The role of melanin concentrator hormone (MCH) in the lateral hypothalamus/perifornical area (LH/PFA) and locus coeruleus (LC) in the ventilatory response to hypercapnia in rats during wakefulness and sleep

Abstract

Central chemoreception is a mechanism performed by the brain which is capable of detecting changes in CO2/pH levels and promoting corrections of these parameters through adjustments in lung ventilation. There are many putative chemosensitive sites, including the Lateral Hypothalamus/Peripheral Area (LH/PFA). The chemosensitive function of this region has been attributed to orexinergic neurons and its activity seems to be influenced by the inhibitory modulation exerted by a neuropeptide produced by neurons of the same region, the melanin concentrating hormone (MCH). It is known that in addition to establishing synapses within the LH/PFA, MHCergic neurons also send projections to other chemosensitive nuclei such as the Retrotapezoid Nucleus (RTN) and Locus Coeruleus (LC), but it not known, so far, the role of these synaptic interactions in the hypercapnic ventilatory response. Thus, the present study aims to evaluate the role of MCHergic neurotransmission, via MCH-R1 receptors, in LH/PFA and Locus Coeruleus in the hypercapnic ventilatory response and body temperature in rats during wakefulness and sleep, in the light and dark phase of the cycle diurnal. For this purpose, we will measure EEG, EMG, body temperature and pulmonary ventilation of non-anesthetized Wistar rats before and after the microinjection of MCH or the MCH-1 receptor antagonist bilaterally in the LH/PFA or Locus Coeruleus, during room air followed by hypercapnia (7%CO2). (AU)