Date of Award

Spring 5-2020

Document Type

Honors Thesis

Degree Name

Bachelor of Arts

Department

Psychology

Advisor/Committee Chair

Joanna Workman, Ph.D.

Committee Member

Damian Zuloaga, Ph.D

Abstract

The maternal experience has been associated with alterations in behavior and in many different areas of the brain. Soon after giving birth and throughout the postpartum period, maternal behavior and care of offspring in particular have been shown to stimulate the dopaminergic system in postpartum women and rats alike. Around 15% of women who give birth develop postpartum depression (PPD), which has been associated with downregulation of dopamine activity. This experiment tested whether the removal of offspring immediately after parturition would alter the anxiety and depressive-like behavior of dams, as well as the expression of dopaminergic neurons. Adult female Sprague-Dawley rats remained with their pups (pup-remain) or had their pups removed (pup-remove) on postpartum day (PD) 1. As an additional control, age-matched nulliparous rats remained undisturbed except for testing. Depressive-like behavior, anxiety-like behavior, and anhedonia were tested using the forced swim test (FST), open field test (OFT), and sucrose preference test (SPT), respectively. To identify the presence of dopaminergic neurons, brains were processed for tyrosine-hydroxylase (TH), a rate-limiting enzyme that synthesizes dopamine. TH-expression was visualized in the ventral tegmental area (VTA) because of the key role the VTA plays in the reward system and the projection to dopaminergic pathways. Rats that had their pups removed displayed greater depression-like behavior, as measured by immobility in the FST. However, here was no significant effect of experimental group on the optical density of TH expression in the VTA. These results point to the possibility that while pup-remove rats showed increased depression-like behavior, the dopaminergic activity in the VTA associated with pup presence is not driving an antidepressant effect for the pup-remain dams. This work could further our understanding of how the maternal experience affects the brain, and the neurological changes behind PPD.

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