Nayrton Flávio Moura Rocha

Evidences for a progressive microglial activation and increase in iNOS expression in rats submitted to a neurodevelopmental model of schizophrenia: Reversal by clozapine

Schizophrenia was proposed as a progressive neurodevelopmental disorder. In this regard herein we attempted to determine progressive inflammatory and oxidative alterations induced by a neonatal immune challenge and its possible reversal by clozapine administration. For this end, Wistar rats at postnatal day (PN) 5-7 were administered the viral mimetic polyriboinosinic-polyribocytidilic acid (polyI:C) or saline. A distinct group of animals additionally received the antipsychotic drug clozapine (25mg/kg) from PN60 to 74. At PN35 (periadolescence), 60 (adult) and 74 (adulthood) the animals were submitted to behavioral determinations of prepulse inhibition of the startle (PPI) and Y maze task for working memory evaluation. At PN35 and 74 the animals were sacrificed and the hippocampus (HC), prefrontal cortex (PFC) and striatum (ST) immunostained for Iba-1, a microglial marker, and inducible nitric oxide synthase (iNOS). At PN74 oxidative stress parameters, such as, reduced glutathione levels (GSH) and lipid peroxidation were determined. The results showed a progressive increase of microglial activation and iNOS immunostaining from PN35 to PN74 mainly in the CA2 and CA3 regions of the HC and in the ST. At PN74 neonatal challenge also induced an oxidative imbalance. These inflammatory alterations were accompanied by deficits in PPI and working memory only in adult life that were reversed by clozapine. Clozapine administration reversed microglial activation and iNOS increase, but not the alterations of oxidative stress parameters. Taken together these results give further evidences for a neuroprogressive etiology and course of schizophrenia and that clozapine may partly alleviate this process.

(−)-α-Bisabolol-induced gastroprotection is associated with reduction in lipid peroxidation, superoxide dismutase activity and neutrophil migration

This work examined the gastroprotection of (-)-α-bisabolol, an unsaturated optically active sesquiterpene alcohol obtained by the direct distillation essential oil from plants. (-)-α-Bisabolol has been described as a compound capable of reducing the gastric ulcer area in response to absolute ethanol. We evaluated the gastroprotection of (-)-α-bisabolol in ethanol-induced gastric lesions model through histopathological assessment, measurement of the membrane lipids peroxidation (MDA), myeloperoxidase (MPO) activity, superoxide dismutase (SOD) activity, catalase (CAT) activity and the nitrite amount. Our results showed that (-)-α-bisabolol was able to reduce injuries associated with the administration of ethanol and the formation of thiobarbituric acid reactive substances (MDA) was also able to increase SOD activity and reduce the influx of cells inflammatory (neutrophils) in the gastric mucosa. The effect of (-)-α-bisabolol seems to be unrelated to the nitric oxide. (-)-α-Bisabolol caused a reduction of catalase activity. These findings show that (-)-α-bisabolol is able to decrease oxidative stress and inflammatory event associated with the lesions induced by ethanol.

Gastroprotective activity of isopulegol on experimentally induced gastric lesions in mice: investigation of possible mechanisms of action.

The present study investigated whether isopulegol, a monoterpene present in essential oils of several aromatic plants, would be able to promote some gastroprotective effect and also verified the possible mechanisms involved in this action. For this study, ethanol- and indomethacin-induced gastric ulcer models in mice and histopathological assessment were used. The roles of NO, sulfhydryls (glutathione, GSH), ATP-sensitive K+ channels (KATP channels), and prostaglandins were also investigated. Isopulegol exhibited a dose-related gastroprotective effect against ethanol-induced lesions, while the pretreatment with glibenclamide and indomethacin [but not with N(G)-nitro-l-arginine methyl ester] were able to reverse this action. The pretreatment with isopulegol also restored GSH levels to normal levels and exhibited dose-related gastroprotective effect against indomethacin-induced ulcer. The results suggested that isopulegol presents significant gastroprotective effects in both ethanol- and indomethacin-induced ulcer models, which appear to be mediated, at least in part, by endogenous prostaglandins, KATP channel opening, and antioxidant properties.

Antinociceptive activity of carvacrol (5-isopropyl-2-methylphenol) in mice

Objectives  Carvacrol (5‐isopropyl‐2‐methylphenol) is a monoterpenic phenol which is present in the essential oil of oregano and thyme. We have investigated the behavioural effects of carvacrol in animal models of pain, such as acetic acid‐induced abdominal constriction, formalin and hot‐plate tests in mice. The spontaneous motor activity of animals treated with carvacrol was investigated using open‐field and rotarod tests.

