Radioimmunoassay for 6-D-tryptophan analog of luteinizing hormone-releasing hormone: Measurement of serum levels after administration of long-acting microcapsule formulations

M. Mason-Garcia, S. Vígh, A. M. Comaru-Schally, T. W. Redding, A. Somogyvari-Vigh, J. Horvath

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

A sensitive and specific radioimmunoassay for [6-D-tryptophan]luteinizing hormone-releasing hormone ([D-Trp6]LH-RH) was developed and used for following the rate of liberation of [D-Trp6]LH-RH from a long-acting delivery system based on a microcapsule formulation. Rabbit antibodies were generated against [D-Trp6]LH-RH conjugated to bovine serum albumin with glutaraldehyde. Crossreactivity with LH-RH was less than 1%: there was no significant crossreactivity with other peptides. The minimal detectable dose of [D-Trp6]LH-RH was 2 pg per tube. Intra- and interassay coefficients of variation were 8% and 10%, respectively. The radioimmunoassay was suitable for direct determination of [D-Trp6]LH-RH in serum, permitting the study of blood levels of the analog after single injections into normal men and after once-a-month administration of microcapsules to rats. In men, 90 min after subcutaneous injection of 250 μg of the peptide, serum [D-Trp6]LH-RH rose to 6-12 ng/ml. Luteinizing hormone was increased 90 min and 24 hr after the administration of the analog. Several batches of microcapsules were tested in rats and the rate of release of [D-Trp6]LH-RH was followed. The improved batch of microcapsules of [D-Trp6]LH-RH increased serum concentrations of the analog for 30 days or longer after intramuscular injection. This was accompanied by suppression of testosterone levels for more than 30 days. This radioimmunoassay should be of value for monitoring [D-Trp6]LH-RH during long-term therapy.

Original languageEnglish
Pages (from-to)1547-1551
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume82
Issue number5
DOIs
Publication statusPublished - 1985

ASJC Scopus subject areas

  • General

Fingerprint Dive into the research topics of 'Radioimmunoassay for 6-D-tryptophan analog of luteinizing hormone-releasing hormone: Measurement of serum levels after administration of long-acting microcapsule formulations'. Together they form a unique fingerprint.

  • Cite this