Adrenergic receptors in the cerebellum of olivopontocerebellar atrophy

Using autoradiographic techniques we studied the changes that in adrenergic receptors occurred in the cerebellum of two olivopontocerebellar atrophy (OPCA) patients as compared with a control group. In OPCA cerebellum the densities of total β-adrenoceptors were reduced along the cortex but increased in the white matter. Although mainly the β1 subtype was decreased along the cerebellar cortex, the increase of β-receptors over the white matter was due to a selective raise in the β2 subtype. These findings suggest a post-synaptic neuronal location for the β1 subtype and a glial location for the β2-adrenoceptor. On the other hand, alpha2-adrenoceptors were clearly reduced all along the cerebellar cortex of these OPCA brains, this probably being secondary to the loss of presynaptic adrenergic terminals arising from the locus coeruleus. These results help clarify both the subcellular location of adrenoceptors in human cerebellum and the neurochemical pathophysiology of OPCA.