Hyperactive behavior in female rats in utero-exposed to group B Streptococcus-induced inflammation

Abstract

Group B Streptococcus (GBS) is one the most common bacterium responsible of maternal infections during pregnancy. Offspring in utero-exposed to GBS-induced placental inflammation displayed sex-specific forebrain injuries. Sex differences have been reported in several neuropsychiatric disorders. Hence, we hypothesized that female rats in utero-exposed to GBS may present sex-specific neurobehavioral impairments. Lewis rats were injected intraperitoneally every 12 h from gestational day (G) 19 to G22 with either saline (controls) or inactivated serotype Ia GBS (10⁹ CFU). Before puberty, no difference in terms of spontaneous motor activity, exploratory or anxiety-related behaviors was noticed between experimental conditions. During puberty, GBS-exposed females - but not males - performed worse than same-sex controls in a forced motor task. During adulthood, GBS-exposed females - but not males - displayed increased spontaneous locomotor activity and decreased inhibition. In conclusion, our findings show for the first time that adult females - but not males - in utero-exposed to GBS-induced inflammation presented a hyperactive and disinhibited phenotype emerging after puberty.

Keywords: Chorioamnionitis; Disinhibition; Elevated-plus-maze; Group B Streptococcus; Hyperactivity; Placental inflammation; Rat; Rotarod; Sex difference.