67 - Hormone Regulation of Adult Hippocampal Neurogenesis in the Mammalian Brain

Abstract

Steroid and peptide hormones modulate neurogenesis in the dentate gyrus differentially in male and female adult rodents. Neurogenesis is comprised of at least two components: cell proliferation (the production of new cells) and cell survival (which ultimately results in changes to the number of new neurons that survive to maturity). This chapter focuses on the effects of estrogens, androgens, adrenal steroids, and peptide hormones on hippocampal neurogenesis in the adult male and female rodent. Evidence is reviewed for the co-localization of hormone receptors with markers for neurogenesis to indicate possible mechanisms by which hormones exert their effects to modulate neurogenesis. Estradiol modulates hippocampal neurogenesis and cell death in adult female, but not male, rodents, while testosterone upregulates hippocampal neurogenesis in adult male rodents. Few studies have compared males and females, but existing research suggests a sex difference in the response to stress-regulated hippocampal neurogenesis in the adult. More work is needed to elucidate the effects of hormones on neurogenesis in the dentate gyrus of both male and female rodents across the life span. This is crucial if we are to use our knowledge of how adult neurogenesis is regulated to develop strategies to replace neuron loss in neurodegenerative diseases, which often exhibit sex differences in disease incidence, symptomology, and/or progression.