Endocrinology, Vol 117, 1834-1838, Copyright © 1985 by Endocrine Society

ARTICLES

Thyrotropin-releasing hormone release from rat pancreas is stimulated by serotonin but inhibited by carbachol

P Lamberton, P Wu and IM Jackson

Immunoreactive TRH (IR-TRH) has been found in the mammalian pancreas, with several studies documenting high concentrations in the late fetal/early neonatal period. As the factors regulating pancreatic TRH synthesis and release have not been fully explored, we developed a monolayer culture system of dissociated fetal/neonatal rat pancreatic cells to study the release of TRH from the mammalian pancreas. IR-TRH was detected in the culture medium and the IR material appeared authentic based on parallelism with synthetic TRH in RIA and retention time on HPLC. Potassium-induced depolarization (60 mM KCl) resulted in a 170% increase in TRH release compared to that by the Krebs-Ringer bicarbonate control (P less than 0.05). Serotonin stimulated TRH release, with the maximal effect seen with 10(-6) M (130% increase compared to control; P less than 0.05). Carbachol resulted in a dose- dependent inhibition of TRH release (57% inhibition of release at 10(- 8) M; P less than 0.01 compared to control). There was no effect on release with norepinephrine, epinephrine, dopamine, gamma-aminobutyric acid, or histamine. We conclude the following. 1) Authentic TRH is secreted by fetal/neonatal rat pancreatic cells in culture. 2) The secretion of TRH is stimulated by potassium-induced depolarization in a calcium-dependent manner, suggesting a classic neurosecretory process of release. 3) The secretion of pancreatic TRH may be under specific neurotransmitter control, with serotonin stimulating and acetylcholine inhibiting release of the tripeptide.

This article has been cited by other articles:

				E. A. Nillni and K. A. Sevarino The Biology of pro-Thyrotropin-Releasing Hormone-Derived Peptides Endocr. Rev., October 1, 1999; 20(5): 599 - 648. [Abstract] [Full Text]