The characteristics of in vitro hormone release from rat adenohypophysis provoked by acute chilling

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Abstract
The exposure of rat adenohypophysial tissue to iced media for brief periods of 2–7 min provokes a biphasic release of growth hormone (GH). An increased release of adrenocorticotropin (ACTH) and prolactin (PRL) is also detected in the "instantaneous" first phase which takes place while the tissue is still cold. No detectable movement of Ca2+ into or out of the cells occurs during this phase and the magnitude of release is unaffected when Ca-free media (45Ca2+ uptake or Ca2+ content. This delayed release is unaffected by Ca-free media. The release of the cytoplasmic marker enzyme, lactic dehydrogenase (LDH), was also measured after a brief chill. LDH release was an order of magnitude less than the release of hormone measured in the same experiment indicating that exocytosis was reponsible for hormone release rather than nonspecific damage to the cells. I conclude that the hormone release following a brief chill does not employ a "stimulus–secretion coupling" mechanism. However, as the release is via exocytosis, some common aspect of the release mechanism beyond the "coupling" stage is activated to provoke the release of at least three adenohypophysial hormones, GH, ACTH, and PRL.