THE ONSET OF ALLOMETRIC MAMMARY GROWTH IN THE FEMALE HOODED NORWAY RAT

1953 ◽  
Vol 10 (1) ◽  
pp. 35-45 ◽  
Author(s):  
MARIAN SILVER
Keyword(s):  
Growth Rate ◽  
Anterior Pituitary ◽  
Intact Animal ◽  
Mammary Glands ◽  
Mammary Development ◽  
Female Rat ◽  
Suckling Period ◽  
Intact Female ◽  
Norway Rat ◽  
Endogenous Oestrogen

SUMMARY In order to study the factors involved in the initiation of allometric mammary growth, which occurs at about 3 weeks of age in the intact female rat, an attempt to induce this phase prematurely in the suckling gonadectomized animal by means of oestrogen was made. It was found, however, that the mammary glands were practically insensitive to physiological doses of this hormone during the suckling period unless anterior pituitary (a.p.) extract was also given. The relative mammary growth rate in animals treated with a.p. plus oestrogen from the 10th to 27th day of life was similar to that found in control rats receiving oestrogen alone from the 20th to 36th day, but in the former groups allometry was initiated before the 20th day of life. It is suggested that both the level of endogenous oestrogen secretion and the functional activity of the anterior pituitary may be important in determining the time of onset of allometric mammary development in the intact animal.

A QUANTITATIVE ANALYSIS OF THE ROLE OF OESTROGEN IN MAMMARY DEVELOPMENT IN THE RAT

1953 ◽  
Vol 10 (1) ◽  
pp. 17-NP ◽  
Author(s):  
MARIAN SILVER
Keyword(s):  
Quantitative Analysis ◽  
Relative Rate ◽  
Equilibrium Constants ◽  
Dose Range ◽  
Experimental Period ◽  
Mammary Development ◽  
The Body ◽  
Intact Female ◽  
Oestrogen Treatment ◽  
Norway Rat

SUMMARY A quantitative analysis of mammary development in the gonadectomized Hooded Norway rat treated with various levels of oestradiol dipropionate (Oe. DP.) from the 20th to 80th day of life was carried out. The relative rate of mammary growth in the oestrogen-treated animals was compared with that found in intact and gonadectomized control rats. Over the dose range 0·05–1·0 μg Oe. DP./2 days a positively allometric mammary-growth phase was induced, but the equilibrium constants obtained for all groups, except the males receiving 1·0 μg Oe. DP., were significantly lower than the value of 3·40±0·17 for the intact female. In the majority of oestrogen-treated groups no statistically significant differences between the values of α were found, although the approximate time of onset of the artificially-induced allometric phase of growth appeared to be related to the dose of hormone given. When a dose of Oe. DP. increasing proportionately with the body weight was employed, the resultant rate of mammary growth relative to body growth (α=3·70±0·13) was similar to that found in the intact female. An analysis of the number of ducts and side-buds present in the thoracic glands after various treatments at the end of the 60-day experimental period was made in the female groups. While duct development at all levels of oestrogen treatment was similar to that found in the intact female, the degree of side-bud proliferation appeared to be dependent on the dose of Oe. DP. administered.

scholarly journals The mode of action of anabolic agents: the effect of testosterone on muscle protein metabolism in the female rat

1984 ◽  
Vol 52 (3) ◽  
pp. 515-521 ◽  
Author(s):  
J. A. Martinez ◽  
P. J. Buttery ◽  
J. T. Pearson
Keyword(s):  
Growth Rate ◽  
Body Weight ◽  
Mode Of Action ◽  
Muscle Protein ◽  
Female Rats ◽  
Daily Weight Gain ◽  
Whole Body ◽  
Female Rat ◽  
Trenbolone Acetate ◽  
Muscle Protein Metabolism

1. Testosterone (1 mg/kg body-weight per d) given subcutaneously to female rats increased their growth rate and food conversion efficiency but not their food intake compared with that of the placebo-oil controls. A higher dose of testosterone (10 mg/kg body-weight per d) failed to increase the daily weight gain.2. The increased growth rate of the testosterone-treated rats appeared to occur in the whole body and not specifically in muscle. There were no significant changes in body composition.3. The fractional synthetic rate of gastrocnemius muscle protein was higher in the hormone-treated rats than in controls. This contrasts with previous results for the anabolic agent trenbolone acetate and reflects differences in the mode of action of these two different steroids, both with androgenic properties.

Interaction between estradiol and prolactin on vasoactive intestinal peptide concentrations in the hypothalamus and in the anterior pituitary of the female rat

1982 ◽  
Vol 32 (3) ◽  
pp. 307-313 ◽  
Author(s):  
M. Maletti ◽  
W.H. Rostene (Rotsztejn) ◽  
L. Carr ◽  
H. Scherrer ◽  
D. Rotten ◽  
...  
Keyword(s):  
Vasoactive Intestinal Peptide ◽  
Anterior Pituitary ◽  
Female Rat

Purification of functional lactotrophs and somatotrophs from female rats using fluorescence-activated cell sorting

1990 ◽  
Vol 126 (2) ◽  
pp. 269-274 ◽  
Author(s):  
D. Wynick ◽  
R. Critchley ◽  
M. S. Venetikou ◽  
J. M. Burrin ◽  
S. R. Bloom
Keyword(s):  
Cell Surface ◽  
Cell Sorting ◽  
Anterior Pituitary ◽  
Cell Types ◽  
Female Rats ◽  
Normal Female ◽  
Pituitary Cells ◽  
Female Rat ◽  
Fluorescence Activated Cell Sorting ◽  
Surface Labelling

ABSTRACT As the secretory granules of anterior pituitary cells fuse with the cell surface, there would appear to be sufficient hormone present on the cell surface to be labelled by polyclonal hormone antibodies and thus analysed by flow cytometry. We have therefore applied fluorescence-activated cell sorting to these labelled pituitary cells. Percentage purity and depletion of other cell types was assessed by immunocytochemistry and the reverse haemolytic plaque assay (RHPA). Results demonstrate that fluorescence-activated cell sorting allows almost complete purification of functional lactotrophs and somatotrophs to 96·7 ±1·7 (s.e.m.)% and 98±1·0% respectively by immunocytochemistry, and to 95·8 ±1·1% and 97±0·8% respectively by RHPA. Depletion of other anterior pituitary cell types to less than 2% was demonstrated by both immunocytochemistry and RHPA. Fluorescence-activated cell sorting to this degree of purity was routinely possible with cell yields of 91 ±3·4%. To obtain such purity/depletion, it was necessary to use specific antisera of high titre, at concentrations which ensured maximal cell-surface labelling associated with maximal stimulation of hormonal secretion by the appropriate hypothalamic stimulatory factor. Separating cells on the basis of the intensity of prolactin cell-surface labelling demonstrated a low level of binding of the prolactin antibody to gonadotrophs (but not of sufficient fluorescence intensity to be sorted into the prolactin enriched population), raising the possibility of prolactin receptors on gonadotrophs. We were unable to demonstrate the presence of mammosomatotrophs in the normal female rat, since purified lactotrophs did not contain or secrete GH nor did purified somatotrophs contain or secrete prolactin. Journal of Endocrinology (1990) 126, 269–274

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