Investigation of circadian rhythmicity and the effects of sleep deprivation on MCHergic and orexinergic system response

• Grant number: 15/05666-2
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: June 01, 2015
• End date: March 31, 2019
• Field of knowledge: Biological Sciences - Biology
• Agreement: Coordination of Improvement of Higher Education Personnel (CAPES)
• Principal Investigator: Vânia D'Almeida
• Grantee: Ana Luiza Dias Abdo Agamme
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil

Abstract

Sleep is a physiological process critical for survival, which is regulated by the light/dark synchronizer that has circadian rhythmicity. Sleep is composed by two fundamental stages: non-REM and REM or paradoxical sleep. The hypothalamus is a cerebral area involved in the organism homeostasis, standing out among other functions in the control of circadian rhythmicity and sleep/wake cycle. In the hypothalamus a number of neurotransmitters are synthetized acting in these functions, e.g. orexins and the melanin concentrating hormone (MCH). MCH and orexin were related to several physiological functions as energetic metabolism control, thermoregulation, motor control, humor and emotions and sleep/wake cycle regulation. This last function is evidenced by the increase in the MCHergic neurons activity, which was observed during paradoxical and non-paradoxical sleep, followed by the increase in Mchr1 gene expression during paradoxical sleep. It has been demonstrated that the orexinergic system presents circadian rhythmicity and experiments made in our laboratory showed that the MCHergic system responds differently in two moments of the day (Zeitgeber time- ZT0 and ZT8), however, only when animals were sleep deprived. Considering that data in literature together with data obtained in our previous experiments are not sufficient to determine if MCHergic responses presents circadian rhythmicity, we aim to verify if the MCHergic system presents circadian rhythmicity and if sleep deprivation alters that rhythm. We will also investigate if sleep deprivation alters circadian rhythmicity already described for the orexinergic system. (AU)