Chemical Constituents from Agave applanata and Its Antihyperglycemic, Anti-inflammatory, and Antimicrobial Activities Associated with Its Tissue Repair Capability.

Agave applanata is a Mexican agave whose fresh leaves are employed to prepare an ethanol tonic used to relieve diabetes. It is also applied to skin to relieve varicose and diabetic foot ulcers, including wounds, inflammation, and infections. In this study, the chemical composition of this ethanol tonic is established and its association with antihyperglycemic, anti-inflammatory, antimicrobial, and wound healing activities is discussed. The fresh leaves of A. applanata were extracted with ethanol : H2O (85 : 15). A fraction of this extract was lyophilized, and the remainder was partitioned into CH2Cl2, n-BuOH, and water. CH2Cl2 and n-BuOH fractions were subjected to a successive open column chromatography process. The structure of the isolated compounds was established using nuclear magnetic resonance and mass spectrometry spectra. The antihyperglycemic activity was evaluated through in vivo sucrose and glucose tolerance experiments, as well as ex vivo intestinal absorption and hepatic production of glucose. Wound healing and edema inhibition were assayed in mice. The minimum inhibitory concentrations (MICs) of the hydroalcoholic extract, its fractions, and pure compounds were determined through agar microdilution against the most isolated pathogens from diabetic foot ulcers. Fatty acids, ß-sitosterol, stigmasterol, hecogenin (1: ), N-oleyl-D-glucosamine, ß-daucosterol, sucrose, myo-inositol, and hecogenin-3-O-α-L-rhamnopyranosyl-(1 → 3)-ß-D-xylopyranosyl-(1 → 2)-[ß-D-xylopyranosyl-(1 → 3)-ß-D-glucopyranosyl-(1 → 3)]-ß-D-glucopyranosyl-(1 → 4)-ß-D-galactopyranoside (2: ) were characterized. This research provides evidence for the pharmacological importance of A. applanata in maintaining normoglycemia, showing anti-inflammatory activity and antimicrobial effects against the microorganisms frequently found in diabetic foot ulcers. This plant plays an important role in wound healing and accelerated tissue reparation.

Pharmacological Analysis of the Anti-inflammatory and Antiallodynic Effects of Zinagrandinolide E from Zinnia grandiflora in Mice.

Zinagrandinolide E (1, ZGE) is an elemanolide with antinociceptive action isolated from Zinnia grandiflora (Asteraceae), valued in North México and southwestern United States for pain relief. Herein, we report the anti-inflammatory and antiallodynic action of ZGE (1) in carrageenan-induced inflammation and tactile allodynia in mice and in a neuropathic pain model in hyperglycemic mice. Local peripheral administration of ZGE (1-30 µg/paw) induced dose-dependent acute anti-inflammatory and antiallodynic effects. The anti-inflammatory effect was comparable to diclofenac (30 µg/paw). Intrathecal (i.t.) administration of ZGE (30 µg) in acute experiments did not affect carrageenan-induced inflammation but significantly reduced tactile allodynia in a dose-dependent fashion. In long-term experiments (15 or 6 days), using two different scheme treatments (pretreatment or post-treatment), ZGE (3-30 µg/paw) showed antiallodynic but not anti-inflammatory action. Local peripheral (3-30 µg/paw) or intrathecal (3-30 µg) administration of ZGE partially reversed tactile allodynia in hyperglycemic mice, better or comparable, respectively, with those of pregabalin (30 µg/paw or 30 µg i.t.). The effects were dose-dependent. According to the pharmacological tools employed, the anti-inflammatory and antiallodynic activities of ZGE are multitarget; these involve the opioidergic, serotoninergic, and GABAergic systems, as well as the NO-cGMP-ATP-sensitive K+ channel signaling pathway.

Sigma-1 receptor antagonist (BD-1063) potentiates the antinociceptive effect of quercetin in neuropathic pain induced by chronic constriction injury.

Neuropathic pain is characterized by the presence of hyperalgesia and allodynia. Pharmacological treatments include the use of antiepileptics such as pregabalin or gabapentin, as well as antidepressants; however, given the role of the sigma-1 receptor in the generation and maintenance of pain, it has been suggested that sigma-1 receptor antagonists may be effective. There are also other alternatives that have been explored, such as the use of flavonoids such as quercetin. Due to the relevance of drug combinations in therapeutics, the objective of this work was to evaluate the effect of the combination of BD-1063 with quercetin in a chronic sciatic nerve constriction model using the "Surface of Synergistic Interaction" analysis method. The combination had preferable additive or synergistic effects, with BD-1063 (17.8 mg/kg) + QUER (5.6 mg/kg) showing the best antinociceptive effects. The required doses were also lower than those used individually to obtain the same level of effect. Our results provide the first evidence that the combination of a sigma-1 receptor antagonist and the flavonoid quercetin may be useful in the treatment of nociceptive behaviors associated with neuropathic pain, suggesting a new therapeutic alternative for this type of pain.

Affinin and hexahydroaffinin: Chemistry and toxicological profile.

The present work aimed to determine the safety parameters of two new alkamides, affinin and hexahydroaffinin, with antinociceptive activity. To predict the preliminary acute toxicity, we used the acute and subchronic toxicity (50 mg/kg, orally [po]) in Swiss Webster mice. Genotoxicity assayed via analysis of cell micronuclei of the femoral bone marrow in mice; at the same time, metabolic parameters determined from peripheral blood samples. Furthermore, to discard the neuropharmacological effects, we assessed the ambulatory activity in mice to determine the possible effects in the central nervous system. Finally, we used capsaicin as a positive control of alkamides. According to our results, hexahydroaffinin (LD50 ≥ 5,000 mg/kg, po) is significantly less noxious than affinin (LD50 = 1,442.2 mg/kg, po) or capsaicin (LD50 = 489.9 mg/kg, po). In subchronic administration, we did not observe any changes in hematological or biochemical parameters in any compound analyzed from peripheral blood samples. Finally, the data from the genotoxicity assay showed micronuclei formation in 28%, 5%, and 3% of mice in the capsaicin, affinin, and hexahydroaffinin groups, respectively. With the results obtained in the present investigation, we suggest that affinin and hexahydroaffinin are not only useful candidates for possible new drugs but also safe compounds.

Antinociceptive Potential of Zinnia grandiflora.

An aqueous extract prepared from the aerial parts of Zinnia grandiflora was found not to induce acute toxicity (LD50> 5g/kg, p.o.) in mice when tested by the Lorke method. This extract showed notable antinociceptive and anti-inflammatory actions when evaluated by the formalin- (ED50 = 224.62 ± 38.17 mg/kg, p.o.) and the carrageenan-induced paw edema models in mice, respectively. The organic-soluble fractions obtained by partitioning the infusion with CH2Cl2 and EtOAc were also active in the formalin test. The most important antinociceptive effect was observed with the CH2Cl2 fraction; extensive fractionation of the latter yielded three new elemanolides, namely, zinagranolides D-F (1-3), which were characterized structurally by spectroscopic means. The structure of compound 2 was established unequivocally by an X-ray crystallographic analysis. This compound exerted a significant antinociceptive effect in the formalin assay, better than that of diclofenac used as a positive control.

Antinociceptive and Antihyperalgesic Activity of a Traditional Maya Herbal Preparation Composed of Pouteria Campechiana, Chrysophyllum Cainito, Citrus Limonum, and Annona Muricata.

Preclinical Research The purpose of this work was to assess the antinociceptive and antihyperalgesic properties of an herbal preparation, composed of four vegetal species: Pouteria campechiana (P. campechiana), Chrysophyllum cainito (C. cainito), Citrus limonum (C. limonum), and Annona muricata (A. muricata), that is commonly used in combination (PCCA) in traditional Mayan medicine for the treatment of diabetes and pain. An ethanolic extract of PCCA was prepared at a ratio of 1:1:1:1 for each plant. The systemic antinociceptive effect of PCCA extract (50-600 mg/kg, p.o.) was dose-dependent in the rat formalin (1%) producing 66% antinociceptive response at 400 mg/kg, p.o. A concentration-dependent antinociceptive effect of the PCCA extract (20-160 mg/paw) was also demonstrated in the rat capsaicin (0.2%) test. The PCCA extract (100-400 mg/kg, p.o.) had antihyperalgesic effects in alloxan diabetic rats. These findings demonstrate the antinociceptive and antihyperalgesic effects of PCCA and supports the use of the plant extracts in Mayan folk medicine. Drug Dev Res 78 : 91-97, 2017. © 2017 Wiley Periodicals, Inc.

The Effect of Gabapentin and Tramadol in Cancer Pain Induced by Glioma Cell in Rat Femur.

Preclinical Research The presence of pain as part of the cancer process is variable. Glioblastoma multiform (GBM) can produce bone metastasis, a condition that involves other pathological phenotypes including neuropathic and inflammatory pain. Tramadol and gabapentin are drugs used in the treatment of neuropathic pain. However, there are no studies evaluating their analgesic effects in bone metastasis. We produced a pain model induced by the inoculation of glioma cells (105 ) into the rat femur, by perforating the intercodiloid fossa. Painful behavior was evaluated by measuring mechanical allodynia using the Von Frey test while thermal hyperalgesia was assessed in the plantar test. Histopathological features were evaluated and antinociceptive responses were compared using tramadol and gabapentin. The inoculation of cells inside the right femur produced nociceptive behaviors. Tramadol and gabapentin produced an anti-allodynic effect in this condition, but tramadol did not produce an anti-hyperalgesic response. The development of this model will allow us to perform tests to elucidate the pathology of bone metastasis, cancer pain, and in particular the pain produced by glioma. Drug Dev Res 78 : 173-183, 2017. © 2017 Wiley Periodicals, Inc.

Antihyperalgesic Activity of Rhodiola rosea in a Diabetic Rat Model.

Preclinical Research Rhodiola rosea L. (Crassulaceae) is used for enhancing physical and mental performance. Recent studies demonstrated that R. rosea had anti-inflammatory activity in animal models, for example, carrageenan- and nystatin-induced edema in rats, possibly by inhibiting phospholipase A2 and cyclooxygenases-1 and -2. In addition, R. rosea had antinociceptive activity in thermal and chemical pain tests as well as mechanical hyperalgesia. The purpose of the present study was to assess the antihyperalgesic effect of an ethanol extract of Rhodiola rosea (R. rosea) in a diabetic rat model. Rats were administered a single dose of streptozotocin (STZ; 50 mg/kg, i.p.) and hyperalgesia was evaluated four weeks later. Formalin-evoked (0.5%) flinching was increased in diabetic rats compared with nondiabetic controls Systemic (1-100 mg/kg, i.p.) and local (0.1-10 mg/paw into the dorsal surface of the right hind paw) administration of R. rosea ethanol extract dose-dependently reduced formalin-induced hyperalgesia in diabetic rats. The antihyperalgesic effect of R. rosea was compared with gabapentin. These results suggest that R. rosea ethanol extract may have potential as a treatment for diabetic hyperalgesia.

The Antinociceptive Effects of Tramadol and/or Gabapentin on Rat Neuropathic Pain Induced by a Chronic Constriction Injury.

Preclinical Research The current work evaluates the interaction between two commonly used drugs, tramadol (Tra) and gabapentin (Gbp). Dose-response curves (DRC) and isobolographic analysis were used to confirm their synergistic antihyperalgesic and anti-allodynic responses in a rat neuropathic pain model involving chronic constriction injury of the sciatic nerve and in von Frey and acetone tests. Tra and Gbp produced dose-dependent antihyperalgesic and anti-allodynic effects. Dose-response studies of combinations of Tra and Gbp in combination showed the DRC was leftward-shifted compared to the DRCs for each compound alone. One combination demonstrated both antihyperalgesic and anti-allodynic effects greater than those observed after individual administration. The remaining combinations demonstrated an additive effect. The Tra+Gbp combination demonstrated a potentiative effect with smaller doses of Tra. Additionally, it was determined lethal dose 50 (LD50 ) of Tra alone and tramadol + Gbp 10 using mice to 48 h post administration. The DRC (death) were similar for Tra alone and in Tra in combination, despite the improved effectiveness of Tra in the presence of GBP, 10 mg/kg. A combination of these drugs could be effective in neuropathic pain therapy because they can produce potentiative (at a low dose) or additive effects. Drug Dev Res 77 : 217-226, 2016. © 2016 Wiley Periodicals, Inc.

[Proposal for early detection of ethanol consumption in students of the Universidad Autónoma del Estado de Morelos]. / Propuesta para la detección temprana del consumo de etanol en estudiantes de la Universidad Autónoma del Estado de Morelos.

