined the main factor for the three grass varieties were: height from the floor, middle width of the fully elongated last leaf, and biomass.

Objetivo: mostrar una aplicación del análisis de componentes principales en la reducción de la dimensionalidad de variables derivadas de la evaluación agronómica de tres variedades de pasto. Métodos: los pastos evaluados fueron Ryegrass (Lolium sp. L.), híbrido tetraploide (Foster), anual diploide (Southern Star) y anual tetraploide (Beef Builder). Igualmente se destacan las propiedades estadísticas y la forma de programación en el paquete estadístico SAS. Resultados: se observó que las variables que definieron el factor principal para las tres variedades fueron: altura desde el piso, ancho de la parte media de la última hoja completamente elongada y biomasa.

O objetivo principal deste trabalho foi mostrar uma aplicação da análise de componentes principais na redução da dimensionalidade de variáveis derivadas da avaliação agronômica de três variedades de capim azevém (Lolium sp. L), a saber, híbrido tetraplóide (Foster), anual diplóide(Southern Star) e anual tetraploide (BeefBuilder). Também se destacam as propriedades estatísticas e a programação no pacote estatístivo SAS. Resultados: como um resultado notável do processo de pesquisa foi observado que as variáveis que definiram o principal fator para as três variedades foram: altura do solo, a largura da parte meia da última folha totalmente alongada e a biomassa.

Initial diet composition affects weight gain and total length of Pacu (Piaractus brachypomus) larvae / La dieta usada en la primera alimentación afecta la ganancia de peso y longitud total de larvas de cachama blanca (Piaractus brachypomus) / Efeitos dos alimentos utilizados na primeira alimentação sobre ganho de peso e comprimento total em larvas de pirapitinga (Piaractus brachypomus)

Weigh gain, length, and survival of Pacu (Piaractus brachypomus) larvae were analyzed after they were fed one of four diets. At 36 hours post-hatching larvae were fed for the first time and during three consecutive days: Artemia salina nauplii (T1), wild plankton filtered to 200 microns (T2) , concentrated powder with 48% crude protein (T3) or no diet (fasting, T4). Animals were kept at a density of 70 larvae per liter. Statistically significant differences were observed with respect to the final weight for T1, T2, T3, and T4 (2.2 ± 0.3a, 1.7 ± 0.3b, 1.5 ± 0.3bc, 1.5 ± 0.2c mg, respectively) , final length (6.37 ± 0.29a, 0.20b ± 6.16, 5.95 ± 0.27c, 0.26c ± 5.87 mm, respectively), weight gain (0.77 ± 0.39a, 0.31b ± 0.34, 0.16 ± 0.37bc, 0.08 ± 0.21 c mg, respectively) and length gain (0.39 ± 0.17A, 0.18 ± 0.15b, 0.16c ± -0023, -0102 ± 0.15c mm, respectively). The T1 diet had the best results for optimal growth, followed by T2. The survival rate was not statistically different among treatments. These data suggest that the initial diet composition can affect subsequent growth characteristics of Pacu larvae.

Se evaluó la ganancia de peso, la longitud y la supervivencia de larvas de cachama blanca (Piaractus brachypomus) alimentadas con varias dietas. A las 36 horas post-eclosión las larvas se alimentaron por primera vez y durante tres días consecutivos con nauplios de Artemia salina (T1), plancton silvestre filtrado a 200 μm (T2), concentrado pulverizado con 48% de proteína bruta (T3), o ayuno (T4). Los animales se mantuvieron a una densidad de 70 larvas por litro. Se observaron diferencias estadísticas significativas (p<0.05) con respecto al peso final para los tratamientos T1, T2, T3, y T4 (2.2 ± 0.3a; 1.7 ± 0.3b; 1.5 ± 0.3bc; 1.5 ± 0.2c mg, respectivamente), longitud final (6.37 ± 0.29a; 6.16 ± 0.20b; 5.95 ± 0.27c; 5.87 ± 0.26c mm, respectivamente), ganancia de peso (0.77 ± 0.39a; 0.34 ± 0.31b; 0.16 ± 0.37bc; 0.08 ± 0.21c mg, respectivamente) y ganancia de longitud (0.39 ± 0.17a; 0.18 ± 0.15b; -0.023 ± 0.16c; -0.102 ± 0.15c mm, respectivamente). El T1 presentó los mejores resultados, seguido por T2. El porcentaje de sobrevivencia no tuvo diferencia estadística significativa entre tratamientos.

