a1_Young intact (18 days of age) and adult ovariectomized (OV-X, ovariectomized between 21 to 24 days of age) C3H/Di mice were used to measure the estrogenicity on the basis of the growth response of mammary epithelial structures and weight of the uterus. The percentage area of the mammary fat pad occupied by mammary epithelial structures was progressively increased by 17ß estradiol from dose 0.001 µg.d-1. The maximum effective dose of estradiol was 0.01 µg.d-1 and the dose 10 µg.d-1 of estradiol decreased mammary size to control levels (inverted-U-shaped dose-response curve). Progesterone alone progressively stimulated mammary growth in young intact females from dose 125 µg.d-1, in adult OV-X animals from dose 1000 µg.d-1. Both in young intact and adult OV-X animals, uterine weight progressively increased during estradiol treatment. Progesterone alone had no effect on uterine weight in young intact animals; in adult OV-X animals, uterine weight was increased starting from dose 250 µg.d-1. Progesterone acted synergistically with estradiol to produce higher mammary growth than that in females treated with estradiol alone. The effects of a combination of estradiol plus progesterone in the mammary gland were mimicked by norethindrone acetate and inhibited by cortisol in both young intact and adult OV-X animals. Testosterone inhibited estradiol plus progesterone stimulated growth of mammary gland only in OV-X animals, but stimulated uterine weights in both young intact and adult OV-X animals. Spleen weight and size of mammary lymph nodes were not affected by estradiol, progesterone, norethindrone acetate or testosterone, but were decreased by cortisol. Cortisol also decreased the percent area of the mammary fat pad occupied by mammary epithelial structures, but had no effect on weight of the uterus. These results show that bioassay of estrogenicity in females is not specific., a2_Mammary and uterine growth is stimulated not only by estrogens but also by progesterone and testosterone, respectively. ., J. Škarda., and Obsahuje bibliografii
a1_Young intact (18 days old) and adult castrated males of CBA and C3H/Di mice were used for measuring the estrogenicity on the basis of growth response of mammary epithelial structures and the weight of seminal vesicles. It was demonstrated that heavier young males had disproportionally heavier seminal vesicles (sex steroid-responsive organs) than small animals at day 33 of age (that is on the day when experimental animals were killed and organs dissected). However, the weight of the spleen (sex steroid-nonresponsive organ) was proportionally related to body weight. To minimize variability in hormone responsiveness, all animals were weighed at the age of 18 days and only males weighing 8±1 g were used for hormone treatment. The percentage area of mammary fat pad occupied by mammary epithelial structures was progressively increased by 17ß estradiol from dose 0.01 µg.d-1. The maximum effective dose of estradiol was 0.1 µg.d-1 and dose 10 µg.d-1 of estradiol decreased mammary size to control level (inverted-U-shaped dose-response curve). Progesterone alone stimulated mammary growth only in high doses (500 µg.d-1 and higher) in young intact males, but had no effect on mammary growth in adult castrated animals. In young intact males, estradiol alone, or progesterone alone decreased the weight of seminal vesicles. No such inhibitory effect of these hormones was noted in adult castrated males. Progesterone acted synergistically with estradiol to produce higher mammary growth compared to that in males treated with estradiol alone. In the presence of progesterone seminal vesicles weight was decreased by estradiol given in such low doses as 0.001 µg.d-1 of estradiol, which is 10 times lower than that effective in animals treated with estradiol alone. On the other hand, in the adult castrated males a combination of estradiol plus progesterone stimulated seminal vesicles weight., a2_The effects of a combination of estradiol plus progesterone in the mammary gland were mimicked by norethindrone acetate (a synthetic steroid exhibiting progestantial and estrogenic activities) and inhibited by both testosterone and cortisol. Estradiol, progesterone, norethindrone acetate, or testosterone did not affect spleen weight and size of mammary lymph nodes. However, cortisol significantly decreased not only spleen weights but also size of mammary lymph nodes. These results show that simultaneous evaluation of mammary gland growth, seminal vesicles, and the spleen weight in the same animal is suitable for bioassay of estrogenicity as well as for detection of androgenic and antiandrogenic activities., J. Škarda., and Obsahuje bibliografii