Abstract
Synaptophysin is an integral membrane protein abundant in the synaptic vesicle and is found in nerve terminals throughout the brain. Its function has been implicated in various aspects of synaptic vesicle cycling such as biogenesis of vesicles, the regulation of the SNARE complex formation, synaptic vesicle fusion with plasma membrane, endocytosis and recycling of synaptic vesicles. It was recently suggested that synaptophysin is also involved in the modulation of activity-dependent synapse formation under a competitive condition. In this study, we examined at the individual level whether tactile stimulation selectively influenced the synaptophysin mRNA expression level in the somatosensory cortex of rats. Anesthetized rats were caressed on the back by an experimenter' s palms for twenty minutes and the mRNA expression levels in the somatosensory cortex responsible for the back and in the visual cortices five minutes afterwards were determined using quantitative PCR methodology. The synaptophysin mRNA expression level was selectively higher in the experimental group than in the control group in the somatosensory cortex but not in the visual cortex. This result suggests that the mRNA expression level of synaptophysin induced by neuronal activity is related to the regulation of synapse formation or remodeling or both. [J Physiol Sci. 2006;56 Suppl:S166]
