Metabolic rhythm abnormalities in mice lacking VIP-VPAC2 signaling

Area of Science:

• Neuroscience
• Chronobiology
• Metabolism

Background:

• The suprachiasmatic nuclei (SCN) govern circadian rhythms in physiology and behavior.
• Vasoactive intestinal polypeptide (VIP) and its receptor (VPAC2) are vital for SCN neuron communication and rhythm synchronization.
• Previous studies showed VIP signaling deficits impair SCN neuronal firing and locomotor activity rhythms.

Purpose of the Study:

• To investigate the role of VIP signaling in the circadian regulation of metabolism and feeding behavior.
• To determine how VIP or VPAC2 deficiency affects metabolic and feeding rhythms under different lighting conditions.

Main Methods:

• Comparison of metabolic and feeding rhythms in wild-type mice versus mice lacking VIP or VPAC2.
• Assessment of rhythms under diurnal (12:12-h light-dark) and constant light conditions.
• Measurement of overall metabolic rate in VPAC2-knockout mice.

Main Results:

• Mice deficient in VIP or VPAC2 exhibit advanced metabolic and feeding rhythms under diurnal conditions.
• These rhythms dampen and deteriorate in constant light in VIP- or VPAC2-deficient mice.
• VPAC2-knockout mice show a significantly reduced overall metabolic rate compared to wild-type controls.

Conclusions:

• VIP signaling is essential for the temporal regulation of metabolism and feeding behavior.
• Disruptions in SCN function via VIP signaling impairment profoundly affect metabolic and feeding rhythms.
• Metabolic and feeding rhythms in VIP-deficient mice appear less susceptible to light masking.