Diabetes-induced electrophysiological alterations on neurosomes in ganglia of peripheral nervous system.

Diabetes mellitus (DM) leads to medical complications, the epidemiologically most important of which is diabetic peripheral neuropathy (DPN). Electrophysiology is a major component of neural functioning and several studies have been undertaken to elucidate the neural electrophysiological alterations caused by DM and their mechanisms of action. Due to the importance of electrophysiology for neuronal function, the review of the studies dealing predominantly with electrophysiological parameters and mechanisms in the neuronal somata of peripheral neural ganglia of diabetic animals during the last 45 years is here undertaken. These studies, using predominantly techniques of electrophysiology, most frequently patch clamp for voltage clamp studies of transmembrane currents through ionic channels, have investigated the experimental DPN. They also have demonstrated that various cellular and molecular mechanisms of action of diabetic physiopathology at the level of biophysical electrical parameters are affected in DPN. Thus, they have demonstrated that several passive and active transmembrane voltage parameters, related to neuronal excitability and neuronal functions, are altered in diabetes. The majority of the studies agreed that DM produces depolarization of the resting membrane potential; alters excitability, increasing and decreasing it in dorsal root ganglia (DRG) and in nodose ganglion, respectively. They have tried to relate these changes to sensorial alterations of DPN. Concerning ionic currents, predominantly studied in DRG, the most frequent finding was increases in Na+, Ca2+, and TRPV1 cation current, and decreases in K+ current. This review concluded that additional studies are needed before an understanding of the hierarchized, time-dependent, and integrated picture of the contribution of neural electrophysiological alterations to the DPN could be reached. DM-induced electrophysiological neuronal alterations that so far have been demonstrated, most of them likely important, are either consistent with the DPN symptomatology or suggest important directions for improvement of the elucidation of DPN physiopathology, which the continuation seems to us very relevant.

Diabetes mellitus differently affects electrical membrane properties of vagal afferent neurons of rats.

To study whether diabetes mellitus (DM) would cause electrophysiological alterations in nodose ganglion (NG) neurons, we used patch clamp and intracellular recording for voltage and current clamp configuration, respectively, on cell bodies of NG from rats with DM. Intracellular microelectrodes recording, according to the waveform of the first derivative of the action potential, revealed three neuronal groups (A0 , Ainf , and Cinf ), which were differently affected. Diabetes only depolarized the resting potential of A0 (from -55 to -44 mV) and Cinf (from -49 to -45 mV) somas. In Ainf neurons, diabetes increased action potential and the after-hyperpolarization durations (from 1.9 and 18 to 2.3 and 32 ms, respectively) and reduced dV/dtdesc (from -63 to -52 V s-1 ). Diabetes reduced the action potential amplitude while increasing the after-hyperpolarization amplitude of Cinf neurons (from 83 and -14 mV to 75 and -16 mV, respectively). Using whole cell patch clamp recording, we observed that diabetes produced an increase in peak amplitude of sodium current density (from -68 to -176 pA pF-1 ) and displacement of steady-state inactivation to more negative values of transmembrane potential only in a group of neurons from diabetic animals (DB2). In the other group (DB1), diabetes did not change this parameter (-58 pA pF-1 ). This change in sodium current did not cause an increase in membrane excitability, probably explainable by the alterations in sodium current kinetics, which are also induced by diabetes. Our data demonstrate that diabetes differently affects membrane properties of different nodose neuron subpopulations, which likely have pathophysiological implications for diabetes mellitus.

The Essential Oil of Hyptis crenata Inhibits the Increase in Secretion of Inflammatory Mediators.

Background: Hyptis crenata is a plant of great ethnopharmacological importance widely distributed in South American countries. In Northeast Brazil, teas or infusions of its aerial parts are used in folk medicine to treat several acute and chronic inflammatory diseases. In a previous work we have demonstrated that the essential oil of H. crenata (EOHc) has an antiedematogenic effect. The aim of this work was to evaluate the effect of EOHc on cytokines secretion and cellular infiltration. Methods: Peritonitis and paw edema models induced by carrageenan were used to determine leucocyte count, myeloperoxidase (MPO) activity, nitrite, and cytokines secretion. Results: EOHc (10−300 mg/kg) significantly inhibited leucocyte migration and reduced the neutrophil count (control: 1.46 × 103 ± 0.031 × 103/mL) of the total leucocytes population in extracellular exudate (control: 2.14 × 103 ± 0.149 × 103/mL) by 15.00%, 43.29%, 65.52%, and 72.83% for the doses of 10, 30, 100, and 300 mg/kg EOHc, respectively (EC50: 24.15 mg/kg). EOHc (100 mg/kg) inhibited the increase in myeloperoxidase activity and completely blocked the increase in nitrite concentration induced by carrageenan. EOHc markedly reduced the pro-inflammatory cytokines (IL-6, MCP-1, IFN-γ, TNF-α, and IL-12p70) and increased IL-10, an anti-inflammatory cytokine (compared to control group, p < 0.05). Conclusions: This study demonstrates that EOHc has a long-lasting anti-inflammatory effect mediated through interference on MPO activity, and nitrite, and cytokines secretion. This effect, coupled with low EOHc toxicity, as far as results obtained in mice could be translated to humans, suggests that EOHc has great potentiality as a therapeutic agent.

Essential Oil of Croton zehntneri Prevents Conduction Alterations Produced by Diabetes Mellitus on Vagus Nerve.

Autonomic diabetic neuropathy (ADN) is a complication of diabetes mellitus (DM), to which there is no specific treatment. In this study, the efficacy of the essential oil of Croton zehntneri (EOCz) in preventing ADN was evaluated in the rat vagus nerve. For the two fastest conducting myelinated types of axons of the vagus nerve, the conduction velocities and rheobase decreased, whilst the duration of the components of the compound action potential of these fibers increased. EOCz completely prevented these DM-induced alterations of the vagus nerve. Unmyelinated fibers were not affected. In conclusion, this investigation demonstrated that EOCz is a potential therapeutic agent for the treatment of ADN.

Antispasmodic effects of the essential oil of Croton zehnteneri, anethole, and estragole, on tracheal smooth muscle.

Croton zehntneri is a plant well adapted to the semi-arid climate of northeastern region of Brazil. The essential oil of C. zehntneri (EOCz) has been described to have several pharmacologic properties, including effect on airflow resistance of in vivo respiratory system. For this reason, we investigated the hypothesis that EOCz and its major constituents, anethole and estragole, have antispasmodic activity on tracheal muscle. In tracheal rings of Wistar rats, maintained in Krebs-Henseleit's solution, EOCz, anethole and estragole inhibited contractions induced by 60mM [K+], ACh (10µM), Ba2+ and Phorbol dibutirate (1 µM). For EOCz, anethole and estragole, the IC50 for inhibition of KCl-induced contractions were 145.8 ± 14.8, 89.9 ± 7.4 and 181.0 ± 23.3 µg/mL, respectively, and for ACh-induced contraction, they were 606.1 ± 122.0, 160.5 ± 33.0 and 358.6 ± 49.2 µg/mL. Pharmacodynamic efficacy was maximal in all cases. These data in Ba2+-induced contraction and the differential IC50 suggested that blockade of Voltage Dependent Calcium Channels (VDCC) is a component of the mechanism of action of the three agents. Evaluation of the direct effect of anethole, on VDCC, showed inhibition of the Ca2+ current through this type of channel. These results show that EOCz and the constituents have antispasmodic activity and the mechanism includes blockade of VDCC channels.

Effect of an aqueous extract of Chrysobalanus icaco on the adiposity of Wistar rats fed a high-fat diet / Efecto del extracto acuoso de Chrysobalanus icaco sobre la adiposidad de ratas Wistar alimentadas con una dieta alta en grasas

OBJECTIVE: the purpose of this study was to investigate the effects of Chrysobalanus icaco on adiposity and its mechanism of action in the gene and protein expression of acetyl-CoA carboxylase (ACC), a key enzyme in lipogenesis. METHOD: Wistar rats were divided into a regular or control group (CG) and a high-fat diet (HFD) group. HFD was treated with saline or aqueous extract of Chrysobalanus icaco (AECI) for four weeks. Body weight and food intake were assessed. Subcutaneous, retroperitoneal and periepididymal adipose tissue samples were collected and weighed. Adipocytes from periepididymal tissue were isolated and analyzed. The gene and protein expression of ACC in subcutaneous tissue was determined. RESULTS: AECI showed no effect on intake or body weight. However, the weight of the fat pads and the gene and protein expression of ACC were lower, and glucose tolerance was improved. CONCLUSION: the aqueous extract of Chrysobalanus icaco proved beneficial for the treatment of obesity, preventing fat storage and improving glycemic homeostasis

OBJETIVO: el objetivo de este estudio fue investigar los efectos del extracto acuoso de Chrysobalanus icaco (AECI) en la adiposidad y su mecanismo de acción en la expresión génica y proteica de la acetil-CoA-carboxilasa (ACC), una enzima clave para la lipogénesis. MÉTODOS: se usaron ratones macho Wistar que se asignaron a una dieta estándar de control (CG) o a una rica en grasa (HFD). La HFD se trató con solución salina o con extracto acuoso de Chrysobalanus icaco (AECI) durante cuatro semanas. Se evaluaron el peso corporal y el consumo alimentario. Se aislaron y analizaron muestras de tejido adiposo subcutáneo, retroperitoneal y periepididímico. Se determinó la expresión génica y proteica de ACC en el tejido subcutáneo. RESULTADOS: el AECI no mostró ningún efecto sobre la ingesta de alimento y tampoco sobre el peso corporal. Sin embargo, el tratamiento con AECI redujo el peso de los tejidos adiposos y la expresión génica y proteica de ACC, y mejoró también la tolerancia a la glucosa. CONCLUSIÓN: Chrysobalanus icaco (AECI) resultó ser beneficioso para el tratamiento de la obesidad, previniendo el almacenamiento de grasa y mejorando la homeostasis glucémica

Effect of an aqueous extract of Chrysobalanus icaco on the adiposity of Wistar rats fed a high-fat diet.

INTRODUCTION: Objective: the purpose of this study was to investigate the effects of Chrysobalanus icaco on adiposity and its mechanism of action in the gene and protein expression of acetyl-CoA carboxylase (ACC), a key enzyme in lipogenesis. Method: Wistar rats were divided into a regular or control group (CG) and a high-fat diet (HFD) group. HFD was treated with saline or aqueous extract of Chrysobalanus icaco (AECI) for four weeks. Body weight and food intake were assessed. Subcutaneous, retroperitoneal and periepididymal adipose tissue samples were collected and weighed. Adipocytes from periepididymal tissue were isolated and analyzed. The gene and protein expression of ACC in subcutaneous tissue was determined. Results: AECI showed no effect on intake or body weight. However, the weight of the fat pads and the gene and protein expression of ACC were lower, and glucose tolerance was improved. Conclusion: the aqueous extract of Chrysobalanus icaco proved beneficial for the treatment of obesity, preventing fat storage and improving glycemic homeostasis.

INTRODUCCIÓN: Objetivo: el objetivo de este estudio fue investigar los efectos del extracto acuoso de Chrysobalanus icaco (AECI) en la adiposidad y su mecanismo de acción en la expresión génica y proteica de la acetil-CoA-carboxilasa (ACC), una enzima clave para la lipogénesis. Métodos: se usaron ratones macho Wistar que se asignaron a una dieta estándar de control (CG) o a una rica en grasa (HFD). La HFD se trató con solución salina o con extracto acuoso de Chrysobalanus icaco (AECI) durante cuatro semanas. Se evaluaron el peso corporal y el consumo alimentario. Se aislaron y analizaron muestras de tejido adiposo subcutáneo, retroperitoneal y periepididímico. Se determinó la expresión génica y proteica de ACC en el tejido subcutáneo. Resultados: el AECI no mostró ningún efecto sobre la ingesta de alimento y tampoco sobre el peso corporal. Sin embargo, el tratamiento con AECI redujo el peso de los tejidos adiposos y la expresión génica y proteica de ACC, y mejoró también la tolerancia a la glucosa. Conclusión: Chrysobalanus icaco (AECI) resultó ser beneficioso para el tratamiento de la obesidad, previniendo el almacenamiento de grasa y mejorando la homeostasis glucémica.

