Oxytocin receptors in rat involuting mammary gland

1983 ◽  
Vol 61 (7) ◽  
pp. 631-635 ◽  
Author(s):  
Melvyn S. Soloff ◽  
Michael H. Wieder
Keyword(s):  
Alkaline Phosphatase ◽  
Mammary Gland ◽  
Fold Increase ◽  
Myoepithelial Cells ◽  
Oxytocin Receptor ◽  
Secretory Cells ◽  
Specific Marker ◽  
Oxytocin Receptors ◽  
Pregnancy And Lactation ◽  
Receptor Number

Oxytocin-receptor concentrations in the rat mammary gland were determined by Scatchard analyses with [3H]oxytocin. There was about a 100-fold increase in the number of receptors per mammary gland between the 1st day of pregnancy and late lactation. The number of receptors then fell markedly during postweaning mammary regression, but rose again during a second pregnancy and lactation cycle. The changes in oxytocin-receptor number corresponded to changes in alkaline phosphatase activity per mammary gland. These results strongly support data suggesting that alkaline phosphatase, like oxytocin receptors, is a specific marker for mammary myoepithelial cells. Despite the fall in oxytocin-receptor number per mammary gland during postweaning regression, the concentration of receptors, expressed per milligram of protein, increased 10-fold over lactating levels on the 6th day of regression. Thereafter, receptor concentrations declined, but were still elevated about fivefold over lactating levels on the 15th day of regression. It is likely that the increased concentration of receptors was due to a decrease in the relative amount of nontarget secretory cells. The factors that regulate the concentration of oxytocin receptors on mammary myoepithelial cells are presently unknown; however, the involuting mammary system may be practical for obtaining enriched populations of oxytocin-sensitive myoepithelial cells.

scholarly journals Localized actions of progesterone in hypothalamus involve oxytocin

1989 ◽  
Vol 86 (17) ◽  
pp. 6798-6801 ◽  
Author(s):  
M Schumacher ◽  
H Coirini ◽  
M Frankfurt ◽  
B S McEwen
Keyword(s):  
Receptor Binding ◽  
Fold Increase ◽  
Ovarian Hormones ◽  
Estradiol Benzoate ◽  
Ventromedial Hypothalamus ◽  
Oxytocin Receptor ◽  
Behavioral Effects ◽  
Female Rat ◽  
Surrounding Area ◽  
Oxytocin Receptors

Two ovarian hormones, estradiol and progesterone, which facilitate mating behavior in the female rat by acting on the ventromedial nuclei (VMN) of the hypothalamus, induce changes in oxytocin receptor binding in this brain region. Estradiol induced a 4-fold increase in the oxytocin receptor binding of the VMN and surrounding area and increased the number and immunostaining of oxytocin fibers in an area lateral to the ventral VMN. Progesterone, in estrogen-primed rats, caused the induced oxytocin receptors to spread over the area containing the oxytocin fibers. Infusion of oxytocin into the ventromedial hypothalamus increased the display of lordosis behavior only in females primed with both estradiol benzoate and progesterone. Thus, the sequential actions of two ovarian hormones bring a neuropeptide and its receptors into register and enable the neuropeptide to exert behavioral effects.

Production of parathyroid hormone-related protein by the rat mammary gland in pregnancy and lactation

1992 ◽  
Vol 263 (6) ◽  
pp. E1077-E1085 ◽  
Author(s):  
M. Rakopoulos ◽  
S. J. Vargas ◽  
M. T. Gillespie ◽  
P. W. Ho ◽  
H. Diefenbach-Jagger ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Parathyroid Hormone ◽  
Mammary Tissue ◽  
Secretory Cells ◽  
Related Protein ◽  
Sprague Dawley ◽  
Parathyroid Hormone Related Protein ◽  
Pregnancy And Lactation ◽  
Rat Mammary Gland ◽  
In Pregnancy

Production of parathyroid hormone-related protein by the rat mammary gland in pregnancy and lactation. Am. J. Physiol. 263 (Endocrinol. Metab. 26): E1077-E1085, 1992.--Production of parathyroid hormone-related protein (PTHrP) by the mammary gland of Sprague-Dawley rats has been examined using immunohistochemistry and in situ hybridization to detect PTHrP and PTHrP mRNA, respectively. PTHrP and PTHrP mRNA could be demonstrated in nests of epithelial cells of the developing mammary gland at day 14 of pregnancy and in the epithelial secretory cells lining the alveoli during the latter stages of pregnancy and during lactation. A specific radioimmunoassay was also used to measure the concentration of PTHrP secreted in the milk throughout lactation. The concentration of PTHrP in milk was relatively low initially but increased during the latter stages of lactation, whereas calcium concentrations remained virtually constant throughout lactation. No correlation was found between the concentrations of calcium and PTHrP in rat milk. These results show that PTHrP is present in rat milk and also in mammary tissue before parturition, and therefore it may assist in the development of the mammary gland during pregnancy.

