Developmental Patterns of Plasma and Testicular Testosterone in Mice From Birth to Adulthood

Abstract

Male mice were raised in cohabitation with females from birth to 90 days. Testosterone was measured every 10 days in plasma and testes. Sex difference in body weight was related to the pre-pubertal increase of testosterone levels in males. The weight of the seminal vesicle was positively correlated with circulating testosterone levels between 1 and 40 days but not between 50 and 90 days Testosterone concentrations in the plasma and testes were high at birth: 630 pg/ml and 58.0 \ m=+-\ 17.7 ng/100 mg; they subsequently decreased during the first days of life and remained low until day 20: 240 \m=+-\ 110 pg/ml and 0.1 \ m=+-\0.03 ng/100 mg. The testosterone levels then increased rapidly between days 20 and 30 and especially between 30 and 40 reaching their maxima: 5770 \ m=+-\ 1720 pg/ml and 123.7 \ m=+-\ 18.3 ng/100 mg testis. This increase was transitory and testosterone levels fell after day 40. By 90 days, the testosterone levels, 440 \ m=+-\ 65 pg/ml and 43.2 \ m=+-\ 5.5 ng/100 mg testis, were comparable to those measured at birth. Plasma testosterone and age were positively correlated between 1 and 40 days, and negatively between 50 and 90 days. The first fertile matings occurred at age 40 days.In spite of a large body of research, the physiological mechanisms responsible for sexual maturation remain poorly understood (Odell 8c Swerdloff 1976). One important factor for their understanding involves a systematic study of the secretion of sex hormones from birth to puberty. The present report deals with the variations of plasma and testicular testosterone in mice between 1 and 90 days of age and the correlations between the levels of this hormone and the development of seminal vesicle, spermatogenesis and the appearance of fertility. MATERIALS AND METHODSMice of the Swiss strain (CD-I, Charles River) were raised in the laboratory under identical conditions of temperature (20 ± 1°C), lighting (daylight) and nutrition (com¬ plete pelleted chow and water given freely). Immediately after delivery the litters were reduced to 6 pups, 3 males and 3 females. After weaning on the 20th day, the 6 pups stayed in cohabitation until sacrifice. Litters which appeared in the cages were immediately removed. 15 males were sacrificed every 10 days from birth to 90 days. Blood was obtained by cardiac puncture without anticoagulant under light ether anaes¬ thesia. Testosterone was measured in the right testis of each male. Testosterone was determined on pooled samples of plasma (15 animals) on the one day and ten day old mice, in individual samples for the other stages. Testosterone was also measured in females, in pooled samples of plasma in the one day (100 animals), 10 -20 -30 and 40 (15 animals each) day-old animals.Testosterone was measured by the radioimmunoassay method previously described (Veyssiere et al. 1976). The antibody was prepared in rabbits against testosterone 3-0-carboxy-methyl-oxime bovine albumine. The major cross reacting steroid, 5a-dihydrotestosterone (74°/o) was separated by chromatography on a celite colum...

Minireview: The Neuroendocrinology of the Suprachiasmatic Nucleus as a Conductor of Body Time in Mammals

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Molecular genetics of prostate cancer

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The fertility of hypothyroid male mice

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