Effect of Aqueous Extract Rauvolfia Vomitoria Roots on the Hippocampus of Wistar Rats


Zainab Mahmood Bauchi
Department of Human Anatomy, Faculty of Medicine, Ahmadu Bello University, Zaria zbauchi@abu.edu.ng +2348028543774
Kenneth James Jamo
Department of Human Anatomy, Faculty of Medicine, Ahmadu Bello University, Zaria
Sunday Abraham Musa
Department of Human Anatomy, Faculty of Medicine, Ahmadu Bello University, Zaria
Akpulu Stephen Peter
Department of Human Anatomy, Faculty of Medicine Ahmadu Bello University, Zaria
Abdulwahab Alhassan
Department of Human Physiology, Faculty of Medicine, Ahmadu Bello University, Zaria

All Correspondence to: Zainab Mahmood Bauchi Department of Human Anatomy, Faculty of Medicine,
Ahmadu Bello University, Zaria zbauchi@abu.edu.ng +2348028543774

Rauvolfia vomitoria is a natural medicinal herb which has been used over the years for the treatment of hypertension and mental disorders. The effect of aqueous extract of Rauvolfia vomitoria root bark on the cyto-architecture of the hippocampus and the weights of adult male Wister rats was studied. 20 Wister rats weighing between 200g to 350g were used for this study. They were divided into four groups, 1, 2, 3 and 4 of five rats each. Groups 2, 3 and 4 were the experimental groups, while group 1 was the control group. Oral doses of 250mg mg, 500mg/mg and 1000mg/kg of body weight were administered to rats in groups 2, 3 and 4 respectively for fifteen days while group 1 (the control) received distilled water. Weights of the animals were taken intermittently in the course of the administration. On the sixteenth day, the animals were humanely sacrificed. There were observed reduction in the weights of the experimental groups compared to the control, which were found to be statistically insignificant. Histological results showed distortion of the pyramidal cells in the pyramidal layer of the hippocampus, compared to the control group. This extract affects the hippocampal cytoarchitecture and has no significant effect on weight. Thus the use of the drug should be limited to management of diseased conditions at well monitored and regulated dosages.
Key words: cytoarchitecture, weight, oral administration, pyramidal cells.

Drugs of plants origins have served through the ages as the mainstay in the treatment of variety of diseases and preservation of human health (Pousset and Poisson, 1965). Rauvolfia vomitoria is one of such widely used plants for medicinal purposes. Rauvolfia vomitoria is a medicinal plant which grows in the humid and tropical secondary forests of Africa and used traditionally to treat variety of ailments (Sofowora, 1993).
Rauvolfia vomitoria preparations are used in the treatment of ailments of the central nervous system such as: Psychosis, Schizophrenia, insanity, insomnia, epilepsy and management of hypertension. It is also used as a sedative; an antipyretic, anticancer, anxiolytic and emetic preparation (Oliver- Bever, 1982; Principe, 1989; Oudhia, 2002). In combination with lime (citrus aurantium), it has shown positive results in the treatment of type-2 diabetes (Campbell and Mcgaard, 2006).
Rauvolfia vomitoria afzel is a plant native to the coasts and inlands of West Africa (Sofowora, 1982). This plant is
popular amongst herbalists and traditional physicians, mostly of the cultures of west to central Africa. The plant is known in English as swizzle stick (poison devils’ pepper). Local names include: Akata in Edo; Mmoneba Uto Enyin in Efik; Wada in Hausa; Akanta in Ibo and Asofeye in Yoruba (Muango, 2009).
The hippocampus forms part of the structures that make up the medial edges of the cerebral cortex called the limbic system. The hippocampus is involved in the encoding process of short term explicit memory, spatial memory and learning and also involved in olfaction (Singh, 1997; Ganong, 2006). The extracts of Rauvolfia vomitoria are implicated in the treatment of some hippocampal disorders thus the extracts have a direct effect on the hippocampus.
This research work aims to establish the actual effect of Rauvolfia vomitoria on the cytoarchitecture of the hippocampus as well as to investigate if those effects can have consequential effects on physically observable changes on the experimental animals (The adult male Wistar rats).

Leaves of Rauvolfia vomitoria were collected from Emagaba II, Ogugu Kogi State. Sample was taken from the whole collection for identification in the herbarium of the Department of Biological Sciences of A.B.U. Zaria where it was then identified as Specimen Voucher 2719. Roots of the plant were collected in bulk and put up for extraction in the department of Pharmacognosy and Drug Development (ABU Zaria). The roots were dried under laboratory conditions (temperature and pressure) and then grounded to powder using a pistil and mortar. The powdered root of Rauvolfia vomitoria weighing about 2kg was soaked in 4 litres of distilled water for about 24 hours. The filtrate was then collected in a beaker using separating funnel. The water in it was then evaporated on an evaporating dish in a hot water bath powered by electricity. The set up was allowed to run for 24 hours after which the thick, brownish extract weighing about 62.8g was then collected for onward toxicity studies and administration.

20 Wistar rats (Rattus norvegnus) used in this study were obtained from the department of Human Anatomy, ABU Zaria. These animals were housed in a clean environment, kept in separate cages and provided with food and water for two (2) weeks to acclimatize. Efforts were put in as much as possible, in the handling of the animals, to conform to conventional guidelines of the Natural Regulation for Animal Research Reviewed Protocols which were consonant with the International Animal Welfare Guideline.

Twenty (20) male Wistar rats, weighing 200-350kg were used for the rest of the studies. They were divided into four groups: I, II, III and IV with each group comprising of five animals and administered the aqueous root extract of Rauvolfia vomitoria orally for 15 days.
Group I: Received distilled water

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