Monoterpenoid terpinen-4-ol inhibits voltage-dependent Na+ channels of small dorsal root ganglia rat neurons.

The monoterpenoid terpinen-4-ol (4TERP) is known to inhibit cell excitability, has low toxicity and important pharmacological activities, which are likely related to neural excitability, such as anti-inflammatory, antiepileptic and antinociceptive effects. However, the pharmacological characteristics and mechanisms underlying the effects of 4TERP on blockade of neural action potential are not completely elucidated. Since Na+ current (INa) through voltage-dependent Na+ channels (NaV) is a major mechanism for excitability, the present study investigated the pharmacological characteristics and mechanisms of the action of 4TERP on INa through NaV. For this aim, dissociated small neurons of dorsal root ganglia of adult rats were used for whole cell patch-clamp recordings. 4TERP concentration-dependently inhibits INa (IC50 0.8 ±â€¯0.3 mM; pharmacological efficacy 42.89 ±â€¯5.54%). 4TERP interfered with INa through a mechanism with various components, which includes predominantly channel pore block and sensitivity to frequency of use. In presence of 4TERP (3 mM), decreasing stimulation from 5 Hz to very low frequency (75 s of quiescence previously to stimulation) induced INa decrease to 65.17 ±â€¯5.86% of control. 4TERP also altered (left shift) voltage sensitivity of the steady state activation of NaV. Data are discussed aiming to interpret the importance of blockade of INa through NaV as participant of 4TERP-induced inhibition of membrane excitability.

Diabetes mellitus alters electrophysiological properties in neurons of superior cervical ganglion of rats.

Diabetic neuropathy is the most prevalent complication associated with diabetes mellitus (DM). The superior cervical ganglion (SCG) is an important sympathetic component of the autonomic nervous system. We investigated the changes in cellular electrophysiological properties and on Na+K+-ATPase activity of SCG neurons of rats with DM induced by streptozotocin (STZ). Three types of action potentials (AP) firing pattern were observed in response to a long (1 s) depolarizing pulse. Whilst some neurons fired a single AP (single firing phasic, SFP), others fired few APs (multiple firing phasic, MFP). A third type fired APs during more than 80% of the stimulus duration (tonic-like, TL). The occurrence of SFP, MFP and TL was 84.5, 13.8, and 1.7%, respectively. SFP and MFP differed significantly in their membrane input resistance (Rin). At the end of the 4th week of its time course, DM differently affected most types of neurons: DM induced depolarization of resting membrane potential (RMP), decreased AP amplitude in SFP, and decreased Rin in MFP. DM decreased spike after-hyperpolarization amplitude in MFP and the duration in SFP. Based on the RMP depolarization, we investigated the Na+K+-ATPase action and observed that DM caused a significant decrease in Na+K+-ATPase activity of SCG. In conclusion, we have demonstrated that DM affects several parameters of SCG physiology in a manner likely to have pathophysiological relevance.

Hypoglycaemic effect of resveratrol in streptozotocin-induced diabetic rats is impaired when supplemented in association with leucine.

Studies have shown synergistic and independent effects of leucine and resveratrol (RSV) as possible therapeutic agents to ameliorate metabolic disorders. Thus, the objective of this study was to investigate the effects of supplementation with leucine and RSV, alone and in combination, on metabolic changes in white adipose tissue of neonatally STZ-induced diabetic rats. After weaning, the rats were treated with trans-resveratrol (0.6 mg/kg/dose) and/or leucine (1.35 mg/kg/dose) administered orally. The animals were euthanized at age 16 weeks for blood analyses. Subcutaneous (SC), periepididymal (PE) and retroperitoneal (RP) fat pads were weighed. Adipocytes from PE and RP pads were isolated for morphometric analysis. Long-term supplementation with RSV promoted adiposity recovery, prevented hypoinsulinemia and improved the metabolic profile of the diabetic rats. However, some of these effects were impaired when RSV was associated with leucine. The diabetic rats supplemented with leucine alone showed no significant improvement in metabolic disorders.

