scholarly journals The effect of pregnancy and lactation on the collagen content of the mammary gland of the rat

1956 ◽  
Vol 132 (3) ◽  
pp. 476-481 ◽  
Author(s):  
Margaret L. R. Harkness ◽  
R. D. Harkness
Keyword(s):  
Mammary Gland ◽  
Collagen Content ◽  
Pregnancy And Lactation

scholarly journals Regulation of lipogenic capacity in lactating rats

1982 ◽  
Vol 208 (3) ◽  
pp. 611-618 ◽  
Author(s):  
M R Grigor ◽  
A Geursen ◽  
M J Sneyd ◽  
S M Warren
Keyword(s):  
Mammary Gland ◽  
Fatty Acid ◽  
Malic Enzyme ◽  
Fatty Acid Synthase ◽  
Specific Activity ◽  
Mammary Glands ◽  
Lipogenic Enzymes ◽  
Pregnancy And Lactation ◽  
Specific Activities

1. The rate of mammary-gland lipogenesis measured in vivo from 3H2O was suppressed after decreasing the milk demand by decreasing the number of pups from ten to two or three, as well as by giving diets containing lipid [Grigor & Warren (1980) Biochem. J. 188, 61-65]. 2. The specific activities of the lipogenic enzymes fatty acid synthase, glucose 6-phosphate dehydrogenase and ‘malic’ enzyme increased between 6- and 10-fold in the mammary gland and between 2- and 3-fold in the livers during the first 10 days of lactation. The increases in specific activity coupled with the doubling of liver mass which occurred during pregnancy and lactation resulted in considerable differences in total liver activities when compared with virgin animals. 3. Although consumption of a diet containing 20% peanut oil suppressed the activities of the three lipogenic enzymes in the livers, only the ‘malic’ enzyme was affected in the mammary glands. 4. In contrast, decreased milk demand did not affect the specific activities of any of the liver enzymes, whereas it resulted in suppression of all three lipogenic enzymes of the mammary glands. There was no effect on either the cytoplasmic malate dehydrogenase or the lactate dehydrogenase of the mammary gland. 5. In all the experiments performed, the activity of the fatty acid synthase correlated with the amount of material precipitated by the rabbit antibody raised against rat fatty acid synthase.

β-Adrenergic Receptors in the Rat Mammary Gland during Pregnancy and Lactation: Characterization, Distribution, and Coupling to Adenylate Cyclase

Endocrinology ◽  
1990 ◽  
Vol 126 (1) ◽  
pp. 565-574 ◽  
Author(s):  
BIANCA MARCHETTI ◽  
MICHEL-A FORTIER ◽  
PATRICK POYET ◽  
NICOLLE FOLLEA ◽  
GEORGES PELLETIER ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Adenylate Cyclase ◽  
Adrenergic Receptors ◽  
Pregnancy And Lactation ◽  
Rat Mammary Gland ◽  
Β Adrenergic Receptors

Developmental expression of pIgR gene in sheep mammary gland and hormonal regulation

2002 ◽  
Vol 69 (1) ◽  
pp. 13-26 ◽  
Author(s):  
AURORE RINCHEV-ALARNOLD ◽  
LUCETTE BELAIR ◽  
JEAN DJIANE
Keyword(s):  
Gene Expression ◽  
Mammary Gland ◽  
Hormonal Regulation ◽  
Mrna Level ◽  
Immunohistochemical Analysis ◽  
Developmental Expression ◽  
Secretory Iga ◽  
Mrna Levels ◽  
Immunoglobulin Receptor ◽  
Pregnancy And Lactation

