Ethanolic extract of Erythrina velutina Willd ameliorate schizophrenia-like behavior induced by ketamine in mice.

Background Schizophrenia is a chronic mental disorder, characterized by positive, negative and cognitive symptoms. In general, several plants have shown activity in diseases related to the central nervous system (e.g., Erythrina velutina (EEEV), also known as "mulungu"). For this reason, we aimed to investigate the effects of standardized ethanol extract obtained from the stem bark of EEEV on the schizophrenia-like behaviors induced by ketamine (KET) administration. Methods Swiss mice were treated with KET (20 mg/kg, i.p.) or saline for 14 days. In addition, from 8th to 14th days, saline, EEEV (200 or 400 mg/kg, p.o.) or olanzapine (OLAN 2 mg/kg, p.o.) were associated to the protocol. On the 14th day of treatment, schizophrenia-like symptoms were evaluated by the prepulse inhibition of the startle reflex (PPI), locomotor activity evaluated by the open field test (OFT), spatial recognition memory evaluated by the Y-maze task and social interaction test (SIT). Results KET has caused deficits in PPI, and it has also has caused hyperlocomotion in OFT and deficits in SIT as compared to control. EEEV in both doses used, reversed behavioral changes induced by KET, likewise results obtained with the administration of OLAN. Conclusions Taken together, the results demonstrate that the standard extract of EEEV was able to revert schizophrenia-like symptoms, due to the administration in repeated doses of ketamine. Thus, our findings lead to a new perspective for the use of EEEV an interesting alternative for drug discovery in schizophrenia.

Involvement of monoaminergic systems in anxiolytic and antidepressive activities of the standardized extract of Cocos nucifera L.

Extracts from the husk fiber of Cocos nucifera are used in folk medicine, but their actions on the central nervous system have not been studied. Here, the anxiolytic and antidepressant effects of the standardized hydroalcoholic extract of C. nucifera husk fiber (HECN) were evaluated. Male Swiss mice were treated with HECN (50, 100, or 200 mg/kg) 60 min before experiments involving the plus maze test, hole-board test, tail suspension test, and forced swimming test (FST). HECN was administered orally (p.o.) in acute and repeated-dose treatments. The forced swimming test was performed with dopaminergic and noradrenergic antagonists, as well as a serotonin release inhibitor. Administration of HECN in the FST after intraperitoneal (i.p.) pretreatment of mice with sulpiride (50 mg/kg), prazosin (1 mg/kg), or p-chlorophenylalanine (PCPA, 100 mg/kg) caused the actions of these three agents to be reversed. However, this effect was not observed after pretreating the animals with SCH23390 (15 µg/kg, i.p.) or yohimbine (1 mg/kg, i.p.) The dose chosen for HECN was 100 mg/kg, p.o., which increased the number of entries as well as the permanence in the open arms of the maze after acute and repeated doses. In both the forced swimming and the tail suspension tests, the same dose decreased the time spent immobile but did not disturb locomotor activity in an open-field test. The anxiolytic effect of HECN appears to be related to the GABAergic system, while its antidepressant effect depends upon its interaction with the serotoninergic, noradrenergic (α1 receptors), and dopaminergic (D2 dopamine receptors) systems.

Inhibition of ketamine-induced hyperlocomotion in mice by the essential oil of Alpinia zerumbet: possible involvement of an antioxidant effect.

OBJECTIVES: The antipsychotic, hypnotic, myorelaxant and antioxidant effects of the essential oil of Alpinia zerumbet (EOAZ) were studied. METHODS: EOAZ (50, 100 and 200 mg/kg i.p.) was administered once to mice for the determination of antipsychotic activity (evaluated by ketamine-induced hyperlocomotion), hypnotic activity (induced by sodium pentobarbital, 40 mg/kg i.p.), motor coordination (rotarod test), antioxidant effects (determination of lipid peroxidation and GSH levels), as well as alterations in nitric oxide levels (determination of nitrite content). KEY FINDINGS: EOAZ at doses of 100 and 200 mg/kg prevented ketamine hyperlocomotion, as did haloperidol (0.2 mg/kg i.p). EOAZ at a dose of 200 mg/kg decreased sleep latency, while all doses increased sleeping time. There was no effect on motor coordination. The in-vitro antioxidant capacity of the oil caused a decrease in lipid peroxidation and increase in GSH levels. EOAZ also prevented the decrease in nitrite content caused by oxidative stress. CONCLUSIONS: The results suggest antipsychotic and antioxidant effects for the EOAZ that may have promising efficacy for the treatment of schizophrenia.

Central nervous system effects of the essential oil of the leaves of Alpinia zerumbet in mice.

OBJECTIVES: Alpinia zerumbet, known in Brazil as colônia, is popularly used as a diuretic, antihypertensive, anti-ulcerogenic and sedative. Based on this, we have investigated the central effects of the essential oil isolated from A. zerumbet leaves. METHODS: Mice were treated once with 50 or 100 mg/kg of the essential oil, intraperitoneally, 30 min before being submitted to behavioural models of: locomotor activity (open-field), catalepsy, anxiety (elevated plus maze), depression (forced swimming test and tail suspension tests) as well as apomorphine-induced stereotypy. KEY FINDINGS: Results showed a dose-related decrease on locomotor activity and apomorphine-induced stereotypy. There was a decrease to the order of 55% of the grooming behaviour with both doses studied. The essential oil 100 mg/kg increased cataleptic activity (167%) and the immobility time in the forced swimming and tail suspension tests. Pretreatment with haloperidol (0.2 mg/kg, i.p.) alone also decreased locomotion, increased cataleptic activity and immobility time in the tail suspension test. No alterations in the elevated plus maze test were registered. CONCLUSIONS: The essential oil of A. zerumbet leaves had depressant and possible antipsychotic activity, since it could reverse the stereotypy induced by apomorphine, presenting effects comparable with those obtained with haloperidol treatment.

