Cardiovascular responses to centrally administered serotonin in conscious normotensive and spontaneously hypertensive rats.
Serotonin (5-HT, 1-10 micrograms), injected into the lateral ventricle of the urethanized, and conscious normotensive and spontaneously hypertensive rats produced a dose-dependent increase in blood pressure. In conscious rats, there was mainly a decrease in heart rate while variable changes in heart rate were elicited by intraventricular (i.c.v.) administration of 5-HT in anesthetized animals. These pressor responses and bradycardia caused by 5-HT in conscious rats were reduced by pretreatment with i.c.v. methysergide (25 micrograms). Microinjection of 5-HT (2.5-5 micrograms) directly into the medial hypothalamus and the anterior hypothalamus/preoptic area of conscious normotensive rats caused a pressor response accompanied by variable changes in heart rate. The present results indicate that urethane can affect the HR response to 5-HT injected i.c.v. without having a marked influence on the pressor response. These findings, which show that 5-HT produced a rise in BP independent of the anesthetized or conscious state and of normotension or hypertension, further confirm the idea that 5-HT plays a pressor role in the central regulation of the cardiovascular system.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000503:physiopathology*; D007276:Injections, Intraventricular; D008297:Male; D008784:Methysergide / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000008:administration & dosage / Q000494:pharmacology*
D012701:Serotonin; D008784:Methysergide