HOMEPRODUCTSCOMPANYCONTACTFAQResearchDictionaryPharmaSign Up FREE or Login

Effects of intracerebroventricular injections of 5-HT on systemic vascular resistances of conscious rats.

Abstract
The aims of this study were to determine (i) the effects of intracerebroventricular (i.c.v.) injections of 5-hydroxytryptamine (5-HT, 10μg) on mean arterial blood pressure (MAP), heart rate (HR) and mesenteric (MR), renal (RR) and hindquarter (HQR) vascular resistances of conscious rats, (ii) the central 5-HT receptor subtype which mediates these effects, and (iii) the role of nitric oxide (NO) in the expression of these responses. The i.c.v. injection of 5-HT had minor effects on MAP but produced a decrease in HR (-18±4%), which lasted for 20min. The i.c.v. injection of 5-HT elicited marked increases in MR (+50±7%) and reductions in HQR (-31±3%). These responses occurred promptly and lasted for 25-35min. 5-HT also produced a transient decrease in RR (-26±8% at 10min). All of these responses were prevented by the prior i.c.v. injection of the 5-HT1/5-HT2-receptor antagonist, methysergide (10μg). The intravenous injection of the NO synthesis inhibitor, L-NAME (25μmol/kg), produced a sustained pressor response, bradycardia and increases in MR, RR and HQR. Subsequent i.c.v. injection of 5-HT produced a minor pressor response (+7±2%), bradycardia (-18±3%), an increase in MR (+52±8%) but no decreases in RR or HQR. This study demonstrates that i.c.v. 5-HT differentially affects peripheral vascular resistances by activation of central 5-HT1/5-HT2-receptors. It appears that L-NAME did not interfere with the central actions of 5-HT as it did not prevent the 5-HT-induced bradycardia or mesenteric vasoconstriction. Since the 5-HT-induced falls in RR and HQR were abolished by L-NAME, it is possible that these responses are mediated by an active neurogenic process involving the release of NO within the vasculature.
AuthorsRobin L Davisson, James N Bates, Alan Kim Johnson, Stephen J Lewis
JournalMicrovascular research (Microvasc Res) Vol. 95 Pg. 116-23 (Sep 2014) ISSN: 1095-9319 [Electronic] United States
PMID25128748 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)
CopyrightCopyright © 2014 Elsevier Inc. All rights reserved.
Chemical References
  • Enzyme Inhibitors
  • Serotonin Antagonists
  • Nitric Oxide
  • Serotonin
  • Nitric Oxide Synthase
Topics
  • Animals
  • Blood Flow Velocity
  • Blood Pressure (drug effects)
  • Consciousness
  • Enzyme Inhibitors (pharmacology)
  • Heart Rate (drug effects)
  • Hindlimb
  • Injections, Intraventricular
  • Male
  • Muscle, Skeletal (blood supply)
  • Nitric Oxide (metabolism)
  • Nitric Oxide Synthase (antagonists & inhibitors, metabolism)
  • Rats
  • Rats, Sprague-Dawley
  • Regional Blood Flow
  • Renal Circulation (drug effects)
  • Serotonin (administration & dosage)
  • Serotonin Antagonists (pharmacology)
  • Splanchnic Circulation (drug effects)
  • Time Factors
  • Vascular Resistance (drug effects)

Join CureHunter, for free Research Interface BASIC access!

Take advantage of free CureHunter research engine access to explore the best drug and treatment options for any disease. Find out why thousands of doctors, pharma researchers and patient activists around the world use CureHunter every day.
Realize the full power of the drug-disease research graph!


Choose Username:
Email:
Password:
Verify Password:
Enter Code Shown: