Date of Award


Document Type


Degree Name

Master of Arts



First Advisor

Dr. Craig Howard Kinsley

Second Advisor

Dr. Kelly G. Lambert

Third Advisor

Dr. Frederick J. Kozub


The hippocampus displays hormone induced plasticity during estrus. Pregnancy, which exposes a female to a significantly longer duration of elevated estrogen and progesterone, results in even greater changes in neurons in the CA1 region of the hippocampus, with late-pregnant and lactating females displaying a significantly higher concentration of apical dendritic spines. Hippocampal astrocytes were increased in number and showed more and thicker processes in late-pregnant and lactating females. Such anatomical changes may also enhance spatial learning and memory. Changes in reproductive capacity may influence the rate at which new neurons are born, so called neurogenesis. In two experiments, neurogenesis in female rats was examined by quantifying the number of new neurons using the DNA marker, bromodeoxyuridine (BrdU), in the region of the DG of virgin, late-pregnant, lactating females, and foster mother virgins. Experiment 1 focused on examining the role of reproductive experience on neurogenesis, and lactating animals showed an increase in the level of neurogenesis with longer duration of pup exposure compared to late-pregnant animals. Experiment 2 examined the role of pups on neurogenesis and showed that animals with longer exposure to pups had a decreased level of neurogenesis compared to foster mothers and primiparous mothers without pup exposure. These data suggest that reproductive experience modifies neurogenesis. The events surrounding pregnancy may focus both resources and mechanisms of neuronal programmed cell death on the production of the maternally efficient brain. Pups may represent a kind of enriched environment, which, has been shown to enhance neurogenesis. Females thus equipped may better respond to the new learning demands and challenges characteristic of motherhood.

Included in

Psychology Commons