Foram utilizadas larvas de pirapitinga (Piaractus brachypomus) foram mantidas em densidade de 70 larvas/L. Por três dias consecutivos, as larvas eram alimentadas com náuplios de Artemia salina (T1), plâncton selvagem filtrado (200 μm) (T2), ração em pó com 48% de PB (T3) e o tratamento controle era mantido em jejum (T4). Os resultados mostraram diferença significativa (p <0.05) no peso final (2.2 ± 0.3 a; 1.7 ± 0.3 b; 1.5 ± 0.3 bc; 1.5 ± 0. 2c mg.), no comprimento final (6.37 ± 0.29 a; 6.16 ± 0.20 b; 5.95 ± 0.27 c; c 5.87 ± 0.26 mm.), no ganho de peso (0.77 ± Um 0.39 a; 0.34 ± 0.31 b; 0.16 ± 0.37 bc; c 0.08 ± 0.21c mg.) e no ganho de comprimento (0.39 ± 0.17 a; 0.18 ± 0.15 b; -0.023 ± 0.16 c; -0.102 ± 0.15c mm). Os tratamentos T1 e T2 mostraram os melhores resultados em relação aos parâmetros anteriormente citados. Contudo, nenhum tratamento mostrou diferença significativa na porcentagem de sobrevivência.

Osteoconductive and osseointegration properties of a commercial hydroxyapatite compared to a synthetic product / Comparación de las propiedades de osteoconducción y osteointegración de una hidroxiapatita reabsorbible comercial con una hidroxiapatita reabsorbible sintetizada / Comparação das propriedades da osteocondução e osteointegração de uma hidroxiapatita reabsorvivel comercial sintetizada

The effects of two types of hydroxylapatite on bone synthesis and properties were evaluated. An osteoconductive resorbable hydroxyapatite (OseoU), synthesized at two different temperatures of calcination (Type A and Type B) was compared with a commercial mixture of hydroxyapatite (Osteogen®), commonly used in several surgical procedures involving bone loss. The synthesis was performed in the laboratories of the University of Antioquia by precipitating a mixture of calcium nitrate and ammonium phosphate. The products obtained and the commercial hydroxyapatite were characterized by scanning electron microscopy (SEM), X- ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and energy dispersive spectroscopy (EDS). Osteoconductive and osseointegration characteristics were measured according to the products ability to induce local cell differentiation into bone forming cells. These characteristics were evaluated in hydroxyapatite implants performed in 70 New Zealand breed rabbits distributed into seven groups of 10 animals each, tested at 7, 14, 21, 28, 42, 60 and 90 days after the surgical procedure.

En el presente artículo se evalúan las propiedades de osteoconducción y osteointegración de una hidroxiapatita reabsorbible (OseoU), procesada a dos temperaturas diferentes de calcinación (Tipo A y Tipo B), con el propósito de compararlas con un preparado comercial de hidroxiapatita (Osteogen®), utilizado para múltiples procedimientos quirúrgicos en los cuales se involucra la pérdida de tejido óseo. La síntesis se realizó en los laboratorios de la Universidad de Antioquia por el método de precipitación acuosa de la mezcla de nitrato de calcio y de fosfato de amonio. Los productos obtenidos y la hidroxiapatita comercial fueron caracterizados por microscopia electrónica de barrido (SEM), difracción de rayos X (DRX), espectroscopia de infrarrojo transformada de Fourier (FTIR) y espectrometría por energía dispersiva (EDS). Las características de osteoconducción y osteointegración fueron medidas de acuerdo a la capacidad de los productos para inducir la diferenciación de células locales a células formadoras de hueso. Dichas características, se evaluaron en implantes de hidroxiapatita realizados en 70 conejos de la raza Nueva Zelanda distribuidos en siete grupos de 10 animales cada uno, evaluados a los 7, 14, 21, 28, 42, 60 y 90 días de efectuado el procedimiento quirúrgico. Los resultados obtenidos demostraron que el OseoU y el Osteogen®, presentaron características similares en cuanto a la estructura cristalina, la composición química y la adsorción, con apreciables diferencias morfológicas con respecto a la forma de las partículas. Al realizar el análisis de varianza no se encontraron diferencias estadísticas significativas para las variables histopatológicas evaluadas en las dos hidroxiapatitas (p>0.05), indicando que las hidroxiapatitas sintetizadas en la Universidad de Antioquia (OseoU) tuvieron el mismo resultado que la hidroxiapatita comercial (Osteogen®) en la osteoconducción y la osteointegración del tejido óseo.

