Progesterone shapes medial temporal lobe volume across the human menstrual cycle
Caitlin M. Taylor,
Laura Pritschet,
Rosanna K. Olsen,
Evan Layher,
Tyler Santander,
Scott T. Grafton,
Emily G. Jacobs
Affiliations
Caitlin M. Taylor
Department of Psychological and Brain Sciences, University of California, Santa Barbara, USA; Corresponding author. Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA, 93106, USA.
Laura Pritschet
Department of Psychological and Brain Sciences, University of California, Santa Barbara, USA
Rosanna K. Olsen
Rotman Research Institute, University of Toronto, USA
Evan Layher
Department of Psychological and Brain Sciences, University of California, Santa Barbara, USA
Tyler Santander
Department of Psychological and Brain Sciences, University of California, Santa Barbara, USA
Scott T. Grafton
Department of Psychological and Brain Sciences, University of California, Santa Barbara, USA; Institute for Collaborative Biotechnologies, University of California, Santa Barbara, USA
Emily G. Jacobs
Department of Psychological and Brain Sciences, University of California, Santa Barbara, USA; Neuroscience Research Institute, University of California, Santa Barbara, USA; Corresponding author. Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA, 93106, USA.
The rhythmic production of sex steroid hormones is a central feature of the mammalian endocrine system. In rodents and nonhuman primates, sex hormones are powerful regulators of hippocampal subfield morphology. However, it remains unknown whether intrinsic fluctuations in sex hormones alter hippocampal morphology in the human brain. In a series of dense-sampling studies, we used high-resolution imaging of the medial temporal lobe (MTL) to determine whether endogenous fluctuations (Study 1) and exogenous manipulation (Study 2) of sex hormones alter MTL volume over time. Across the menstrual cycle, intrinsic fluctuations in progesterone were associated with volumetric changes in CA2/3, entorhinal, perirhinal, and parahippocampal cortex. Chronic progesterone suppression abolished these cycle-dependent effects and led to pronounced volumetric changes in entorhinal cortex and CA2/3 relative to freely cycling conditions. No associations with estradiol were observed. These results establish progesterone’s ability to rapidly and dynamically shape MTL morphology across the human menstrual cycle.
