β-Adrenergic receptor binding in human and rat hypothalamus

Abstract

Quantitative autoradiographic analysis of β-adrenergic binding sites was conducted in human postmortem hypothalamus using the radioligand 125I-pindolol. The focus was on the hypothalamic nuclei most clearly involved in corticotropin-releasing hormone (CRH) release, the PVN and SON. For comparison, the distribution of hypothalamic β-adrenergic receptors was evaluated in the rat. A high level of β-adrenergic receptor binding was found in the human paraventricular nucleus (PVN) and supraoptic nucleus (SON), but not in the rat. The majority of the β-adrenergic receptors found in the human hypothalamus were of the β 2-subtype. In contrast, in the rat hypothalamus, the majority of receptors were of the β 1-subtype. These results show that the anatomical loci exist for direct β-adrenergic influence on hypothalamic neuroendocrine function in the human and that the topography of β-adrenergic receptors is markedly different in the rat and human hypothalamus.