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Abstract:
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Particularly low and high glucocorticoid levels can affect cognitive performance and this impairment appears to be largely mediated by the hippocampus. Previously, we showed that protracted elevation of corticosterone (CORT) levels starting on postnatal day 15 (immediately after the stress-hyporesponsive period) impaired later learning on trace eyeblink conditioning (EBC). Further, at this developmental age, males appeared to be more susceptible to the effects than were females. In the present study we have examined potential anatomical differences in the hippocampus of male rats treated with 21-day- release CORT pellets versus placebo. CORT/placebo pellets were inserted subcutaneously on the back of the neck of 15- day-old rat pups. This was followed by 3 BrdU injections (50mg/kg) on day 16, 17 and 18. On day 28, the rats were sacrificed and brains harvested. Using fluorescent immunohistochemical co-labeling with BrdU, NeuN, GFAP and Sox-10 combined with stereology we have sampled newly differentiated neurons in the dentate gyrus of hippocampus. This allowed us to detect any CORT-induced changes in the dentate gyrus volume, total number of neurons, and neuronal density of young male rats. |
