Posterior hypothalamic receptors involved in the cardiovascular changes elicited by electrical stimulation of the rostral ventrolateral medulla.
The posterior hypothalamic receptors involved in the cardiovascular responses to electrical stimulation of the rostral ventrolateral medulla were investigated in urethane-anaesthetized rats. Electrical stimulation of the rostral ventrolateral medulla produced a significant increase in systolic blood pressure. This response was significantly attenuated by the prior administration of d,l-propranolol (20 micrograms), clonidine (8 micrograms), atropine (8 micrograms) or methysergide (10 micrograms) into the posterior hypothalamus, but not by cimetidine (11 micrograms), chlorpheniramine (12 micrograms), naloxone (10 micrograms) or a vasopressin V1 antagonist (100 ng). The effect of clonidine (8 micrograms) on the pressor response to stimulation of the rostral ventrolateral medulla was antagonized by idazoxan (66 micrograms). These results confirm that the cardiovascular changes elicited by stimulation of the rostral ventrolateral medulla area are, in part, centrally modulated by alpha 2 and beta-adrenoceptors in the posterior hypothalamus which exert respectively, inhibitory and stimulatory effect. Furthermore the results indicate the involvement of posterior hypothalamic cholinergic and serotonergic receptors in the pressor response produced by stimulation of the rostral ventrolateral medulla.
Department of Physiology & Pharmacology, Medical School, Queen's Medical Centre, Nottingham, U.K.
H
H
Bachelard
R
R
Rivest
C A
CA
Marsden
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D004347:Drug Interactions; D004558:Electric Stimulation; D006339:Heart Rate / Q000187:drug effects*; D007034:Hypothalamus, Posterior / Q000187:drug effects*; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000187:drug effects; D012702:Serotonin Antagonists / Q000494:pharmacology*
D000317:Adrenergic alpha-Antagonists; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists