The effect of hypergravity on the inner ear: CREB and syntaxin are up-regulated.

cDNA microarray analysis of differential mRNA expression in the rat inner ear under hypergravity identified 20 up-regulated and 2 down-regulated genes. The results demonstrated that various response and/or adaptation processes occur at the level of the peripheral organs. From among the genes assessed by microarray, up-regulation of CREB and syntaxin was confirmed by real time PCR and these two molecules were found to be immunocytochemically localized in the primary afferent neurons. Since CREB is believed to be involved in the formation of long term memory, and syntaxin is known as one of the synaptic molecules involved in the exocytosis of synaptic vesicles, the up-regulation of CREB and syntaxin may reflect synaptic plasticity occurring in the peripheral vestibular system.