Data from: Prenatal alcohol exposure increases postnatal acceptability of nicotine odor and taste in adolescent rats

Human studies indicate that alcohol exposure during gestation not only increases the chance for later alcohol abuse, but also nicotine dependence. The flavor attributes of both alcohol and nicotine can be important determinants of their initial acceptance and they both share the component chemosensory qualities of an aversive odor, bitter taste and oral irritation. There is a growing body of evidence demonstrating epigenetic chemosensory mechanisms through which fetal alcohol exposure increases adolescent alcohol acceptance, in part, by decreasing the aversion to alcohol's bitter and oral irritation qualities, as well as its odor. Given that alcohol and nicotine have noteworthy chemosensory qualities in common, we investigated whether fetal exposure to alcohol increased the acceptability of nicotine's odor and taste in adolescent rats. Study rats were alcohol-exposed during fetal development via the dams' liquid diet. Control animals received ad lib access to an iso-caloric, iso-nutritive diet throughout gestation. Odorant-induced innate behavioral responses to nicotine odor (Experiment 1) or orosensory-mediated responses to nicotine solutions (Experiment 2) were obtained, using whole-body plethysmography and brief access lick tests, respectively. Compared to controls, rats exposed to fetal alcohol showed an enhanced nicotine odor response that was paralleled by increased oral acceptability of nicotine. Given the common aversive component qualities imbued in the flavor profiles of both drugs, our findings demonstrate that like postnatal alcohol avidity, fetal alcohol exposure also influences nicotine acceptance, at a minimum, by decreasing the aversion of both its smell and taste. Moreover, they highlight potential chemosensory-based mechanism(s) by which fetal alcohol exposure increases the later initial risk for nicotine use, thereby contributing to the co-morbid expression with enhanced alcohol avidity. Where common chemosensory mechanisms are at play, our results suggest broader implications related to the consequence of fetal exposure with one substance of abuse and initial acceptability of others.

已有人体研究表明，妊娠期酒精暴露不仅会提升后代日后出现酒精滥用（alcohol abuse）的风险，还会增加尼古丁依赖（nicotine dependence）的发生概率。酒精与尼古丁的风味属性（flavor attributes）均是影响其初始接受度的核心决定因素，二者共享厌恶性气味（aversive odor）、苦味（bitter taste）与口腔刺激（oral irritation）这类共通的化学感应（chemosensory）特性。越来越多的研究证据显示，存在表观遗传化学感应机制（epigenetic chemosensory mechanisms）：胎儿期酒精暴露可通过降低机体对酒精苦味、口腔刺激特性及其气味的厌恶感，在一定程度上提升青春期个体对酒精的接受度。鉴于酒精与尼古丁具有显著共通的化学感应特性，本研究旨在探究胎儿期酒精暴露是否会提升青春期大鼠对尼古丁气味与味觉的接受度。实验中，实验大鼠的胎儿期酒精暴露通过母鼠的液体饲料（dams' liquid diet）实现；对照组孕鼠则全程自由摄食（ad lib）等热量、等营养的对照饲料。本研究分别采用全身体积描记法（whole-body plethysmography）与短暂舔舐试验（brief access lick tests），检测大鼠对尼古丁气味的气味诱导先天性行为反应（实验1），以及对尼古丁溶液的口腔感觉介导行为反应（实验2）。结果显示，与对照组相比，胎儿期暴露于酒精的大鼠，其对尼古丁气味的反应显著增强，同时对尼古丁的口腔接受度也同步提升。鉴于两种成瘾药物的风味谱中均蕴含共同的厌恶性成分，本研究结果表明：与产后酒精偏好（alcohol avidity）增强类似，胎儿期酒精暴露同样会影响尼古丁的接受度，至少是通过降低机体对其气味与味觉的厌恶感实现。此外，本研究还揭示了潜在的基于化学感应的作用机制：胎儿期酒精暴露会提升个体日后首次接触尼古丁时的使用风险，进而与增强的酒精偏好共同表现为共病（co-morbid）状态。当共通的化学感应机制发挥作用时，本研究结果提示，胎儿期暴露于一种成瘾物质，会对其他成瘾物质的初始接受度产生影响，这一发现具有更广泛的研究意义。