Peripheral 5-carboxamidotryptamine (5-CT) elicits drinking by stimulating 5-HT1-like serotonergic receptors in rats.
Subcutaneous administration of the prototypical 5-HT1-like agonist, 5-carboxamidotryptamine (5-CT), increased 2-h water intake by nondeprived rats (ED50 = 0.04 mumol/kg). The 5-HT1 agonists 8-hydroxy-2-(di-N-propylamino)-tetralin (8-OH-DPAT, 0.04-0.32 mumol/kg) and RU 24969 (0.16 mumol/kg) did not produce drinking. The dipsogenic effect of 5-CT (0.08 mumol/kg) was prevented by the 5-HT1/2 antagonist, methysergide (ID50 = 4 mumol/kg), but not by 16 mumol/kg of the 5-HT2 antagonist, ketanserin; the 5-HT21C antagonist, mianserin; or the 5-HT3 antagonist, MDL 72222, 5-CT also increased drinking and reduced food intake when food-deprived rats were given 2-h access to mash. Methysergide (16 mumol/kg) inhibited both actions of 5-CT but an equimolar dose of the 5-HT1/beta adrenergic antagonist, (-)-propranolol, blocked only the drinking. The 5-HT21C antagonist, ritanserin (16 mumol/kg), altered neither ingestive action of 5-CT although, by itself, ritanserin increased mash intake. The results suggest that activating a subtype of peripheral 5-HT1-like receptor stimulates drinking in rats. This receptor is unlike either the 5-HT1A or the 5-HT1C sites found in the brain. Furthermore, the dipsogenic and anorectic actions of 5-CT occur independently.
Simansky
K J
KJ
Department of Pharmacology, Medical College of Pennsylvania, Eastern Pennsylvania Psychiatric Institute, Philadelphia 19129.
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004327:Drinking Behavior / Q000187:drug effects*; D005247:Feeding Behavior / Q000187:drug effects; D007211:Indoles / Q000494:pharmacology; D008297:Male; D008784:Methysergide / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000187:drug effects*; D012701:Serotonin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D012702:Serotonin Antagonists; D013268:Stimulation, Chemical; D013764:Tetrahydronaphthalenes / Q000494:pharmacology
D007211:Indoles; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D013764:Tetrahydronaphthalenes; C025145:5-methoxy 3-(1,2,3,6-tetrahydro-4-pyridinyl)1H indole; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; C047087:5-carboxamidotryptamine; D008784:Methysergide