The Impact of Melatonin and its Agonist on Endothelin-1 Reactivity in  Isolated Aorta in Continuous Light and Pinealectomized Rats

Evan B. Othman; Ismail M. Maulood

doi:10.21271/ZJPAS.35.2.19

Authors

Evan B. Othman Department of Biology, College of Science, Salahaddin University-Erbil, Kurdistan Region, Iraq
Ismail M. Maulood Department of Biology, College of Science, Salahaddin University-Erbil, Kurdistan Region, Iraq

DOI:

https://doi.org/10.21271/ZJPAS.35.2.19

Keywords:

Melatonin, Ramelteon, Endothelin-1, Continuous Light, Pinealectomy, Rat aorta

Abstract

The purpose of the present study is to investigate the influence of melatonin and its receptor (MT1, and MT2) agonist (Ramelteon) on vascular endothelin-1 (ET-1) reactivity in isolated aortic rings in continuous light emitting diode (LED) exposure and pinealectomized rats. Materials and Methods: Two sets of experiments were performed in this study. In the first experiment, animals were divided into four groups: (control, continuous LED exposure rats, continuous light + Melatonin administration, and continuous light + Ramelteon administration). In the second experiment, animals were categorized into five groups: Control, rats underwent pinealectomy, pinealectomy + Melatonin administration, pinealectomy + Ramelteon administration, and pinealectomy + a continuous LED exposure. Results: The obtained results indicated that in constant light exposure of the rats for 10 weeks, the ET-1-induced aortic ring contraction was markedly reduced.Conversely, melatonin and its agonist (Ramelteon) markedly elevated the ET-1-induced aortic ring contraction. Neither, melatonin nor its agonist supplementation significantly increased ET-1 Emax. Similarly, in the second experiment after 6 weeks of pinealectomy and pinealectomy with continuous light exposure to rats significantly decreased aortic ring contraction. Moreover, ET-1 Emax significantly and ET-1 efficiency and AUC were slightly elevated in pinealectomy with light exposure group compared to the pinealectomized rats. On the other hand, ramelteon shifted the DRC of ET-1 to the left side. Conclusion: The results suggested that most of the melatonin actions on vascular modulation are due to its binding to MT1and MT2 receptors.

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