Nectandra grandiflora essential oil and its isolated sesquiterpenoids minimize anxiety-related behaviors in mice through GABAergic mechanisms.

Nectandra grandiflora Ness (Lauraceae) essential oil (EO) main constituent, the sesquiterpenoid (+)-dehydrofukinone (DHF), has sedative and anticonvulsant effects through GABAergic mechanisms. Other DHF-related sesquiterpenoids have been identified in the EO, such as, dehydrofukinone epoxide (DFX), eremophil-11-en-10-ol (ERM) and selin-11-en-4-α-ol (SEL). However, the neuronal effects of these compounds in mammals remain unknown. Therefore, the aim of this study was to evaluate the anxiolytic potential of the N. grandiflora EO and the isolated compounds in in mice. For this purpose, mice were administered orally with vehicle, 10, 30 or 100 mg/kg EO, DHF, DFX, ERM or SEL or 1 mg/kg diazepam. Locomotion and ethological parameters in the open field (OF) and elevated plus maze (EPM) were recorded. We also examined the effect of DFX, ERM and SEL on the membrane potential and calcium influx in synaptosomes, and the presence of the compounds in the cortical tissue using gas chromatography. EOs and isolated compounds reduced anxiety-related parameters in the EPM (open arms time and entries, end activity, head dipping) and OF (center time and entries, total rearing, unprotected rearing, sniffing, grooming) without alter ambulation or induce sedation. Flumazenil (2 mg/kg, i.p.) altered the anxiolytic-like effect of all treatments and vanished the DFX, ERM and SEL-induced changes in membrane potential. However, FMZ did not blocked the DFX-, ERM- and SEL-induced inhibition of calcium influx. Therefore, our results suggest that N. grandiflora EO and isolated compounds induced anxiolytic-like effect in mice due to positive modulation of GABAa receptors and/or inhibition of neuronal calcium influx.

Antinociceptive and antidepressant-like effects of the crude extract of Vitex megapotamica in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Vitex megapotamica (Spreng) Moldenke has been used in South American folk medicine to treat inflammatory diseases. However, the effects of V. megapotamica on animal models of nociception and depression have not been evaluated. AIM OF THE STUDY: This study investigated whether the crude leaf extract of V. megapotamica exhibits antinociceptive and antidepressant-like effects in a Freund's adjuvant-induced chronic inflammation and depression model. MATERIALS AND METHODS: Chronic inflammation was induced in rats by the intraplantar administration of complete Freund's adjuvant (CFA; 100µl). The effect of oral crude extract of V. megapotamica (VmE; 3-30mg/kg, p.o.) on nociception (thermal hyperalgesia, mechanical allodynia and arthritis score), inflammation (edema, myeloperoxidase activity), immobility (forced swimming test), locomotor activity (open field), gastrointestinal transit, hyperalgesia and naloxone-precipitated morphine withdrawal syndrome was evaluated. Naloxone (0.4mg/kg, i.p.) was used to investigate the involvement of opioid system in the currently described effects of VmE. RESULTS: Crude extract caused antinociceptive/antidepressant-like effects in the CFA-induced chronic inflammation model, which was prevented by naloxone. The VmE extract (10mg/kg, p.o.) did not alter the locomotor activity, gastrointestinal function and inflammatory parameters and did not cause hyperalgesia. CONCLUSION: V. megapotamica induces opioid-dependent antinociception and antidepressant-like effect, without anti-inflammatory activity. The results support the use of VmE as analgesic and antidepressant.

Fish oil attenuates methylmalonate-induced seizures.

Methylmalonic acidemias are inherited metabolic disorders characterized by methylmalonate (MMA) accumulation and neurological dysfunction, including seizures. Dietary fatty acids are known as an important energy source and reduce seizure activity in selected acute animal models. This study investigated whether chronic treatment with fish oil or with oleic acid attenuates MMA-induced seizures and whether maintenance of Na(+),K(+)-ATPase activity was involved in such an effect. Adult male Wistar rats were given fish oil (85 mg/kg), oleic acid (85 mg/kg) or vehicle (0.42% aqueous Cremophor EL™, 4 mL/kg/body weight/day), p.o., for 75 days. On the 73th day a cannula was implanted in the right lateral ventricle with electrodes over the parietal cortex for EEG recording. On the 76th day the animals were injected with NaCl (2.5 µmol/2.5 µL, i.c.v.), or with MMA (2.5 µmol/2.5 µL, i.c.v.), and seizure activity was measured by electroencephagraphic (EEG) recording with concomitant behavior monitoring. The effect of prostaglandin E2 (PGE2) on Na(+),K(+)-ATPase activity of slices of cerebral cortex from NaCl-injected animals was determined. Fish oil increased the latency to MMA-induced tonic-clonic seizures, reduced the mean amplitude of ictal EEG recordings, and prevented PGE2-induced decrease of Na(+),K(+)-ATPase activity in cortical slices in vitro. Oleic acid decreased mean amplitude of ictal EEG recordings. The results support that fish oil decreases MMA-induced seizures. The decreased sensitivity of Na(+),K(+)-ATPase to the inhibitory effect of PGE2 in fish oil-treated animals may be related to the currently reported anticonvulsant activity.

N-Acetylcysteine prevents baker's-yeast-induced inflammation and fever.