The present study determined through analytic techniques the quantification of some biomarkers that have been useful to detect early ethanol consumption in a college population. A group of 117 students of recent entry to the Universidad Autónoma del Estado de Morelos was analyzed. The enzyme determination of aspartate aminotransferase, alanine aminotransferase, and gamma glutamyltransferase as metabolic markers of ethanol, as well as the carbohydrate-deficient transferrin (CDT) detected by high chromatographic liquid (up to 1.8% of CDT), allowed us to identify that 6% of the college population presented a potential risk of alcohol consumption. The use of the biochemical-analytical method overall with the psychological drug and a risk factor instrument established by the Universidad Autónoma del Estado de Morelos permit us to identify students whose substance abuse consumption puts their terminal efficiency at risk as well as their academic level. The timely detection on admission to college can monitor and support a student consumer's substance abuse.

Enhancement of Antihyperalgesia by the Coadministration of N-palmitoylethanolamide and Acetaminophen in Diabetic Rats.

Preclinical Research The objective of this study was to evaluate the pharmacological antihyperalgesic interaction between N-palmitoylethanolamide (PEA) and acetaminophen in diabetic rats using the formalin paw test. Streptozotocin (STZ)-induced diabetic rats received subcutaneous injections in the paw of PEA alone (1-100 µg/paw) or acetaminophen alone (3-300 µg/paw) 15 min before formalin (0.5%) injection. The results revealed concentration-dependent responses produced by PEA (EC50 = 7.19 ± 0.7 µg/paw) and acetaminophen (EC50 = 57.9 ± 1.9 µg/paw). Isobolographic analysis was used to evaluate the pharmacological interaction between the PEA + acetaminophen using the EC50 value and a fixed 1:1 ratio combination. The isobologram demonstrated that the combination investigated in this study produced a synergistic interaction; the experimental value (EC50 = 23.64 ± 1.9 µg/paw) was significantly smaller than those that resulted from theoretical calculations (EC50 = 32.56 µg/paw). These results provide evidence that PEA in combination with acetaminophen could be useful for pain therapy in neuropathic diabetic patients.

Isobolographic analysis of the antinociceptive interaction between ursolic acid and diclofenac or tramadol in mice.

It is considered that natural products used in folk medicine can potentiate the effect of drugs. The aim of this study was to evaluate the pharmacological interaction between ursolic acid, a triterpene isolated from herbal medicines to treat pain, and the analgesics diclofenac or tramadol. Individual dose-response curves of the antinociceptive effect of these compounds were built to calculate the ED50, as well as the pharmacological interaction, by using isobolographic analysis. All treatments decreased significantly and in a dose-dependent manner the writhing behavior with ED50 values of 103.50 ± 19.66, 20.54 ± 6.05, and 9.60 ± 1.69 mg/kg, for ursolic acid, diclofenac, and tramadol, respectively. An isobolographic analysis allowed the characterization of the pharmacological interaction produced by a fixed ratio combination of 1 : 1 and 1 : 3 of equi-effective doses of these compounds. Theoretical antinociceptive ED50 values of ursolic acid-diclofenac were 62.12 ± 10.28 and 41.43 ± 6.69 mg/kg, respectively, not statistically different from those obtained experimentally (44.52 ± 5.25 and 44.89 ± 49.05 mg/kg, respectively), reporting an additive interaction. Theoretical antinociceptive ED50 values of ursolic acid-tramadol (56.56 ± 9.87 and 33.08 ± 5.07 mg/kg, respectively) were significantly lower than those observed experimentally (138.36 ± 49.05 and 67.34 ± 18.98 mg/kg, respectively) reporting antagonism in this interaction. Antinociceptive response obtained from isobolograms in the writhing test was corroborated by using formalin test in mice. Adverse effects such as gastric damage in the ursolic acid-diclofenac combination did not increase in an additive form similarly as with antinociception. Conversely, sedative response was significantly increased in the ursolic acid-tramadol combination. As observed in the formalin test, the antagonism on the antinociceptive response between ursolic acid and tramadol (1 : 1) was not reverted in the presence of the opioid antagonist naltrexone (1 mg/kg, i. p.). These results provide evidence for a differential pharmacological interaction, in which ursolic acid does not interfere with the antinociceptive effect of diclofenac but antagonizes that obtained with tramadol in an independent opioid mechanism. Therefore, medicinal plants containing abundant presence of ursolic acid may also modify efficacy in the alternative combinations for the pain therapy.