Secretory IgA found in external secretions are constituted by polymeric IgA (pIgA) bound to the extra-cellular part of the polymeric immunoglobulin receptor (pIgR). The receptor mediates transcytosis of pIgA across epithelial cells. The aim of the present study was to analyse the evolution of pIgR expression in the sheep mammary gland during the development of the mammary gland and to analyse its hormonal regulation. Gene expression of the pIgR was analysed in sheep mammary gland during pregnancy and lactation. By Northern Blot analysis, we observed that low levels of pIgR mRNA are expressed until day 70 of pregnancy. Accumulation of pIgR mRNA started during the third part of pregnancy and intensified 3 d after parturition to reach highest levels during established lactation (day 70). In situ hybridization analysis was used to confirm the increase in pIgR gene expression per mammary epithelial cell. In order to examine the hormonal regulation of the pIgR expression, virgin ewes were hormonally treated. Treatment with oestradiol and progesterone increased pIgR mRNA levels slightly. Subsequent addition of glucocorticoids induced a significant accumulation of pIgR mRNA in the mammary gland of the treated animals. Immunohistochemical analysis was performed to verify that the increase of pIgR mRNA level was associated with enhancement of the pIgR protein in mammary cells. No increase of pIgR mRNA levels were observed if PRL secretion was blocked by bromocryptine injections throughout the hormonal procedure. In conclusion, the present experiments suggest that the enhancement of pIgR levels during lactation result from combined effects of both prolactin and glucocorticoids.

scholarly journals Has the mammary gland a protective mechanism against overexposure to triiodothyronine during the peripartum period? The prolactin pulse down-regulates mammary type I deiodinase responsiveness to norepinephrine

2004 ◽  
Vol 183 (2) ◽  
pp. 267-277 ◽  
Author(s):  
B Anguiano ◽  
R Rojas-Huidobro ◽  
G Delgado ◽  
C Aceves
Keyword(s):  
Mammary Gland ◽  
Critical Role ◽  
Alveolar Epithelium ◽  
Late Pregnancy ◽  
Protective Mechanism ◽  
Type I ◽  
Key Factor ◽  
Pregnancy And Lactation ◽  
Contrary Effect ◽  
Peripartum Period

Peripartum is a crucial period for mammary gland final differentiation and the onset of lactation. Although the ‘trigger’ for lactogenesis depends on several hormones, a key factor is the peripartum prolactin (PRL) pulse whose deletion results in a failure to initiate milk production. Other hormones having a critical role during this period but exerting a contrary effect are the thyronines. A transitory hypothyroidism occurs at peripartum in serum and several other extrathyroidal tissues, whereas the induction of hyperthyroidism during late pregnancy is associated with the absence of lactation after delivery. We analyzed the mammary gland during pregnancy and lactation for: (a) the type and amount of thyroid receptors (TRs), (b) the local triiodothyronine (T3) generation catalyzed by type I deiodinase (Dio1), (c) the Dio1 response to norepinephrine (NE) and (d) the effect on Dio1 and TRs of blocking the PRL pulse at peripartum. Our data showed that during pregnancy the mammary gland contains Dio1 in low amounts associated with the highest expression of TRα1; whereas during lactation the gland shows high levels of both Dio1 and TRα1. However, at peripartum, both TRs and Dio1 decrease, and Dio1 becomes refractory to NE. This refractoriness disappears when the PRL pulse is blocked by the dopamine agonist bromocriptine. This blockade is also accompanied by a significant decrease in cyclin D1 expression. Our data suggested that the peripartum PRL pulse is part of a protective mechanism against precocious differentiation and/or premature involution of the alveolar epithelium due to T3 overexposure.

scholarly journals Role of Vitamin A in Mammary Gland Development and Lactation

Nutrients ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 80 ◽  
Author(s):  
M. Teresa Cabezuelo ◽  
Rosa Zaragozá ◽  
Teresa Barber ◽  
Juan R. Viña
Keyword(s):  
Retinoic Acid ◽  
Mammary Gland ◽  
Vitamin A ◽  
Vitamin A Deficiency ◽  
Retinoid Signaling ◽  
Nutritional Problem ◽  
Pregnancy And Lactation ◽  
Gland Development

Vitamin A (all-trans-retinol), its active derivatives retinal and retinoic acid, and their synthetic analogues constitute the group of retinoids. It is obtained from diet either as preformed vitamin A or as carotenoids. Retinal plays a biological role in vision, but most of the effects of vitamin A are exerted by retinoic acid, which binds to nuclear receptors and regulates gene transcription. Vitamin A deficiency is an important nutritional problem, particularly in the developing world. Retinol and carotenoids from diet during pregnancy and lactation influence their concentration in breast milk, which is important in the long term, not only for the offspring, but also for maternal health. In this study, we review the role of vitamin A in mammary gland metabolism, where retinoid signaling is required not only for morphogenesis and development of the gland and for adequate milk production, but also during the weaning process, when epithelial cell death is coupled with tissue remodeling.

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