| Sensitivity and
Specificity of the Bioassay of Estrogenicity in
Mammary Gland and Seminal Vesicles of Male Mice
J.
ŠKARDA
Institute
of Animal Physiology and Genetics, Academy of
Sciences of the Czech Republic, Prague, the Czech
Republic
Received June 29, 2001
Accepted October 5, 2001
Summary
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. 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.
.
Key
words
Bioassay
· Estrogenicity · Male · Mammary gland ·
Seminal vesicles
Reprint
requests
Josef Škarda, Institute of Animal Physiology and
Genetics, Academy of Sciences of the Czech
Republic, Přátelství 560, 104 00 Prague
10-Uhříněves, Czech Republic
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