Effect Of Aqueous Extract Of Rauwolfia Vomitoria Root Bark On The Cytoarchitecture Of The Cerebellum And Neurobehaviour Of Adult Male Wistar Rats
M Eluwa, N Idumesaro, M Ekong, A Akpantah, T Ekanem
body weight, cerebellum, neurobehaviour, wistar rat
M Eluwa, N Idumesaro, M Ekong, A Akpantah, T Ekanem. Effect Of Aqueous Extract Of Rauwolfia Vomitoria Root Bark On The Cytoarchitecture Of The Cerebellum And Neurobehaviour Of Adult Male Wistar Rats. The Internet Journal of Alternative Medicine. 2008 Volume 6 Number 2.
Medicinal plants are re-emerging health aid which has been observed in developing countries probably fuelled by the rising costs of orthodox drugs in the maintenance of personal health and well being 1 . One of such medicinal plants is
The alkaloids of
Reserpine is the most abundant and most active alkaloid in
Animals show different behaviour when placed in an environment different from theirs. But if these same animals are for example drugged, they will show behavioural changes even in a known environment. To test the neurobehaviour of experimental animals, standard methods have been provided, but the most widely used is the ‘open field test' 9 . Thus this research is designed to investigate the effect of aqueous extract of
Materials And Methods
Fifteen adult male Wistar rats were bred in the animal house of the Department of Human Anatomy, University of Calabar. They were fed with normal rat chow and water was provided
Preparation of herb extract
The roots of
The animals were weighed before the commencement of the administrations and at the end of administrations. Groups A and B were administered 600mg/kg and 500mg/kg per body weight of
One-way analysis of variance (ANOVA) was used to compare the group's mean for the open field activities, for treatment or administration and their interactions. Thereafter the post-hoc test using student-Newman-Keul method was carried out to find the level of significance at p<0.05. All the results are expressed as mean±standard error of mean.
There was an increase in weight of rats in the control group while there were decreased weights in the experimental groups. Food and water intake was also reduced and the rats were inactive in the experimental groups.
There was a significant (p<0.01) weight loss observed in the two groups of animals administered 600mg/kg and 500mg/kg per body weight extract of
The line crosses of the control (group C) was significantly (p<0.001) higher than groups A and B. Both experimental groups almost had zero line crosses during the course of the experiments. This result is seen in Fig. 2.
Central square frequency and duration
There were no central square frequency and duration in the experimental groups compared to the control.
There were no stretch attends in the experimental groups compared to the control.
The rearing of the control was significantly (p<0.001) higher than the experimental groups. This result is seen in Fig. 3.
Both doses of extract of
The defecation of the control was significantly (p < 0.01, 0.001) higher than the experimental groups. However, the number of urine puddles was not significantly different between the groups and so was not shown
Photomicrograph of the control showed the cerebellar cortex made up of three layers: the outer molecular layer containing stellate and basket cells, the middle Purkinje layer with a single layer of large Purkinje cells, and the inner granular layer contain numerous granule and Golgi cells (Plate 1).
Photomicrograph from group A animals which received 600mg/kg of extract of
In group B, which received 500mg/kg of extract of
The reduction in weights observed in the experimental groups and their lack of activity may be due to the effect of the extract of
The open field apparatus is used to assess the emotionality of animals in a novel environment. It is also used to assess locomotor and exploratory behaviour 12 . The frequency of line crossing strongly correlates with the distance covered and it assesses the horizontal locomotion of the animals. The frequency of line crossing in the groups of rats administered 600mg/kg and 500mg/kg of
There were no central square frequency and duration as well as stretch attends in the experimental groups compared to the control. Since there was a significant lack of line crossing in the experimental groups, it follows that there will be no central square frequency and duration. The lack of stretch attend follows the inactivity of the animals in the experimental groups. Reserpine cause drowsy, hypnotic and sedative tendencies 11 , and these conditions usually result in lack of movement as seen in this study. Thus the animals never portrayed exploratory behaviour.
The frequency of rearing was also significantly lower in both test groups administered 600mg/kg and 500mg/kg of
Grooming is a displacement reaction. It also shows the level of excitability of the animal. In the study, the animals administered 600mg/kg and 500mg/kg of
The exploratory behaviours in rodents have also been used in the open field maze to assess excitability, emotionality and locomotor phenomena 13 . Since all the above parameters/behaviours were reduced following oral administration of both high and low doses of
This is consistent with the fact that one of the main alkaloids found in the plant extract, reserpine, has been found to have some depressive effects on the nervous system. Reserpine causes depletion of the peripheral stores of catecholamines, which accounts for much of the beneficial antihypertensive effect employed over the years 14 . However, depletion of central stores of neurotransmitter amines is responsible for the antipsychotic effects and consequently its adverse side effects such as sedation, depression inability to perform complex tasks and Pseudo-Parkinsonism 15,16 .
The number of faecal boli was also significantly decreased in the test groups when compared to control. This however may not be very informative as there is still some controversy over whether the number of faecal boli and number of urine puddles can be used to accurately assess the level of anxiety in animals in the open field apparatus 17 .
Locomotion activation results from brain activation which manifest as excitation of the central neurons and an increase in cerebral metabolism. Brown et al 18 reported that natural occurring locomotor activation (like searching, grooming and rearing) and inhibition (like rest and sleep) may differ in its underlying mechanisms from similar behaviours induced by drugs.
There were distortions observed in the experimental groups which received 600mg/kg and 500mg/kg of root bark extract of