Influence of the central nucleus of the amygdala on the content of corticotropin-releasing factor in the median eminence.

The central nucleus of the amygdala possesses numerous neurons containing corticotropin-releasing factor (CRF). This study demonstrates a striking decrease of the CRF-like immunoreactivity in the median eminence at both 1 and 2 weeks after bilateral lesions of the amygdaloid central nucleus. Lesion of the amygdaloid central nucleus did not alter the neurophysin-like immunoreactivity in the internal zone of the median eminence, indicating the integrity of the efferent neurophysin-containing fibers of the supraoptic and paraventricular hypothalamic nuclei. However, there was a concomitant decrease of neurophysin and CRF-like immunoreactivity in the external zone of the median eminence. These results substantiate the hypothesis that the amygdaloid central nucleus can influence the content of CRF-like material in the median eminence via a multisynaptic pathway involving the synthesis of CRF at the level of the paraventricular nucleus of the hypothalamus. The exact mechanism by which lesion of the amygdaloid central nucleus influences the CRF content in the median eminence remains to be determined.