EFFECTS OF ACTIVE IMMUNISATION AGAINST STEROIDS UPON CIRCULATING HORMONE CONCENTRATIONS

Male and female Sprague-Dawley rats were actively immunised against testosterone-3-(O-carboxymethyl)oximino-bovine serum albumin (T-3-BSA) or oestradiol(17β)-6-(0-carboxymethyl)oximino-BSA(E2-6-BSA). Animals were test bled at monthly intervals under ether anaesthesia from the jugular vein. Serum was used for hormone analysis by radioimmunoassay throughout. The common finding was that the presence of antisteroid antibodies was accompanied by total serum steroid concentrations showing 100–1000 fold increase over control values. In the male, immunisation against T-3-BSA was also accompanied by elevated LH and FSH, and histological examination of the reproductive tract revealed marked Leydig cell hyperplasia but a reduction in the size of the ventral prostate. The picture in the serum from female rats resembled that from the male except that. LH values did not rise. Persistent vaginal cornification was observed and the ovaries had large fluid-filled cysts although no granulosa cells could be seen lining the cysts, and corpora lutea were absent. In both sexes the ‘free’ circulating testosterone concentration fell over the period of immunisation but neither showed any change in serum prolactin levels. Animals immunised against E2-6-BSA showed certain similarities with the above group in that serum antibody titres rose to the accompaniment of elevated total oestradiol(17β) concentrations but LH was raised only in the females and neither sex showed any differences in FSH or prolactin levels. In the male, testosterone concentrations were significantly above controls in the intermediate stages of immunisation but no pathological changes were observed in the reproductive tract on sacrifice. The vaginal and ovarian picture in the female was similar to that described above although the cysts were rather smaller in size. Both sexes appeared to have slightly raised concentrations of ‘free’ E2.