Coadministration of tramadol and tizanidine in an experimental acute pain model in rat.

Preclinical Research The use of drug combinations to achieve a desired effect is a common practice in pharmacological reaserch and in clinical practice. The present study was designed to evaluate the potential synergistic antinociceptive interactions between tizanidine, an α-2-adrenoceptor agonist and tramadol on formalin-induced nociception in rat using isobolographic analyses. Tramadol (0.1-100 µg/paw) and tizanidine (0.01-10 µg/paw) were injected into the paw prior to formalin injection (1%). Both drugs produced a dose-dependent antinociceptive effect. The EC50 values were estimated for individual drugs, and isobolograms were constructed. Tizanidine (EC50 = 0.125 ± 0.026 µg) was more potent than tramadol (EC50 = 16.45 ± 6.4 µg). The combination of tramadol-tizanidine at fixed ratios of 1:1 (EC50exp = 67.43 ± 11 µg; EC50teo = 8.28 ± 3.2 µg) and 3:1 (EC50exp = 31.25 ± 9.49 µg; CE50teo = 12.36 ± 4.8 µg) generated subadditivity (antagonism). On the basis of the current preclinical data, the pharmacological profile of the combination of tramadol-tizanidine produced antagonism. Thus, the utmost caution is required during the use of this combination in clinical practice, due to their antagonistic interaction.

Antinociceptive effect of LMH-2, a new sigma-1 receptor antagonist analog of haloperidol, on the neuropathic pain of diabetic mice.

This study evaluates the antiallodynic and antihyperalgesic effects of LMH-2, a new haloperidol (HAL) analog that acts as sigma-1 receptor (σ1 R) antagonist, in diabetic mice using a model of neuropathic pain induced by chronic hyperglycemia. Additionally, we compared its effects with those of HAL. Hyperglycemia was induced in mice by nicotinamide-streptozotocin administration (NA-STZ, 50-130 mg/kg). Four weeks later, mechanical allodynia was assessed using the up-down method, and hyperalgesia was evoked with formalin 0.5%. We evaluated antiallodynic and antihyperalgesic effects of LMH-2 (5.6-56.2 mg/kg), HAL (0.018-0.18 mg/kg) and gabapentin (GBP, 5.6-56.2 mg/kg). The results showed that LMH-2 had a more significant antiallodynic effect compared to HAL and GBP (90.4±8.7 vs 75.1±3.1 and 41.9±2.3%, respectively; P<0.05), as well as an antihyperalgesic effect (96.3±1.2 vs 86.9±7.41 and 86.9±4.8%, respectively; P<0.05). Moreover, the antiallodynic and antihyperalgesic effect of both LMH-2 and HAL were completely abolished by PRE-084 (σ1 R agonist); and partially by pramipexole (a D2-like receptor agonist). Finally, the effect of all treatments on the rotarod test, barra, open field and exploratory behaviors showed that LMH-2 did not alter the animals' balance or the exploratory behavior, unlike as HAL or GBP. The molecular docking included indicate that LMH-2 has lower affinity to the D2R than HAL. These results provide evidence that LMH-2 exerts its antinociceptive effects as a σ1 R antagonist without the adverse effects induced by HAL or GBP. Consequently, LMH-2 can be considered a good and safe strategy for treating neuropathic pain caused by hyperglycemia in patients with diabetes.

Neuroprotective evaluation of Tilia americana and Annona diversifolia in the neuronal damage induced by intestinal ischemia.

Tilia americana and Annona diversifolia are plants widely distributed in Mexico and sold in markets for their medicinal properties on the central nervous system (CNS) including possible neuroprotection. Pharmacological studies have corroborated CNS activities due to flavonoid constituents, but evidence of their neuroprotector effects are lacking. This study was conducted to test aqueous and organic extracts of these two plants for neuroprotective effects in a novel experimental model of intestinal ischemia in situ. T. americana and A. diversifolia aqueous and organic extracts were administrated to guinea pigs at an oral dose of 100 and 300 mg/kg for 15 days. Twenty four hours after the last administration, the animals were anesthetized and intestinal ischemia in situ was induced by clamping for 80 min selected branches of the superior mesenteric artery. Ischemic segments placed in an in vitro organ bath were stimulated electrically (0.3 Hz frequency, 3.0 ms duration, 14 V intensity) and chemically (ACh; 1 × 10(-9) to 1×10(-5) M). Neuroprotection was considered present when the depressed contractile response of the ischemic tissue to electrical stimulation was normalized in the treated animals. Results showed that pretreatment with the T. americana hexane and aqueous extracts, but not with those from A. diversifolia, significantly improved responses of the ischemic tissue. These results suggest that T. americana possesses neuroprotective effects against neuronal damage induced by ischemia, and that flavonoids as well as non-polar constituents are involved. Our study supports the use of this plant in folk medicine and suggests its possible effectiveness for stroke prevention.

