Specific effect of putative 5-HT1A agonists, 8-OH-DPAT and gepirone, to increase hypertonic saline consumption in the rat: evidence against a general hyperdipsic action.
Previous reports indicate that 5-HT1A agonists, in addition to benzodiazepines, increase the consumption of hypertonic saline in rehydrating rats. Experiment 1 investigated the effects of 8-OH-DPAT (10-100 micrograms/kg) and gepirone (0.1-3.0 mg/kg) on consumption of water and of saline over a range of concentrations (0.45%-2.8%) in a 30 min drinking test. The two 5-HT1A agonists dose-dependently increased ingestion of two hypertonic salt solutions, but produced little or no increase in the drinking of water, hypotonic or isotonic saline. Experiment 2 demonstrated that 8-OH-DPAT and gepirone did not enhance water consumption in animals given a water preload, or markedly increase drinking quinine-adulterated water. Taken together, the results indicate a selective dose-related effect of the two drugs to increase hypertonic saline drinking; they did not have a general hyperdipsic effect across all salt and water conditions, and they did not increase intake simply because of a low baseline level of consumption. Hence, 5-HT1A agonist act much more selectively than benzodiazepines in their effects on drinking responses.
Cooper
S J
SJ
Department of Psychology, University of Birmingham, United Kingdom.
Fryer
M J
MJ
Neill
J C
JC
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000818:Animals; D001921:Brain / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects*; D008297:Male; D009281:Naphthalenes / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D051381:Rats; D011985:Receptors, Serotonin / Q000187:drug effects*; D012462:Saline Solution, Hypertonic; D013764:Tetrahydronaphthalenes / Q000494:pharmacology*; D014882:Water-Electrolyte Balance / Q000187:drug effects*
D009281:Naphthalenes; D011743:Pyrimidines; D011985:Receptors, Serotonin; D012462:Saline Solution, Hypertonic; D013764:Tetrahydronaphthalenes; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; C039979:gepirone