Programmed cell death in bovine mammary tissue during lactation and involution

Wilde, Colin J.; Addey, Caroline; Li, P.; Fernig, David G.

doi:10.1113/expphysiol.1997.sp004075

Cited by 121 publications

(132 citation statements)

References 32 publications

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“…For example, mRNA abundance of a-, b-and g-casein was observed to fall by up to 95% in rat mammary tissue within 24 h of litter removal (Travers et al, 1996), whereas the abundance of casein and a-lactalbumin mRNA was reduced in bovine mammary tissue 3 days after cessation of milk removal (Goodman and Schanbacher, 1991). Hence, after 7 days, a S1 -casein and a-lactalbumin mRNA were decreased by 85% and 99%, respectively (Wilde et al, 1997). The morphological changes in mammary tissue during the dry period in dairy animals are less pronounced and distinctly different compared with those seen during mammary involution in nonpregnant rodents.…”

Section: Altered Dry Periodsmentioning

confidence: 98%

“…The importance of the absence of prolactin and somatotropin (ST) for mammary gland involution has been shown in rodents (Marti et al, 1999) and has also been demonstrated for cows in vitro (Accorsi et al, 2002). A reduction in the circulating prolactin concentration was shown to accelerate mammary involution and the expression of insulin-like growth-factor binding protein 5 (IGFBP-5), which antagonizes the survival effects of IGF-I (Wilde et al, 1997 and. Moreover, MEC proliferation is stimulated by IGF-I in vitro (McGrath et al, 1991) and in vivo (Collier et al, 1993).…”

Section: Impact On Milk Yieldmentioning

confidence: 99%

“…Impact of shortened dry period and continuous lactation Mammary apoptosis, proliferation and ultrastructure After milk cessation, apoptosis and proliferation occur in the bovine mammary gland Wilde et al, 1997), and their indices are increased within the first 10 days of the dry period (Capuco et al, 2006). Apoptosis occurs in the population of terminally differentiated cells and the first peak of apoptosis occurs during the first 72 h after dry-off in dairy cows (Annen and Collier, 2005;Annen et al, 2008).…”

Section: Impact On Milk Yieldmentioning

confidence: 99%

“…These changes more strictly reflect a change in the secretory state of the mammary gland rather than characteristics of cell loss and tissue regression. Alveolar structure of bovine mammary tissue generally remains intact throughout a typical dry period (Holst et al, 1987;Wilde et al, 1997). The luminal area in mammary tissue reaches a minimum on day 25 of the dry period, whereas stromal area is maximal at the same time in dairy cows (Capuco et al, 1997).…”

Section: Altered Dry Periodsmentioning

confidence: 99%

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Effects of continuous lactation and short dry periods on mammary function and animal health

Collier

Annen-Dawson

Pezeshki

2012

Animal

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The dry period is required to facilitate cell turnover in the bovine mammary gland in order to optimize milk yield in the next lactation. Traditionally, an 8-week dry period has been a standard management practice for dairy cows based on retrospective analyses of milk yields following various dry period lengths. However, as milk production per cow has increased, transitioning cows from the nonlactating state to peak milk yield has grown more problematic. This has prompted new studies on dry period requirements for dairy cows. These studies indicate a clear parity effect on dry period requirement. First parity animals require a 60-day dry period, whereas lactations following later parities demonstrate no negative impact with 30-day dry period or even eliminating the dry period when somatotropin (ST) is also used to maintain milk yields. Shortened dry periods in first parity animals were associated with reduced mammary cell turnover during the dry period and early lactation and increased numbers of senescent cells and reduced functionality of lactating alveolar mammary cells postpartum. Use of ST and increased milking frequency postpartum reduced the impact of shortened dry periods. The majority of new intramammary infections occur during the dry period and persist into the following lactation. There is therefore the possibility of altering mastitis incidence by modifying or eliminating the dry period in older parity animals. As the composition of mammary secretions including immunoglobulins may be reduced when the dry period is reduced or eliminated, there is the possibility that the immune status of cows during the peripartum period is influenced by the length of the dry period.

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Section: Altered Dry Periodsmentioning

confidence: 98%

Section: Impact On Milk Yieldmentioning

confidence: 99%

Section: Impact On Milk Yieldmentioning

confidence: 99%

Section: Altered Dry Periodsmentioning

confidence: 99%

See 2 more Smart Citations

Effects of continuous lactation and short dry periods on mammary function and animal health

Collier

Annen-Dawson

Pezeshki

2012

Animal

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“…At the initiation of lactation, the rapid increase to peak milk yield following parturition is primarily because of an increase in mammary epithelial activity in response to milking. The gradual decline in milk production following peak lactation is anomalous to gradual involution and is predominantly a result of mammary epithelial loss via apoptosis (Wilde et al, 1997;Capuco et al, 2001). Microarray studies on rodent (Master et al, 2002;Clarkson et al, 2004;Stein et al, 2004) and bovine (Suchyta et al, 2003;Singh et al, 2008) mammary tissues have identified multiple cell signalling pathways that may orchestrate the switch from a lactating to a nonlactating phenotype.…”

