Cardiovascular Research Advance Access [Accepted Manuscript] published online on June 30, 2009
Cardiovascular Research, doi:10.1093/cvr/cvp214
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Ovariectomy increases the formation of prostanoids and modulates their role in acetylcholine-induced relaxation and nitric oxide release in the rat aorta
Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, C/Arzobispo Morcillo 4, 28029 Madrid, Spain
Corresponding author: Dr. Mercedes Ferrer, Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, C/Arzobispo Morcillo 4, 28029 Madrid, Spain; tel.: +34 91 497 3112; fax: +34 91 497 5478; e-mail: mercedes.ferrer{at}uam.es
Aims: This study examines the effect of ovarian function on thromboxane A2 (TXA2), prostaglandin (PG) I2, PGF2
and PGE2 release as well as the role of these substances in nitric oxide (NO) release and acetylcholine (ACh)-mediated relaxation.
Methods: Aortic segments from ovariectomized and control female Sprague-Dawley rats were used. Cyclooxygenase (COX-1 and COX-2) expression was studied. ACh-induced relaxation was analyzed in the absence and presence of the COX-2 inhibitor NS-398, the TXA2 synthesis inhibitor furegrelate, the PGI2 synthesis inhibitor tranylcypromine (TCP) or the thromboxane-prostanoid (TP) receptor antagonist SQ-29548. TXA2, PGI2, PGF2
and PGE2 release was measured, and the vasomotor effect of exogenous TXA2, PGI2, PGF2
and PGE2 was assessed. Basal and ACh-induced NO release in the absence and presence of NS-398, furegrelate, TCP or TCP plus furegrelate was studied.
Results: Ovariectomy did not alter or increased COX-1 or COX-2 expression, respectively. NS-398 decreased, and furegrelate did not change, the ACh-induced relaxation in arteries from both groups. SQ29,548 decreased the ACh-induced relaxation only in aortas from ovariectomized rats. TCP decreased the ACh-induced relaxation in both groups, and furegrelate or SQ29,548 totally restored that response only in aortas from control rats. Ovariectomy increased the ACh-induced TXA2, PGI2 and PGE2 release and the contractile responses induced by exogenous TXA2, PGF2
or PGE2, while it decreased the PGI2-induced vasodilator response. In aortas from control rats, NS-398 did not alter the ACh-induced NO release, and furegrelate, TCP or TCP plus furegrelate increased that release. In arteries from ovariectomized rats, NS-398, furegrelate, TCP or TCP plus furegrelate decreased the ACh-induced NO release.
Conclusions: Despite the prevalence of vasoconstrictor prostanoids derived from COX-2 in aortas from ovariectomized rats, the ACh-induced relaxation is maintained, probably as consequence of the positive regulation that prostanoids exert on eNOS activity.
KEYWORDS Ovarian function; TXA2; PGF2
; PGE2; PGI2; endothelial NO; rat aorta
Time for primary review: 20 Days