α 1-Adrenergic receptors in human spinal cord: specific localized expression of mRNA encoding α 1-adrenergic receptor subtypes at four distinct levels

Abstract

α 1-Adrenergic receptors (α 1ARs) are important in lower urinary tract syndromes such as benign prostatic hypertrophy and bladder irritability. Spinal cord α 1ARs have been postulated to play a role in modulating these diseases, yet α 1AR subtype (α 1a, α 1b, α 1d) neuronal localization in human spinal cord has not been described. We therefore tested the hypothesis that α 1AR subtype distribution varies according to specific spinal cord tract and level. In situ hybridization was performed to identify cell bodies containing α 1AR subtype mRNA at four levels of human spinal cord (cervical enlargement, thoracic, lumbar, sacral). α 1AR mRNA is present in ventral gray matter only (ventral>dorsal; sacral>lumbar=thoracic>cervical). Signaling cell bodies were detected in anterior horn motor neurons at all levels; dorsal nucleus of Clarke and intermediolateral columns in cervical enlargement, thoracic and lumbar spinal cord regions; and parasympathetic nucleus in sacral spinal cord. Although all three α 1AR subtypes are present throughout human spinal cord, α 1d mRNA predominates overall. If confirmed at a protein level, these findings may contribute to the development of new therapeutic strategies in the treatment of several human diseases.