Effect of Mimosa pudica (Linn.) extract on anxiety behaviour and GABAergic regulation of 5-HT neuronal activity in the mouse.

Mimosa pudica (Linn.) (M. pudica L.) is a plant used in some countries to treat anxiety and depression. In the present study we investigated the effects of an aqueous extract of M. pudica L. on mouse anxiety-like behaviour using the elevated T maze, and on regulation of dorsal raphe nucleus (DRN) 5-hydroxytryptamine (5-HT) neuronal activity using an in-vitro mouse brain slice preparation. Acute treatment with M. pudica L. extract had an anxiolytic effect on behaviour in the elevated T maze, specifically on inhibitory avoidance behaviour. Acute application of the extract alone had no effect on the activity of DRN 5-HT neurones. However, when co-applied with the GABA(A) receptor agonist THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol), the extract enhanced the inhibitory effect of the THIP on DRN 5-HT neurones. These observed effects of M. pudica L. on both behaviour and GABA modulation of 5-HT neuronal activity are similar to the effects of diazepam, the established anxiolytic and positive modulator of the GABA(A) receptor. This study suggests that the aqueous extract of M. pudica L. contains a positive modulator of GABA(A) receptor function and provides impetus for further investigation of the neuropharmacologically active constituents of the extract.

Anxiolytic activity evaluation of four medicinal plants from Cameroon.

Afrormosia laxiflora (A. laxiflora), Chenopodium ambrosioides (C. ambrosioides), Microglossa pyrifolia (M. pyrifolia) and Mimosa pudica (M. pudica) are plants used in traditional medicine in Cameroon to treat insomnia, epilepsy, anxiety, and agitation. They were evaluated for their anxiolytic like activity in mice. Animal models (elevated plus maze and stress-induced hyperthermia tests) were used. The four plants showed anxiolytic activity. In stress-induced hyperthermia test, A. laxiflora, C. ambrosioides, M. pyrifolia and M. pudica significantly antagonised the increase of temperature. ΔT° decreased from 0.75°C in the control group to 0.36°C at the dose of 110 mg/kg for A. laxiflora; from 1°C in the control group to -1.1°C at the dose of 120 mg/kg for C. ambrosioides; from 1.7°C in the control group to 0.2°C at the dose of 128 mg/kg for M. pyrifolia and from 1.3°C in the control group to 0.5°C at the dose of 180 mg/kg for M. pudica. In the elevated plus maze test, the four plants increased the number of entries into, percentage of entries into, and percentage of time in open arms. A. laxiflora, C. ambrosioides and M. pudica also reduced the percentage of entries and time in closed arms. In addition, C. ambrosioides, M. pyrifolia and M. pudica showed antipyretic activity by reducing the body temperature. The results suggested that C. ambrosioides, M. pyrifolia and M. pudica posses anxiolytic-like and antipyretic activities while A. laxiflora possesses only anxiolytic-like properties. These plants could be helpful in the treatment of anxiety and fever in traditional medicine in Cameroon.

Hypoglycaemic and antihyperglycaemic activity of Ageratum conyzoides L. in rats.

The hypoglycaemic and antihyperglycaemic properties of the aqueous extracts of the leaves of Ageratum conyzoides L. were evaluated in normoglycemic and in streptozotocin-induced diabetic rats, in order to validate its use in folk medicine. Tested animals were given the aqueous extracts of the plant at the doses of 100, 200 and 300mg/kg. These doses were tested also on glucose loaded normal male rats (Oral Glucose Tolerance Test). Of all the doses, the aqueous extracts at 200 and 300mg/kg showed statistically significant hypoglycaemic and antihyperglycaemic activities. For the oral glucose tolerance test, 100mg/kg dose only attenuated significantly the rise of blood glucose in normal fasted rats. Consequently, these results confirmed the hypoglycaemic properties of the leaves of Ageratum conyzoides.

Teratogenic effects, acute and sub chronic toxicity of the leaf aqueous extract of Ocimum suave Wild (Lamiaceae) in rats.

The aqueous extract from the leaves of Ocimum suave was evaluated for acute and sub chronic toxicity and teratogenic effects. Swiss mice were administered single oral doses of 2000, 4000, 6000 and 8000 mg/kg and monitored for death and body weight gained for 7 days (acute toxicity). In sub-acute toxicity, experimental rats, received daily doses of 250, 500 and 1000 mg/kg for 42 consecutive days and the toxic effects were assessed using biochemical and haematological data and histology of vital organs. In a teratogenic study, 1-day pregnant rats were administered orally 500 and 1000 mg/kg of extract daily for 21 consecutive days and 14th day corpora lutea and foetal implants and litter size at birth were noted. Reproductive performance of F(1) generation rats was studied by crossing them at maturity and recording the number, birth weight and physical presentation of the young offspring. Acute intake of extract up to 8000 mg/kg did not produce mortality or significant changes in general behaviour. Sub chronic treatment did not show any change in body and organ weights, feeding habits or behaviour between the control and the treated groups of both sexes. Haematological analysis and blood biochemistry revealed no toxicity effects of the extract. No gross abnormalities or histological changes were observed. Teratogenic and fertility studies did not reveal any toxic manifestations or foetal abnormalities. The leaf aqueous extract of Ocimum suave is non toxic in acute and sub chronic intake.

Antioxidant potential of the methanol-methylene chloride extract of Terminalia glaucescens leaves on mice liver in streptozotocin-induced stress.

AIM: The antioxidant effect of the methanol-methylene chloride extract of Terminalia glaucescens (Combretaceae) leaves was investigated in streptozotocin (STZ)-induced oxidative stress. METHODS: Oxidative stress was induced in mice by a daily dose of STZ (45 mg/kg body weight i.p.) for five days. From day one, before STZ injection, normal and diabetic-test mice received an oral dose of the extract (100 or 300 mg/kg b.w.) daily. Plasma metabolites, lipid peroxidation, and antioxidant enzymes in the liver were assessed and gain in body weight recorded. RESULTS: In normal mice the plant extract reduced food and water intake, blood glucose and LDL-C level and body weight gain, did not affect the lipid peroxidation in the liver, while the antioxidant enzyme activities seemed increased. Blood glucose was decreased (P < 0.05) in normal mice treated with 300 mg/kg extract. Diabetic mice pretreated with 100 mg/kg extract as diabetic control mice (DC) showed significant (P < 0.001) body weight loss, polyphagia and polydipsia, high plasma glucose level, decrease in the liver catalase, peroxidase, and superoxide dismutase activities, and increase in lipid peroxidation. The HDL-C level was lowered (P < 0.05) whereas LDL-C increased. In 300 mg/kg extract-pretreated diabetic mice the extract prevented body weight loss, increase of blood glucose level, lipid peroxidation in liver, food and water intake, and lowering of plasma HDL-C level and liver antioxidants; this extract prevented LDL-C level increase. CONCLUSION: These results indicate that T. glaucescens protects against STZ-induced oxidative stress and could thus explain its traditional use for diabetes and obesity treatment or management.