New directions in Parkinson's research and treatment.

L-DOPA remains the mainstay of therapy for Parkinson's disease (PD). However, the side-effects assocd. with its chronic use have fuelled the search for novel strategies as an alternative to simply supplementing dopamine deficiency. In reviewing with 166 refs., the advances made over the last five years, focus has been given to dopamine agonists, as well as to new MAO inhibitors that appear more effective than the currently used compd., selegiline. A no. of new mols. acting at sites of the neuronal circuit distal from lesioned dopaminergic neurons have also been considered, including NMDA antagonists, adenosine antagonists and anticholinergic agents, this latter group representing the pioneering approach to PD treatment. In addn., new concepts of 'neuroprotection' have led to the exploitation of various agents, esp. anti-oxidants, directed toward slowing or halting disease progression. An entirely new perspective has been provided by methods that apply the techniques of mol. biol. to PD therapy and allow modified dopaminergic neurons capable of synthesizing specific neurotropic factors to be obtained by transfection. Parkinson's research has now progressed extensively, and further understanding of the etiol. of neuronal degeneration will disclose the key to the development of an effective therapy.