Antimutagenic properties of affinin isolated from Heliopsis longipes extract.

CONTEXT: Heliopsis longipes (A. Gray) Blake (Asteraceae), commonly known in Mexico as "chilcuage" or "chilcuan", is widely used as an analgesic and anesthetic agent. Affinin, the major metabolite of this plant, and the ethanol extract of the plant have shown antinociceptive properties in mice. H. longipes plant produces a complex mixture of antioxidant chlorophylls and polyamines as well as a number of possible antimutagens. OBJECTIVE: The current study evaluated the potential utilization of the natural product affinin isolated from H. longipes ethanol extract as an antimutagenic and possibly anticarcinogenic agent. MATERIALS AND METHODS: The Ames assay was used to assess the mutagenic properties of affinin (12.5, 25 and 50 µg/plate) that was added to several mutagens with or without S9 metabolic activation in Salmonella typhimurium (TA98, TA100 and TA102 strains). RESULTS: Heliopsis longipes extract and affinin were not toxic as a reduction in the number of His⁺ revertant bacteria colonies. Affinin (25 and 50 µg/plate) significantly reduced the frameshift mutations that were generated by 2-aminoanthracene (2AA) (40%) and reduced the oxidative DNA damage generated by norfloxacin (NOR) (37-50%). Affinin possessed antioxidant properties that were able to reduce 2AA- and NOR-induced mutations in S. typhimurium TA98 and TA102, respectively. DISCUSSION AND CONCLUSION: Affinin, the principal metabolite of H. longipes, is not mutagenic and possesses antimutagenic activity. These plants are currently used to treat some pain symptoms in Mexico; and antimutagen activity determined could be important to treat some pain symptoms related to antiradical activity.

Spinal dopaminergic D1 and D5 receptors contribute to reserpine-induced fibromyalgia-like pain in rats.

Fibromyalgia is a complex pain syndrome without a precise etiology. Reduced monoamines levels in serum and cerebrospinal fluid in fibromyalgia patients has been reported and could lead to a dysfunction of descending pain modulatory system producing the painful syndrome. This study evaluated the role of D1-like dopamine receptors in the reserpine-induced fibromyalgia-like pain model in female Wistar rats. Reserpine-treated animals were intrathecally injected with different dopamine receptors agonists and antagonists, and small interfering RNAs (siRNAs) against D1 and D5 receptor subtypes. Withdrawal and muscle pressure thresholds were assessed with von Frey filaments and the Randall-Selitto test, respectively. Expression of D1-like receptors in lumbar spinal cord and dorsal root ganglion was determined using real time polymerase chain reaction (qPCR). Reserpine induced tactile allodynia and muscle hyperalgesia. Intrathecal dopamine and D1-like receptor agonist SKF-38393 induced nociceptive hypersensitivity in naïve rats, whilst this effect was prevented by the D1-like receptor antagonist SCH-23390. Moreover, SCH-23390 induced a sex-dependent antiallodynic effect in reserpine-treated rats. Furthermore, transient silencing of D1 and D5 receptors significantly reduced reserpine-induced hypersensitivity in female rats. Reserpine slightly increased mRNA D5 receptor expression in dorsal spinal cord, but not in DRG. This work provides new insights about the involvement of the spinal dopaminergic D1/D5 receptors in reserpine-induced hypersensitivity in rats.

N-palmitoylethanolamide synergizes the antinociception of morphine and gabapentin in the formalin test in mice.

