Development of brain beta-adrenergic receptors after neonatal 6-hydroxydopamine treatment

We used [125I]-cyanopindolol in vitro autoradiography and neonatal 6-hydroxydopamine treatment to study the development of beta-adrenergic receptor subtypes in rat brain. Brain regions receiving locus coeruleus innervation, such as cerebral cortex and cerebellum, displayed low receptor densities at birth and increased in density rapidly during the second and fourth weeks postnatally. By contrast, regions which receive little innervation from the locus coeruleus, such as substantia nigra, striatum, and globus pallidus, displayed relatively high beta-receptor densities even at birth. The striatum appeared to be an exception to these generalizations. 6-Hydroxydopamine administration was associated with an increase in the densities of beta-receptor subtypes and, unexpectedly, with a change in the proportions of the two subtypes. These data support the view that innervation determines the ontogenetic patterns of some receptors in brain.