Oscillation development for neurotransmitter-related genes in the mouse striatum

The aims of this study were to determine (i) whether striatal neuropeptides (dynorphin, enkephalin 1, substance P, cholecystokinin) and dopamine receptors 1 and 2 (D1r and D2r) are regulated by the molecular clock; and (ii) when their oscillations start after birth. Twenty-four-hour mRNA oscillations of these genes were evaluated in the mouse striatum at early postnatal stage (postnatal day 3), preweaning stage (postnatal day 14), and adult (postnatal day 60). At P3, no daily oscillations were observed. A significant time effect was present for D2r, dynorphin, and enkephalin 1 at P14, and for all genes except D1r, at P60. In conclusion, circadian expression of these neurotransmitter-related genes develops in the mouse striatum after birth gradually.