Date of Award

Fall 8-1994

Document Type

Thesis

Degree Name

Master of Arts

Department

Psychology

First Advisor

Dr. Craig Kinsley

Second Advisor

Dr. Fred Kozub

Third Advisor

Dr. Kenneth Blick

Abstract

The effects of prenatal stress on the size of the corpus callosum in rats was investigated using a prenatal heat, light, and restraint stress paradigm that influences the fetal hormonal milieu (Ward, 1972). Females were stressed thrice daily from Day 15 of pregnancy until parturition. Control females were left unstressed throughout their pregnancies. In adulthood (M = 223.16 days of age), male and female offspring from the two groups were sacrificed. Area, perimeter, and length of the corpus callosum were determined from sagittal sections of each brain. Results showed a sex difference for area, perimeter, and length of the corpus callosum, with males having larger values on all three measures. However, when body weight was taken into consideration, these sex differences disappeared. These findings are consistent with Berrebi et al's (1988) study that showed no sex differences in the corpus callosum of older rats (215 days old) as opposed to younger rats ( 110 days old) when brain weight was controlled. Questions, though, remain as to the importance of hormonal influences on body and brain size and the relationship of these same hormones to the size of structures in the brain. No stress effects or sex by stress interactions existed, suggesting that prenatal stress effects on the corpus callosum either diminish with age or do not exist for that particular structure.

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