OBJECTIVE: The antinociceptive pharmacological interaction between N-palmitoylethanolamide (PEA) and morphine (MOR), as well as gabapentin (GBP), was investigated to obtain synergistic antinociception at doses where side effects were minimal. In addition, the possible antinociceptive mechanism of PEA + MOR or PEA + GBP combinations was explored. METHODS: Individual dose-response curves (DRCs) of PEA, MOR and GBP were evaluated in female mice in which intraplantar nociception was induced with 2% formalin. Isobolographic method was used to detect the pharmacological interaction in the combination of PEA + MOR or PEA + GBP. KEY FINDINGS: The ED50 was calculated from the DRC; the order of potency was MOR > PEA > GBP. The isobolographic analysis was obtained at a 1:1 ratio to determine the pharmacological interaction. The experimental values of flinching (PEA + MOR, Zexp = 2.72 ± 0.2 µg/paw and PEA + GBP Zexp = 2.77 ± 0.19 µg/paw) were significantly lower than those calculated theoretically (PEA + MOR Zadd = 7.78 ± 1.07 and PEA + GBP Zadd = 24.05 ± 1.91 µg/paw), resulting in synergistic antinociception. Pretreatment with GW6471 and naloxone demonstrated that peroxisome proliferator-activated receptor alpha (PPARα) and opioid receptors are involved in both interactions. CONCLUSIONS: These results suggest that MOR and GBP synergistically enhance PEA-induced antinociception through PPARα and opioid receptor mechanisms. Furthermore, the results suggest that combinations containing PEA with MOR or GBP could be of interest in aiding the treatment of inflammatory pain.

Phytochemical study and anti-inflammatory, antidiabetic and free radical scavenger evaluations of Krameria pauciflora methanol extract.

The plant Krameria pauciflora MOC et. Sessé ex DC. is used as an anti-inflammatory and antidiabetic in traditional medicine. The aim of this study was to evaluate the in vivo anti-inflammatory and antidiabetic effects of a methanol extract from the roots of K. pauciflora. Dichloromethane and ethyl acetate extracts obtained by partitioning the methanol extract were also evaluated. Complete methanol and dichloromethane extracts showed anti-inflammatory effects at 3 mg/kg. An anti-inflammatory effect similar to indomethacin (10 mg/kg) was observed when the methanol and dichloromethane extracts, which contain a cycloartane-type triterpene and an sterol, were administered orally at several doses (3, 10, 30 and 100 mg/kg), whereas no anti-inflammatory effect was observed at any dose for the ethyl acetate extract, which contains catechin-type flavonoids. The antidiabetic effect of each extract was also determined. An antihyperglycaemic effect was observed in diabetic rats, but no effect in normoglycaemic animals was observed when the methanol extract was administrated at 30 mg/kg. All of the extracts exhibited radical scavenger activity. Additionally, constituents from all of the extracts were identified by NMR. This article supports the use of K. pauciflora as an anti-inflammatory because it exhibits a similar effect to indomethacin. However, its antidiabetic effect is not completely clear, although it could be useful for preventing diabetic complications.

Synergistic interaction between haloperidol and gabapentin in a model of neuropathic nociception in rat.

Preclinical studies have reported that sigma-1 receptor antagonists may have efficacy in neuropathic pain states. The sigma-1 receptor is a unique ligand-operated chaperone present in crucial areas for pain control, in both the peripheral and central nervous system. This study assesses the synergistic antihyperalgesic and antiallodynic effect of haloperidol, a sigma-1 antagonist, combined with gabapentin in rats with peripheral neuropathy. Wistar rats male were subjected to chronic constriction injury (CCI) of the sciatic nerve. The effects of systemic administration of gabapentin and the sigma-1 receptor antagonist, haloperidol, were examined at 11 days post-CCI surgery. An analysis of Surface of Synergistic Interaction was used to determine whether the combination's effects were synergistic. Twelve combinations showed various degrees of interaction in the antihyperalgesic and antiallodynic effects. In hyperalgesia, three combinations showed additive effects, four combinations showed supra-additive effects, and three combinations produced an effect limited by the maximum effect. In allodynia, five combinations showed additive effects, two combinations showed supra-additive effects, and five combinations produced antihyperalgesic effects limited by the maximum effect. These findings indicate that the administration of some specific combination of gabapentin and haloperidol can synergistically reduce nerve injury-induced allodynia and hyperalgesia. This suggests that the haloperidol-gabapentin combination can improve the antiallodynic and antihyperalgesic effects in a neuropathic pain model.