scholarly journals Calmodulin content of rat mammary tissue and isolated cells during pregnancy and lactation

1984 ◽  
Vol 219 (3) ◽  
pp. 927-934 ◽  
Author(s):  
T L Riss ◽  
P J Bechtel ◽  
C R Baumrucker
Keyword(s):  
Marked Change ◽  
Myoepithelial Cells ◽  
Mammary Tissue ◽  
Secretory Cells ◽  
Isolated Cells ◽  
Pregnant Rats ◽  
Heat Treated ◽  
Pregnancy And Lactation ◽  
Cell Fractions ◽  
Glucose 6 Phosphate Dehydrogenase

The calmodulin content of heat-treated extracts of rat mammary tissue and isolated cells was measured by using stimulation of cyclic nucleotide phosphodiesterase (PDE) activity and radioimmunoassay (r.i.a.) procedures. The calmodulin content of mammary tissue increased 2.5-fold near the time of parturition, remained at the elevated level during lactation, then, after the onset of involution, decreased to values similar to those measured from mammary tissue of pregnant rats. When tissue from 15 animals in different stages of pregnancy, lactation and involution were compared, the r.i.a. gave 2.6-fold higher results than the PDE assay. To investigate further the increase in calmodulin content of mammary tissue, secretory and myoepithelial cells were enzymically dissociated from rat mammary tissue during different stages of pregnancy, lactation and involution. Protein, DNA, lactose, glucose-6-phosphate dehydrogenase and alkaline phosphatase were assayed to characterize the cell fractions. By using r.i.a., the calmodulin content per mg of protein in isolated secretory-cell fractions was high near parturition, then decreased and remained relatively constant during lactation. The amount of calmodulin expressed per mg of DNA in secretory cells did not show a marked change near parturition, suggesting a constant amount of calmodulin per cell. The calmodulin content of myoepithelial cells dissociated from mammary tissue and measured by using r.i.a. was 6-fold lower than in secretory cells and remained relatively constant during the course of lactation. The changing levels of calmodulin in rat mammary tissue during development are suggested to be related to proliferation and destruction of secretory epithelial cells, events that occur near parturition and involution respectively.

scholarly journals Immunocytochemical identification of proliferating cell types in mouse mammary gland.

1990 ◽  
Vol 38 (11) ◽  
pp. 1541-1547 ◽  
Author(s):  
A Sapino ◽  
L Macrì ◽  
P Gugliotta ◽  
G Bussolati
Keyword(s):  
Cell Proliferation ◽  
Mammary Gland ◽  
Smooth Muscle Actin ◽  
Cell Types ◽  
Myoepithelial Cells ◽  
Mouse Mammary Gland ◽  
Staining Procedure ◽  
Secretory Cells ◽  
Alpha Smooth Muscle Actin

To study cell proliferation in different cell types and segments of the mammary gland, we devised a dual staining procedure, combining nuclear labeling by 5-bromo-2'-deoxy-uridine (BrdU) uptake (revealed by a dark-brown precipitate) and an alternative (red or blue) cytoplasmic labeling by antibodies specific for the differentiation proteins of epithelial, myoepithelial, and secretory cell types. The following markers, revealed by APAAP or beta-galactosidase procedure, were selected: alpha-smooth muscle actin for the myoepithelial cells, keratin (detected by AE1 monoclonal) for the luminal epithelial cells, alpha-lactalbumin and beta-casein for the secretory cells. To follow the full process of organogenesis, the study was conducted in mouse mammary glands from virgin, primed, and lactating animals and from glands cultured in vitro under specific hormone stimulation. Cell proliferation was localized mainly in focal areas (end buds), and mostly corresponded to "null" undifferentiated cells. Estrogen and progestin stimulation induced a relative increase of proliferating differentiated cells of either epithelial or myoepithelial type, localized in ducts and alveolar structures. Prolactin stimulation induced proliferation in secretory cells.

