Ameliorative Effect of Heinsia crinita (Bush Apple) on Dihydrocodeine-Induced Memory Impairment and Hippocampal Neurodegeneration in Wistar Rats

Abstract

Dihydrocodeine is a short-acting narcotic opioid that is used as a pain reliever for moderate pain and to treat diarrhoea and unproductive cough. It has become a common drug of abuse due to its accessibility and psychoactive property. Its adverse effects can lead to physical and psychological dependence and addiction, which results in oxidative stress through multiple mechanisms and inflammatory reactions, malfunctioning cholinergic and dopaminergic systems, and eventual neurodegeneration that affects the structure and functions of different brain regions. The leaves of H. crinita have been reportedly used to treat diverse diseases and exhibit neuroprotective effects. This study aimed to evaluate Heinsia crinita's ability to ameliorate dihydrocodeine-induced cognitive dysfunction and hippocampal structural damage in adult Wistar rats. The animals were grouped into six groups (1–6; n = 5). Control group; dihydrocodeine group; dihydrocodeine + naloxone groups; and dihydrocodeine + Heinsia crinita aqueous leaf extract (ALHC) at 100 mg/kg, 200 mg/kg, and 300 mg/kg. Spatial learning and memory were evaluated using Morris Water Maze (MWM); dopamine level and hippocampal neurodegeneration using haematoxylin and eosin, cresyl fast violet and glial fibrillary acidic protein. The results revealed a deficit in spatial memory and learning, decreased dopamine levels, cytoarchitectural distortion of the CA3 region of the hippocampus, astrogliosis, and reduced Nissl substance following codeine treatment. However, ALHC treatment improved spatial memory and learning, increased dopamine levels, restored the cytoarchitecture, increased staining intensity, and reduced astrocyte reaction in the CA3 area of the hippocampus in Wistar rats. This indicates the ameliorative ability of H. crinita in dihydrocodeine-induced neurotoxicity.