Cardiovascular effects of 5-HT1A receptor agonists injected into the dorsal raphe nucleus of conscious rats.
The aim of this study was to investigate the cardiovascular effects of the 5-HT1A receptor agonists, 8-OH-DPAT (8-hydroxy-2-(di-n-propylamino)tetralin), flesinoxan and 5-carboxamidotryptamine (5-CT) following injection into the dorsal raphe nucleus of conscious rats. 8-OH-DPAT (0.5-2.5 micrograms), hypotension, bradycardia and flat body posture. In contrast, injection of 8-OH-DPAT (0.5 microgram) into the median raphe nucleus caused no cardiovascular changes or flat body posture. (-)Pindolol (0.5 microgram dorsal raphe nucleus) had little effect on cardiovascular parameters, but significantly attenuated the cardiovascular effects of 8-OH-DPAT (0.5 microgram dorsal raphe nucleus). N-Methylatropine (1 mg/kg i.v.) antagonised the cardiovascular effects of 8-OH-DPAT (0.5 microgram dorsal raphe nucleus), suggesting these were vagally mediated. Both pretreatments also appeared to reduce 8-OH-DPAT-induced flat body posture. The results suggest that 8-OH-DPAT activates 5-HT1A receptors in the dorsal raphe nucleus to cause hypotension and bradycardia.
Connor
H E
HE
Department of Neuropharmacology, Glaxo Group Research Ltd., Ware, Herts, U.K.
Higgins
G A
GA
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001286:Atropine Derivatives / Q000494:pharmacology; D001522:Behavior, Animal / Q000187:drug effects; D002404:Catheterization; D006439:Hemodynamics / Q000187:drug effects*; D007267:Injections; D007275:Injections, Intravenous; D008297:Male; D010869:Pindolol / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011903:Raphe Nuclei / Q000187:drug effects; D051381:Rats; D011985:Receptors, Serotonin / Q000187:drug effects*; D012701:Serotonin / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology*; D013764:Tetrahydronaphthalenes / Q000494:pharmacology
D000959:Antihypertensive Agents; D001286:Atropine Derivatives; D010879:Piperazines; D011985:Receptors, Serotonin; D013764:Tetrahydronaphthalenes; D012701:Serotonin; C056895:flesinoxan; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; C006649:methylatropine; C047087:5-carboxamidotryptamine; D010869:Pindolol