ABSTRACT
Background: Crinum zeylanicum is widely used in the ethno-therapeutic management of folk management of epilepsy, pain, neuropsychiatric, and dementing disorders in Nigeria. The current study was carried out to evaluate the possible mechanism of the memory enhancing the effect of C. zeylanicum extract and alkaloidal rich fraction in Wistar rats. Methods: The effect of Crinum zeylanicum bulb extract (250, 500, and 1000 mg/kg body weight orally), alkaloidal rich fraction (10, 20, and 40 mg/kg body weight p.o.), normal saline (10 ml/kg orally), or Eserine (0.3 mg/kg body weight i.p.) on spatial memory in rats was evaluated using the Y-maze. The blood samples obtained from rats in all treatment groups were evaluated for cholinesterase activities using modified Michelle electrometric method. Results: The extract and the alkaloid significantly (p<0.05) and dose-dependently increased spontaneous alternation behavior of rats in Y-maze. The extract produced 20.00%, 35.55%, and 52.00% inhibition of cholinesterase activity in the blood at 250, 500, and 1000 mg/kg body weight, respectively. The alkaloid produced 56.67%, 62.67%, and 68.67% inhibition of cholinesterase activity in blood at 10, 20, and 40 mg/kg body weight (p.o.). Eserine a standard cholinesterase inhibitor at 0.3 mg/kg body weight produced a significant increase in spontaneous alternation behavior and produced 73.33% inhibition of blood cholinesterase activity. Data obtained from the study showed that the enhanced spontaneous alternation behavior observed in rats treated with the extract, and the alkaloid may be due to facilitation of cholinergic transmission resulting from inhibition of cholinesterase activity. Conclusion: The extract, as well as its partially purified alkaloid, possesses potential that may be employed for therapeutic management of Alzheimer’s disease.
ABSTRACT
The use of β- adrenoceptor blocking agents (β -blockers) in the clinical treatment of cardiovascular disorders and glaucoma are associated with enhancedvigilance, attention, reward, learning and memory. The present study was designed to explore the possible role of Carvedilol, an adrenergic antagonist in ameliorating scopolamineinduced neurotoxicity in rats. Mice were divided into control and treatment groups. Control mice for each test received 10 ml normal saline/kg while the treatment groups (n = 6) received Carvedilol (2.5, 5 and 10 mg/kg orally) and1 mg scopolamine/kg intraperitoneally). One hour after sildenafil and thirty minutes after scopolamine administration orally and intraperitoneally respectively, the animals were assessed for 5 minutes on elevated plus maze, Y-maze and open-field. The parametersmeasured on the EPM were memory acquisition and memory retention latencies with and without scopolamine while spontaneous alternation behaviour was measured in Ymaze. The effect of Carvedilol on locomotion was assessed in mice using open field.Carvedilol significantly (p<0.001) shortened memory acquisition and retrieval latencies in mice with scopolamine–induced cognitive deficit. Carvedilol produced significant (p<0.0001) increase in spontaneous alternation behaviour in both memory intact and memory deficit models. Carvedilol however, had no effect on locomotor activity of mice. The results suggest that Carvedilol enhanced memory acquisition and retrieval in cognitive deficit and cognitive intactmice.It also improved short term memory as indicated by increase in spontaneous alternation behaviour in mice.Carvedilol may therefore be useful in management of dementing disorders such as Alzheimer’s disease.