Inhibins in childhood and puberty.
Inhibin is a heterodimeric glycoprotein that consists of an alpha-subunit linked to either a betaA subunit (inhibin A) or to a betaB subunit (inhibin B) and it exists in at least six different isoforms. These isoforms can not be measured separately by immunoassays. In boys, serum inhibin B levels change in concert with the increase in gonadotrophins. Associated with the postnatal activation of gonadotrophin secretion, the early inhibin B secretion is sustained until the age of 18-24 months; thereafter serum concentrations subside. In boys, between Tanner stages G1 and G2, serum inhibin B concentration again increases, but then plateaus. Inhibin A levels in human males are below the detection limit, but in girls, during the postnatal activation of gonadotrophin secretion, both serum inhibin A and inhibin B concentrations are measurable. Serum inhibin B levels correlate positively with age several years before the clinical onset of puberty, suggesting increasing follicular activity in late prepuberty. During female puberty, the inhibin B level increases from Tanner stage B1 through stage B3, suggesting high follicular activity before the development of ovulatory menstrual cycles, but serum inhibin A levels become measurable later in puberty, in agreement with the idea that inhibin A is mainly produced by the corpus luteum.
Raivio
Taneli
T
Biomedicum Helsinki, Institute of Biomedicine/Physiology, University of Helsinki, PO Box 63 (Haartmaninkatu 8), FIN-00014 Helsinki, Finland.
Dunkel
Leo
L
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006066:Gonads / Q000254:growth & development / Q000502:physiology; D006801:Humans; D007265:Inhibins / Q000097:blood / Q000737:chemistry / Q000502:physiology*; D008297:Male; D011627:Puberty / Q000502:physiology*; D012741:Sexual Maturation / Q000502:physiology
D007265:Inhibins