Concentrationsof LI-

A sensitive heterologous radioimmunoassay for porcine prolactin (pPRL) has been developed. Anti-ovine prolactin antibody was raised in rabbits which allowed a final dilution of 1:500 000. The separation of free and antibody bound [125I]pPRL is based on the double antibody solid phase system. The assay is specific for pPRL. There is no cross-reaction with pLH, pFSH and pTSH; little cross-reaction (1.35 %) was found with pGH. The smallest detectable amount was 0.08 ng per tube. During lactation high plasma levels are found with great fluctuations. After weaning the plasma PRL levels fall to basal levels within a few hours.After thyrotrophin-releasing hormone (TRH) administration plasma concentrations increase within a few minutes.In our study on the fertility of the female pig we became interested in a pos¬ sible role of prolactin in the function of the ovary. Therefore we developed a heterologous radioimmunoassay in order to measure prolactin in porcine blood plasma. A homologous radioimmunoassay for pPRL has been reported pre¬ viously by Threlfall et cd. (1974). With this assay no significant differences were detected between plasma PRL levels of virgin gilts, sows at midgestation, sows at 112th day of gestation and sows during the suckling period (PRL values ranged from 140.7 to 167.1 ng/ml). The only significant difference re¬ ported was between suckling and non-suckling post-partum sows (167.1 and 115.3 ng/ml respectively). Brinkley et al. (1973) obtained data on plasma PRL

In order to exert their biological effects, steroid hormones must enter the cells of target tissues and after binding to specific receptor molecules must remain for a prolonged period of time in the nucleus. Therefore the endogenous levels and the subcellular distribution of estradiol, estrone, DHEAS, DHEA ad 5-Adiol were measured in normal breast tissues and in malignant and nonmalignant breast tumors from pre- and postmenopausal women. For estradiol the highest tissue levels were found in the malignant samples. No differences were seen in these levels between pre- and postmenopausal women despite the largely different peripheral blood levels. For estrone no differences were found between the tissues studied. Although the estradiol concentration was higher in the estradiol-receptor-positive than in the receptor-negative tumors, no correlation was calculated between the estradiol and the receptor consent. Striking differences were seen between the breast and uterine tissues for the total tissue concentration of estradiol, the ratio between estradiol and estrone, and the subcellular distribution of both estrogens. At similar receptor concentrations in the tissues these differences cannot easily be explained. Regarding the androgens, the tissue/plasma gradient was higher for DHEA than for 5-Adiol, and for DHEAS there was very probably a much lower tissue gradient. The highly significant correlation between the androgens suggests an intracellular metabolism of DHEAS to DHEA and 5-Adiol. Lower concentrations of DHEAS and DHEA were observed in the malignant tissues compared with the normal ones and the benign lesions. For 5-Adiol no differences were found and therefore these data do not support our original hypothesis on the role of this androgen in the etiology of breast abnormalities. Hence the way in which adrenal androgens express their influence on the breast cells remains unclear.

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