Interactions between circadian clocks and feeding behaviour

The muti-oscillatory circadian system consists of the suprachiasmatic clock (SCN) the master clock, located above the optic chiasm of the anterior hypothalamus, and many peripheral clocks. The SCN clock synchronizes the other peripheral oscillators located in each organ. The SCN clock is a self-sustaining circadian oscillator maintaining the daily behavioural, physiological, and neuroendocrine rhythms. The zeitgebers such as light and food are potent synchronizers for the SCN and other peripheral clocks. The thesis was aimed to understand different aspects of the interactions between circadian clocks and feeding behaviour in nocturnal species. We showed in the first and second parts that the ultradian feeding affects the central and peripheral clocks in mice and rats. In the first part, we concluded that the ultradian feeding in mice has major impacts on the SCN clock output and the peripheral clock in the liver, while in the second part ultradian feeding in rats does not have impact on the SCN clock but it affects peripheral clocks and lipid metabolism. In the third part, we showed the differential effects of diet and time restricted feeding in brown adipose tissue and skeletal muscle peripheral clocks. In the fourth part, we showed the role of clock gene Rev-erbα on feeding behaviour and energy metabolism by comparing between global and brain specific knock-out mice. The present studies reveal the interdependency of the circadian clocks and feeding behaviour, and their effects on whole-body metabolism.

Keywords: Suprachiasmatic clock, ultradian (6-meal) feeding, time restricted feeding, Rev-erbα.