OBJECTIVE AND DESIGN: To investigate whether N-acetylcysteine (NAC) alters baker's-yeast-induced fever and inflammation. MATERIAL OR SUBJECTS: Male Wistar rats (26-28 days old) injected with baker's yeast (135 mg/kg, intraperitoneal) or prostaglandin E(2) (300 ng/100 µL, intrathecal). TREATMENT: Rats were injected with NAC (500 mg/kg, subcutaneous, or 50 µg/100 µL, intrathecal) 1 h before, or 2 h after, pyrogen injection. METHODS: Rectal temperature changes induced by baker's yeast, PGE(2) and NAC were followed up over time. Four hours after baker's yeast injection, total leukocytes, protein, interleukin (IL)-1ß, tumor necrosis factor (TNF)-α and nonprotein thiol content were assessed in peritoneal lavage and hypothalamus. RESULTS: Systemic administration of NAC decreased leukocytes, protein, IL-1ß and TNF-α levels in peritoneal lavage, and decreased IL-1ß levels in the hypothalamus. The central administration of NAC prevented baker's-yeast-induced fever, but did not alter the febrile response elicited by prostaglandin E(2). CONCLUSION: These results suggest an anti-inflammatory and antipyretic role for NAC in yeast-induced peritonitis.

Spinal levels of nonprotein thiols are related to nociception in mice.

UNLABELLED: Oxidative stress markers are thought to be related to nociception. Because thiolic compounds are important antioxidants, we investigated the relationship between thiols, endogenous or exogenous, and nociception. Systemic or spinal, but not peripheral, administration of the exogenous thiolic compound N-acetyl-L-cysteine (NAC) reduced nociception induced by intraplantar capsaicin injection. Moreover, we detected an increase in lipid peroxidation and 3-nitrotyrosine and a decrease in nonprotein thiolic levels in the lumbar spinal cord of capsaicin-injected animals. All these effects were prevented by NAC treatment (i.p. and i.t.). Our findings confirm a role for the spinal cord in NAC actions because systemic NAC administration also reduced the nociception trigged by intrathecal injection of capsaicin. Moreover, adjuvant-induced arthritis, but not paw incision, also -decreases nonprotein thiol levels in the spinal cord. Similarly, NAC produced antinociception in adjuvant-treated animals, but not in paw-incised animals. Finally, we investigated the role of endogenous thiol compounds in the nociceptive process administrating buthionine-suphoxamine (BSO), an inhibitor of glutathione-synthesis. Intrathecal BSO treatment decreased nonprotein thiol levels in the spinal cord, as well as induced mechanical allodynia and chemical and thermal hyperalgesia. In conclusion, our results indicate a critical role for nonprotein thiols in nociception at the level of the spinal cord. PERSPECTIVE: The results presented here indicate that the loss of nonprotein thiols in the spinal cord is involved in pain development. Therefore, the administration of thiolic compounds or other strategies allow thiol levels to be maintained and could be a beneficial action in the therapy of painful conditions.

Creatine decreases convulsions and neurochemical alterations induced by glutaric acid in rats.

Glutaric acidemia type I (GA-I) is an inherited metabolic disease characterized by striatal degeneration, seizures, and accumulation of glutaric acid (GA). Considering that GA impairs energy metabolism and induces reactive species generation, we investigated whether the acute administration of creatine, an amino acid with antioxidant and ergogenic properties, protects against the seizures and neurochemical alterations (inhibition of Na(+),K(+)-ATPase and increased protein carbonylation) induced by the intrastriatal injection of GA (4 micromol/striatum). We also investigated whether creatine protected against the GA-induced inhibition of glutamate uptake in vitro. Creatine administration (300 mg/kg, p.o.) decreased seizures (evidenced by electrographic changes), protein carbonylation and Na(+),K(+)-ATPase inhibition induced by GA. However, creatine, at a dose capable of fully preventing GA-induced protein carbonylation (50 and 150 mg/kg, p.o.), did not prevent convulsions and Na(+),K(+)-ATPase inhibition, suggesting that the anticonvulsant activity of creatine in this experimental model is not related to its antioxidant action. Creatine also protected against the GA-induced inhibition of l-[(3)H]glutamate uptake in synaptosomes, suggesting that creatine may reduce the deleterious effects of GA by maintaining glutamate uptake in the synaptic cleft. Therefore, considering that creatine significantly attenuates the deleterious effects of GA assessed by behavioral and neurochemical measures, it is plausible to propose the use of this amino acid as an adjuvant therapy in the management of glutaric acidemia.

Baker yeast-induced fever in young rats: characterization and validation of an animal model for antipyretics screening.

In this study we describe a low-cost and reliable method for inducing fever in young male rats (28-30 days of age, 75-90 g), which seems suitable for the screening of new antipyretics. The effects of temperature measuring procedure-induced stress on the basal rectal temperature and on Baker yeast-induced hyperthermia was assessed. Rectal temperature (T) was recorded every hour for 12 h (07:00-19:00 h) with a lubricated thermistor probe. The animals were injected intraperitoneally with baker yeast (0.25, 0.135, 0.05 g/kg) or the equivalent volume of saline at 7:00 h. The administration of 0.135 g/kg baker yeast induced a sustained increase in rectal temperature for 4 h. Classical (dipyrone and acetaminophen) and novel (MPCA and FPCA) antipyretics, at doses that had no effect per se, reverted baker yeast-induced fever. The method presented induces a clear-cut fever, which is reverted by antipyretics commonly used in human beings and selected novel antipyretics in small animals. The method also allows antipyretic evaluation with low amount of drugs, due to the use of small animals and to the small variability of the pyretic response, which ultimately causes a significant reduction in the number of animals necessary for antipyretic evaluation. Therefore, this study describes an animal model of fever that is not only advantageous from the economical and technical point of view, but that also bears ethical concerns.