Stress-induced phosphorylation of SNAP-25.

Synaptosomal-associated protein of 25 kDa (SNAP-25), a t-SNARE protein, plays a crucial role in neurotransmitter release by exocytosis. Protein kinase C phosphorylates SNAP-25 at Ser(187), however the physiological significance of this phosphorylation event in brain function remains unclear. In the present study, we found that SNAP-25 phosphorylation increased rapidly in the mouse brain following cold-water restraint stress. Both basal and stress-induced phosphorylation of SNAP-25 were high in stress-related brain regions, including the cerebral cortex, hippocampus, and amygdala, and the extent of phosphorylation increased with increasing amounts of stress. Intravenous administration of adrenaline increased SNAP-25 phosphorylation, although stress-induced phosphorylation was still observed in adrenalectomized mice. These results indicate that SNAP-25 phosphorylation is regulated in a stress-dependent manner through both central and peripheral mechanisms.