Effects of chronic nicotine administration in drinking water on Neuropeptide Y mRNA expression in mesocorticolimbic system structures in rat brain
Project no. 1111 · Status: Kapanmış · 2018
Summary
Introduction and Aim: Nicotine addiction is the main factor that makes it difficult to fight against tobacco products, which is at the top of the preventable health problems. The withdrawal and negative affectivity that occur in the case of nicotine deficiency, which has highly addictive effects, cause people to re-adopt nicotine. Studies in the literature indicate that this negative affectivity may be related to Neuropeptide Y, one of the most common neuropeptides in our brain. On the other hand, there is no study investigating the regulation of NPY mRNA in the mesocorticolimbic system, which is accepted as the brain's reward center during abstinence. In this study, it is aimed to investigate the changes to expression levels of NPY mRNA in different mesocorticolimbic regions of Wistar rats after forced oral nicotine exposure and withdrawal. Methods: Thirty-eight adults male Wistar rats were used for this study. Rats were divided into 4 groups as Control group (n = 8), Chronic nicotine administration group (0-W; n = 10), 24-hour withdrawal group (24-W; n = 10) and 48-hour withdrawal group (48-W; n = 10). The forced oral nicotine administration study took 12 weeks. In the first week, 0.2% saccharine water was given to controls, and water containing 0.2% saccharine and 25 mg / L nicotine was given to other groups. In the second week, the nicotine level in the water of the nicotine applied groups was increased to 50 mg / L. In the third week, the amount of saccharin applied to all groups was reduced from 0.2% to 0.1%, and from the fourth week, saccharin administration was completely stopped. At the end of 12 weeks, Control and Nicotine groups were decapitated 60 minutes after the removal of drinking bottles. 24-W group and the 48-W group were decapitated after 24 hours and 48 hours, respectively. The prefrontal cortex, septum, dorsal striatum, nucleus accumbens, amygdala, hippocampus, medial hypothalamic area and ventral tegmental area were dissected from the animals' brains. NPY mRNA expression was quantified using qRT-PCR. Statistical analysis of the data obtained was made with IBM SPSS v 25.0 software. Results: When expression levels of NPY mRNA were evaluated, an increase was observed in the 48-W group in the PFC region compared to the other groups (p <0.001). There was an increase in the 24-W group in the amygdala region compared to the control (p = 0.027) and 48-W groups (p = 0.036). In addition, NPY mRNA level in the 0-W group in the hippocampus region was observed to be higher than the control (p = 0.007) and 48-W (p = 0.048) groups. Conclusion: The data obtained from this study indicate that NPY may regulate negative affective state during nicotine consumption and withdrawal.