Circadian Dexras1 in rats: Development, location and responsiveness to light.

Dexras1 has been shown to exhibit clock-dependent rhythm in mice suprachiasmatic nucleus (SCN), and its genetic deletion modulates circadian responses to photic and nonphotic cues. We show that the rhythmic expression of Dexras1 mRNA and protein in rat SCN already oscillates with low amplitude at postnatal day 3 and can be detected as early as embryonic day 20. In contrast, its expression in peripheral tissues is not rhythmic in adult rats either. The Dexras1 protein is expressed predominantly in the dorsomedial part of the SCN and the light pulse has only a limited effect on its expression. Our data provide the descriptive basis for speculation about the Dexras1 involvement in the rat circadian physiology.