The Effects of Synthetic Sex Hormones on Cognitive Abilities, Affective State, the Gut-Brain Axis, and Acute Immune and Stress Reactivity During Puberty and Adulthood

Abstract

Combined oral contraceptives (COCs) are one of the most widely used forms of hormonal contraception by both adolescent and adult human females. While they are very effective at preventing pregnancy, they may also have effects on the central nervous system, cognition, and behaviour. However, there are a lot of inconsistencies reported on these effects. One possible explanation for these discrepancies could be that the effects of COCs on the brain are age-dependent and may be more pronounced during puberty and adolescence. The mechanisms underlying the effects of COCs on the brain and behaviour also remain unclear. The current thesis was designed to address these knowledge gaps and to investigate possible mechanisms through which COCs could impact the brain, cognitive abilities, and gut microbiome composition in an age-dependent manner in a mouse model (Article 1). Subsequently, we examined the effects of pubertal COC exposure on mental health outcomes such as depression-like and anxiety-like behaviors (Article 2). Lastly, we investigated whether COCs alter immune and stress responses in pubertal and adult CD-1 mice (Article 3). Together, the studies included in this dissertation furthers our understanding of the impact of combined oral contraceptives use during puberty and adulthood on women’s health including the brain, behaviour, gut microbiome as well as stress and immune systems.