Dose-dependent quinine toxicity of intracranial auditory relay centre (inferior colliculus) in male albino Wistar rats is reversible

Abstract

BACKGROUND: The toxicity of quinine treatment on intracranial auditory relay center, inferior colliculus (IC), of male albino Wistar rats was investigated. MATERIALS AND METHOD: Thirty-five male rats weighing between 180 and 200 g were used for the study. They were randomly divided into seven groups of five animals per group with Group 1 serving as the control. Groups 2, 3, and 4 received 10, 20, and 30 mg of quinine per kilogram body weight, respectively, for 7 days, while Groups 5, 6, and 7 received 10, 20, and 30 mg of quinine per kilogram body weight, respectively, for 7 days and then allowed to recover over time for another 7 days. The animals were sacrificed under chloroform anesthesia; The brain tissues were perfused with phosphate buffer solution, harvested, processed, stained using hematoxylin and eosin staining technique and observed histologically under light microscope. RESULTS: The IC of the Group 1 (control) showed normal histological features with the neurons appearing distinct with conspicuous cellular population. Seven-day quinine-treated groups (Groups 2-4) revealed mild-to-severe cellular distortion. Seven days after the withdrawal of quinine, the tissue sections appeared to have recovered completely with more neuronal density and cellular regeneration in the IC of Groups 5, 6, and 7. This study has revealed that quinine induces a dose-dependent toxicity on the IC of rats. CONCLUSION: It can also be concluded that, there is likelihood of complete natural recovery of the cellular cytoarchitecture and neuronal cell regeneration after 7 days of withdrawal of quinine.