[Status of hypothalamic dopamine receptors in spinocerebellar degenerations]

The sensitivity of hypothalamic dopaminergic D2-receptors was studied in 52 patients with various spinocerebellar degenerations (SCD). Radioimmunoassay of blood prolactin enabled the state of these receptors to be evaluated before and after loading with D2-receptor agonist (bromocriptine) and antagonist (metoclopramide). In all forms of SCD, the rate of blood prolactin decrease in response to bromocriptine, was significantly lower than control values, which demonstrated the lower sensitivity of D2-receptors in the hypothalamic tubero-infundibular region to agonists. Metoclopramide caused a higher increase in blood prolactin levels than in the controls. The findings suggest that the state of the receptors was altered in SCD patients. A relationship between the impairments found and the clinical and morphological manifestations of different SCD forms is discussed.