Acute Administration of Methionine Affects Performance of Swiss Mice in Learning and Memory Paradigms.

Methionine, an essential amino acid, plays an essential role in the central nervous system CNS development. It serves as a crucial intermediate in the methylation, trans-sulfuration and amino- phosphorylationpathways,necessary for the synthesis of nucleic acids, phospholipids, hormones, neurotransmitters, antioxidants, polyamines, catecholamines and other biogenic amines. The effect of methionine on learning and memory in mice was investigated using Morris water maze (MWM), Elevated plus maze(EPM) and Y maze (YM). Animals were administered with distilled water (control), methionine (1,700mg/kg); folate (3mg/kg) or methionine (1700mg/kg) plus folate (3mg/kg) for 14 days. Escape latency and time spent in target quadrants; transfer latency and percentage spontaneous alternations were measured in the MWM, EPM and YM respectively. The animals were anaesthetized with inhalational chloroform and their brains subsequently harvested, homogenized and assayed for acetylcholinesterase24 hours after the experiment.Folate significantly(p<0.05) increased transfer latency (53.33 ± 12.62) as compared to control (20.1 ± 5.01) and reduced spontaneous alternations significantly (25.0 ± 8.9) when compared to control (44.33 ± 3.07). When folate was combined with methionine there was also a significant increase in transfer latency (43.0 ± 14.39) when compared with control (20.1 ± 5.01). Folate-methionine combination also significantly reduced spontaneous alternations (20.4 ± 8.4) as compared to the control (44.33 ± 3.07) much more than folate alone. Acetylcholinesterase activities in all groups were not statistically significant. It can be concluded that acute methionine administration has some benefits in memory enhancement. However, a short course folate supplementation impairslearning and working memory especially when combined with methioninewhich may be as a result of sudden overwhelming of the methylation cycle, leading to homocysteinemia which is pro-dementia.

Evaluation of the antipsychotic potential of aqueous fraction of Securinega virosa root bark extract in mice.

Securinega virosa (Roxb ex. Willd) Baill. is a plant which is commonly used in African traditional medicine in management of mental illness. Previous study showed that the crude methanolic root bark extract of the plant possesses antipsychotic activity. In this study, the antipsychotic potential of the residual aqueous fraction of the plant was evaluated using two experimental models, apomorphine induced stereotypic climbing behaviour and swim induced grooming, all in mice. The effect of the fraction on haloperidol-induced catalepsy was also evaluated. The fraction significantly reduced the mean climbing score at the highest dose tested (500 mg/kg). In the swim-induced grooming test, the fraction significantly and dose-dependently (125-500 mg/kg) decreased the mean number and mean duration of swim-induced grooming activity in mice. Similarly, the standard haloperidol (1 mg/kg) significantly (p < 0.001) decreased the mean grooming episodes and duration. However, the fraction did not significantly potentiate haloperidol-induced catalepsy. These results suggest that the residual aqueous fraction of methanol root bark extract of Securinega virosa contains biological active principle with antipsychotic potential.

Psychopharmacological potentials of methanol leaf extract of Securinega virosa Roxb (Ex Willd) Baill. in mice.

Schizophrenia is a highly disabling chronic psychiatric illness. The existing antipsychotic agents are associated with untoward effects and drug interactions leading to the intensification of search for newer agents with better efficacy and safety profile. Securinega virosa is a commonly used medicinal plant in African traditional medicine. The decoction of the leaves of the plant in combination with other plants is used in the management of mental illness. In this study, we evaluate the antipsychotic potential of the methanol leaf extract (25, 50 and 100 mg kg(-1)) of the plant using apomorphine-induced stereotypic climbing behavior and swim-induced grooming tests, all in mice. The CNS depressant effect was also evaluated using ketamine-induced sleep test mice. The extract at the highest dose tested (100 mg kg(-1)) significantly reduced the apomorphine (1 mg kg(-1))-induced stereotypic climbing behavior after 30 min. Similarly, haloperidol (2 mg kg(-1)), the standard agent significantly (p<0.001) decreased the mean climbing behavior. In the swim-induced grooming test, the extract significantly (p<0.01) and dose-dependently decreased the total grooming time. Similarly, haloperidol (2 mg kg(-1)) significantly (p<0.001) decreased the mean grooming activity. The extract significantly increased the total ketamine-induced sleep duration at doses of 50 and 100 mg kg(-1). These findings suggest that the extract possesses antipsychotic and sedative potentials and lend credence to the ethnomedical use of the leaves of the plant in the management of mental illness.

Behavioural effects of the methanolic root bark extract of Securinega virosa in rodents.

Securinega virosa is used traditionally as sedative in children and in mental illnesses. In this study, the behavioral effects of methanolic root bark extract of S. virosa were investigated in mice. The results revealed that the extract significantly (P<0.05) and dose-dependently reduced the onset and prolonged the duration of sleep. The extract significantly (P<0.05) decreased exploratory activity and reduced the rate of apomorphine-induced stereotyped climbing at the doses tested (6.25-25 mg/kg). It also produced a significant and dose-dependent motor coordination deficit in mice at the doses tested (P<0.01). The intraperitoneal median lethal dose in mice was 774.6 mg/kg while the preliminary phytochemical screening revealed the presence of alkaloids, tannins, saponins and flavonoids. These results suggest that methanolic root bark extract of S. virosa contains biologically active principles that are sedative in nature and lend pharmacological credence to the ethnomedical use of the plant.

PRELIMINARY GASTROINTESTINAL STUDIES OF METHANOL EXTRACT OF INDIGOFERA PULCHRA WILLD IN RODENTS.

In this study, the effect of the methanol extract of Indigofera pulchra Willd. (Papillionaceae) was investigated against castor oil induced diarrheoa. Its effects on perfused isolated rabbit jejunum and guinea pig ileum were also evaluated. The extract produced a dose-dependent protection against the castor oil-induced diarrheoa in mice with the highest protection (100%), obtained at 200 mgkg-1 comparable to that of loperamide (5 mgkg-1), a standard antidiarrhoeal drug. The extract (0.4 - 6.4 mgml-1) produced a concentration relaxation of the rabbit jejunum. However, no observable effect was noticed when the guinea pig ileum was treated. The extract blocked the contractile effect of acetylcholine (2 × 10-8 gml-1) and histamine (4 × 10-7 gml-1) on both rabbit jejunum and guinea pig ileum. Phytochemical screening revealed the presence of flavonoids, tannins, saponins and steroids. The intraperitoneal median lethal dose (LD50) value for the extract was found to be 2154.0 mgkg-1. The results obtained revealed that the extract possesses pharmacologically active compounds with gastrointestinal relaxant and antidiarrhoeal activities and may possibly explain the use of the plant in traditional medicine for the treatment of gastrointestinal disorder.