No presente estudo foram avaliadas as propriedades de ostecondução e osteointegração de uma hidroxiapatita reabsorvivel (OseoU), processada a duas temperaturas de calcinaçao (Tipo A e B), com o propósito de serem comparadas com um produto comercial (Osteogen®), utilizado para múltiples procedimentos cirúrgicos nos quais se envolve a perda do tecido osso. Asíntese foi realizada nos laboratorios da Universidad de Antioquia pelo método de precipitação aquosa da mistura de nitrato de cálcio e fosfato de amônio. Os produtos obtidos e a hidroxiapatita comercial foram caracterizados por microscopia eletrônica de barrido (SEM), difração raios X (DRX), espectroscopia de infravermelho transformada de Fourier (FTIR) e espectrometria por energia dispersiva (EDS). As características de osteocondução e osteointegração foram mensuradas de acordo à capacidade dos produtos para induzir a diferenciação das células locais formadoras do osso. Estas características foram avaliadas em implantações de hidroxiapatita realizadas em 70 coelhos da raça Nova Zelândia distribuídos em sete grupos de 10 animais cada um, avaliados aos 7, 14, 21, 28, 42, 60 e 90 dias de efetuado o procedimento cirúrgico. Os resultados obtidos demonstraram que o OseoU e o Osteogen® apresentaram características similares em quanto à estrutura cristalina, a comparação química e à absorção, com apreciáveis diferenças morfológicas com respeito à forma das partículas. Ao realizar as análises de variâncias não foram encontradas diferencias estatísticas significativas para as variáveis histopatológicas avaliadas nas duas hidroxiapatitas (p>0.05), indicando que as hidroxiapatitas sintetizadas na Universidad de Antioquia (OseoU) tiveram o mesmo resultado que a hidroxiapatita comercial (Osteogen®) em osteocondução e osteointegração do tecido ósseo.

Efectos en el tracto reproductivo, digestivo y pérdida de pesocorporal del ave semipesada sometida a descanso ovárico / Efeitos no trato reprodutivo, digestivo e perda do peso de aves semi-pesadossubmetidas a descanso ovárico / The effects on the reproductive and digestive tract and loss of body weight of the Brown egg layers submitted to ovarian rest

Esta investigación evaluó la aplicación del descanso ovárico (DO) en aves semipesadas y el efecto quetienen la edad y la duración del ayuno sobre el tracto reproductivo y gastrointestinal. Se utilizaron 840ponedoras de la línea Hy-Line Brown® con 64 semanas de edad, se evaluaron tres edades de inducciónal DO (65, 70 y 75 semanas) y tres períodos de ayuno (cinco, diez y quince días), en un modelo estadísticocompletamente aleatorizado, anidado, efecto fijo y balanceado. Se sacrificaron aves para evaluar el pesocorporal, peso del tracto digestivo, peso del tracto reproductivo (ovario y oviducto), porcentaje de folículoscon diámetro igual o superior a diez mm (LYF) y el porcentaje de pérdida de peso del ave. El modelo fuesignificativo (p<0.05) para todas las variables evaluadas; la edad presentó efecto significativo (p<0.05) enel peso del ovario y el porcentaje de folículos (LYF), mientras que la duración del ayuno anidado en laedad presentó efecto significativo (p<0.05) en todas las variables, lo que indica un mayor efecto del períodode ayuno en contraste con la edad de aplicación del DO sobre las variables evaluadas. El peso del ovario(edad 65:15.87 ±15.11; edad 70: 7.92 ± 5.46; y edad 75: 7.54 ± 4.96) y porcentaje de folículos (LYF) (edad65: 43.75 ± 21.54; la edad 70 18.05 ± 8.72 y edad 75: 8.33 ± 6.85), mostraron tendencia en la disminucióna medida que aumenta la edad, comportamiento que está asociado con la disminución gradual del númerode folículos y la ampliación del tiempo entre la maduración de una onda folicular y la siguiente normaldel ave a medida que envejece (Kim y Donalson, 2000; North y Bell, 1990). Los porcentajes de pérdida de peso (edad 65: 24.24 ± 8.53%; edad 70: 20.91 ± 5.50% y edad 75: 20.88 ± 7.15%), fueron menores encomparación con los reportes en líneas livianas, posiblemente debido al contenido de reservas lipídicas,lo que ofrece al ave semipesada la capacidad de tolerar el ayuno.

