Local Intra-arterial Infusion of Growth Hormone into the Mammary Glands of Sheep and Goats: Effects on Milk Yield and Composition, Plasma Hormones and Metabolites

McDowell, GH; Hart, I. C.; Ac, Kirby

doi:10.1071/bi9870181

Cited by 42 publications

(13 citation statements)

References 13 publications

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“…The present results are consistent with results of a limited number of previous studies which have shown that exogenous GH is galactopoietic in the lactating ewe (Dracy and Jordan 1954;Jordan and Shaffhausen 1954;Hart et al 1985;McDowell et al 1987c). Thus, milk yield and the yields of the major milk constituents were increased and milk fat content was raised during injections of GH.…”

Section: Tissue Blood Flowssupporting

confidence: 82%

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Short-term Effects of Exogenous Growth Hormone: Effects on Milk Production and Utilization of Nutrients in Muscle and Mammary Tissues of Lactating Ewes

McDowell

Leenanuruksa²,

Niumsup³

et al. 1988

Aust. Jnl. Of Bio. Sci.

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Exogenous bovine growth hormone at a dose of 0·1 mg kg-1liveweight increased yields of milk and milk constituents and milk fat content when injected over 5 days into ewes in mid-lactation. These changes in milk production were associated with changes in the supply to, and utilization of, nutrients by leg muscle and mammary tissues.Arterial concentrations of glucose and non-esterified fatty acids increased significantly, concentrations of lactate and 3-hydroxybutyrate tended to increase, and concentrations of triglycerides associated with very low-density lipoproteins decreased significantly. Growth hormone increased mammary uptake of nonesterified fatty acids, decreased mammary uptake of very low-density lipoproteins and tended to reduce the release of lactate from leg muscle. Oxidation of non-esterified fatty acids in the whole body and mammary tissue was increased by growth hormone and there was a tendency for reduction of glucose oxidation in mammary tissues.During injection of growth hormone, blood flow to leg muscle and mammary tissues increased as did the calculated ratio of blood flow : milk yield. These changes in blood flow, together with changes in arterial concentrations and tissue utilizations of key metabolites, were sufficient to account for the synthesis of extra milk and milk constituents.Extra keywords: milk yield, milk components, arterio-venous differences of nutrients across leg muscle and mammary tissue, oxidation of glucose and non-esterified fatty acids, plasma triglycerides, blood flow.

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Section: Tissue Blood Flowssupporting

confidence: 82%

“…There is now evidence to show that exogenous GH does not exert direct effects on the mammary gland in vivo (McDowell et al 1987c) or in vitro (Skarda et al 1982;Gertler et al1983), at least when the hormone is administered over periods of a few days.…”

Section: Introductionmentioning

confidence: 99%

Short-term Effects of Exogenous Growth Hormone: Effects on Milk Production and Utilization of Nutrients in Muscle and Mammary Tissues of Lactating Ewes

McDowell

Leenanuruksa²,

Niumsup³

et al. 1988

Aust. Jnl. Of Bio. Sci.

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“…Messenger RNA for GH receptors has been detected in bovine mam¬ mary gland (Glimm et al 1990;Hauser et al 1990), but it is not clear whether the receptor protein is expressed, since conventional receptor studies fail to show GH binding (Akers, 1985;Keys & Djiane, 1988 (Gertler et al 1983;Fekry et al 1989) or in vivo (McDowell et al 1987). GH may, therefore, act on mammary tissue at least in part via IGFs (see Prosser et al 1989).…”

Section: Introductionmentioning

confidence: 96%

Receptor binding of insulin-like growth factor-I to mammary microsomes from non-pregnant, pregnant and lactating sheep

Winder¹,

Wheatley²,

Forsyth³

1993

Journal of Endocrinology

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Sucrose density centrifugation was used to prepare a partially purified membrane fraction from the mammary glands of non-pregnant, pregnant and lactating sheep. The binding of 125I-labelled insulin-like growth factor-I (IGF-I) was dependent on membrane protein concentration, pH, time and temperature. The binding showed the characteristics of a type-1 IGF receptor, being displaced by IGF-I (median effective dose (ED50) 0.55 nmol/l), less effectively by IGF-II (ED50 8.8 nmol/l) and least effectively by insulin. Glucagon, ovine prolactin and ovine placental lactogen could not displace binding. A molecular weight of 135,000 was determined by affinity cross-linking using disuccinimidyl suberate; this was consistent with the reported size of the type-1 receptor alpha-subunit. Scatchard analysis was used to determine binding affinity and numbers of IGF-I-binding sites. A single class of high-affinity binding sites was found in all physiological states. In non-pregnant sheep and sheep at days 40, 75 and 110-120 of pregnancy and at term, the binding affinity was similar (apparent dissociation constant (Kd) 2.73 +/- 0.31 nmol/l, n = 22). In lactating sheep (weeks 1, 4 and 10), the binding affinity was significantly (P = 0.02) higher (Kd 0.77 +/- 0.06 nmol/l n = 9). Binding capacity was similar in non-pregnant and pregnant sheep (1005 +/- 113 fmol/mg, n = 19), but fell by parturition and remained low in lactation (570 +/- 52 fmol/mg membrane protein, n = 12). The results suggest that the mammary growth of pregnancy is not regulated at the level of the type-1 IGF receptor.

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“…Growth hormone itself appears to have no direct effect on the mammary gland (McDowell, Hart & Kirby, 1987) and could act via IGF-1. Preliminary evidence suggests that local infusions of IGF-1 via the mammary artery may stimulate milk output (Prosser, Fleet, Corps et al 1988).…”

Section: Discussionmentioning

confidence: 96%

Potentiation of Growth Hormone Activity in Sheep Using McNcclcnal Antibodies

Pell

Johnsson²,

Pullar³

et al. 1989

Journal of Endocrinology

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Monoclonal antibody OA11 was raised against ovine GH; its effects on GH activity were examined in a target species relevant for animal production in vivo. The monoclonal antibody was found to enhance the galactopoietic response to exogenous GH in adult lactating ewes and also to potentiate the diabetogenic activity of both exogenous and endogenous GH in ewe lambs. Thus it was shown that GH activity may be manipulated above its usual dose-response range in normal, intact animals of commercial importance via immunological means.

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Local Intra-arterial Infusion of Growth Hormone into the Mammary Glands of Sheep and Goats: Effects on Milk Yield and Composition, Plasma Hormones and Metabolites

Cited by 42 publications

References 13 publications

Short-term Effects of Exogenous Growth Hormone: Effects on Milk Production and Utilization of Nutrients in Muscle and Mammary Tissues of Lactating Ewes

Short-term Effects of Exogenous Growth Hormone: Effects on Milk Production and Utilization of Nutrients in Muscle and Mammary Tissues of Lactating Ewes

Receptor binding of insulin-like growth factor-I to mammary microsomes from non-pregnant, pregnant and lactating sheep

Potentiation of Growth Hormone Activity in Sheep Using McNcclcnal Antibodies

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