Tamoxifen inhibits the myoprotective action of oestrogen at sexual maturity in laying hens.

MA Mitchell*, Ailsa J Carlisle, DA Sandercock, Rani Prasad

*Corresponding author for this work

Research output: Contribution to journalMeeting Abstract

Abstract

Previous studies have demonstrated a growth associated myopathy in modern broiler chickens reflected in an elevated plasma activity of the intracellular muscle enzyme creatine kinase (CK). In broilers onset of ovarian steroid secretion or administration of estradiol were shown to exert an apparent myoprotective effect possibly mediated by occupation of the oestrogen receptor (ER). It is not known if such mechanisms exist in other birds or if muscle membrane integrity is enhanced at the beginning of lay in strains less predisposed to spontaneous myopathy than the rapidly growing broiler lines. Fourteen 23 week old white leghorn hens in full lay were divided into two groups. One group received 4mgkg−1 of tamoxifen per day for 4 days whilst the other group received vehicle. Blood samples were obtained before the first injection and then at three day intervals for a total period of five weeks. Plasma CK activity was influenced by both treatment and time (p<0.001). Peak activity occurred in the tamoxifen group at the end of treatment (p<0.05) and was maintained until day 8. Hepatic egg yolk precursor synthesis was reduced significantly by the anti-oestrogen (p<0.05) until day 29 and egg production was inhibited within 3-5 days an effect which persisted for 4 to 5 weeks. The anti-oestrogen markedly elevated plasma CK activity in laying birds suggesting that ER modulation may influence maintenance of muscle membrane integrity and the development of myopathy in normal laying hens at sexual maturity. It is suggested that estradiol controls the synthesis of intracellular components involved in the regulation of sarcoplasmic calcium concentration thereby exerting a myoprotective effect. These findings may have important implications for the maintenance of muscle function during egg production when increased calcium demand, intake and mobilisation may constitute a threat to intracellular calcium homeostasis and the consequent induction of myopathy.
Original languageEnglish
Article numberAbstract 294
Pages (from-to)67
Number of pages1
JournalPoultry Science
Volume78
Publication statusPrint publication - 1999
Externally publishedYes
Event88th Annual Meeting of the Poultry Science Association 1999 - University of Arkansas, Springdale, United States
Duration: 8 Aug 199911 Aug 1999
https://www.poultryscience.org/abstracts.asp?autotry=true&ULnotkn=true

Fingerprint

tamoxifen
muscular diseases
Muscular Diseases
Tamoxifen
sexual maturity
laying hens
estrogens
Estrogens
creatine kinase
muscles
broiler chickens
Creatine Kinase
Calcium
calcium
Muscles
Birds
Ovum
egg production
estradiol
Estradiol

Keywords

  • Laying hen
  • Myoprotective effect
  • Oestrogen
  • Tamoxifen
  • Oestrogen receptor
  • Plasma CK activity
  • Creatine kinase
  • Muscle membrane integrity
  • Intracellular calcium regulation
  • Oestrogen receptor modulation
  • Myopathy

Cite this

@article{b6928e8f2c2549daac992169ac7903e4,
title = "Tamoxifen inhibits the myoprotective action of oestrogen at sexual maturity in laying hens.",
abstract = "Previous studies have demonstrated a growth associated myopathy in modern broiler chickens reflected in an elevated plasma activity of the intracellular muscle enzyme creatine kinase (CK). In broilers onset of ovarian steroid secretion or administration of estradiol were shown to exert an apparent myoprotective effect possibly mediated by occupation of the oestrogen receptor (ER). It is not known if such mechanisms exist in other birds or if muscle membrane integrity is enhanced at the beginning of lay in strains less predisposed to spontaneous myopathy than the rapidly growing broiler lines. Fourteen 23 week old white leghorn hens in full lay were divided into two groups. One group received 4mgkg−1 of tamoxifen per day for 4 days whilst the other group received vehicle. Blood samples were obtained before the first injection and then at three day intervals for a total period of five weeks. Plasma CK activity was influenced by both treatment and time (p<0.001). Peak activity occurred in the tamoxifen group at the end of treatment (p<0.05) and was maintained until day 8. Hepatic egg yolk precursor synthesis was reduced significantly by the anti-oestrogen (p<0.05) until day 29 and egg production was inhibited within 3-5 days an effect which persisted for 4 to 5 weeks. The anti-oestrogen markedly elevated plasma CK activity in laying birds suggesting that ER modulation may influence maintenance of muscle membrane integrity and the development of myopathy in normal laying hens at sexual maturity. It is suggested that estradiol controls the synthesis of intracellular components involved in the regulation of sarcoplasmic calcium concentration thereby exerting a myoprotective effect. These findings may have important implications for the maintenance of muscle function during egg production when increased calcium demand, intake and mobilisation may constitute a threat to intracellular calcium homeostasis and the consequent induction of myopathy.",
keywords = "Laying hen, Myoprotective effect, Oestrogen, Tamoxifen, Oestrogen receptor, Plasma CK activity, Creatine kinase, Muscle membrane integrity, Intracellular calcium regulation, Oestrogen receptor modulation, Myopathy",
author = "MA Mitchell and Carlisle, {Ailsa J} and DA Sandercock and Rani Prasad",
year = "1999",
language = "English",
volume = "78",
pages = "67",
journal = "Poultry Science",
issn = "0032-5791",
publisher = "Oxford University Press",

}

Tamoxifen inhibits the myoprotective action of oestrogen at sexual maturity in laying hens. / Mitchell, MA; Carlisle, Ailsa J; Sandercock, DA; Prasad, Rani.

