Gestation-induced cell proliferation in the rat brain.

The states of pregnancy and lactation bring about a range of physiological and behavioral changes in the adult mammal that prepare the mother to care for her young. In the present study, the effects of pregnancy on cell proliferation in the subventricular zone (SVZ) in female rats were examined. This region has been identified as a site of neurogenesis in adult rodents. To examine the proliferating cell population, control and pregnant rats were injected with bromodeoxyuridine (BrdU, 90 mg/kg, i.v.) and euthanized 1 h following injection. BrdU was visualized using diaminobenzidine. Changes in BrdU-labeled cells occurred in the female rat brain over pregnancy with significant increases found in the SVZ on day 21 when compared with cycling diestrous females. No changes were evident in the dentate gyrus of the hippocampus as a function of gestation. These data demonstrate that, in the rat, as in mice, gestation stimulates an increase in the number of new cells in selected regions of the central nervous system.