Growth hormone releasing factor and somatomedin C production: extrahypothalamic localization and possible functional significance.

Growth hormone-releasing factor (GRF) is found in the highest concentration (albeit lower compared to other hypothalamic regulatory hormones) in the hypothalamus. There is mounting evidence that GRF-like immunoreactivity is found in other sites in the CNS and in the periphery. The role of GRF, other than to stimulate growth hormone secretion by the somatotroph, is unknown. In addition generation of IGF-1 in response to GRF appears to be dependent on an intact pituitary.