Further studies on the radioimmunoassay of gonadotropin-releasing hormone: effect of radioiodination, antiserum and unextracted serum on levels of immunoreactivity in serum. [/sup 125/I tracer technique]

Journal Article · Sat Oct 01 04:00:00 EDT 1977 · Endocrinology; (United States)

OSTI ID:5372518

Nett, T M; Adams, T E

Studies were undertaken to determine the effect of method of radioiodination, antisera and sera on levels of endogenous gonadotropin-releasing hormone (GnRH)-like activity in serum as quantified by radioimmunoassay. GnRH was radioiodionated. Unlabeled GnRH, monoiodo-GnRH and diiodo-GnRH were separated on the QAE Sephadex columns. Levels of immunoassayable GnRH-like activity in sera of ewes were lower (P less than 0.05) when antiserum R-42 (high affinity) was used for quantification than when antiserum R-31 (low affinity) was used. Furthermore, levels of immunoassayable GnRH-like activity in sera were lower when monoiodo-GnRH from the lactoperoxidase radioiodination was used for quantification than when other radioiodinated preparations were used with either the high affinity or low affinity antiserum. Incubations of GnRH with sera and subsequent fractionation on 0.8 x 20 cm columns of Sephadex G-25 indicated that macromolecular components of serum bind radioiodinated GnRH. This was particularly evident after radioiodination of GnRH by the chloramine-T procedure. Binding of (/sup 3/H)GnRH or unlabeled GnRH to macromolecular components of sera could not be demonstrated. To determine if serum was capable of destroying the immunological activity of GnRH, 1.0 ng unlabeled GnRH was incubated at 0, 22 or 37 C from 0 to 240 min with 1.0 ml aliquots of pools of sera obtained from cattle, dogs, horses, humans, rats and sheep. The disappearance of GnRH was determined by radioimmunoassay. The half-disappearance times for GnRH incubated in sera at 37 C ranged from less than 15 min in sera from horses to approximately 240 min in sera from humans and sheep. Intermediate half-disappearance times were noted for GnRH in sera of cattle, dogs, and rats. The half-disappearance time of GnRH in serum from all species increased dramatically at lower temperatures.

• Research Organization: Colorado State Univ., Fort Collins
• OSTI ID: 5372518
• Journal Information: Endocrinology; (United States), Journal Name: Endocrinology; (United States) Vol. 101:4; ISSN ENDOA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BLOOD SERUM
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
HORMONES
HYDROGEN ISOTOPES
IMMUNE REACTIONS
IMMUNE SERUMS
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
NUCLEI
ODD-EVEN NUCLEI
PEPTIDE HORMONES
PITUITARY HORMONES
RADIOASSAY
RADIOIMMUNOASSAY
RADIOISOTOPES
TRACER TECHNIQUES
TRITIUM
YEARS LIVING RADIOISOTOPES