title: Alpha1-adrenoceptor subtypes in rat epididymis and the effects of sexual maturation.
abstract: We have characterized the expression of alpha1-adrenoceptor in epididymis from rats in different stages of sexual maturation: 40 (immature), 60 (young adult), and 120 (adult) days of age. Plasma testosterone levels were low in the immature animals but increased significantly in the 60- and 120-day-old animals. These changes were followed by a progressive increase in rat body weight and in caput and cauda epididymis relative weight. Reverse transcription polymerase chain reaction assay indicated that alpha1a-, alpha1b-, and alpha1d-adrenoceptor transcripts were present in both caput and cauda epididymis from adult rats. Ribonuclease protection assays further indicated that the expression of these alpha1-adrenoceptor transcripts differed with age and epididymal region analyzed. Prazosin (nonselective alpha1 antagonist), 5-methyl urapidil (alpha1A-selective), and BMY 7378 (alpha1D-selective) displaced [3H]prazosin binding curves in caput and cauda epididymis from 40- and 120-day-old rats. The potency order for these antagonists, as calculated from the negative logarithm of the inhibition constant (pK(i)) values for the high-affinity sites, indicated a predominant population of alpha1A-adrenoceptor subtype in caput and cauda epididymis from adult animals. Differences in pK(i) values in caput and cauda epididymis from immature and adult animals also suggested that the relative amount of alpha1-adrenoceptors, at the protein level, is modulated by sexual maturation. Taken together, the changes in alpha1-adrenoceptor expression during sexual maturation may suggest specific roles for these receptors in epididymal function.
authors.affiliation: Section of Experimental Endocrinology, Department of Pharmacology, Universidade Federal de São Paulo-Escola Paulista de Medicina, 04044-020 São Paulo, Brazil.
authors.forename: Daniel B C
authors.initials: DB
authors.lastname: Queiróz
authors.forename: Fúlvio R
authors.initials: FR
authors.lastname: Mendes
authors.forename: Catarina S
authors.initials: CS
authors.lastname: Porto
authors.forename: Maria Christina W
authors.initials: MC
authors.lastname: Avellar
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D004822:Epididymis / Q000187:drug effects / Q000378:metabolism*; D017403:In Situ Hybridization; D008297:Male; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D023282:Nuclease Protection Assays; D009929:Organ Size / Q000187:drug effects / Q000502:physiology; D011224:Prazosin / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000302:isolation & purification; D011869:Radioligand Assay; D051381:Rats; D017208:Rats, Wistar; D018340:Receptors, Adrenergic, alpha-1 / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012741:Sexual Maturation / Q000502:physiology*; D013739:Testosterone / Q000097:blood
chemical_list: D000317:Adrenergic alpha-Antagonists; D012333:RNA, Messenger; D018340:Receptors, Adrenergic, alpha-1; D013739:Testosterone; D011224:Prazosin