Effects of chronic administration of efavirenz on the nissl substances on the intracranial visual relay centres of adult Wistar rats

Abstract

The effects of chronic administration of efavirenz commonly used as part of highly active antiretroviral therapy (HAART) for the treatment of Human Immunodeficiency Virus (HIV) type-1 therapy on the nissl substance of the intracranial visual relay centres namely the superior colliculus and lateral geniculate body of adult wistar rats were carefully studied. The rats of both sexes (n=20), with an average weight of 200g were randomly assigned into treatment (n=10) and control (n=10) groups. The rats in the treatment group received 600mg/70kg body weight of efavirenz dissolved in distilled water daily for 30 days through the orogastric tube. The control group received equal volume of distilled water daily for 30 days through the same route. The rats were fed with grower’s mash obtained from Edo Feeds and Flour Mill Limited, Ewu, Edo state, Nigeria and given water liberally. The rats were sacrificed by cervical dislocation method on the thirty-first day of the experiment. The superior colliculus and lateral geniculate body were carefully dissected out and quickly fixed in 10% formal saline for histological study. The histological findings indicated that the treated sections of the superior colliculus and lateral geniculate body showed that the nissl substances were less intensely stained as compared to the control. The parenchyme was vacuolated, there were evidence of hypertrophy and more spaces between the axonal mesh around the sparsely distributed neurons as compared to the control group. The treated section of the superior colliculus showed neurons with faintly stained nissl substances of various sizes and with evidence of hypertrophy while that of the lateral geniculate body showed less intense and enlarge nissl substances with characterized microcytic changes. Chronic administration of efavirenz may have an adverse effect on the nissl substances of the superior colliculus and lateral geniculate body of adult wistar rats. It is recommended that further studies aimed at corroborating these observations be carried out.

Keywords: Efavirenz, Nissl Substance, Superior Colliculus, Lateral Geniculate Body, Wistar Rats