DataSheet2_Early-Life Exposure to Non-Absorbable Broad-Spectrum Antibiotics Affects the Dopamine Mesocorticolimbic Pathway of Adult Rats in a Sex-Dependent Manner.docx

Gut microbiota with a stable, rich, and diverse composition is associated with adequate postnatal brain development. Colonization of the infant’s gut begins at birth when parturition exposes the newborn to a set of maternal bacteria, increasing richness and diversity until one to two first years of age when a microbiota composition is stable until old age. Conversely, alterations in gut microbiota by diet, stress, infection, and antibiotic exposure have been associated with several pathologies, including metabolic and neuropsychiatric diseases such as obesity, anxiety, depression, and drug addiction, among others. However, the consequences of early-life exposure to antibiotics (ELEA) on the dopamine (DA) mesocorticolimbic circuit are poorly studied. In this context, we administered oral non-absorbable broad-spectrum antibiotics to pregnant Sprague-Dawley dams during the perinatal period (from embryonic day 18 until postnatal day 7) and investigated their adult offspring (postnatal day 60) to assess methylphenidate-induced conditioned place preference (CPP) and locomotor activity, DA release, DA and 3,4-dihydroxyphenylacetic acid (DOPAC) content in ventral tegmental area (VTA), and expression of key proteins within the mesocorticolimbic system. Our results show that ELEA affect the rats conduct by increasing drug-seeking behavior and locomotor activity induced by methylphenidate of males and females, respectively, while reducing dopamine striatal release and VTA content of DOPAC in females. In addition, antibiotics increased protein levels of DA type 1 receptor in prefrontal cortex and VTA of female rats, and tyrosine hydroxylase in VTA of adult male and female rats. Altogether, these results suggest that ELEA alters the development of the microbiota-gut-brain axis affecting the reward system and the response to abuse drugs in adulthood.

肠道菌群（gut microbiota）的组成稳定、丰富且多样，与正常的产后脑发育密切相关。婴儿肠道的菌群定植始于分娩时，此时分娩过程使新生儿接触到一系列母体细菌，菌群的丰富度与多样性逐步提升，直至1~2岁时形成稳定的菌群组成，并维持至老年。反之，饮食、应激、感染及抗生素暴露所引发的肠道菌群失调，与多种病理状态相关，包括代谢疾病与神经精神疾病，如肥胖、焦虑、抑郁、药物成瘾等。然而，生命早期抗生素暴露（early-life exposure to antibiotics, ELEA）对多巴胺（dopamine, DA）中脑皮层边缘回路的影响，目前尚缺乏深入研究。基于此，本研究在围产期（胚胎第18天至出生后第7天）对孕龄斯普拉格-道利（Sprague-Dawley）大鼠给予口服非吸收性广谱抗生素，并对其成年子代（出生后第60天）开展实验，以评估哌甲酯诱导的条件位置偏爱（conditioned place preference, CPP）、自发活动、多巴胺释放、腹侧被盖区（ventral tegmental area, VTA）内多巴胺与3,4-二羟基苯乙酸（3,4-dihydroxyphenylacetic acid, DOPAC）的含量，以及中脑皮层边缘系统内关键蛋白的表达水平。本研究结果显示，生命早期抗生素暴露会改变大鼠的行为模式：分别增加雄性与雌性大鼠的哌甲酯诱导觅药行为与自发活动，同时降低雌性大鼠的纹状体多巴胺释放及腹侧被盖区的DOPAC含量。此外，抗生素暴露可提升雌性大鼠前额叶皮层与腹侧被盖区内的多巴胺1型受体蛋白表达水平，同时上调成年雌雄大鼠腹侧被盖区内的酪氨酸羟化酶蛋白水平。综上，上述结果表明，生命早期抗生素暴露会扰乱微生物群-肠-脑轴的发育，进而影响成年后的奖赏系统与成瘾药物应答反应。