Abnormal regulation of prolactin release in idiopathic Parkinson's disease.

Levodopa with carbidopa suppressed prolactin release induced by thyrotrophin releasing hormone less effectively in patients with idiopathic Parkinson's disease than in normal subjects. This finding supports the view that the biochemical defect in idiopathic Parkinson's disease extends to the hypothalamus and is not confined to the basal ganglia. Aetiological considerations in Parkinson's disease should encompass a widespread disorder of neurotransmission whose extent merits further investigation.