A CRF ANTAGONIST ATTENUATES STRESS-INDUCED INCREASES IN NA TURNOVER IN EXTENDED BRAIN-REGIONS IN RATS

We investigated the effects of intracerebroventricular (i.c.v.) admini stration of a corticotropin-releasing factor (CRF) antagonist, alpha-h elical CRF9-41 (ahCRF), on increases in noradrenaline (NA) turnover ca used by immobilization stress in rat brain regions. Pretreatment with ahCRF (50 or 100 mug) significantly attenuated increases in levels of 3-methoxy-4-hydroxyphenylethyleneglycol sulfate (MHPG-SO4), the major metabolite of NA in rat brain, in the locus coeruleus (LC) region. and attenuated the MHPG-SO4/NA ratio after immobilization stress for 50 m in in the cerebral cortex, hippocampus, amygdala, midbrain and hypotha lamus. However, stress-induced increases in plasma corticosterone leve ls were not decreased significantly by pretreatment with ahCRF. These results suggest that CRF, released during stress, causes increases in NA release in extended brain regions of stressed rats.