Adult neurogenesis in the dentate gyrus of the hippocampus is altered with stress
exposure and has been implicated in depression. High levels of corticosterone (CORT)
suppress neurogenesis in the dentate gyrus of male rats. However both acute and chronic
stress do not consistently reduce adult hippocampal neurogenesis in female rats. Therefore,
this study was conducted to investigate the effect of different doses of corticosterone
on hippocampal neurogenesis in male and female rats. Rats received 21 days of s.c.
injections of either oil, 10 or 40 mg/kg CORT. Subjects were perfused 24 h after the
last CORT injection and brains were analyzed for cell proliferation (Ki67-labeling)
or immature neurons (doublecortin-labeling). Results show that in both males and females
high CORT, but not low CORT, reduced both cell proliferation and the density of immature
neurons in the dentate gyrus. Furthermore, high CORT males had reduced density in
immature neurons in both the ventral and dorsal regions while high CORT females only
showed the reduced density of immature neurons in the ventral hippocampus. The high
dose of CORT disrupted the estrous cycle of females. Further, the low dose of CORT
significantly reduced weight gain and increased basal CORT levels in males but not
females, suggesting a greater vulnerability in males with the lower dose of CORT.
Thus we find subtle sex differences in the response to chronic CORT on both body weight
and on neurogenesis in the dorsal dentate gyrus that may play a role in understanding
different vulnerabilities to stress-related neuropsychiatric disorders between the
Copyright 2010 IBRO. Published by Elsevier Ltd. All rights reserved.