Effect of various protein levels in the diet on mammary gland growth in rats

Pyska, H.; Styczynski, H.

doi:10.1017/s0022029900017581

Cited by 8 publications

(2 citation statements)

References 15 publications

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“…Mammary development during pregnancy and in lactation is influenced by nutrition in both rodents and ruminants. Feeding either a restricted amount of a nutritionally appropriate diet (Knight & Peaker, 1982) or adequate amounts of protein-deficient diets (Pyska & Styczynski, 1979) to pregnant rodents impairs mammary development. Cell proliferation was measured in the later work and was reduced, but whether these treatments also increased apoptosis is not known.…”

Section:     Nutritionmentioning

confidence: 99%

Mammary apoptosis and lactation persistency in dairy animals

Stefanon

Colitti

Gabai

et al. 2002

Journal of Dairy Research

125

123

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The decline in milk yield after peak lactation in dairy animals has long been a biological conundrum for the mammary biologist, as well as a cause of considerable lost income for the dairy farmer. Recent advances in understanding the control of the mammary cell population now offer new insights on the former, and a potential means of alleviating the latter. The weight of evidence now indicates that a change in mammary cell number, the result of an imbalance between cell proliferation and cell removal, is a principal cause of declining production. Further, it suggests that the persistency of lactation, the rate of decline in milk yield with stage of lactation, is strongly influenced by the rate of cell death by apoptosis in the lactating gland. Mammary apoptosis was first demonstrated during tissue involution after lactation, but has now been detected during lactation, in mammary tissue of lactating mice, goats and cattle. Those factors that determine the rate of cell death by apoptosis are as yet poorly characterized, but include the frequency of milking in lactating goats. Initial evidence suggests that nutrition also is likely to influence cell survival after peak lactation, an important factor being the degree of oxidative stress imposed by feed and the tissue's ability to deal with, and prevent damage by, reactive oxygen species. Comparison of cows in calf or not pregnant during declining lactation also indicates a likely influence of reproductive hormones, with oestradiol and progesterone acting to preserve mammary ductal and alveolar integrity during the dry period, while allowing a degree of apoptosis and cell replacement. In each case, the molecular mechanisms controlling mammary cell survival (or otherwise) are as yet poorly defined. On the other hand, more persistent lactations are likely to benefit animal welfare through fewer calvings and by placing less emphasis on maximal production at peak lactation, and modelling of persistent lactation with longer calving intervals indicates their likely economic benefits. In these circumstances, there is considerable incentive to elucidate the determinants of mammary apoptosis, and the factors controlling the dynamic balance between cell proliferation and cell death in the lactating mammary gland

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Section:     Nutritionmentioning

confidence: 99%

Mammary apoptosis and lactation persistency in dairy animals

Stefanon

Colitti

Gabai

et al. 2002

Journal of Dairy Research

125

123

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“…Also, if the lactating gland produces large amounts of chalone it may be secreted into the milk in sufficiently large quantities to affect the development of the mammary gland of the sucking young, a mechanism that was proposed many years ago when it was suggested that growth might be suppressed in young, sucking rats, rather than stimulated by prepubertal hormone release following weaning (Cowie, 1949 (Sykes, Wrenn & Hall, 1948). Hormone-stimulated mammary growth is inhibited by a 50% reduction in food intake (Srivastava & Turner, 1966), and protein deficiencies in the diet also lead to reduced mammary growth in virgin and pregnant rats (Pyska & Styczynski, 1979).…”

Section: Systemic Endocrine Controlmentioning

confidence: 99%

Development of the mammary gland

Knight¹,

Peaker²

1982

Reproduction

139

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Functional differentiation of virgin mouse mammary epithelium in explant culture is dependent upon extracellular proline

Smith

1987

Journal Cellular Physiology

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Depletion of proline from insulin, hydrocortisone, and prolactin-containing medium prior to incubating virgin mouse mammary explants prevents both DNA synthesis and functional differentiation in the mammary epithelial cells; however, DNA synthesis in the mammary stroma and total incorporation of radioactive amino acids into total protein appears to continue without hindrance. Removal of glycine instead of proline had no deleterious effect on either DNA replication in the hormone-stimulated epithelium or in its functional differentiation. Functional differentiation was determined by the induction of casein and alpha-lactalbumin synthesis in the insulin, hydrocortisone, and prolactin (IFPrl)-treated explant cultures. As a control, the induction of mouse mammary tumor virus (MMTV) gene expression, a corticosteroid-regulated function, was also measured. Neither the absence of proline or glycine prevented the glucocorticoid stimulation of MMTV gene expression. In contrast to mammary tissue from virgin mice, explants from nonpregnant primiparous mice responded fully to IFPrl stimulation with respect to DNA, casein, and alpha-lactalbumin synthesis in medium depleted of proline. These data suggest that the uncommitted epithelium of virgin mouse mammary glands requires the presence of exogenous proline in order to respond to lactogenic hormonal signals. We have demonstrated earlier that DNA synthesis is a prerequisite of functional differentiation in virgin mouse mammary explants (Smith and Vonderhaar, 1981, Dev. Biol., 88:167-179; Vonderhaar and Smith, 1982, J. Cell Sci, 53:97-114), although cytological differentiation proceeded unencumbered in explants prevented from synthesizing DNA. Here, without proline, neither cytological nor functional differentiation can be induced; this suggests that proline provides an essential metabolic interlock in the acquisition of lactogenic hormone responsiveness in uncommitted mouse mammary tissue.

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Effect of various protein levels in the diet on mammary gland growth in rats

Cited by 8 publications

References 15 publications

Mammary apoptosis and lactation persistency in dairy animals

Mammary apoptosis and lactation persistency in dairy animals

Development of the mammary gland

Functional differentiation of virgin mouse mammary epithelium in explant culture is dependent upon extracellular proline

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