Melatonin Reduces Excitability in Dorsal Root Ganglia Neurons with Inflection on the Repolarization Phase of the Action Potential.

Melatonin is a neurohormone produced and secreted at night by pineal gland. Many effects of melatonin have already been described, for example: Activation of potassium channels in the suprachiasmatic nucleus and inhibition of excitability of a sub-population of neurons of the dorsal root ganglia (DRG). The DRG is described as a structure with several neuronal populations. One classification, based on the repolarizing phase of the action potential (AP), divides DRG neurons into two types: Without (N0) and with (Ninf) inflection on the repolarization phase of the action potential. We have previously demonstrated that melatonin inhibits excitability in N0 neurons, and in the present work, we aimed to investigate the melatonin effects on the other neurons (Ninf) of the DRG neuronal population. This investigation was done using sharp microelectrode technique in the current clamp mode. Melatonin (0.01-1000.0 nM) showed inhibitory activity on neuronal excitability, which can be observed by the blockade of the AP and by the increase in rheobase. However, we observed that, while some neurons were sensitive to melatonin effect on excitability (excitability melatonin sensitive-EMS), other neurons were not sensitive to melatonin effect on excitability (excitability melatonin not sensitive-EMNS). Concerning the passive electrophysiological properties of the neurons, melatonin caused a hyperpolarization of the resting membrane potential in both cell types. Regarding the input resistance (Rin), melatonin did not change this parameter in the EMS cells, but increased its values in the EMNS cells. Melatonin also altered several AP parameters in EMS cells, the most conspicuously changed was the (dV/dt)max of AP depolarization, which is in coherence with melatonin effects on excitability. Otherwise, in EMNS cells, melatonin (0.1-1000.0 nM) induced no alteration of (dV/dt)max of AP depolarization. Thus, taking these data together, and the data of previous publication on melatonin effect on N0 neurons shows that this substance has a greater pharmacological potency on Ninf neurons. We suggest that melatonin has important physiological function related to Ninf neurons and this is likely to bear a potential relevant therapeutic use, since Ninf neurons are related to nociception.

Phytomodulatory proteins promote inhibition of hepatic glucose production and favor glycemic control via the AMPK pathway.

Phytomodulatory proteins from the latex of the medicinal plant Calotropis procera has been shown to be implicated in many pharmacological properties. However there is no current information about their activity on glucose metabolism, although the latex is used in folk medicine for treating diabetes. In this study the phytomodulatory proteins (LP) from C. procera latex were assessed on glycemic homeostasis. Control animals received a single intravenous dose (5 mg/kg) of LP or saline solution (CTL). Four hours after treatment, the animals were euthanized and their livers were excised for analysis by western blot and RT-PCR AMP-activated protein kinase (AMPK), phosphoenolpyruvate carboxykinase (PEPCK) and tumor necrosis factor alpha (TNF-α). In vivo tests of intraperitoneal tolerance to insulin, glucose and pyruvate were also performed, and the effect of LP administration on fed glycemia was studied followed by blood analysis to determine serum insulin levels. Treatment with LP reduced glycemia two hours after glucose administration (LP: 87.2 ± 3.70 mg/dL versus CTL: 115.6 ± 8.73 mg/dL). However, there was no change in insulin secretion (CTL: 14.16 ± 0.68 mUI/mL and LP: 14.96 ± 0.55 mUI/mL). LP improved the insulin sensitivity, represented by a superior glucose decay constant during an insulin tolerance test (kITT) (4.17 ± 0.94%/min) compared to the CTL group (0.82 ± 0.72%/min), and also improved glucose tolerance at 30 min (105.2 ± 12.4 mg/dL versus 154.2 ± 18.51 mg/dL), while it decreased hepatic glucose production at 15 and 30 min (LP: 75.5 ± 9.31 and 52.5 ± 12.05 mg/dL compared to the CTL: 79.0 ± 3.02 and 84.5 ± 7.49 mg/dL). Furthermore, there was a significant inhibition of gene expression of PEPCK (LP: 0.66 ± 0.06 UA and CTL: 1.14 ± 0.22 UA) and an increase of phosphorylated AMPK (LP: 1.342 ± 0.21 UA versus CTL: 0.402 ± 0.09 UA). These findings confirm the effect of LP on glycemic control and suggest LP may be useful in diabetes treatment. However, the pharmacological mechanism of LP in PEPCK modulation still needs more clarification.

