Microstructure of the dentate gyrus and spontaneous alternation behaviour of male Wistar rats following Rauvolfia vomitoria and Gongronema latifolium extracts administration

Abstract

Rauvolfia vomitoria (RV) and Gongronema latifolium (GL) are medicinal plants used for the local treatment of various health issues. Their activities on the brain motivated this investigation on the histology and immunohistochemistry of the dentate gyrus and spontaneous alternation behaviour (SAB) of adult Wistar rats following RV root bark and GL leaf extract administrations. Twenty young adult Wistar rats (130–160 g) were assigned into four groups: Group 1 served as the control (5 mL/kg of distilled water placebo), while the test groups 2–4 were, respectively, singly administered 200 of mg/kg of RV, 200 of mg/kg of GL, and their combination. The administrations were oral and lasted for seven days. A T-maze SAB test was carried out, and the animals were sacrificed immediately after ketamine hydrochloride intraperitoneal anaesthesia. Serial sections of the hippocampal region from perfused rat brains were stained with Cresyl fast violet and immunolabelled with neuronal nuclei (NeuN) for neurons and glial fibrillary acidic protein (GFAP) for astrocytes. Results indicated that SAB was significantly (p < 0.05) lower in the test groups. Histologically, Nissl was less distributed in the RV and GL-only groups but not in the combined group, while there was less NeuN positivity in the RV group, with the GL and RV + GL groups not affected. There was less positive GFAP expression in individual RV and GL groups, but not in the RV + GL combined group, all compared with the control. In conclusion, the combination of RV and GL did not improve SAB but modulated Nissl, NeuN, and GFAP expression in the dentate gyrus.