Transepithelial potential difference in the goat mammary gland and its change during hand milking, and administration of oxytocin and catecholamines

1992 ◽  
Vol 59 (4) ◽  
pp. 469-478 ◽  
Author(s):  
Nikolaj P. Alekseev ◽  
Alexander G. Markov ◽  
Yuri A. Tolkunov
Keyword(s):  
Mammary Gland ◽  
Myoepithelial Cells ◽  
Phase Changes ◽  
Potential Difference ◽  
Secretory Cells ◽  
Initial Value ◽  
Short Term ◽  
Two Phase ◽  
Lactating Goats ◽  
Noradrenaline And Adrenaline

SummaryThe reaction of secretory epithelium and myoepithelial cells in the alveoli to hand milking and i.v. injection of oxytocin and catecholamines was studied in lactating goats. The reaction of secretory cells was assessed by changes in the transepithelial (blood–milk) potential difference (PD), and the contractile reaction of myoepithelial cells by the growth of intramammary pressure (IP). The initial value of PD was 24·6 ± 0·6 mV, that of IP 3·32 ± 0·08 kPa (24·9 ± 0·6 mmHg). Milking and oxytocin administration caused a rise in PD and an increase in IP. After noradrenaline and adrenaline injections two-phase PD changes and a short-term rise in IP were recorded. Isoproterenol, a β-agonist, caused a rise in PD but did not affect IP. Phenylephrine, an α-agonist, caused two-phase and one-phase changes in PD. Simultaneously, a rise in IP was recorded. The results show that the reaction of the mammary gland to the substances administered is complex. Myoepithelial and secretory cells respond differently to short-term rises in the level of mediators and hormones in the blood.

A HISTOLOGICAL AND FUNCTIONAL STUDY OF THE MAMMARY GLAND IN NORMAL AND AGALACTIC SOWS

1958 ◽  
Vol 17 (1) ◽  
pp. 63-NP ◽  
Author(s):  
B. A. CROSS ◽  
R. F. W. GOODWIN ◽  
I. A. SILVER
Keyword(s):  
Alkaline Phosphatase ◽  
Mammary Gland ◽  
Epithelial Cells ◽  
Dose Response ◽  
Myoepithelial Cells ◽  
Functional Study ◽  
Milk Ejection ◽  
Histological Changes ◽  
Alveolar Structure ◽  
Clinical Cases

SUMMARY 1. A method has been devised for obtaining repeated biopsy samples from the mammaryglands of sows, and by its use the histological changes associated with farrowing have been studied. 2. Before farrowing, the alveoli were at first small and filled with a hyaline eosinophilic secretion. Progressive distension of the alveoli followed, accompanied by a gradual replacement of the eosinophilic material by basophilic secretion and the onset of fat secretion. At farrowing the alveoli were contracted and their contents evacuated. 3. Acute involutional changes seen in the engorged glands of early-weaned animals, or animals that were suckled with one teat occluded, were characterized by solidification of the alveoli, swollen degenerating epithelial cells and, later, stromal proliferation. Little alveolar structure remained after 8 days. 4. Descriptions are given of three main types of mammary defect that were detected histologically in clinical cases of agalactia. 5. In experiments on milk ejection, recorded manometrically, the dose-response relation to injected oxytocin was determined. Two out of three sows responded to 10 mu. and maximal responses were obtained with doses of 200–500 mu. 6. The occurrence of myoepithelial cells in the sow's mammary gland has been demonstrated by the alkaline phosphatase technique.

Production of parathyroid hormone-related protein by the rat mammary gland in pregnancy and lactation

2006 ◽  
Vol 263 (6) ◽  
pp. E1077-E1085 ◽  
Author(s):  
M. Rakopoulos ◽  
S. J. Vargas ◽  
M. T. Gillespie ◽  
P. W. Ho ◽  
H. Diefenbach-Jagger ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Parathyroid Hormone ◽  
Mammary Tissue ◽  
Secretory Cells ◽  
Related Protein ◽  
Sprague Dawley ◽  
Parathyroid Hormone Related Protein ◽  
Pregnancy And Lactation ◽  
Rat Mammary Gland ◽  
In Pregnancy

Production of parathyroid hormone-related protein by the rat mammary gland in pregnancy and lactation. Am. J. Physiol. 263 (Endocrinol. Metab. 26): E1077-E1085, 1992.--Production of parathyroid hormone-related protein (PTHrP) by the mammary gland of Sprague-Dawley rats has been examined using immunohistochemistry and in situ hybridization to detect PTHrP and PTHrP mRNA, respectively. PTHrP and PTHrP mRNA could be demonstrated in nests of epithelial cells of the developing mammary gland at day 14 of pregnancy and in the epithelial secretory cells lining the alveoli during the latter stages of pregnancy and during lactation. A specific radioimmunoassay was also used to measure the concentration of PTHrP secreted in the milk throughout lactation. The concentration of PTHrP in milk was relatively low initially but increased during the latter stages of lactation, whereas calcium concentrations remained virtually constant throughout lactation. No correlation was found between the concentrations of calcium and PTHrP in rat milk. These results show that PTHrP is present in rat milk and also in mammary tissue before parturition, and therefore it may assist in the development of the mammary gland during pregnancy.

