Modulation by thyroid hormones of rat parotid amylase secretion stimulated by 5-hydroxytryptamine.
The effects of 5-hydroxytryptamine (5-HT) upon amylase secretion by rat parotid glands were studied in three groups of animals: (a) intact control rats (euthyroid rats); (b) hypothyroid rats obtained by surgical thyroidectomy 2 wk before the experiments; and (c) hyperthyroid rats obtained by the administration of sodium l-triiodothyronine for 2 wk before the experiments. Hyperthyroid rats showed significantly higher baseline amylase release than control rats. When the glands were stimulated with 5-HT (30 micro m), amylase release was significantly lower in the hypothyroid group and higher in the hyperthyroid rats than in control group. Addition of cholinergic, adrenergic or substance P antagonists did not modify 5-HT-stimulated amylase activity. The effects of 5-HT were partly but significantly blocked by the addition of 10 micro m methysergide (HT1/2/7 receptor blocker) in the three groups of rats. In contrast, 10 micro m ketanserine (HT2A receptor blocker) partly blocked the response to 5-HT only in the hyperthyroid animals. It was concluded that 5-HT induces amylase secretion by rat parotid glands through specific serotoninergic receptors, and that thyroid status modulates the 5-HT effect.
Ostuni
Mariano Aníbal
MA
INSERM U.410, Faculté Xavier Bichat, Paris, France. ostuni@bichat.inserm.fr
Houssay
Alberto Bernardo
AB
Tumilasci
Omar René
OR
D000681:Amylases / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D006980:Hyperthyroidism / Q000139:chemically induced / Q000201:enzymology*; D007037:Hypothyroidism / Q000201:enzymology*; D008297:Male; D008784:Methysergide / Q000494:pharmacology; D010306:Parotid Gland / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000502:physiology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D013961:Thyroid Gland / Q000502:physiology; D014284:Triiodothyronine
D012702:Serotonin Antagonists; D014284:Triiodothyronine; D012701:Serotonin; D000681:Amylases; D008784:Methysergide