Gastroprotection of (-)-α-bisabolol on acute gastric mucosal lesions in mice: the possible involved pharmacological mechanisms

(‐)‐α‐Bisabolol is an unsaturated, optically active sesquiterpene alcohol obtained by the direct distillation essential oil from plants such as Vanillosmopsis erythropappa and Matricaria chamomilla. (‐)‐α‐Bisabolol has generated considerable economic interest, since it possesses a delicate floral odor and has been shown to have anti‐septic and anti‐inflammatory activity. The aim of this work was to evaluate the gastroprotective action of (‐)‐α‐bisabolol on ethanol and indomethacin‐induced ulcer models in mice, and further investigate the pharmacological mechanisms involved in this action. The oral administration of (‐)‐α‐bisabolol 100 and 200 mg/kg was able to protect the gastric mucosa from ethanol (0.2 mL/animal p.o.) and indomethacin‐induced ulcer (20 mg/kg p.o.). Administration of l‐NAME (10 mg/kg i.p.), glibenclamide (10 mg/kg i.p.) or indomethacin (10 mg/kg p.o.) was not able to revert the gastroprotection promoted by (‐)‐α‐bisabolol 200 mg/kg on the ethanol‐induced ulcer. Dosage of gastric reduced glutathione (GSH) levels showed that ethanol and indomethacin reduced the content of non‐protein sulfhydryl (NP‐SH) groups, while (‐)‐α‐bisabolol significantly decreased the reduction of these levels on ulcer‐induced mice, but not in mice without ulcer. In conclusion, gastroprotective effect on ethanol and indomethacin‐induced ulcer promoted by (‐)‐α‐bisabolol may be associated with an increase of gastric sulfydryl groups bioavailability leading to a reduction of gastric oxidative injury induced by ethanol and indomethacin.

Mechanisms involved in the gastroprotective activity of esculin on acute gastric lesions in mice.

This work describes the gastroprotective actions of esculin (6,7-dihydroxycoumarin-6-o-glucoside) against indomethacin- or ethanol-induced lesions and verifies the role of nitric oxide, ATP-dependent K(+) channels, prostaglandins, transient receptor potential vanilloid 1 and antioxidant effects in the gastroprotective mechanism of esculin in the ethanol-induced gastric lesion model. The intragastric administration of esculin at doses of 12.5, 25 and 50 mg/kg was able to protect the gastric mucosa against ethanol (0.2 mL/animal p.o.), and esculin at doses of 25 and 50 mg/kg protected against indomethacin-induced lesions (20mg/kg p.o.). Administration of l-NAME (10mg/kg i.p.), glibenclamide (10mg/kg i.p.) or indomethacin (10mg/kg p.o.), but not capsazepine (5mg/kg p.o.), was able to reduce the gastroprotection promoted by esculin (25mg/kg) on the ethanol-induced lesions. Measurements of nitrite, a NO metabolite, were increased in the group that was pretreated with esculin. In terms of antioxidant activity as a gastroprotective mechanism of esculin, the results show that pre-treatment with esculin decreased the amount of GSH, increased SOD activity, did not interfere with the CAT activity and decreased both the MPO activity and the MDA amount. In conclusion, pre-treatment with esculin confers significant gastroprotective and antioxidant activity and leads to a reduction in gastric injury; the mechanisms underlying these effects include stimulation of endogenous prostaglandins, nitric oxide synthesis, opening of K(ATP) channels and reduction of free radicals or modulation of antioxidant enzyme systems.

Melatonin: Pharmacological Aspects and Clinical Trends

ABSTRACT Melatonin, N-acetyl-5-methoxytryptamine, the major hormone produced by the pineal gland under the influence of the dark/light cycle, has been shown to have a large number of therapeutic possibilities. It has been utilized in several countries for circadian rhythm disorders, sleep disturbances, jet lag, and sleep–wake cycle disturbances in blind people, and shift workers. In our mechanism of act, the Gi protein-coupled metabotropic melatonin receptors MT1 and MT2 are the primary mediators of the physiological actions of melatonin. This hormone plays an important role in the regulation of physiological and neuroendocrine functions, such as synchronization of seasonal reproductive rhythms and entrainment of circadian cycles. In addition to its chronobiological role, several pharmacological effects of melatonin have been reported in mammals including sedative, antioxidant, anxiolytic, antidepressant, anticonvulsant, and analgesic activities. There is some evidence from clinical trials that melatonin can be helpful in that event. Current trends of pharmacological functions of melatonin pointed out its use in the treatment of neurodegenerative and neoplastic diseases. These effects and uses of melatonin are mentioned but further confirmatory studies are needed in most of them.

Anxiolytic-like effects of standardized extract of Justicia pectoralis (SEJP) in mice: Involvement of GABA/benzodiazepine in receptor

Justicia pectoralis (Acanthaceae) is used as an antiinflammatory, antimicrobial and bronchodilator, and its extract exerts an anxiolytic‐like effect profile in animal models. This work presents the behavioral effects of an aqueous standardized extract of Justicia pectoralis (SEJP) in animal models, such as the elevated plus maze (EPM), light/dark, open field, rota rod and pentobarbital sleep time. The extract was administered intragastrically to male mice at single doses of 50, 100 and 200 mg/kg, while diazepam 1 or 2 mg/kg was used as a standard drug and flumazenil 2.5 mg/kg was used to evaluate the participation of benzodiazepinic receptors. The results showed that, similar to diazepam (1 mg/kg), SEJP significantly modified all the observed parameters in the EPM test, without altering the general motor activity in the open field, rota rod and pentobarbital sleep time tests. Flumazenil reversed not only the diazepam effect but also the SEJP effect. In the same way, all doses of SEJP increased the time of permanence in the light box in the light/dark test. The results showed that SEJP presented an anxiolytic‐like effect, disproving sedative effects. Copyright

TRP and ASIC channels mediate the antinociceptive effect of citronellyl acetate

BACKGROUND Citronellyl acetate (CAT), a monoterpene product of the secondary metabolism of plants, has been shown in the literature to possess several different biological activities. However, no antinociceptive abilities have yet been discussed. Here, we used acute pain animal models to describe the antinociceptive action of CAT. METHODS The acetic acid-induced writhing test and the paw-licking test, in which paw licking was induced by glutamate and formalin, were performed to evaluate the antinociceptive action of CAT and to determine the involvement of PKC, PKA, TRPV1, TRPA1, TRPM8 and ASIC in its antinociceptive mechanism. To do so, we induced paw-linking using agonists. RESULTS CAT was administered intragastrically (25, 50, 75, 100 and 200 mg/kg), and the two higher doses caused antinociceptive effects in the acetic acid model; the highest dose reduced pain for 4h after it was administered (200 mg/kg). In the formalin test, two doses of CAT promoted antinociception in both the early and later phases of the test. The glutamate test showed that its receptors are involved in the antinociceptive mechanism of CAT. Pretreatment with CAT did not alter locomotor activity or motor coordination. In an investigation into the participation of TRP channels and ASICs in CATs antinociceptive mechanism, we used capsaicin (2.2 μg/paw), cinnamaldehyde (10 mmol/paw), menthol (1.2 mmol/paw) and acidified saline (2% acetic acid, pH 1.98). The results showed that TRPV1, TRPM8 and ASIC, but not TRPA1, are involved in the antinociceptive mechanism. Finally, the involvement of PKC and PKA was also studied, and we showed that both play a role in the antinociceptive mechanism of CAT. CONCLUSION The results of this work contribute information regarding the antinociceptive properties of CAT on acute pain and show that, at least in part, TRPV1, TRPM8, ASIC, glutamate receptors, PKC and PKA participate in CATs antinociceptive mechanism.

Evaluation of the anti-inflammatory activity of riparin II (O-methil- N-2-hidroxi-benzoyl tyramine) in animal models

Riparin II (RipII), an alkamide isolated from the green fruit of Aniba riparia, was tested in the various animal models of inflammation to investigate its anti-inflammatory activity. Male Wistar rats (180-240g) were treated with RipII by gavage at doses 25 or 50mg/kg, before initiating the inflammatory responses. The tests used were paw edema induced by carrageenan, dextran, histamine or serotonin; peritonitis induced by carrageenan and fMLP, as well as the measurement of MPO activity, TNF-α and Il-1β amount in the peritoneal fluid. In the animal models of carrageenan and dextran-induced paw edema, the animals treated with RipII showed lower edema than those of the control group. Treatment with RipII also reduced the paw edema induced by histamine but not serotonin. In the carrageenan-induced peritonitis model, treatment with RipII reduced leukocyte migration, the MPO activity and the amount of TNF-α and IL-1β in the peritoneal fluid. In summary, these results indicate that RipII has an anti-inflammatory activity in chemical models of acute inflammation. RipII might be directly or indirectly inhibiting the activity, production or release of pro-inflammatory mediators involved in the generation of the pain associated with inflammation.