Some histological and histochemical effects of Aqueous extract of the leaves of Neem on the superior colliculus and lateral geniculate body of adult male Wistar Rats ( Rattus norvegicus )
Objectives: This study investigated the effect of the crude extract of the leaves of Azadirachta indica on the intracranial visual relay centers of adult male Wistar rats. It also investigated the effects of the extract on the activities of some enzymes of carbohydrate metabolism namely lactate dehydrogenase (LDH), succinate dehydrogenase (SDH) and NADH-diaphorase. This was with a view to evaluating its effect on the histology of the superior colliculus and lateral geniculate body of Wistar rats. Methods: Thirty-six adult male Wistar rats with an average weight of 200g were distributed into 6 groups A to F. Groups A to E were treated orally with crude extract of Neem leaves at different repeated doses of (500, 400, 300, 200 and 100) mg/ml per kg body weight respectively for 3, 5, 7, 9 and 11 days. Each group had a pair–matched control. The rats were sacrificed on days 4, 6, 8, 10 and 12 days respectively and the superior colliculus and lateral geniculate body were examined microscopically after staining for histological and histochemical analyses.Group F served as the withdrawal effect group to determine the level of tolerance of the animals to the administered extract. Results: The results showed distortions in the histoarchitecture of the superior colliculus and lateral geniculate body of rats treated with crude extract of Neem leaves at the dose of 100mg/ml per kilogram body weight for 11 days. On microscopic evaluation, it was observed that the  histochemical staining intensities showing the activity of LDH, SDH and NADH-diaphorase decreased in treatment groups of both the superior colliculus and lateral geniculate body implying that the administered extract had adverse effects on these two intracranial visual relay centers. The withdrawal effect group however shows signs of recovery. Conclusion: The study concluded that the crude extract of leaves of Neem had an inhibitive effect on the activities of enzymes of carbohydrate metabolism namely LDH, SDH and NADH-diaphorase as shown by the decrease in the staining intensities observed, and a degenerative effect on the neurons of the superior colliculus and lateral geniculate body of adult male Wistar rats. Keywords: Neem, Superior Colliculus, Lateral Geniculate Body, Carbohydrate Metabolism