Rotations induced by L-dopa in parkinsonian rats are reduced by an ingestion of amino acids.

We studied the effect of amino acid load on L-dopa-induced rotational behavior in rats with unilateral lesion of the nigrostriatal pathway. Pretreatment of rats with an ingestion of high concentration of amino acids significantly reduced the number of rotations induced by subcutaneously injected L-dopa. These results provide the experimental basis for clinical observations that dietary protein affects the response to L-dopa in parkinsonian patients.