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

Abstract

BackgroundNicotine is a subject of continuous research because of its likely ameliorative effects on neurologic and neurodegenerative disorders.PurposeThis study examined the effects of its chronic subcutaneous administration on hippocampal and striatal microstructure in both female and male rats.MethodsForty 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.ResultsThe 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.ConclusionThe 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.

Histomorphological Effects of Nicotine on Selected Parts of the Brain of Adult Wistar Rats

“…The pyramidal and granular layers of animals administered nicotine for 21 days, showed a transient elevation in cell count which was very apparent down the group. This hypothesis further buttresses the fact that acute administration of nicotine, lead to moderate hyperplasia and hypertrophy as previously documented and is in accordance with a work by Adeniyi and Musa in 2011 who concluded that nicotine administration caused hyperplasia in the hippocampus and that of Ijomone et al (2015), who reported hippocampal hypoplasia. [50,53] The reason for this is likely the time of administration of nicotine.…”

“…[54] The current study displayed a dose and time dependant progressive increase in neuronal population which suggests severe hyperplasia. However, this study also demonstrated that chronic administration of nicotine led to increase cell proliferation rather than neurodegeneration as noted by Adeniyi and Musa (2011), Ijomone et al (2015). [50,53] Possible reasons for the dissimilarity could be attributed to difference in mode of nicotine administration.…”

“…However, this study also demonstrated that chronic administration of nicotine led to increase cell proliferation rather than neurodegeneration as noted by Adeniyi and Musa (2011), Ijomone et al (2015). [50,53] Possible reasons for the dissimilarity could be attributed to difference in mode of nicotine administration. In the current study, nicotine was administered orally which implied it was actively metabolized in the liver causing an unchanged fraction of the drug to pose a significant effect.…”

“…Furthermore, Ijomone et al in 2015, used the subcutaneous route which implied that nicotine had a slower absorptive rate as compared to the oral route of drug administration. [53] For further studies as regards to this study, electron microscopy is advised as it investigates the ultrastructure of tissues.…”

“…[52] A study on the hippocampal and striatal histomorphology following chronic nicotine administration in male and female rats was carried out by Ijomone et al in 2015. [53] Nicotine was administered at a dose of 0.25, 2.00 and 4.00µg/kg for 28 days. This study showed a significant increase in percentage of neurons with degenerative features in hippocampus and striatum of both male and female rats.…”