A Direct Assay for Oestrone Sulphate and Its Use to Investigate the Effect of Ampicillin on Plasma Levels of Oestrone Sulphate

Summary

A direct radioimmunoassay for measuring plasma levels of oestrone sulphate has been developed using 8-anilino-2-naph-thalene sulphonic acid to displace oestrone sulphate from plasma binding proteins. Oestrone sulphate was assayed by using an antiserum raised against oestrone glucuronide which cross-reacted 100% with oestrone sulphate. The direct assay gave a good analytical recovery of oestrone sulphate and there was a good correlation (r=0.82, P < 0.001) for plasma levels of oestrone sulphate measured by the direct assay and a method involving steroid conjugate extraction and enzyme hydrolysis. The mean (±S.D.) plasma level of oestrone sulphate in men was 1100±280 pg/ml. The effect of taking the antibiotic, Ampicillin, on plasma levels of oestrone sulphate was investigated in four men. Plasma levels of oestrone sulphate were significantly reduced after taking Ampicillin for 5 days. Ampicillin may act to lower plasma levels of oestrone sulphate by reducing the growth of bacteria in the gut or by inhibiting oestrogen sulphotransferase activity.

Key-Words

Oestrone Sulphate - Direct Assay - Antibiotic - Plasma