Section: Introductionmentioning

confidence: 99%

Epigenetics: a possible role in acute and transgenerational regulation of dairy cow milk production

Singh

Molenaar

Swanson

et al. 2012

Animal

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A potential role for epigenetic mechanisms in the regulation of mammary function in the dairy cow is emerging. Epigenetics is the study of heritable changes in genome function that occur because of chemical changes rather than DNA sequence changes. DNA methylation is an epigenetic event that results in the silencing of gene expression and may be passed on to the next generation. However, recent studies investigating different physiological states and changes in milk protein gene expression suggest that DNA methylation may also play an acute, regulatory, role in gene transcription. This overview will highlight the role of DNA methylation in the silencing of milk protein gene expression during mastitis and mammary involution. Moreover, environmental factors such as nutrition may induce epigenetic modifications of gene expression. The current research investigating the possibility of in utero, hence cross-generational, epigenetic modifications in dairy cows will also be discussed. Understanding how the mammary gland responds to environmental cues provides a potential to enhance milk production not only of the dairy cow but also of her daughter.Keywords: epigenetics, DNA methylation, transgeneration, milk production, dairy cows ImplicationsEpigenetic regulation of gene expression is emerging as a hitherto unknown level of biological control. We will discuss how epigenetics may be part of the enormously complex regulatory pathways underpinning milk production. Not only may epigenetic regulation be directly involved in milk production of the mother ('acute epigenetics'), but it may also indirectly affect milk production in its offspring through transgenerational epigenetics, by effects on foetal development in utero. Gaining a clearer understanding of this level of regulatory control may lead to new insights in optimizing milk production not only in today's cows but also in future generations. IntroductionMilk production in dairy cows is influenced by numerous factors, including the environment (e.g. nutrition, photoperiod and heat stress), hormones, local factors within the mammary gland (e.g. autocrine, paracrine and homeostatic feedback systems), diseases (e.g. mastitis) and management practises (e.g. milking frequency). At the cellular level, these factors influence both the number and the activity of the mammary epithelial cells that synthesize milk. Multiple cell signalling pathways have been identified that play a role in regulating milk synthesis (Suchyta et al., 2003;Connor et al., 2008;Finucane et al., 2008;Singh et al., 2008). At the initiation of lactation, the rapid increase to peak milk yield following parturition is primarily because of an increase in mammary epithelial activity in response to milking. The gradual decline in milk production following peak lactation is anomalous to gradual involution and is predominantly a result of mammary epithelial loss via apoptosis (Wilde et al., 1997;Capuco et al., 2001). Microarray studies on rodent (Master et al., 2002;Clarkson et al., 2004;Stein et al., 2004) an...

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Influence of microenvironment on mammary epithelial cell survival in primary culture

et al. 1999

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Mammary epithelial cells cultured on Engelbreth-Holm-Swarm (EHS) matrix form multicellular structures termed mammospheres, in which cells and matrix become arranged around a central luminal space. In the presence of lactogenic hormones, cells within mammospheres become polarized, form tight intercellular junctions, and secrete milk proteins vectorially into the luminal space. This study examined the mechanism of lumen formation. Histological examination of developing mammospheres showed that cavitation was associated spatially and temporally with the appearance of fragmented nuclear material in apoptotic bodies, and with the presence of cells positively labeled by terminal deoxynucleotide transferase-mediated deoxyuridine nick end-labeling (TUNEL). Analysis of [(32)P]-deoxynucleotide end-labeled genomic DNA by electrophoresis and autoradiography showed DNA laddering indicative of apoptosis. A transient increase in laddering coincided with both lumen formation and the presence of TUNEL-positive cells. Lumen formation, DNA laddering, and detection of TUNEL-positive cells were all accelerated when matrix composition was altered. They were also impaired coordinately when caspase inhibitor was present during the first two days of culture. Therefore, lumen formation in mammosphere cultures is due to selective apoptosis of centrally located cells. Mammosphere cavitation was accompanied by redistribution of matrix constituents to the mammosphere periphery. Western blotting and Western ligand blotting of culture medium showed that lumen formation was also associated with a transient increase in insulin-like growth factor binding protein-5 (IGFBP5), a factor implicated in mammary apoptosis in vivo. We propose that epithelial cell survival during mammosphere development is induced selectively through stabilization by basement membrane constituents, which may act directly on the epithelial cell or confer protection against autocrine apoptotic factors.

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Programmed cell death in bovine mammary tissue during lactation and involution

Cited by 121 publications

References 32 publications

Effects of continuous lactation and short dry periods on mammary function and animal health

Effects of continuous lactation and short dry periods on mammary function and animal health

Epigenetics: a possible role in acute and transgenerational regulation of dairy cow milk production

Influence of microenvironment on mammary epithelial cell survival in primary culture

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