Antianxiety effects of riparin I from Aniba riparia (Nees) Mez (Lauraceae) in mice.

This work presents the behavioral effects of riparin I (methyl ether of N-benzoyl tyramine) from unripe fruit of Aniba riparia (Lauraceae) on the elevated plus maze, open field, rota rod and hole board tests in mice. Riparin I was administered acutely by intraperitoneal (i.p.) and oral routes to male mice at doses of 25 and 50 mg/kg. The results showed that riparin I (25 and 50 mg/kg, i.p. and per os) increased the number of entries and the time of permanence in the open arms in the plus maze test. Similarly, in the hole board test, riparin I in both routes increased the number of head dips. Riparin I with both doses and routes had no effects on spontaneous motor activity in mice or in the rota rod test, but decreased the number of groomings. These results showed that riparin I by both administration routes has effects on the central nervous system with antianxiety effects on the plus maze and hole board tests. The substance is devoid of myorelaxant effects.

Cocaine alters catalase activity in prefrontal cortex and striatum of mice.

Catalase is one of the enzymes that convert hydrogen peroxide (H2O2) to H2O presenting a protective role against free radicals. In this study, catalase activity was determined in homogenates of striatum (ST) and prefrontal cortex (PFC) in order to examine the participation of oxidative stress (OS) on cocaine actions in mice brain. Male Swiss mice were injected (i.p.) with cocaine at low (10 and 30 mg/kg) and high doses (90 mg/kg), and observed for 1 h. After cocaine overdose (90 mg/kg) some animals presented only status epilepticus (SE) while others died after seizures. These animals were dissected and divided in two groups, SE and death. Catalase activity was also determined after pretreatment with the anticonvulsant drug, diazepam, alone or injected before cocaine 90 mg/kg, and after seizures induced by a high dose of bupropion, a known inhibitor of NE and DA reuptake used for comparison. Results showed a decrease in catalase activity of the PFC and ST after SE and death induced by cocaine and bupropion overdoses. Cocaine at low doses decreased the enzyme activity only in ST. Diazepam treatment alone and before cocaine overdose did not interfere with catalase activity. This reduction in catalase activity may reflect an increase in H2O2 content in PFC and ST. Previous data reports that H2O2 inhibits dopamine transporter activity, suggesting that the decrease in catalase activity may potentiate the toxic mechanism of drugs that inhibit monoamines reuptake. As far as we know, this is the first report showing an involvement of OS in the cocaine's central mechanism of action.

Study of antinociceptive effect of isolated fractions from Petiveria alliacea L. (tipi) in mice.

The acetate (FA), hexanic (FH), hydroalcoholic (FHA) and precipitated hydroalcoholic (FHAppt) fractions from the root of Petiveria alliacea L. were evaluated for antinociceptive effect using the abdominal constriction induced by acetic acid, hot-plate, formalin tests. The open field and rota rod tests were used to evaluate psychomotor function and myorelaxant activity. The fractions were administered intraperitoneally in mice at doses of 100 and 200 mg/kg. Inhibitions of abdominal constrictions were observed with all doses of the fractions, as compared to control. FH and FHAppt, at both doses, reduced the nociception produced by formalin in the 1st (0-5 min) and 2nd (20-25 min) phases, however FHA (100, 200 mg/kg) and FA 200 mg/kg presented significant inhibition on the 1st and 2nd phases, respectively, of this test. A reduction of the locomotor activity was observed in the open field test with all the fractions. These fractions failed to affect the motor coordination in the rota rod test. Results showed that the different fractions of Petiveria alliacea L. have different antinociceptive potentials as demonstrated in the experimental models of nociception in mice, supporting folk medicine use of this plant.

Antidiabetic activity of Bauhinia forficata extracts in alloxan-diabetic rats.

The antidiabetic activity of aqueous, ethanolic and hexanic extracts of Bauhinia forficata was investigated in a model of alloxan-induced diabetes in rats. The biochemical parameters studied were: plasma glucose, serum triglycerides, cholesterol, high density lipoprotein (HDL), and low density lipoprotein (LDL). Extracts were administered daily for 7 d at doses of 200 and 400 mg/kg, p.o., 48 h after alloxan injection (60 mg/kg, i.v.). The alloxan-diabetic rats showed significant reductions in plasma glucose, triglycerides, total cholesterol and HDL-cholesterol after treatment with the extracts and glibenclamide (used as standard) as compared to the diabetic controls. Levels of LDL were not altered. In conclusion, our results showed that the plant extracts when administered by gavage may reduce glucose, triglycerides, total cholesterol and HDL-cholesterol levels. These results suggest the validity of the clinical use of B. forficata in the treatment of diabetes mellitus type II.