The effects on the reproductive and digestive tract and loss of body weight of the Brown egg layerssubmitted to ovarian rest. This research evaluated the application of the ovarian rest (OR) on brown egglayers and the effect the age and duration of feed withdrawal have over the reproductive and gastrointestinaltract. 840 Hy-Line Brown ® layers were used at 64 weeks of age in which three ages of induction to theOR (65.70 and 75 weeks) and three feed withdrawal periods (five, ten and fifteen days) in a completelyrandomized statistical model, nested, of balanced and fixed effect. Sacrifices were carried out in order toevaluate body weight, weight of the digestive and reproductive tract (ovary and oviduct), follicle percentagewith a diameter equal to or higher than ten mm (LYF) and the percentage of the bird’s weight loss. Themodel was significant (p<0.05) for all the variables evaluated; the age presented a significant effect(p<0.05) over the ovary weight and the follicle percentage (LYF), while the duration of the feed withdrawalrelated to the age had a significant effect (p<0.05) on all the variables, which indicates a greater effect ofthe feed withdrawal period contrasted to the age of the application of the OR upon the variables evaluated.The ovary’s weight (age 65:15.87 to ± 15.11; age 70: 7.92b ± 5.46; and age 75: 7.54b ± 4.96) and thefollicle percentage (65: 43.75 to ± 21.54; age 70 18.05b ± 8.72 and age 75: 8.33b ± 6.85) showed a loweringtendency as the age increased. This type of behavior is associated with the gradual decrease in the numberof follicles and the extended time between the maturation of one follicular wave and the next as the layerages (Kim, Donalson, 2006; North, Bell, 1990). The weight loss percentages (age 65: 24.24 ± 8.53%; age70: 20.91 ± 5.50% and age 75: 20.88 ± 7.15%) were low compared to the reports on white egg layers,possibly due to the content of lipidic reserves which offers the brown egg...

Foi avaliado o descanso ovárico (DO) em galinhas semipesadas e o efeito da idade e a duração do jejumsobre o trato reprodutivo e gastrointestinal. Foram utilizadas 840 galinhas poedoras da linha Hy-LineBrown® com 64 semanas de idade, foram avaliadas três idades de indução ao DO (65, 70 e 75 semanas) etrês períodos de jejum (cinco, dez e quinze dias), utilizando um modelo desenho completamente aleatório,aninhado , efeito fixo e balanceado. As aves foram sacrificadas para avaliar o peso corporal, peso do tratodigestivo, peso do trato reprodutivo (ovário e oviduto), porcentagem de folículos com diâmetro igual ousuperior a dez mm (LYF) e a porcentagem da perdida de peso da ave. O modelo foi significativo (p<0.05)para todas as variáveis avaliadas; a idade foi significativa (p<0.05) no peso do ovário e a LYF e a duraçãodo jejum aninhado na idade apresentou efeito significativo (p<0.05) em todas as variáveis, o que indicouum maior efeito do período de jejum do que a idade sobre as variáveis avaliadas. O peso do ovário (idade65:15.87 ±15.11; idade 70: 7.92 ± 5.46; e idade 75: 7.54 ± 4.96) e percentagem de folículos (idade 65: 43.75± 21.54; idade: 70: 18.05 ± 8.72 e idade 75: 8.33 ± 6.85), mostraram tendência na diminuição à medidaque aumenta a idade. As percentagens de perda de peso (idade 65: 24.24 ± 8.53%; idade 70: 20.91 ± 5.50%e idade 75: 20.88 ± 7.15%) e as três idades apresentaram uma relação direta entre a duração dos períodosde jejum e o efeito na atrofia reprodutiva e perda de peso, permitindo determinar que não é necessáriosubmeter a jejuns superiores a dez dias.