Handling in Infancy: Increased Levels of the Hypothalamic Corticotropin Releasing Factor (CRF) Following Exposure to a Novel Situation 1

Summary

The levels of the corticotropin releasing factor (CRF) were determined in the hypothalamus of rats by injecting crude extracts of the median eminence into assay animals pretreated with dexamethasone phosphate. Exposure to ether caused a 64% increase in hypothalamic CRF levels within 5 min and return to normal by 3 hr. Hypothalamic levels of CRF were then determined in 2 groups of adult rats following exposure to a novel environment; 1 group had been handled in infancy and a second group constituted the nonhandled controls. No significant difference was noted between the two groups at 5 min but the handled group had a significantly greater amount of CRF present than the nonhandled controls at 15 min after exposure to the novel environment. This agrees with previous findings that handled animals release less corticosterone than nonhandled animals when exposed to a novel environment and suggest that a functionally different mechanism for release of CRF may exist as a result of infantile stimulation.