SEX-DEPENDENT EFFECTS OF EARLY LIFE SENSORY OVERSTIMULATION ON LATER LIFE BEHAVIORAL FUNCTION IN RATS
Abstract Body
Digital media exposure in infants has doubled over the past two decades, leading to a rise in detrimental effects that extend across multiple domains including language, cognition, and socio-emotional skills. Excessive early life media exposure (and the accompanying audiovisual stimulation) may constitute a form of sensory overstimulation (SOS) and has been linked to increased risk for developing later life psychiatric disorders (i.e., depression, autism). Yet, the biological mechanisms by which early life SOS increases later life psychopathology-related phenotypes remain poorly understood. Here, we sought to assess the impact of early life SOS on later life behavioral, cognitive, and hypothalamic-pituitary-adrenal (HPA) axis function in rats. To this end, developing male and female rats were exposed to excessive audiovisual stimulation from postnatal day (PND) 10-40 and levels of the stress hormone corticosterone (CORT) were measured at PND 23, 41 and 61. Animals were tested for anxiety-like behavior, working memory, social motivation, compulsive behavior, and spatial learning/cognition (n=6-8 per group) from PND 50-60. In males, SOS reduced anxiety-like, and compulsive behavior compared to controls (p < 0.05). In females, SOS reduced social motivation (p < 0.05) but enhanced spatial learning/cognition (p < 0.01). No differences were observed for CORT levels, suggesting no impact of early life SOS on HPA-axis function. Our results demonstrate sex-specific effects of early life SOS on distinct behavioral domains in adult rats. By modeling a rising clinical issue in a preclinical setting, we can better understand how SOS induces behavioral and physiological changes that increase risk for psychiatric disease.
