Figure 7.

SCN and ARC coordination for diurnal temperature decrease in the MnPO. The MnPO receives SCN and ARC efferents that control the temperature. During the night, an SCN-mediated activation of ARC α-MSH (Guzmán-Ruiz et al., 2014) sustains high Tb during the night (1) (Nakamura et al., 2011). In the last part of the dark phase, AVP is released from SCN terminals (2), the hypothermic effects of AVP are counteracted by α-MSH activity in the ARC as long as it is night (1,2). At the onset of the light phase, the SCN inhibits the activity of α-MSH neurons (3) (Guzmán-Ruiz et al., 2014). Without α-MSH thermogenic counteraction, AVP is able to exert its hypothermic effect (4). Top curves illustrate the rhythmic patterns of α-MSH activity in the ARC (green), AVP release from the SCN (blue), and Tb (red) modulated at the level of the MnPO. Bottom schemes illustrate the neuronal interaction between the nuclei. Black and white bars indicate the dark and light phases, respectively.