Abstract |
The effects of the 5-HT receptor agonist, 5-methoxytryptamine, on plasma glucose levels were investigated in rats. 5-Methoxytryptamine induced a significant hyperglycemia above the dosage of 1 mg/kg. 5-Methoxytryptamine-induced hyperglycemia was antagonized by pretreatment with the 5-HT1 and 5-HT2 receptor antagonist, methysergide, or the 5-HT2A receptor antagonist, ketanserin, whereas the 5-HT3 and 5-HT4 receptor antagonist, tropisetron, and the 5-HT4 receptor antagonist, SDZ 205-557 (2-methoxy-4-amino-5-chloro-benzoic acid 2-(diethylamino) ethyl ester), showed no effect. In addition, the peripheral 5-HT2 receptor antagonist, xylamidine, reduced 5-methoxytryptamine-induced hyperglycemia. These results suggest that 5-methoxytryptamine-induced hyperglycemia is mediated by the peripheral 5-HT2A receptor, although it has a high affinity for the 5-HT4 receptor. Adrenodemedullation abolished the 5-methoxytryptamine-induced hyperglycemia. 5-Methoxytryptamine did not affect the blood levels of the pancreatic hormones, insulin and glucagon. The hyperglycemia induced by 5-methoxytryptamine was not affected by pretreatment with dexamethasone which inhibits corticosterone release. These results indicate that 5-methoxytryptamine-induced hyperglycemia is elicited by a facilitated adrenaline release from the adrenal gland. Therefore, it is suggested that the 5-HT2A receptor may be partly involved in the pharmacological effects induced by the 5-HT4 receptor agonist, 5-methoxytryptamine.
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Authors | J Yamada, Y Sugimoto, T Yoshikawa, K Horisaka |
Journal | European journal of pharmacology
(Eur J Pharmacol)
Vol. 323
Issue 2-3
Pg. 235-40
(Apr 04 1997)
ISSN: 0014-2999 [Print] Netherlands |
PMID | 9128844
(Publication Type: Journal Article)
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Chemical References |
- Blood Glucose
- Insulin
- Receptor, Serotonin, 5-HT2A
- Receptors, Serotonin
- Serotonin Antagonists
- Serotonin Receptor Agonists
- 5-Methoxytryptamine
- Dexamethasone
- Glucagon
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Topics |
- 5-Methoxytryptamine
(pharmacology)
- Adrenal Medulla
(physiology)
- Animals
- Blood Glucose
(analysis)
- Dexamethasone
(pharmacology)
- Glucagon
(blood)
- Insulin
(blood)
- Male
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT2A
- Receptors, Serotonin
(drug effects, physiology)
- Serotonin Antagonists
(pharmacology)
- Serotonin Receptor Agonists
(pharmacology)
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