Activation of the serotonergic 5-HT1A receptor in the paraventricular nucleus of the hypothalamus inhibits water intake and increases urinary excretion in water-deprived rats.
The paraventricular nucleus (PVN) may be considered as a dynamic mosaic of chemically-specified subgroups of neurons. 5-HT(1A) is one of the prime receptors identified and there is expressed throughout all magnocellular regions of the PVN. Several reports have demonstrated that a subpopulation of the magnocellular neurons expressing 5-HT(1A) receptors are oxytocin (OT) neurons and activation of 5-HT(1A) receptors in the PVN increases the plasma OT. Increasing evidence shows that OT inhibits water intake and increases urinary excretion in rats. The aim of this study was to investigate the role of serotonergic 5-HT(1A) receptors in the lateral-medial posterior magnocellular region of the PVN in the water intake and diuresis induced by 24 h of water deprivation. Cannulae were implanted in the PVN of rats. 5-HT injections in the PVN reduced water intake and increased urinary excretion. 8-OH-DPAT (a 5-HT(1A) agonist) injections blocked the water intake and increased urinary output in all the periods of the observation. pMPPF (a 5-HT(1A) antagonist) injected bilaterally before the 8-OH-DPAT blocked its inhibitory effect on water intake and its diuretic effect. We suggest that antidipsogenic and diuretic responses seem to be mediated via 5-HT(1A) receptors of the lateral-medial posterior magnocellular region of the PVN in water-deprived rats.
Department of Physiology, São Paulo State University at Araraquara, UNESP, Brazil.
Patrícia
P
de Souza Villa
José Vanderlei
JV
Menani
Gabriela Maria Pavan
GM
de Arruda Camargo
Luiz Antônio
LA
de Arruda Camargo
Wilson Abrão
WA
Saad
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000008:administration & dosage / Q000819:agonists / Q000494:pharmacology; D000631:Aminopyridines / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000818:Animals; D004231:Diuresis / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects / Q000502:physiology*; D004347:Drug Interactions; D008297:Male; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D010879:Piperazines / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D044282:Receptor, Serotonin, 5-HT1A / Q000378:metabolism*; D012701:Serotonin / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000008:administration & dosage / Q000494:pharmacology; D013997:Time Factors; D014868:Water Deprivation
D000631:Aminopyridines; D010879:Piperazines; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D044282:Receptor, Serotonin, 5-HT1A; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; C099463:4-(2' methoxyphenyl)-1-(2'-(N-(2''-pyridinyl)-4-fluorobenzamido)ethyl)piperazine