Sex differences in subcutaneous adipose tissue redox homeostasis and inflammation markers in control and high-fat diet fed rats.

The development of obesity-related metabolic disorders is more evident in male in comparison with female subjects, but the mechanisms are unknown. Several studies have shown that oxidative stress is involved in the pathophysiology of obesity, but the majority of these studies were performed with male animals. The aim of this study was to evaluate the sex-related differences in subcutaneous adipose tissue redox homeostasis and inflammation of rats chronically fed a high-fat diet. NADPH oxidase (NOX), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase activities were evaluated in the subcutaneous adipose tissue (SC) of adult male and female rats fed either a standard chow (SCD) or a high-fat diet (HFD) for 11 weeks. NOX2 and NOX4 messenger RNA (mRNA) levels, total reduced thiols, interleukin (IL)-1ß, tumor necrosis factor α (TNF-α), and IL-6 were also determined. Higher antioxidant enzyme activities and total reduced thiol levels were detected in SC of control male compared with female rats. Chronic HFD administration increased NOX activity and NOX2 and NOX4 mRNA levels and decreased SOD and GPx activities only in male animals. IL-1ß, TNF-α, and IL-6 levels, as well as Adgre1, CD11b, and CD68 mRNA levels, were also higher in SC of males after HFD feeding. In SC of females, catalase activity was higher after HFD feeding. Taken together, our results show that redox homeostasis and inflammation of SC is sexually dimorphic. Furthermore, males show higher oxidative stress in SC after 11 weeks of HFD feeding owing to both increased reactive oxygen species (ROS) production through NOX2 and NOX4 and decreased ROS detoxification.

1,8-Cineole blocks voltage-gated L-type calcium channels in tracheal smooth muscle.

1,8-Cineole is a cyclic monoterpenoid used in folk medicine for treatment of numerous respiratory diseases and other infections. 1,8-Cineole has anti-inflammatory, antioxidant, and myorelaxant effects, as well as low toxicity. In the present study, the effects of 1,8-cineole on contractility and voltage-gated calcium channels (VGCC) in tracheal smooth muscle were investigated. Intact and dissociated tracheal smooth muscle were used for muscle contraction and patch-clamp recordings, respectively. In experiments involving muscle contraction, 1,8-cineole potentiated contractions at low concentrations and relaxed contractions induced by isotonic K+ at high concentrations. AMTB (a TRPM8 channel blocker) reduced the potentiation induced by 1,8-cineole while indomethacin (a COX inhibitor) did not block this effect. In dissociated myocytes, 1,8-cineole partially blocked Ba2+ currents through VGCC in a concentration-dependent manner. 1,8-Cineole shifted the steady-state activation and inactivation curves to the left and also reduced the current decay time constant. In conclusion, 1,8-cineole has a dual effect on tracheal smooth muscle contraction resulting in a biphasic effect. Our data suggest that the potentiation effect is mediated by activation of TRPM8 channels and the relaxation effect is mediated by the blockage of L-type VGCC.

Hydroxyl Group and Vasorelaxant Effects of Perillyl Alcohol, Carveol, Limonene on Aorta Smooth Muscle of Rats.

The present study used isometric tension recording to investigate the vasorelaxant effect of limonene (LM), carveol (CV), and perillyl alcohol (POH) on contractility parameters of the rat aorta, focusing in particular on the structure-activity relationship. LM, CV, and POH showed a reversible inhibitory effect on the contraction induced by electromechanical and pharmacomechanical coupling. In the case of LM, but not CV and POH, this effect was influenced by preservation of the endothelium. POH and CV but not LM exhibited greater pharmacological potency on BayK-8644-induced contraction and on electromechanical coupling than on pharmacomechanical coupling. In endothelium-denuded preparations, the order of pharmacological potency on electrochemical coupling was LM < CV < POH. These compounds inhibited also, with grossly similar pharmacological potency, the contraction induced by phorbol ester dibutyrate. The present results suggest that LM, CV and POH induced relaxant effect on vascular smooth muscle by means of different mechanisms likely to include inhibition of PKC and IP3 pathway. For CV and POH, hydroxylated compounds, it was in electromechanical coupling that the greater pharmacological potency was observed, thus suggesting a relative specificity for a mechanism likely to be important in electromechanical coupling, for example, blockade of voltage-dependent calcium channel.

