ABSTRACT
Growth hormone does not act as a body growth-promoting hormone during the postnatal period in the guinea-pig. To determine whether it affects uterine and mammary growth, guinea-pigs of 8-9 weeks of age were treated with either recombinant bovine GH (bGH; 0.5 mg per animal) or vehicle for 10 days. Uterine and mammary weights were not changed by treating the animals with bGH. The amount of available cytosolic oestradiol receptor per unit of uterine weight or DNA content, or in whole uteri was increased in bGH-treated animals (7.3- to 14.0-fold) when compared with controls. The nuclear uterine oestradiol receptor concentration was 3.3- to 6.7-fold higher than in controls. The dissociation constant values did not differ between control and bGH-treated animals, suggesting that uterine oestradiol receptors are regulated by GH through changes in the number of binding sites rather than alteration of their binding affinity. Mammary growth and oestradiol receptor levels were unaffected by bGH treatment. The results of this investigation demonstrate that injected bGH selectively affects the oestradiol receptor level in guinea-pig uterine tissue.
Subject(s)
Growth Hormone/pharmacology , Receptors, Estrogen/drug effects , Uterus/metabolism , Animals , Binding Sites/drug effects , Cell Nucleus/metabolism , Cytosol/metabolism , DNA/analysis , Female , Guinea Pigs , Mammary Glands, Animal/anatomy & histology , Organ Size/drug effects , Proteins/metabolism , RNA/analysis , Uterus/anatomy & histology , Uterus/chemistryABSTRACT
The effect of estradiol valerate and progesterone on mammary growth of prepubertal (20, 25 and 30 days of age) female and prepubertal (15, 20 and 30 days of age) and adult male C3H/Di mice were studied. Estradiol treatment had no effect on mammary growth in 30 day old females, but mammary growth of 20 and 25 day old females showed clear inhibition. In contrast, treatment with progesterone alone stimulated both the growth of ducts and formation of alveolar buds. In males, the injection of estradiol valerate resulted in a stimulation of the growth of mammary rudiment. The treatment with progesterone alone stimulated the growth of mammary ducts and the formation of alveolar buds in males treated from day 15 and 20 of age, while mammary growth of those treated from day 30 of age was low and the growth of mammary rudiment of adult males was not stimulated at all. The mammogenic effect of progesterone was not affected by time of weaning of males but it was inhibited by simultaneous application of testosterone. An age dependent decrease of the mammogenic effect of progesterone in males is related to an increase in plasma concentration of testosterone.
