Abstract
Homer1a/Vesl-1S is an activity-inducible member of the scaffold protein family Homer/Vesl, which is known to link metabotropic glutamate receptors (mGluRs) to endoplasmic calcium release channels such as inositol-1,4,5-triphosphate receptors (IP3Rs) or ryanodine receptors. Homer 1a is regarded also to regulate such Homer-mediated coupling. It has been reported that Homer 1a is involved in short-term synaptic transmission. However, it is still unclear whether Homer 1a takes part in induction of long-term depression (LTD), a form of long-term synaptic plasticity. To examine the roles of Homer 1a in inducing LTD in the rat visual cortex, Homer 1a protein was injected by diffusion from whole-cell patch pipettes. The results revealed that Homer 1a injection suppresses LTD dependent on mGluRs, but not that dependent on N-methyl-D-aspartate receptors (NMDARs). Then, induction of endogenous Homer 1a by electroconvulsive shock (ECS) was attempted. Homer 1a thereby induced was also able to reduce LTD magnitude significantly. Reduction of LTD expression after ECS was recovered by injection of anti-Homer 1a antibodies. These results suggest that endogenously induced Homer 1a may serve as a regulator of mGluR-mediated long-term synaptic transmission. [J Physiol Sci. 2007;57 Suppl:S147]
