[The effect of CRF antagonist on immobilization stress-induced increases in noradrenaline release in rat brain regions].

We investigated the effects of intracerebroventricular (i.c.v.) administration of corticotropin-releasing factor (CRF) antagonist, alpha-helical CRF9-41 (ahCRF) on stress-induced increases in noradrenaline (NA) release in rat brain regions. Pretreatment with ahCRF (50 or 100 micrograms) attenuated significantly the stress-induced increases in levels of 3-methoxy-4-hydroxyphenylethyleneglycol sulfate (MHPG-SO4), the major metabolite of NA in rat brain, in the locus coeruleus region, cerebral cortex, hippocampus, amygdala and hypothalamus. Plasma corticosterone levels were not decreased significantly by administration of ahCRF. From these results, it is suggested that stress-induced increases in NA release in the rat brain regions are attenuated by ahCRF and thus that CRF, released during the stress, cause increases in NA release in these regions.