Fonseca Elisa M, Dias Mirela B, Bícego Kênia C, Gargaglioni Luciane H
Department of Animal Morphology and Physiology, Sao Paulo State University-UNESP FCAV at Jaboticabal, SP, Brazil.
Department of Physiology, Institute of Bioscience, Sao Paulo State University-UNESP, Botucatu, SP, Brazil.
Respir Physiol Neurobiol. 2016 Apr;224:90-9. doi: 10.1016/j.resp.2014.11.014. Epub 2014 Nov 27.
Recent reports have suggested that orexins, also known as hypocretins, play an important role in the modulation of respiratory control in mammals, but there are no data available describing the role of the orexinergic system in the peripheral and central chemoreception of non-mammalian vertebrates. Therefore, the present study was designed to examine the localization of orexin-immunoreactive neurons in the brain of toads (Rhinella schneideri) and to investigate the contribution of orexin receptor-1 (OX1R) to the hypoxic and hypercarbic ventilatory responses of these animals during light and dark phases. Our results demonstrated that the orexinergic neurons of R. schneideri are located in the suprachiasmatic nucleus of the diencephalon. Additionally, the intracerebroventricular injection of SB-334867 (OX1R selective antagonist) attenuated the ventilatory response to hypercarbia during the dark phase by acting on tidal volume and breathing frequency, while during the light phase, SB-334867 attenuated the ventilatory response to hypoxia by acting on tidal volume only. We conclude that in the toad R. schneideri, orexinergic neurons are located in the suprachiasmatic nucleus and that OX1R contributes to hypercarbic and hypoxic chemoreflexes.
最近的报告表明，食欲素（也称为下丘脑泌素）在哺乳动物呼吸控制的调节中起重要作用，但尚无数据描述食欲素能系统在非哺乳动物脊椎动物外周和中枢化学感受中的作用。因此，本研究旨在检查蟾蜍（南美蟾蜍）脑中食欲素免疫反应性神经元的定位，并研究食欲素受体-1（OX1R）在这些动物明暗周期中对低氧和高碳酸血症通气反应的贡献。我们的结果表明，南美蟾蜍的食欲素能神经元位于间脑的视交叉上核。此外，脑室内注射SB-334867（OX1R选择性拮抗剂）通过作用于潮气量和呼吸频率，减弱了暗周期中对高碳酸血症的通气反应，而在明周期中，SB-334867仅通过作用于潮气量减弱了对低氧的通气反应。我们得出结论，在南美蟾蜍中，食欲素能神经元位于视交叉上核，并且OX1R参与高碳酸血症和低氧化学反射。