In: Poultry Science, Vol. 78, Abstract 294, 1999, p. 67.

Research output: Contribution to journalMeeting Abstract

TY - JOUR

T1 - Tamoxifen inhibits the myoprotective action of oestrogen at sexual maturity in laying hens.

AU - Mitchell, MA

AU - Carlisle, Ailsa J

AU - Sandercock, DA

AU - Prasad, Rani

PY - 1999

Y1 - 1999

N2 - Previous studies have demonstrated a growth associated myopathy in modern broiler chickens reflected in an elevated plasma activity of the intracellular muscle enzyme creatine kinase (CK). In broilers onset of ovarian steroid secretion or administration of estradiol were shown to exert an apparent myoprotective effect possibly mediated by occupation of the oestrogen receptor (ER). It is not known if such mechanisms exist in other birds or if muscle membrane integrity is enhanced at the beginning of lay in strains less predisposed to spontaneous myopathy than the rapidly growing broiler lines. Fourteen 23 week old white leghorn hens in full lay were divided into two groups. One group received 4mgkg−1 of tamoxifen per day for 4 days whilst the other group received vehicle. Blood samples were obtained before the first injection and then at three day intervals for a total period of five weeks. Plasma CK activity was influenced by both treatment and time (p<0.001). Peak activity occurred in the tamoxifen group at the end of treatment (p<0.05) and was maintained until day 8. Hepatic egg yolk precursor synthesis was reduced significantly by the anti-oestrogen (p<0.05) until day 29 and egg production was inhibited within 3-5 days an effect which persisted for 4 to 5 weeks. The anti-oestrogen markedly elevated plasma CK activity in laying birds suggesting that ER modulation may influence maintenance of muscle membrane integrity and the development of myopathy in normal laying hens at sexual maturity. It is suggested that estradiol controls the synthesis of intracellular components involved in the regulation of sarcoplasmic calcium concentration thereby exerting a myoprotective effect. These findings may have important implications for the maintenance of muscle function during egg production when increased calcium demand, intake and mobilisation may constitute a threat to intracellular calcium homeostasis and the consequent induction of myopathy.

AB - Previous studies have demonstrated a growth associated myopathy in modern broiler chickens reflected in an elevated plasma activity of the intracellular muscle enzyme creatine kinase (CK). In broilers onset of ovarian steroid secretion or administration of estradiol were shown to exert an apparent myoprotective effect possibly mediated by occupation of the oestrogen receptor (ER). It is not known if such mechanisms exist in other birds or if muscle membrane integrity is enhanced at the beginning of lay in strains less predisposed to spontaneous myopathy than the rapidly growing broiler lines. Fourteen 23 week old white leghorn hens in full lay were divided into two groups. One group received 4mgkg−1 of tamoxifen per day for 4 days whilst the other group received vehicle. Blood samples were obtained before the first injection and then at three day intervals for a total period of five weeks. Plasma CK activity was influenced by both treatment and time (p<0.001). Peak activity occurred in the tamoxifen group at the end of treatment (p<0.05) and was maintained until day 8. Hepatic egg yolk precursor synthesis was reduced significantly by the anti-oestrogen (p<0.05) until day 29 and egg production was inhibited within 3-5 days an effect which persisted for 4 to 5 weeks. The anti-oestrogen markedly elevated plasma CK activity in laying birds suggesting that ER modulation may influence maintenance of muscle membrane integrity and the development of myopathy in normal laying hens at sexual maturity. It is suggested that estradiol controls the synthesis of intracellular components involved in the regulation of sarcoplasmic calcium concentration thereby exerting a myoprotective effect. These findings may have important implications for the maintenance of muscle function during egg production when increased calcium demand, intake and mobilisation may constitute a threat to intracellular calcium homeostasis and the consequent induction of myopathy.

KW - Laying hen

KW - Myoprotective effect

KW - Oestrogen

KW - Tamoxifen

KW - Oestrogen receptor

KW - Plasma CK activity

KW - Creatine kinase

KW - Muscle membrane integrity

KW - Intracellular calcium regulation

KW - Oestrogen receptor modulation

KW - Myopathy

M3 - Meeting Abstract

VL - 78

SP - 67

JO - Poultry Science

JF - Poultry Science

SN - 0032-5791

M1 - Abstract 294

ER -