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DURING the course of efforts to determine the distribution of growth hormone–releasing factor (GHRF) in rat hypothalamus, a substance that inhibited growth hormone release was unexpectedly detected by Krulich et al.1 Their findings, reported in 1968, led them to hypothesize that the secretion of growth hormone from the pituitary was regulated by two different, interacting neurohumoral factors — one stimulatory, the other inhibitory — each under the control of the nervous system. Their hypothesis has since been substantiated by more specific methods. At about the same time, Hellman and Lernmark found a factor in extracts of pigeon pancreatic islets that . . .
Seymour Reichlin (1983) studied this question.