|کد مقاله||کد نشریه||سال انتشار||مقاله انگلیسی||ترجمه فارسی||نسخه تمام متن|
|5554548||1558877||2017||6 صفحه PDF||سفارش دهید||دانلود رایگان|
Opioids contribute to the regulation of cerebral vascular tone. The purpose of this study was to examine the effects of herkinorin, a non-opioid Î¼-opioid receptor agonist derived from salvinorin A, on blood vessels in the rat retina and to investigate the mechanism underlying the herkinorin-induced retinal vasodilatory response. Ocular fundus images were captured using an original high-resolution digital fundus camera in vivo. The retinal vascular responses were evaluated by measuring the diameter of retinal arterioles in the fundus images. Both systemic blood pressure and heart rate were continuously recorded. Herkinorin increased the retinal arteriolar diameter without significantly changing mean blood pressure and heart rate. The retinal vasodilator response to herkinorin was almost completely prevented following treatment with naloxone, a nonselective opioid receptor antagonist and H-D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP), a selective Î¼-opioid receptor antagonist. NÏ-nitro-L-arginine methyl ester, a nonselective nitric oxide (NO) synthase inhibitor, or indomethacin, a cyclooxygenase inhibitor, significantly attenuated the herkinorin-induced retinal vasodilator responses. In addition, NÏ-propyl-L-arginine, an inhibitor of neuronal NO synthase, diminished the herkinorin-induced retinal vasodilator responses. Seven days after an intravitreal injection of N-methyl-D-aspartic acid, loss of inner retinal neurons and abolishment of the retinal vasodilator response to herkinorin were observed. These results suggest that herkinorin dilates rat retinal arterioles through stimulation of retinal Î¼-opioid receptors. The Î¼-opioid receptor-mediated retinal vasodilator response is likely mediated by NO generated by neuronal NO synthase. Retinal neurons play an important role in the retinal vasodilator mechanism involving Î¼-opioid receptors in rats.
Journal: European Journal of Pharmacology - Volume 803, 15 May 2017, Pages 124-129