Pre-Reproductive Excessive Alcohol and Maternal Immune Activation Differentially Affect Offspring Behavior, Neurobiology, and Brain Volume in a Sex-Dependent Manner.

While the harmful effects of alcohol use during pregnancy are well recognized, less is understood about how maternal alcohol consumption during adolescence, prior to reproduction, may affect offspring. This is especially concerning given the high prevalence of adolescent alcohol use, particularly in females. This study investigates how maternal pre-reproductive alcohol exposure, combined with a maternal immune activation (MIA) during pregnancy, a well-established neurodevelopmental risk factor, affects offspring. Female Wistar rats were subjected to intermittent binge-like alcohol consumption during adolescence and later mated with naïve males. On gestational day 15, dams received either saline or a mild dose of the viral mimic Poly I:C. Maternal care was monitored, and stress axis components were analyzed in both dams and their offspring. Adult offspring underwent behavioral testing, MRI, neurochemical and neuroimmune analyses, metabolic profiling, and voluntary alcohol consumption assessments. Maternal alcohol exposure prior to reproduction led to increased offspring body weight, memory impairments, altered HPA axis function, microglial reductions, and enlarged cerebellar volumes, with most outcomes showing sex-specific differences, including opposing neurochemical responses. Interestingly, MIA, but not maternal alcohol, induced elevated alcohol intake in offspring and disrupted sensorimotor gating. MIA-exposed dams also showed impaired maternal care and reproductive HPA axis dysregulation. These findings demonstrate that adolescent alcohol use before reproduction has significant intergenerational consequences and that even mild immune challenges during pregnancy can independently disrupt offspring development. Results underscore the importance of sex as a biological variable and call for targeted preventive strategies.