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James I. Raeside

ABSTRACT

The urinary excretion of dehydroepiandrosterone (DHA), oestrone (OE1) and 17β-oestradiol (OE2) has been estimated during the administration of a number of hormones to an intact mature male pig. Daily intramuscular injections of corticotrophin (300 IU) or cortisone acetate (500 mg) resulted in a decrease in the levels of OE1, OE2 and DHA. Following the daily injection of human chorionic gonadotrophin (2500 IU) the excretion of all three steroids increased greatly. The daily oral administration of 30 mg Norlutin acetate (17α-ethynyl-19-nortestosterone acetate) appeared to be more effective than 30 mg Norlutin (17α-ethynyl-19-nortestosterone) in suppressing steroid production by the boar.

Considerable daily variation occurred in the amounts of OE1, OE2 and DHA excreted in the urine during »control« periods, and some evidence of a seasonal variation in levels of urinary steroids was observed.

Throughout the investigation a high degree of correlation existed between the urinary excretion of DHA and both oestrogens. It was concluded that the data provide strong support for the view that the large quantities of DHA in the urine of the normal boar arise from steroid biosynthesis in the testes.

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James I Raeside, Chad R Wilkinson and Gabrielle Farkas

High levels of estrogen secretion is a characteristic of steroidogenesis in the pig testis in both the adult and newborn male. We have now examined the ability of fetal gonads to secrete estrogens, and compared it with testosterone secretion during prenatal development. Fetuses were recovered from sows (N=33) at 27–114 (term) days of gestation. Gonads were removed for organ culture in TC-199 medium, or used as minced tissues or free cell preparations when taken later in development. Organ cultures were maintained for 96 h with luteinizing hormone added for the last 72 h for one gonad of each pair. Estrone, estradiol-17β and testosterone were measured by radioimmunoassay in media samples. Trace amounts of estrone were detected almost as early as testosterone secretion commenced, but quantities sufficient for confirmation by radioimmunoassay after chromatography were not seen until day 35 of gestation. Estrogen production increased to >0.37 nmol·gonad−1·4 h−1 at term. Testosterone secretion in organ culture was increased by luteinizing hormone but no effect was seen on estrone levels for the first half of pregnancy. Thus, estrogen secretion is a feature of steroidogenesis in the porcine testes even in the early stages of fetal development.

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Franz Schwarzenberger, Geoffrey S Toole, Heather L Christie and James I Raeside

Plasma concentrations for several androgens and estrogens were determined in male domestic pigs from birth to eight months of age. Samples (N = 6) of blood were collected from Yorkshire males at weekly intervals from birth to four weeks, and thereafter at monthly intervals to eight months. Radioimmunoassays were done without extraction from plasma for dehydroepiandrosterone sulphate, androstenedione and estrone sulphate. Other steroids were measured after solid-phase extraction, separate elution of unconjugated and conjugated fractions, and solvolysis of sulpho-conjugated steroids (testosterone, 5α-androstane-3β, 1 7β-diol, epiandrosterone, 19-nortestosterone and estradiol-177β). All steroids showed a peak in plasma levels at 2–4 weeks after birth. Concentrations remained low from 2–5 months and rose markedly thereafter. Most steroids were present in much greater quantities as sulpho-conjugated compounds. Concentrations of testosterone sulphate and testosterone were similar (9.4 μmol/l) at three weeks but the sulphated form predominated after six months of age. This study shows that during postnatal development the testes of the domestic pig are remarkably active in steroidogenesis with a peak at 2–4 weeks after birth. Also, the range of steroid products seen at this stage is comparable to that shown by the mature boar.