Date of Award

Spring 5-1995

Document Type


Degree Name

Master of Arts



First Advisor

Dr. Craig H. Kinsley

Second Advisor

Dr. Fred Kozub

Third Advisor

Dr. Kelly Lambert


Formerly non-responsive females will display maternal behavior (MB) following pregnancy and parturition. The behavioral alterations are believed to occur in response to hormonal changes that accompany pregnancy. The medical pre optic area (MPOA) regulates hormone-induced MB. The current study examined neuronal changes which might account for the modified behavior. Twenty adult female Sprague-Dawley rats were assigned a hormone condition: ovariectomized (OVX), ovariectomized/hormone-treated (P+E2), intact diestrus (DI), or pregnant (PREG). Animals were killed, and their brains fixed in Golgi-Cox solution. Somata of the MPOA and related cortex were measured in each group using a Bioquant imaging system. Pregnant females had significantly larger somal areas in the MPOA than all other groups. Cortical soma size remained relatively unchanged between groups. These data suggest that the hormonal changes characteristic of pregnancy are capable of modifying neurons in the adult central nervous system. Modifications in the MPOA neuron, therefore, may play a role in the onset, maintenance, and retention of MB.

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