A role of thyrotropin-releasing hormone in insulin secretion by isolated rat pancreatic islets.
Insulin-secreting pancreatic beta cells also express thyrotropin-releasing hormone (TRH). Although the physiological role of TRH in this localization is unclear, its participation in glucoregulation has been implied. To test this hypothesis, we blocked the last step of post-translational maturation of the TRH molecule by disulfiram, which is an active inhibitor of peptide alpha-amidation (PAM) within pancreatic islet cells. The treatment of male rats with 200 mg/kg/day of disulfiram during a 5-day period resulted in a low PAM activity, a high insulin content and its basal secretion from pancreatic islets, and the inability to release insulin in response to glucose (16.7 mM) or hypo-osmotic (30%) challenge in vitro. The addition of TRH (1 nM) to the medium during incubation restored the insulin content and both basal and glucose stimulated insulin secretions to control levels.


CONCLUSIONS
TRH plays an important role in the mechanism of insulin secretion and its response to glucose stimulation.
Najvirtová
Miroslava
M
Institute of Experimental Endocrinology, Slovak Academy of Sciences, Vlárska 3, 83306, Bratislava, Slovak Republic.
Bacová
Zuzana
Z
Mátéffyová
Adela
A
Strbák
Vladimír
V
D000818:Animals; D005947:Glucose / Q000494:pharmacology; D007038:Hypotonic Solutions / Q000494:pharmacology; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D009997:Osmotic Pressure; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology* / Q000502:physiology
D007038:Hypotonic Solutions; D007328:Insulin; D013973:Thyrotropin-Releasing Hormone; D005947:Glucose