EurekaMag.com logo
+ Site Statistics
References:
47,893,527
Abstracts:
28,296,643
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

Lactogenic actions of different growth hormone preparations in pregnant and lactating rats






Journal of Endocrinology 142(3): 535-545

Lactogenic actions of different growth hormone preparations in pregnant and lactating rats

We studied the capacity of different GH preparations, natural human (h)GH, recombinant hGH (rhGH), rat (r)GH, ovine (o)GH, bovine (b)GH and porcine (p)GH, and ovine prolactin (oPRL), to stimulate lactogenesis in ovario-hysterectomized pregnant rats or intact lactating rats treated with bromocriptine (BC). Ovariohysterectomy (OVX-HYS) performed at 0800 h on day 19 of pregnancy induced lactogenesis, i.e. increases in mammary casein and lactose and positive response to the oxytocin test, 28 h later. Lactogenesis was prevented by treatment with BC (1.5 mg/kg) immediately after surgery (OVX-HYS-BC). The hormones were given at doses of 0.25 or 0.5 mg/rat (except rhGH given only at 0-5 mg/rat) at 1200 and 2000 h on day 19, Casein was increased by both doses of oPRL and hGH, rhGH and 0.25 mg oGH, and lactose by both doses of oPRL, rhGH and 0.25 mg rGH. The other GH preparations had no effect. The oxytocin test demonstrated the presence of milk in the mammary tissues of the OVX-HYS rats and in the OVX-HYS-BC plus oPPL (0.25 and 0.5 mg) or rhGH-treated groups. Injection of BC to pregnant rats at 2000 h on day 20 and at 0800 h on day 21 decreased Etter growth on the first 4 days postpartum. Two-thirds of the litters resumed growth after day 4, indicating the recuperation of milk production, while the rest never recuperated. Serum prolactin in BC-treated rats was reduced until day 4 postpartum. On day 6 the rats which had recuperated had normal values, while those which had still not recuperated had lower values. BC-treated rats were injected s.c. with 0.25 mg each of oPRL, hGH, rGH, oGH, bGH or pGH, or 0.25 or 0.5 mg rhGH/rat, immediately postpartum and 12, 24 and 36 h later. hGH and 0-5 mg rhGH induced levels of milk production similar to controls except on day 3. oPRL and rhGH (0.25 mg), induced a partial reversion of the effect of BC. rGH and oGH had a slight effect on days 1 and 2 and all the litters resumed growth on day 7. In contrast, pGH and bGH were inactive. The affinity of hGH for the prolactin receptor, measured as displacement of 125I-labelled oPR-L binding to crude liver membranes, was comparable with that of oPRL. While rhGH was ten times less active than oPRL, rPRL was 100 times lower and all the other GH preparations had at least 10-4 times lower capacity to displace 125I-labelled oPRL. These results indicate that both natural and recombinant hGHs are potent inductors of milk synthesis in pregnant or lactating rats, most probably due to their actions at the level of the prolactin receptor. rGH and oGH have a partial action, while pGH and bGH seem to be inactive. The actions of non-human GHs may be explained by their somatogenic properties exclusively, and indicate that GH may play a role in the optimization of milk production during lactation and an accessory role in the induction of lactogenesis in pregnant rats.


Accession: 002646836

PMID: 7964304

DOI: 10.1677/joe.0.1420535



Related references

Hallowes, R.C.; Wang, D.Y.; Lewis, D.J., 1973: The lactogenic effects of prolactin and growth hormone on mammary gland explants from virgin and pregnant Sprague-Dawley rats. Effects of insulin (I), corticosterone (C), ovine prolactin (P) and bovine growth hormone (GH) on DNA, RNA and casein synthesis were studied in mammary explants taken from virgin and pregnant Sprague-Dawley rats and cultured in Medium 199 up to 96...

Von Berswordt Wallrabe, R.; Turner, C.W., 1960: Effect of lactogenic hormone, growth hormone and thyroxine in the lactating albino rat. Effects of lactogenic hormone (LGH) alone and in combination with growth hormone (GH) and L-thyroxine (T4) upon lactation in the rat have been studied. All rats were nursed on day 14 of lactation with aid of 1 USP unit of oxytocin (OXT) under stan...

Wiegand, M., 1937: The effect of follicular hormone on the lactogenic action of the prepituitary of lactating rats. ADMINISTRATION of folliculin to rats after parturition (which suppressed lactation) caused a decrease in the lactogenic hormone content of their pituitaries, which was similar to that of non-pregnant and pregnant animals.

Grosvenor, C.E.; Turner, C.W., 1959: Lactogenic hormone requirements for milk secretion in intact lactating rats. A technique is described for determination of amount of lactogenic hormone required for milk secretion in intact lactating rats. Rats were isolated from their litters for 12 hours on day 14 post partum, then deeply anesthetized with 4.5 mg/100 g N...

Grosvenor, C.E.; Turner, C.W., 1958: Pituitary lactogenic hormone concentration and milk secretion in lactating rats. The role of the lactogenic hormone in maintaining lactation in the rat has been studied by comparing milk secretion with the change in concentration of pituitary lactogenic hormone resulting from nursing on each of days 2, 6, 10, 14 and 21 postpar...

Lyon, Robert, 1942: Lactogenic hormone prolongs the time during which decidu-omata may be induced in lactating rats. Deciduomata were induced in lactating rats as late as the 24th post-partum day when they had been injected with 100 I.U. of lactogenic hormone daily for 4 days. The corpora lutea of lactation were large and healthy well past the time they ordinari...

Peterson, F.C.; Brooks, C.L., 1997: Identification of a motif associated with the lactogenic actions of human growth hormone. Human growth hormone (hGH) stimulates somatogenic and lactogenic actions through the GH and prolactin (PRL) receptors, respectively. In contrast, nonprimate GHs stimulate only somatotropic action. Phe-44, of the human GH sequence is present in all...

Anonymous, 2008: Lactogenic effects of growth hormone in post-partum lactating riverine buffaloes (Bubalus bubalis)

Li.C.H.; Ingle.D.J., 1949: Lack of effect of lactogenic hormone upon organ weights, nitrogen and phosphorus balance, and the fat and protein content of liver and carcass in male rats given lactogenic hormone. Male rats of approx. 300 g. initial wt. were force-fed a medium carbohydrate fluid diet. Following a control period of 14 days, 8 rats.were given 1 mg. of pure lactogenic hormone in 3 divided injns. per day for 10 days. An equal number of control...

Tuchmann, D.Plessis, H.; Gershon, R., 1957: Effects of lactogenic hormone on the hormonal inbalance of pregnant rats treated by reserpine. Comptes Rendus Hebdomadaires des Seances de L'academie des Sciences 245(6): 738-740