Vasopressin in circadian function of SCN

The suprachiasmatic nucleus (SCN) that acts as the primary circadian pacemaker in mammals is responsible for orchestrating multiple circadian rhythms in every organism. A network structure in the SCN composed of multiple types of neurons orchestrates the circadian rhythms. Despite speculations regarding the working of the clock, the molecular mechanisms governing it is far from clear. The molecular mechanism seems to be woven around the genes present and their linking with the neuromodulators. With the advancement in knowledge regarding the role of neuromodulators in the workings of the clock, especially that of Arginine vasopressin (AVP) and vasoactive intestinal peptide (VIP), the entire picture of the mechanisms involved and therefore the importance of these neuromodulators has changed considerably. AVP seems to be very important for the functioning of the clock and its role has been well established based on the evidence available at present. Enormous research is going on to study the role of AVP and new roles are likely to be assigned to AVP in the execution of function in the SCN. Of late, there have been reports indicating linkage of AVP with jet lag in a positive way, suggesting vasopressin signalling as a possible remedy for ill effects and their improvement. Studies also show circadian rhythm disturbances in mood disorders and the same is related to AVP levels in the SCN. Various findings are thus in accordance with strong suggestions for a critical role for AVP in SCN function.