Cellular NeuroscienceDopamine receptor-mediated regulation of neuronal “clock” gene expression
Section snippets
Preparation of primary cultures of striatal neurons and drug treatments
For the preparation of primary neuronal cultures from the striatum, we used ICR mice (Harlan, Indianapolis, IN, USA). Mice were housed in a temperature-controlled room under conditions of a 14-h light/10-h dark cycle (lights on at 5 am). The experimental protocols were approved by the Institutional Animal Care and Ethics Committee of the University of Illinois at Chicago. All experiments were performed under these approved experimental protocols and the number of the subjects kept controlled by
Results
DA receptors and clock genes are expressed in striatal neurons in culture (Fig. 1). Gene specific primer pairs (see Table 1 for primer sequences) detected the expected size PCR products in gel electrophoresis for D1 (404 bp), D2 (532 bp), and D3 (536 bp) DA receptors and the clock genes, mPer1 (387 bp), mClock (534 bp), mBmal1 (471 bp), and mNPAS2 (458 bp) (Fig. 1). Moreover, mCLOCK and D2 DA receptor proteins co-exist in the same neurons in culture (Fig. 1). Since co-labeling studies revealed
Discussion
In this study using DA receptor specific drugs (i.e. agonists), we demonstrated that DA receptor-mediated intracellular signaling differentially regulates neuronal clock gene expression at the cellular level (i.e. striatal neurons in culture). Further, we found that when given systemically, the DA receptor agonist quinpirole regulates the striatal expression of the clock gene mPer1 depending on the time of injection.
As a part of the mesolimbic system, the striatum is primarily involved in the
Conclusion
In conclusion, using a neuronal culture model (i.e. primary striatal cultures) in vitro as well as a protracted DA receptor-specific drug treatment protocol in vivo, we have demonstrated that DA receptors mediate neuronal clock gene expression. Our results clarify at least in part the underlying mechanisms of the regulatory role of the psychostimulant/DA system on clock gene expression dynamics. Future studies using neuronal culture models are needed to understand the underlying mechanisms of
Acknowledgments
We acknowledge support from the Psychiatric Institute, UIC and by NIH grants R01 DA15072 (T.U.), R01 MH61572 (H.M.), and K01 MH069839 (R.S.).
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