Title

Hormones and social behavioral development: Influences of corticosterone in the neonate rat

Date of Award

2010

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Psychology/Experimental

First Advisor

Casey Cromwell, PhD

Second Advisor

Huber Robert, PhD (Committee Member)

Third Advisor

Meserve Lee, PhD (Committee Member)

Fourth Advisor

Musher-Eizenman Dara, PhD (Committee Member)

Abstract

Exposure to prenatal stress (PNS) has been shown to induce a set of psychological and behavioral changes in the developing offspring. The rat model was used to investigate whether PNS and/or pharmacological corticosterone manipulations produce changes in the ability of the pup to express social motivation. The first experiment was designed to replicate previous work on PNS and extend the investigation on socially-mediated behaviors. The second experiment attempts to replicate the findings of Experiment 1 by mimicking PNS behaviors through direct corticosterone administration. Finally, the third Experiment was designed to investigate whether the effects of PNS could be ameliorated by administration of the drug metyrapone. The measures used to assess socially-mediated behaviors are 1) separation vocalizations, 2) conditioned odor preference, 3) conditioned odor aversion, and 4) anesthetized dam approach and duration of contact. Results of the first experiment did not replicate those of previous studies (Harmon et al., 2009). Experiment 2 found that direct corticosterone administration is not able to mimic both the physiological and behavioral deficits observed in the PNS model. The third experiment demonstrated that metyrapone was not able to restore the socially-mediated behaviors in PNS rats. These findings indicate that PNS has a much more dynamic impact on rat pup physiology than just elevations in corticosterone. Additionally, attempts to lower corticosterone in PNS pups via administration of metyrapone aren’t sufficient to restore atypical behaviors in PNS rats.This dissertation has implications for the treatment of psychological disorders, like autism spectrum disorder, involving disruptions in learning and social behaviors and raises concerns using elevated corticosterone levels as a model for PNS deficits.