Effects of corticotropin releasing factor on locomotor activity in hypophysectomized rats.

Corticotropin releasing factor (CRF) injected intracerebroventricularly to hypophysectomized and sham hypophysectomized rats produced a dose dependent increase in locomotor activity, but in untreated hypophysectomized rats 10X more CRF was needed to produce a significant increase in activity. Concomitant daily supplements of rat growth hormone, thyroxine, and corticosterone to the hypophysectomized rats eliminated locomotor activity differences between the two groups. There was no statistically significant difference in locomotor response to either saline, 0.1 micrograms CRF, 1.0 micrograms CRF or 10.0 micrograms CRF in the group of animals receiving hormonal supplements. These results demonstrate that CRF can produce behavioral activation in rats independently of its effects on releasing hormones from the pituitary gland.