The Role of Serotonin Modulators in Nicotine Reward and Reinforcement: A Conditioned Place Preference Investigation

Nicotine addiction remains a significant public health challenge, driving the need for effective treatment strategies. While various pharmacological approaches have been explored, targeting neurotransmitter and neuromodulator systems offers a promising avenue. These systems, particularly those involving dopamine, play a pivotal part in interceding the rewarding effects of nicotine and the development of dependence. Serotonin, a pivotal neuromodulator, exerts a profound influence on dopamine pathways. By interacting with these pathways, serotonin can significantly impact the substantiating effects of nicotine. Understanding the intricate interplay between serotonin and dopamine systems is pivotal for developing new remedial interventions that effectively address the intricacies of nicotine dependence.

The purpose of this research study was to examine the potential roles played by serotonin and its receptors in nicotine addiction by examining the involvement of serotonin modulators in the development of conditioned location preference in mice after exposure to nicotine.

Mice were subjected to conditioned place preference (CPP) training with nicotine. After induction of CPP, the extinction session was given for the disappearance of CPP. There were a total of five groups, each having six animals that participated in the experiments, including group 1 (controls; normal saline), group 2 (nicotine A; 0.25 mg/kg), group 3 (nicotine B; 0.5 mg/kg), group 4 (nicotine C; 0.75 mg/kg), and group 5 (standard drug; fluoxetine). All drugs were given through the subcutaneous route. The treatment of serotonin modulators, i.e., fluoxetine (100 mg/kg), a selective serotonin reuptake inhibitor (SSRI), was given before the priming dose of nicotine, and the effect of the serotonin modulator was observed.

On day 17th, the CPP values were 390.16 s, 235.66 s, and 219.16 s, respectively, for nicotine A, nicotine B, and nicotine C in the black compartment groups; however, in the white compartment groups, the CPP values were 347.16 s, 588 s, and 549.66 s, respectively, for nicotine A, nicotine B, and nicotine C.

Using the conditioned place preference (CPP) paradigm, we administered both drugs in a context in which their rewarding properties could be measured. Fluoxetine produced a significant but less robust CPP than nicotine. A single injection of fluoxetine was found to reduce nicotine-induced CPP. Moreover, the rewarding properties of nicotine were completely abolished in response to repeated fluoxetine injections. Long-term fluoxetine users may benefit more from the drug than those who have only used it occasionally or in small doses, according to the study.