Table_8_Sex Differences in the Ventral Tegmental Area and Nucleus Accumbens Proteome at Baseline and Following Nicotine Exposure.XLSX

Sex differences in behaviors relevant to nicotine addiction have been observed in rodent models and human subjects. Behavioral, imaging, and epidemiological studies also suggest underlying sex differences in mesolimbic dopamine signaling pathways. In this study we evaluated the proteome in the ventral tegmental area (VTA) and nucleus accumbens (NAc) shell in male and female mice. Experimental groups included two mouse strains (C3H/HeJ and C57BL/6J) at baseline, a sub-chronic, rewarding regimen of nicotine in C3H/HeJ mice, and chronic nicotine administration and withdrawal in C57BL/6J mice. Isobaric labeling with a TMT 10-plex system, sample fractionation, and tandem mass spectrometry were used to quantify changes in protein abundance. In C3H/HeJ mice, similar numbers of proteins were differentially regulated between sexes at baseline compared with within each sex after sub-chronic nicotine administration. In C57BL/6J mice, there were significantly greater numbers of proteins differentially regulated between sexes at baseline compared with within each sex after chronic nicotine administration and withdrawal. Despite differences by sex, strain, and nicotine exposure parameters, glial fibrillary acidic protein (GFAP) and dopamine and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32, Ppp1r1b) were repeatedly identified as significantly altered proteins, especially in the VTA. Further, network analyses showed sex- and nicotine-dependent regulation of a number of signaling pathways, including dopaminergic signaling. Sub-chronic nicotine exposure in female mice increased proteins related to dopaminergic signaling in the NAc shell but decreased them in the VTA, whereas the opposite pattern was observed in male mice. In contrast, dopaminergic signaling pathways were similarly upregulated in both male and female VTA after chronic nicotine and withdrawal. Overall, this study identifies significant sex differences in the proteome of the mesolimbic system, at baseline and after nicotine reward or withdrawal, which may help explain differential trajectories and susceptibility to nicotine addiction in males and females.

在啮齿类动物模型与人类受试者中，均已观察到与尼古丁成瘾相关的行为学性别差异。行为学、影像学与流行病学研究同样提示，中脑边缘多巴胺信号通路存在潜在的性别差异。本研究对雄性与雌性小鼠的腹侧被盖区（ventral tegmental area, VTA）和伏隔核壳区（nucleus accumbens shell, NAc）的蛋白质组进行了评估。实验分组包括两种品系的小鼠（C3H/HeJ与C57BL/6J）的基线状态组、C3H/HeJ小鼠的亚慢性奖赏性尼古丁给药组，以及C57BL/6J小鼠的慢性尼古丁给药与戒断组。采用TMT 10-plex同量异位素标记、样品分级分离与串联质谱技术对蛋白质丰度变化进行定量分析。在C3H/HeJ小鼠中，基线状态下的性别间差异调控蛋白质数量，与亚慢性尼古丁给药后单一性别内的差异调控蛋白质数量相近。在C57BL/6J小鼠中，基线状态下的性别间差异调控蛋白质数量，显著高于慢性尼古丁给药与戒断后单一性别内的差异调控蛋白质数量。尽管存在性别、品系与尼古丁暴露参数的差异，但胶质纤维酸性蛋白（glial fibrillary acidic protein, GFAP）与32 kDa多巴胺和cAMP调节的磷酸蛋白（dopamine and cAMP-regulated phosphoprotein of 32 kDa, DARPP-32, Ppp1r1b）被反复鉴定为显著差异表达的蛋白质，尤其在腹侧被盖区中。此外，网络分析显示多条信号通路存在性别与尼古丁依赖的调控，其中包括多巴胺能信号通路。在雌性小鼠中，亚慢性尼古丁暴露使伏隔核壳区的多巴胺能信号相关蛋白质表达上调，却使腹侧被盖区的此类蛋白质表达下调；而雄性小鼠则呈现相反的模式。与之相反，慢性尼古丁给药与戒断后，雄性与雌性小鼠的腹侧被盖区多巴胺能信号通路均呈现相似的上调趋势。总体而言，本研究明确了中脑边缘系统蛋白质组在基线状态、尼古丁奖赏暴露或戒断后的显著性别差异，该差异或有助于解释男女在尼古丁成瘾的易感性与发展轨迹上的异质性。