[Effects of intracerebroventricular administration of endomorphin-1 on blood pressure in anesthetized rats].
OBJECTIVE
To observe the effects of intracerebroventricular administration of endomorphin-1 on blood pressure in anesthetized rats and to assess its mechanism.


METHODS
Variations of mean arterial pressure (MAP) were observed after icv injection of endomorphine-1 in rats. The effects of i.v. or icv of various blockers, naloxone, phentolamine, propranolol, atropine and N omega-nitro-L-arginine, on the variation of MAP caused by endomorphin-1 were observed.


RESULTS
Endomorphin-1 was shown to decrease MAP. The decrease in MAP was blocked by naloxone. Pretreatments with icv phentolamine and propranolol showed no effect on the vasodepression induced by icv endomorphin-1. However, pretreatment with icv atropine (25 micrograms.kg-1) attenuated the vasodepression. Pretreatments with i.v. phentolamine, propranolol and N omega-nitro-L-arginine showed no effect on the vasodepression induced by icv endomorphin-1. But, pretreatment with i.v. atropine (50 micrograms.kg-1) and bilateral vagotomy attenuated the vasodepression.


CONCLUSIONS
Intracerebroventricular administration of endomorphin-1 produces vasodepressor response in anesthetized rats, which is mediated by opioid receptor. The vasodepression is associated with the central M cholinoceptor and the excitation of the vagus.
Wu
N
N
Department of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou 730000, China.
Huo
X F
XF
Chen
Q
Q
Yang
D J
DJ
Wang
R
R
D000758:Anesthesia; D000818:Animals; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D007276:Injections, Intraventricular; D007278:Injections, Spinal; D008297:Male; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009842:Oligopeptides / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D017450:Receptors, Opioid, mu / Q000819:agonists; D014628:Vagotomy
D000959:Antihypertensive Agents; D018727:Muscarinic Antagonists; D009842:Oligopeptides; D017450:Receptors, Opioid, mu; C105293:endomorphin 1; D001285:Atropine