Electrophysiologic alterations in the excitability of the sciatic and vagus nerves during early stages of sepsis.

BACKGROUND: Nonspecific and delayed diagnosis of neurologic damage contributes to the development of neuropathies in patients with severe sepsis. The present study assessed the electrophysiologic parameters related to the excitability and conductibility of sciatic and vagus nerves during early stages of sepsis. MATERIALS AND METHODS: Twenty-four hours after sepsis induced by cecal ligation and puncture (CLP) model, sciatic and vagus nerves of septic (CLP group) and control (sham group) rats were removed, and selected electric stimulations were applied to measure the parameters of the first and second components of the compound action potential. The first component originated from fibers with motor and sensory functions (Types Aα and Aß fibers) with a large conduction velocity (70-120 m/s), and the second component originated from fibers (Type Aγ) with sensorial function. To evaluate the presence of sensorial alterations, the sensitivity to non-noxious mechanical stimuli was measured by using the von Frey test. Hematoxylin and eosin staining of the nerves was performed. RESULTS: We observed an increase of rheobase followed by a decrease in the first component amplitude and a higher paw withdrawal threshold in response to the application of von Frey filaments in sciatic nerves from the CLP group compared to the sham group. Differently, a decrease in rheobase and an increase in the first component amplitude of vagal C fibers from CLP group were registered. No significant morphologic alteration was observed. CONCLUSION: Our data showed that the electrophysiologic alterations in peripheral nerves vary with the fiber type and might be identified in the first 24 h of sepsis, before clinical signs of neuromuscular disorders.

Lipid transfer protein isolated from noni seeds displays antibacterial activity in vitro and improves survival in lethal sepsis induced by CLP in mice.

In the present study, we aimed to evaluate the antibacterial activity of a lipid transfer protein isolated from Morinda citrifolia L. seeds, named McLTP1, and to investigate its effect in the cecal ligation and puncture (CLP) mouse sepsis model. Antimicrobial assays revealed that McLTP1 (12.5-800 µg/mL) significantly reduced Staphylococcus aureus (ATCC 6538P and ATCC 14458) and Staphylococcus epidermidis (ATCC 12228) planktonic growth, reaching maximal inhibition of approximately 50% and 98%, respectively. Furthermore, McLTP1 inhibited biofilm formation of both S. aureus strains, achieving percentages ranging from 39.1% to 69.1% (200-800 µg/mL) for ATCC 6538P and 34.4%-63% (12.5-800 µg/mL) for ATCC 14458. A synergistic interaction between McLTP1 and oxacillin against S. aureus and S. epidermidis was also observed, as determined by fractional inhibitory concentration indices of 0.18 and 0.38, respectively. McLTP1 showed no significant inhibitory effect against Gram-negative bacteria. In the in vivo experiments, sepsis was lethal to 83% of the animals, 72 h after CLP. In contrast, 100% of the animals treated with McLTP1 (8 mg/kg) before (intraperitoneal injection or oral dose) or after (oral dose) CLP were still alive 3 days later. In addition, oral or intraperitoneal administration of McLTP1 (8 mg/kg) significantly reduced the body weight loss, fever, leukocytosis, organ damage, and the level of inflammatory serum cytokines induced by sepsis. In conclusion, McLTP1 could be exploited for its antimicrobial properties, and can be considered a potential therapeutic candidate for the management of clinical sepsis.

Combined treatment with melatonin and insulin improves glycemic control, white adipose tissue metabolism and reproductive axis of diabetic male rats.

AIMS: Melatonin treatment has been reported to be capable of ameliorating metabolic diabetes-related abnormalities but also to cause hypogonadism in rats. We investigated whether the combined treatment with melatonin and insulin can improve insulin resistance and other metabolic disorders in rats with streptozotocin-induced diabetes during neonatal period and the repercussion of this treatment on the hypothalamic-pituitary-gonadal axis. MAIN METHODS: At the fourth week of age, diabetic animals started an 8-wk treatment with only melatonin (0.2 mg/kg body weight) added to drinking water at night or associated with insulin (NHP, 1.5 U/100 g/day) or only insulin. Animals were then euthanized, and the subcutaneous (SC), epididymal (EP), and retroperitoneal (RP) fat pads were excised, weighed and processed for adipocyte isolation for morphometric analysis as well as for measuring glucose uptake, oxidation, and incorporation of glucose into lipids. Hypothalamus was collected for gene expression and blood samples were collected for biochemical assays. KEY FINDINGS: The treatment with melatonin plus insulin (MI) was capable of maintaining glycemic control. In epididymal (EP) and subcutaneous (SC) adipocytes, the melatonin plus insulin (MI) treatment group recovered the insulin responsiveness. In the hypothalamus, melatonin treatment alone promoted a significant reduction in kisspeptin-1, neurokinin B and androgen receptor mRNA levels, in relation to control group. SIGNIFICANCE: Combined treatment with melatonin and insulin promoted a better glycemic control, improving insulin sensitivity in white adipose tissue (WAT). Indeed, melatonin treatment reduced hypothalamic genes related to reproductive function.

Hepatoprotective Effect of Essential Oils from Hyptis crenata in Sepsis-Induced Liver Dysfunction.

No specific therapeutics are available for the treatment of sepsis-induced liver dysfunction, a clinical complication strongly associated with the high mortality rate of septic patients. This study investigated the effect of the essential oil of Hyptis crenata (EOHc), a lamiaceae plant used to treat liver disturbances in Brazilian folk medicine, on liver function during early sepsis. Sepsis was induced by the cecal ligation and puncture (CLP) model. Rats were divided into four groups: Sham, Sham+EOHc, CLP, and CLP+EOHc. EOHc (300 mg/kg) was orally administered 12 and 24 h after surgery. The animals were sacrificed for blood collection and liver tissue samples 48 h after surgery. Hepatic function was evaluated by measuring serum bilirubin, alkaline phosphatase (ALP), aspartate aminotransferase, and alanine aminotransferase (ALT) levels. The levels of malondialdehyde and the activity of superoxide dismutase, catalase, and GSH peroxidase (GSH-Px) were measured for assessment of oxidative stress. Liver morphology was analyzed by hematoxylin and eosin staining. EOHc normalized serum ALP, ALT, and bilirubin levels and inhibited morphological changes. In addition, we observed that EOHc inhibited elevation in hepatic lipid peroxidation and reduction of the glutathione peroxidase activity induced by sepsis. Our data show that EOHc plays a protective effect against liver injury induced by sepsis.

Effects of 1,8-cineole on Na(+) currents of dissociated superior cervical ganglia neurons.

1,8-Cineole is a terpenoid present in many essential oil of plants with several pharmacological and biological effects, including antinociceptive, smooth muscle relaxant and ion channel activation. Also, 1,8-cineole blocked action potentials, reducing excitability of peripheral neurons. The objective of this work was to investigate effects of 1,8-cineole on Na(+) currents (INa(+)) in dissociated superior cervical ganglion neurons (SCG). Wistar rats of both sexes were used (10-12 weeks old, 200-300g). SCG's were dissected and neurons were enzymatically treated. To study 1,8-cineole effect on INa(+), the patch-clamp technique in whole-cell mode was employed. 1,8-Cineole (6.0mM) partially blocked INa(+) in SCG neurons. The effect stabilized within ∼150s and there was a partial recovery of INa(+) after washout. Current density was reduced from -105.8 to -83.7pA/pF, corresponding to a decrease to ∼20% of control. 1,8-Cineole also reduced the time-to-peak of INa(+) activation and the amplitude and decay time constants of INa(+) inactivation. Current-voltage plots revealed that 1,8-cineole left-shifted the V1/2 of both activation and inactivation curves by ∼10 and ∼20mV, respectively. In conclusion, we demonstrate that 1,8-cineole directly affects Na(+) channels of the SCG by modifying several gating parameters that are likely to be the major cause of excitability blockade.