Melanin-concentrating hormone (MCH) is a hypothalamic neuropeptide involved in a broad range of homeostatic functions including regulation of the hypercapnic chemoreflex. We evaluated whether MCH modulates the hypercapnic ventilatory response by acting in the lateral hypothalamic area (LHA) and/or in the locus coeruleus (LC). Here, we measured pulmonary ventilation ( E), body temperature, EEG and EMG of unanesthetized male Wistar rats before and after microinjection of MCH [0.4 mM] into the LHA and LC, or the MCH1-R antagonist (SNAP-94847 [63 mM]), into the LHA, in room air and in 7% CO2 during wakefulness and sleep, in the dark and light periods. MCH intra-LHA caused a decreased CO2 ventilatory response during wakefulness and sleep, while SNAP-94847 intra-LHA increased this response, during wakefulness in the light period. In the LC, MCH or the MCH1-R antagonist caused no change in the hypercapnic ventilatory response. Our results suggest that MCH, in the LHA, exerts an inhibitory modulation of the hypercapnic ventilatory response during the light-inactive period in rats.
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Coordenação de Aperfeiçoamento de Pessoal de Nivel Superior (CAPES)
FAPESP:2019/17693-5
FAPESP: 2018/01781-0
CAPES: 88887.194785/2018-00