Effects of gastrin-releasing peptide on basal and stimulated thyroid hormone secretion in the mouse.
Recently, gastrin releasing peptide (GRP) was demonstrated to occur within normal thyroidal C cells. In the present study, the effects of GRP on basal and stimulated thyroid hormone secretion were investigated in the mouse according to the McKenzie technique. Iodine-deficient mice were pretreated with 125I and thyroxine. GRP was found dose-dependently to increase the basal radioiodine levels after iv injection, reflecting a stimulation of basal thyroid hormone secretion. The effect was maximal at a dose level of 3.0 nmol/animal, and at 2 h after injection, when GRP had increased blood radioiodine levels to 152 +/- 8% compared with 96 +/- 5% in controls (P less than 0.001). GRP seemed to exert additive effects on thyroid hormone secretion with vasoactive intestinal peptide and with TSH at a threshold dose level. In contrast, GRP did not influence the stimulatory effects of either a half-maximal dose level of TSH or noradrenaline. Furthermore, neither L-propranolol nor methylatropine influenced the GRP-induced thyroid hormone secretion. It is concluded that GRP has the capacity to stimulate basal thyroid hormone secretion in the mouse.
Ahrén
B
B
Department of Pharmacology, Lund University, Sweden.
D000818:Animals; D001286:Atropine Derivatives / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D019886:Gastrin-Releasing Peptide; D051379:Mice; D008815:Mice, Inbred Strains; D009638:Norepinephrine / Q000494:pharmacology; D010455:Peptides / Q000008:administration & dosage*; D011433:Propranolol / Q000494:pharmacology; D013963:Thyroid Hormones / Q000378:metabolism*; D013972:Thyrotropin / Q000494:pharmacology; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
D001286:Atropine Derivatives; D010455:Peptides; D013963:Thyroid Hormones; D014660:Vasoactive Intestinal Peptide; D019886:Gastrin-Releasing Peptide; C006649:methylatropine; D013972:Thyrotropin; D011433:Propranolol; D009638:Norepinephrine