Immunohistochemical demonstration of beta-arenoreceptor in the rat brain - with reference to the central control of blood pressure -

Using anti-beta₂-adrenoreceptor antibody, we examined immunohistochemically the localization of adrenoreceptor in the rat central nervous system at both lightmicroscopic and electronmicroscopic level. In the areas which are known to be involved in the control of blood pressure, such as the hypothalamus, the nucleus of the solitary tract and the locus coeruleus, there were a number of adrenoreceptor-like immunoreactive (ADR-IR) structures. They were mainly associated with cellular surface of the neuron. However, those localized within the cytoplasm or the nerve fiber were also observed. Immunoelectron microscopic analysis revealed that the ADR-IR structures were associated with post-synaptic density and cytoplasmic organella (endoplasmic reticulum, vesicle). Ultrastructural feature of the ADR-IR fiber was characterized by the synaptic vesicles with immunoreaction products. In addition, we detected that the running pattern of the ADR-IR fibers was often quite similar to that of tyrosine hydroxylase-immunoreactive (i.e. catecholaminergic) fibers. These findings suggest the presence of the presynaptic autoreceptor.In the present study, we have clearly demonstrated the cellular and subcellular localization of adrenoreceptors in the areas related to blood pressure control immunocytochemically. These results suggest the immunocytochemical method should be quite useful for further investigation OF the CNS control of blood pressure.