Modulation by corticotropin-releasing factor of monoamine metabolism in the lateral hypothalamus

Corticotropin-releasing factor (CRF) was injected into the lateral hypothalamus of conscious unrestrained rats and the local concentration of monoamines in the vicinity of the microinjection monitored by microdialysis. The concentration of norepinephrine and MHPG in the dialysis fluid from the lateral hypothalamic areas of rats fasted for 24 h was nearly 4 times higher than in fed rats. Following the injection of 2 micrograms of CRF into the lateral hypothalamus of fasted rats there was a rapid decline in levels of both norepinephrine and 3-methoxy-4-hydroxyphenylglycol (MHPG) to the level in fed rats after 60-90 min. The changes in MHPG and norepinephrine in the fed rats were not significant There was no difference in serotonin concentration between fasted and fed animals, although the mean value for 5-hydroxyindoleacetic acid (5-HIAA) was slightly increased. Following the injection of CRF, there was a fall in serotonin in the fed rats but not in the fasted animals. There was a fall in the concentration of 5-HIAA in both the fasted and fed rats so that at 30, 60 and 90 min their concentrations were not significantly different. The concentration of DOPAC in the lateral hypothalamus was twice as high in the fasted as in the fed rats. Following injection of CRF there was a rapid decline in DOPAC concentrations in the fasted rats and a small decline in the fed rats. By the end of 30 min after the injection of CRF, concentrations of DOPAC were similar in fed and fasted rats.(ABSTRACT TRUNCATED AT 250 WORDS)