scholarly journals CELL CONTACTS IN THE MOUSE MAMMARY GLAND

1973 ◽  
Vol 56 (3) ◽  
pp. 797-818 ◽  
Author(s):  
Dorothy R. Pitelka ◽  
Susan T. Hamamoto ◽  
Joan G. Duafala ◽  
Michael K. Nemanic
Keyword(s):  
Mammary Gland ◽  
Gap Junctions ◽  
Freeze Fracture ◽  
Myoepithelial Cells ◽  
Mouse Mammary Gland ◽  
Secretory Cells ◽  
Thin Sections ◽  
Cell Contacts ◽  
Junctional Complexes ◽  
Rate Of Movement

The nature and distribution of cell contacts have been examined in thin sections and freeze-fracture replicas of mammary gland samples from female C3H/Crgl mice at stages from birth through pregnancy, lactation, and postweaning involution. Epithelial cells of major mammary ducts at all stages examined are linked at their luminal borders by junctional complexes consisting of tight junctions, variable intermediate junctions, occasional small gap junctions, and one or more series of desmosomes. Scattered desmosomes and gap junctions link ductal epithelial and myoepithelial cells in all combinations; hemidesmosomes attach myoepithelial cells to the basal lamina. Freeze-fracture replicas confirm the erratic distribution of gap junctions and reveal a loose, irregular network of ridges comprising the continuous tight-junctional belts. Alveoli develop early in gestation and initially resemble ducts. Later, as alveoli and small ducts become actively secretory, they lose all desmosomes and most intermediate junctions, whereas tight and gap junctions persist, The tight-junctional network becomes compact and orderly, its undulating ridges oriented predominantly parallel to the luminal surface. It is suggested that these changes in junctional morphology, occurring in secretory cells around parturition, may be related to the greatly enhanced rate of movement of milk precursors and products through the lactating epithelium, or to the profound and recurrent changes in shape of secretory cells that occur in relation to myoepithelial cell contraction, or to both.

A freeze-fracture study of tight junction structure in sheep mammary gland epithelium during pregnancy and lactation

1982 ◽  
Vol 49 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Geoffrey Morgan ◽  
F. B. Peter Wooding
Keyword(s):  
Mammary Gland ◽  
Tight Junction ◽  
Tight Junctions ◽  
Lateral Surface ◽  
Freeze Fracture ◽  
Mammary Epithelium ◽  
Secretory Cells ◽  
Pregnancy And Lactation ◽  
Fracture Study ◽  
Junction Structure

SUMMARYFreeze fractures of the tight junctions at the apices of sheep mammary secretory cells showed that the junction at 72 d of pregnancy was significantly wider than at any later stage. The number of ridges in the junction only increased significantly between 122 and 142 d of pregnancy. The initially even distribution of intramembrane particles across the tight junction changed gradually until in the fully lactating animal there were far more particles on the lateral surface of the plasmalemma. Possible correlations between these changes, the alterations in permeability of the mammary epithelium, and the differences in hormone levels are briefly discussed.

EFFECT OF LOCALLY IMPLANTED OESTROGEN ON THE RESPONSE OF THE RAT'S LACTATING MAMMARY GLAND TO OXYTOCIN

1973 ◽  
Vol 73 (4) ◽  
pp. 700-712 ◽  
Author(s):  
J. D. Bruce ◽  
X. Cofre ◽  
V. D. Ramirez
Keyword(s):  
Mammary Gland ◽  
Mammary Glands ◽  
Myoepithelial Cells ◽  
Recording System ◽  
Saline Infusion ◽  
High Dose ◽  
Low Doses ◽  
Milk Ejection ◽  
Lactating Mammary Gland ◽  
Small Rise

ABSTRACT On the day following delivery (day 1 of lactation) one abdominal mammary gland was implanted with oestrogen and the contralateral gland received an empty needle. At 2, 5 or 10 days of lactation the rats were anaesthetized with pentobarbital and the nipples of both abdominal glands were cannulated and their pressures recorded by means of transducers coupled to an amplifier and recording system. The normal mammary glands of 5-day lactating rats responded to very low doses of oxytocin (Syntocinon®, Sandoz) (5× 10−8 mU) with a rhythmic elevation in pressure. However, saline infusion also evoked a small rise in intra-mammary pressure. Earlier (2 days) and later (10 days) in lactation the responses were smaller. Oestrogen decreases significantly the milk ejection response to oxytocin, and the effect was maximal at day 10 of lactation. Histological observations confirmed the diminished reaction of the gland to oxytocin, since the milk was retained in the alveoli of rats bearing a mammary-oestrogen implant. A paradoxical rise in pressure was detected in normal as well as in oestrogen-implanted glands when the lowest dose of oxytocin was injected in lactating rats which had previously received a high dose of oxytocin (50 mU or 500 mU). These results reinforce the hypothesis that oestrogen alters the milk ejection response to oxytocin and that the mechanism is probably related to changes in the contractility of the myoepithelial cells.

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