The Relationship Between Lactation and the Release of Prolactin and Growth Hormone in the Goat

Hart, I. C.

doi:10.1530/jrf.0.0390485

Cited by 28 publications

(14 citation statements)

References 37 publications

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“…In this respect our data are consistent with those of others who have reported increases in plasma growth hormone following milking in goats (Hart and Flux 1973;Hart 1974;Marta11975) and sheep (Martal 1975). However, Tucker (1971) failed to observe an increase in plasma growth hormone following milking in cows, and Reynaert and colleagues (Reynaert and Peeters 1971;Reynaert et al 1972) measured increases in plasma growth hormone infrequently following milking.…”

Section: Discussionsupporting

confidence: 93%

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The Importance of Prolactin for Initiation. of Lactation in the Pregnant Ewe

Gow¹,

McDowell²,

Jenkin³

1983

Aust. Jnl. Of Bio. Sci.

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A single injection of ergocryptine (0, 5 mg/kg liveweight) given to ewes O· 5-20 days prepartum or two injections (0' 5 mg/kg liveweight per injection) given c. 30 and 10 days prepartum reduced concentrations of plasma prolactin to negligible « 5 ng/ml) values for 4 weeks after parturition, but did not affect concentrations of growth hormone and placental lactogen.Milking of treated ewes had no effect on concentrations of plasma prolactin during the first 4 weeks of lactation, but concentrations of growth hormone were increased during the 10-20 min period after milking. The half-life of prolactin in plasma was estimated as 21 min.In spite of the dramatic effect of ergocryptine on plasma prolactin all treated ewes secreted copious quantities of milk of normal composition. Mean daily yields of ewes treated with ergocryptine were not significantly different (P > 0'05) from those of untreated control ewes, but the mean ± s.e.m. of total milk production over the first 3 weeks of lactation for ergocryptine-treated ewes was significantly lower (P < 0'05) than that of control ewes (9·5±1·11 v. 14·1±1·20 kg milk).The results suggest that prolactin is not an essential component of the lactogenic and galactopoietic complexes of hormones in the ewe.

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Section: Discussionsupporting

confidence: 93%

“…The release of ACTH, glucocorticoids, oxytocin (Tucker 1974) and growth hormone (Hart and Flux 1973;Hart 1974;Martal 1975) at milking may account for the galactopoietic effects which often have been attributed to prolactin. Notwithstanding, prolactin may be necessary for optimum milk production.…”

Section: Discussionmentioning

confidence: 99%

The Importance of Prolactin for Initiation. of Lactation in the Pregnant Ewe

Gow¹,

McDowell²,

Jenkin³

1983

Aust. Jnl. Of Bio. Sci.

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“…Hodson, & Simpkins, 1978). No evidence suggests that bromocriptine has any consistent effect on levels of ACTH (corticotropin), GH (somatotropin or growth hormone), or vasopressin in normal subjects (Fluckiger, 1976(Fluckiger, , 1980Hart, 1974;Mehta & Tolls, 1979;Yanai & Nagasawa, 1970.…”

Section: Endocrine Effectsmentioning

confidence: 99%

The lactation–blocking drug bromocriptine and its application to studies of weaning and behavioral development

Martin

Bateson

1982

Developmental Psychobiology

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An experimental method for blocking maternal lactation is reviewed and the possible application of this technique for experimentally manipulating weaning is considered. Maternal milk production can be inhibited using the prolactin-suppressing drug bromocriptine. The suitability of bromocriptine for use in behavioural experiments is considered. The pharmacology of bromocriptine (CB 154) is briefly outlined and a compilation of the reported lactation-inhibiting doses for various species is presented. The possible endocrine and behavioral side-effects and the toxicity of the drug are discussed. It is concluded that, in most species studied so far, the drug is relatively free from significant side-effects at the low doses needed to suppress lactation. Guidelines for the practical use of bromocriptine are suggested. Finally, some ideas about the possible application of the drug to the study of behavioral development and parent-offspring relationships are discussed.

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“…It is well established in other species that during lactation, plasma PRL levels are high and that suckling and/or milking results in a release of pituitary PRL, as demonstrated in the rat (Amenomori et al 1970;Blake 1974), goat (Bryant et al 1968;Hart 1974), sheep (Fell et al 1972;Lamming et al 1974;Kann 8c Martinet 1975), cow (Johke 1969;Karg 8c Schams 1970) and human Tyson et al 1972).…”

mentioning

confidence: 99%

Radioimmunoassay for Porcine Prolactin: Plasma Levels During Lactation, Suckling and Weaning and After TRH Administration

Landeghem¹,

Wiel²

1978

Acta Endocrinologica

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A sensitive heterologous radioimmunoassay for porcine prolactin (pPRL) has been developed. Anti-ovine prolactin antibody was raised in rabbits which allowed a final dilution of 1:500 000. The separation of free and antibody bound [125I]pPRL is based on the double antibody solid phase system. The assay is specific for pPRL. There is no cross-reaction with pLH, pFSH and pTSH; little cross-reaction (1.35 %) was found with pGH. The smallest detectable amount was 0.08 ng per tube. During lactation high plasma levels are found with great fluctuations. After weaning the plasma PRL levels fall to basal levels within a few hours.After thyrotrophin-releasing hormone (TRH) administration plasma concentrations increase within a few minutes.In our study on the fertility of the female pig we became interested in a pos¬ sible role of prolactin in the function of the ovary. Therefore we developed a heterologous radioimmunoassay in order to measure prolactin in porcine blood plasma. A homologous radioimmunoassay for pPRL has been reported pre¬ viously by Threlfall et cd. (1974). With this assay no significant differences were detected between plasma PRL levels of virgin gilts, sows at midgestation, sows at 112th day of gestation and sows during the suckling period (PRL values ranged from 140.7 to 167.1 ng/ml). The only significant difference re¬ ported was between suckling and non-suckling post-partum sows (167.1 and 115.3 ng/ml respectively). Brinkley et al. (1973) obtained data on plasma PRL

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The Relationship Between Lactation and the Release of Prolactin and Growth Hormone in the Goat

Cited by 28 publications

References 37 publications

The Importance of Prolactin for Initiation. of Lactation in the Pregnant Ewe

The Importance of Prolactin for Initiation. of Lactation in the Pregnant Ewe

The lactation–blocking drug bromocriptine and its application to studies of weaning and behavioral development

Radioimmunoassay for Porcine Prolactin: Plasma Levels During Lactation, Suckling and Weaning and After TRH Administration

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