Research reportRauwolfia vomitoria inhibits olfaction and modifies olfactory bulb cells

- Body weight loss resulting from either/both appetite loss or sedation.
- Poor performance in the buried food test possibly from olfaction inhibition.
- Traumatic neuronal and astroglia changes in the olfactory bulb.

The rising cost of orthodox medication has endeared so many to the use of herbs for the management of neurological conditions. Rauwolfia vomitoria (RV) one of such herbs is a rainforest shrub whose parts are used locally in the management of psychiatry and other medical issues. Its usefulness though not in doubt is wrapped with adverse reports as its active constituents depletes brain monoamine and dopamine stores. This motivated this research on the effects of the root bark extract on olfaction and the olfactory bulb of adult Wistar rats. Eighteen adult Wistar rats (220 g average) were divided into three groups (n = 6); control (placebo), 200 mg/kg and 400 mg/kg RV root bark extract, respectively. The oral administration lasted for seven days and on day 8, test of olfaction was carried out and the animals immediately anaesthetized with ketamine hydrochloride (i.p.) and perfuse-fixed with 10% neutral buffered formalin. All the brains were processed for histology and immunoreactivity. Results showed loss of body weights and olfaction in the 200 mg/kg and 400 mg/kg RV groups. There was hypertrophy and atrophy of mitral cells respectively, in the 200 mg/kg and 400 mg/kg RV groups, while there was hyperplasia of cells in the internal granular and plexiform layers of both groups. There was decreased neuron specific enolase (NSE) and neurofilament (NF) expression in the 200 mg/kg RV group, while NF and glial fibrillary acidic protein (GFAP) expression was decreased in the 400 mg/kg RV group. However, NSE expression was enhanced in the 400 mg/kg group, while GFAP expression was enhanced in the 200 mg/kg RV group. These results suggest that these doses of RV affect olfaction and appetite, and stimulate adverse cellular changes in the olfactory bulb.