Effect of methanol leaf extract of <i>Nicotiana tabacum</i> (tobacco) on long-term memory in Wistar rats

Background and aim: The dentate gyrus, an important part of hippocampal formation responsible for the formation of episodic memory as well as exploration of new environments. Nicotiana tabacum is a neurotoxic plant but its effects on long-term memory have not been fully explored. This study assessed the effects of Methanol Leaf Extract of Nicotiana tabacum (MLNT) on long-term memory using elevated plus maze (EPM) and step-down inhibitory apparatus (SDIA). Methodology: Twenty male rats were divided into four groups of five animals each. Group A was the control which was administered with distilled water. Groups B to D were treated with 150, 300 and 600 mg/kg body weight of MLNT respectively. Treatment was done orally for twenty-eight days, following which animals were exposed to the EPM and SDIA. At the end of the experiment, the animals were sacrificed. The brain was dissected and fixed in Bouin’s fluid for histochemical routine. The data obtained for behavioral studies were analyzed using Graph Pad Prism Version 20. Results: The results obtained for both EPM AND SDIA showed no significant difference in the MLNT treated groups when compared to the control. However, histochemical analysis of the dentate gyrus revealed neurodegeneration in all treated groups when compared to the control. Conclusion: The outcomes of the study revealed that MLNT is a potential neurotoxicant through the histoarchitectural distortion of the dentate gyrus of the Wistar rats.