Radioimmunoassay of inhibin: serum responses to unilateral and bilateral orchidectomy

Journal Article · Tue Nov 01 00:00:00 EST 1988 · Endocrinology; (United States)

DOI:https://doi.org/10.1210/endo-123-5-2323· OSTI ID:6801301

Schanbacher, B

An overnight double antibody RIA using a rabbit antiserum to porcine inhibin alpha-chain (Tyr30) (1-30) NH2 (pI alpha(1-30)), radioiodinated pI alpha(1-30), and a preprecipitated second antibody complex has been developed to measure inhibin concentrations in sera and other biological fluids. The assay is accurate, precise (intraassay coefficient of variation, 4.8%), sensitive (25 pM; 2.5 fmol/tube), and specific for inhibin. The synthetic reference standard pI alpha(1-30) produced a displacement curve that paralleled intact male ovine and bovine sera, crude bovine follicular fluid, and a partially purified porcine follicular fluid reference preparation (WHO/NIH 86/690). Bilateral castration of prepubertal and postpubertal ram lambs resulted in a rapid decrease in serum inhibin concentrations and a subsequent increase in serum FSH. Inhibin levels were high in prepubertal lambs (approximately 375 pM), but these levels were not sustained near the time of puberty (approximately 180 pM). Intensive sampling by jugular venipuncture after castration indicated a 50% drop in circulating inhibin levels within 2 h of testes removal with chronic castrate levels (approximately 75 pM) achieved by 6 h postcastration. A rapid fall in circulating levels of inhibin was also observed after unilateral castration, but these values stabilized within hours to levels intermediate (i.e. approximately 200 pM) to those of intact and bilateral castrate rams. Hemicastrates exhibited a more subtle rise in serum FSH after testis removal, with FSH and inhibin levels of prepubertal hemicastrates returning to mature intact ram values by 15 weeks of age. Serum inhibin levels remained low and FSH levels high at 14 days in unilateral castrate postpubertal rams. Inhibin immunoreactivity increased abruptly in castrate ewes and rams injected iv with 5 ml bovine follicular fluid.

• Research Organization: Department of Agriculture, Clay Center, NE (USA)
• OSTI ID: 6801301
• Journal Information: Endocrinology; (United States), Vol. 123:5
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
PROTEINS
RADIOIMMUNOASSAY
AGE DEPENDENCE
FSH
IODINE ISOTOPES
QUALITY CONTROL
SHEEP
ANIMALS
CONTROL
DOMESTIC ANIMALS
GONADOTROPINS
HORMONES
IMMUNOASSAY
IMMUNOLOGY
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
ORGANIC COMPOUNDS
PEPTIDE HORMONES
PITUITARY HORMONES
RADIOASSAY
RADIOIMMUNOLOGY
RUMINANTS
TRACER TECHNIQUES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques