A simple model to explain the motor fluctuations seen in Parkinson's disease

Cloning and spatial and temporal expression of the zebrafish dopamine D1 receptor

Dopamine plays important roles in the regulation of central nervous system (CNS) development and functions. In vertebrates, two families of dopamine receptors, collectively known as dopamine D1 and D2 receptors, have been identified. Recently, dopamine receptors have been targeted by pharmacological and therapeutic studies of neurological disorders, such as Parkinson's disease. Here, we report a study on the molecular characterization of dopamine D1 receptor in zebrafish (Danio rerio). We cloned the full-length cDNA of a zebrafish dopamine D1 receptor, designated as drd1. The sequence of drd1 shares high homology to the sequences of dopamine D1 receptors in mammalian, amphibian, and other fish species. drd1 is expressed in the CNS. The first drd1 expression was observed at approximately 30 hours postfertilization, at which time the expression was seen in the developing diencephalon and hindbrain. In developing retinas, the expression of drd1 was detected in the inner nuclear layer with the exception of the marginal zones. In adult retinas, drd1 expression was detected in most cell types in the inner and outer nuclear layers as well as ganglion cell layer. Differential expression of drd1 in developing and adult retinas may play various roles in regulating visual system functions.

Parkinson's disease: prospects for improved drug therapy

L-Dopa has long been the mainstay of therapy for Parkinson's disease but its long-term shortcomings, principally uncoordinated, spasmodic or irregular movements (dyskinesias) and fluctuating control of motor symptoms (on/off fluctuations), are well documented. The postulated neuroprotective properties of L-deprenyl, often used as an adjunct to L-dopa, are under scrutiny and doubts have also been raised regarding its safety. Alternative therapeutic approaches are clearly needed. In this review, Jim Hagan, Derek Middlemiss, Paul Sharpe and George Poste outline some new approaches to treatment, with an emphasis on novel, selective dopamine receptor agonists. In addition, Parkinson's disease is commonly thought to be caused by the neurotoxic effects of an unidentified agent but recent data indicate a greater genetic component than previously recognized. Developments in the genetics of Parkinson's disease may provide the key to the next generation of therapeutics.