Cardiovascular effects produced by R-(+)-8-hydroxy-2-(di-n-propylamino) tetralin in the preoptic area of conscious rats.
Experiments were designed to test the hypothesis that activation of forebrain 5-HT1A receptors elicits cardiovascular responses. The microinjection of R-(+)-8-hydroxy-2-(di-n-propylamino) tetralin [(+)-8-OH-DPAT], a selective 5-HT1A receptor agonist, in the preoptic area of conscious rats increased blood pressure and heart rate at doses of 0.2-20 nmol; lower doses (0.002 and 0.02 nmol) were ineffective. The concomitant administration of methiothepin, a non-selective 5-HT receptor antagonist, into the preoptic area attenuated the responses. In addition, the tachycardia elicited by (+)-8-OH-DPAT was abolished by the peripheral beta-adrenoceptor antagonist sotalol, but not by atropine methyl nitrate. Finally, the tachycardia, but not the hypertension, was also produced by (+)-8-OH-DPAT in urethane-anesthetized rats. These results suggest that activation of 5-HT1A receptors in the preoptic area or an adjacent region of the forebrain produces: (1) an increase in heart rate consistent with sympathoadrenal activation; and (2) an increase in blood pressure which might be the result of sympathoexcitation or secondary to behavioral arousal.
Szabó
A
A
Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City 66160-7417, USA.
Bowman
M
M
Braun
C J
CJ
Alper
R H
RH
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects*; D008297:Male; D008719:Methiothepin / Q000494:pharmacology; D008845:Microinjections; D010276:Parasympatholytics / Q000494:pharmacology; D011301:Preoptic Area; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000187:drug effects*; D044263:Receptors, Serotonin, 5-HT1; D012702:Serotonin Antagonists / Q000008:administration & dosage / Q000494:pharmacology*
D010276:Parasympatholytics; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D012702:Serotonin Antagonists; D008719:Methiothepin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D001285:Atropine