Implication of long term Nicotine exposure on pain hypersensitivity and cognitomotor functions following repetitive pain stimuli in Wistar rats

Okpe, Ebifetei and Adienbo, Ologhaguo Macstephen and Chuemere, Arthur Nwafor (2025) Implication of long term Nicotine exposure on pain hypersensitivity and cognitomotor functions following repetitive pain stimuli in Wistar rats. International Journal of Science and Research Archive, 14 (3). 053-060. ISSN 2582-8185

This study investigates the impact of long-term nicotine exposure on pain hypersensitivity and cognitomotor functions after repeated pain stimuli in Wistar rats. The experimental design consisted of three phases of drug administration: short-term, 14 days; sub-chronic, 35 days; and long-term, 105 days, with treatment groups including nicotine (low: 0.1 mg/kg, high: 0.2 mg/kg), morphine (low: 5 mg/kg, high: 10 mg/kg), and their combination. Pain sensitivity was measured by the tail immersion, analgesy meter, and Randall-Selitto tests, while cognitive and motor functions were measured by the Navigational Maze and Rotarod tests, respectively. Results showed that morphine diminished pain hypersensitivity in a dose-dependent manner but that tolerance developed over time. Nicotine displayed dose-dependent analgesic properties, with higher doses significantly improving pain thresholds and enhancing cognitive performance, especially under conditions of chronic pain. Treatment of combined nicotine and morphine in a synergistic way resulted in better pain relief, improvement of cognitive, and motor functions than with each medicine separately taken. Low-dose nicotine was less effective not only in pain but also in cognitomotor assessment. These findings point to the potency of nicotine, especially in high doses, both as a cognitive enhancer and as an adjuvant to opioids for pain management. The study therefore suggests that a tailored, multi-drug therapeutic approach is in order if the shortcomings of classical analgesics are to be overcome and pain-induced cognitive and motor impairment reduced. Future studies will need to further determine the clinical applicability of these results while taking into account the risks of nicotine addiction.