A Study Of The Cardiovascular Toxic Effects Of Zingiber Officinale (Ginger) In Adult Male Albino Rats And Its Possible Mechanisms Of Action

Abstract

Ginger is a world known food plant which is equally reputed for its medicinal properties. The aim of the work is to study the acute and subacute cardiovascular toxicity of ginger in adult male albino rats and its possible mechanisms of action. The in- vivo studies included eighty four adult male albino rats for the acute and subacute toxicity experiments. The rats were divided into 7 groups each one consisted of 12 rats. All rats received ginger orally in saline. Each of the in- vivo studies included 2 control groups, the negative and positive control rats. In the acute toxicity study, rats received ginger in a single dose of 2500 mg/ kg. In the subacute toxicity study group VI and VII received ginger in a daily dose of 50 mg/ kg and 500 mg/ kg respectively for 28 days. After 24 hours of the acute toxicity and 28 days of the subacute experiments six rats of each group were used for blood pressure and heart rate recording. The other 6 rats were used for histopathological study of the cardiac tissue. The in- vitro experiments included 6 rabbits each weighing 1.5- 2 kg. Ginger (5mg/ml) was incubated with the aortic spiral strip of each rabbit to investigate the possible mechanisms of action of Ginger. It was concluded that; single dose of 2500 mg/ kg ginger can be a toxic by causing severe hypotension and bradycardia with induction of prenecrotic changes in cardiac tissue. The administration of ginger in a dose of 50 mg/ kg for 28 days produced bradycaria with waviness in cardiac muscle fibers. Ginger in a dose of 500 mg/ kg produced both hypotension and bradycardia with degenerative changes in cardiac myocyte tissue. The hypotensive and bradycardic effects of ginger may be partially due to induction of vasodilatation by increasing nitric oxide release or synthesis and partially due to a calcium channel blocking effect. Also, a cholino-mimetic effect could be contributed in the cardiovascular effects of ginger. While the In-vitro results revealed that ginger is a partial vasorelaxant as it produced a relaxant effect on rabbit's aortic strip procontracted with phenylephrine, while preincubation with L-nitroarginine methyl ester (L-NAME) significantly attenuated the ginger-induced relaxation indicating that the vasodilator effect of ginger is partially mediated through nitric oxide synthesis or release from L-NAME.