Serotoninergic modulation of sodium appetite in the rat.
There are two mechanisms leading to an enhancement of salt intake: one is induced by a sodium deficit and the other is need-free. The serotonin involvement in need-induced and/or need-free sodium appetite is interesting to consider because related drugs are already used against another cardiovascular risk factor, obesity. The effect of dexfenfluramine (1.5 or 3 mg/kg), an anorectic drug enhancing 5-HT transmission, and of metergoline (2 or 4 mg/kg), a 5-HT antagonist, was assessed in need-induced (depletion-induced), subsequent need-free, and spontaneous sodium appetite. Dexfenfluramine (3 mg/kg) decreased by 75% to 90% the depletion-induced intake of an aversive 3% NaCl solution, as well as the spontaneous intake of a less aversive 1.8% NaCl solution. Water intake was not diminished under these conditions. Metergoline significantly increased salt intake in need-free conditions in rats with either a history of three previous depletions or not. These results confirm the involvement of serotonin in sodium appetite and extend this involvement to both need-induced (natriorexis) and need-free (natriophilia) conditions. The metergoline experiments also suggest that 5-HT exerts a tonic inhibition on salt intake.
Rouah-Rosilio
M
M
Neurobiologie des Régulations, URA CNRS 637, Collège de France, Paris.
Orosco
M
M
Nicolaidis
S
S
D000818:Animals; D001066:Appetite / Q000187:drug effects / Q000502:physiology*; D001921:Brain / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005277:Fenfluramine / Q000494:pharmacology; D008711:Metergoline / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology; D012701:Serotonin / Q000502:physiology*; D012982:Sodium, Dietary / Q000008:administration & dosage*; D014882:Water-Electrolyte Balance / Q000187:drug effects / Q000502:physiology*
D011985:Receptors, Serotonin; D012982:Sodium, Dietary; D008711:Metergoline; D005277:Fenfluramine; D012701:Serotonin