Hippocampal and striatal histomorphology following chronic nicotine administration in female and male rats

Nicotine is a subject of continuous research because of its likely ameliorative effects on neurologic and neurodegenerative disorders. This study examined the effects of its chronic subcutaneous administration on hippocampal and striatal microstructure in both female and male rats. Forty adult female and male Wistar rats were divided into 4 groups. Three experimental groups were administered nicotine via subcutaneous injections at doses of 0.25, 2 and 4 mg/kg body weight for 28 days. Control groups received normal saline. Following administration, routine processing of brain tissues was carried out. Sections obtained were stained using routine H&E methods for general histological appearance, Cresyl violet methods for nissl substances, and Bielschwolsky silver impregnation method for neuritic plaques and neurofibrillary tangles. The study showed significant increase in percentage of neurons showing degenerating features in the hippocampus and striatum of both female and male rats following the higher doses of nicotine treatment. Only female rats showed positive agyrophilic (black-coloured) aggregations in the hippocampal and striatal regions after nicotine treatment. The present study indicates that higher dose of chronic nicotine administration may induce hippocampal and striatal neurodegenerative changes. However, further studies using more specific method for studying neurodegeneration within brain regions is recommended.