Secretion pattern of immunoreactive inhibin in men.
Chronological changes in serum concentrations of inhibin, a gonadal glycoprotein hormone, were studied in healthy male volunteers (age 24-27 years). Secretion profiles of immunoreactive inhibin (ir-inhibin) were compared with those of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone. Blood samples were collected every 15 min for 24 h. Serum inhibin concentrations were measured by a two-site immunoenzymatic assay with antibodies raised against distinct epitopes of the recombinant 1-32 amino acids of the alpha-subunit of human inhibin. The normal range for men was 0.79-3.1 U/l x 10(-3), the sensitivity of the assay was 0.1 U/l x 10(-3) (cv: within-assay, 6.8%; between-assay, 8.2%). Luteinizing hormone and FSH were measured by immunoradiometric assay and testosterone by radioimmunoassay. Secretion profiles of inhibin and testosterone were tested for diurnal variations by cosinor rhythmometry. Highest ir-inhibin concentrations were observed in the morning at 08.00 h, with peak values of 2.45-3.20 U/l x 10(-3). During the evening and the night, ir-inhibin levels were relatively low; lowest concentrations were observed between 01.00 h and 02.00 h at night: 1.20-1.86 U/l x 10(-3). Highest testosterone levels were observed in the morning (20.5-36.6 pmol/l), lowest concentrations were detected at night (7.35-12.6 pmol/l). Cosinor rhythmometry supported the suggestion that there is a clear circadian secretion of ir-inhibin and testosterone, respectively. The secretion pattern of ir-inhibin was analyzed by the Cluster pulse analysis computed algorithm, which identified four to seven inhibin pulses per day, depending on the person under observation.2+ volunteers follow a clear diurnal rhythm.(ABSTRACT TRUNCATED AT 250 WORDS)
Brennemann
W
W
Institut für Klinische Biochemie, Universität Bonn, Germany.
Sommer
L
L
Stoffel-Wagner
B
B
Bidlingmaier
F
F
Klingmüller
D
D
D000328:Adult; D002940:Circadian Rhythm; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D007124:Immunoenzyme Techniques; D015592:Immunoradiometric Assay; D007265:Inhibins / Q000097:blood / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D009994:Osmolar Concentration; D011863:Radioimmunoassay; D012016:Reference Values; D012680:Sensitivity and Specificity; D013739:Testosterone / Q000097:blood
D013739:Testosterone; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone