And Lactogenic Hormones

K5. Koenig, V. L., and King, E., Extraction studies of sheep pituitary gonadotropic and lactogenic hormones in alcoholic acetate buffers. Arch. Biochem. Biophys. 26, 219-229 (1950). 

E. Bricas and C. Fromageot, Naturally occurring peptides, Advances in Protein Chem. 6,4 (1953). C. H. Li, Hormones of the anterior pituitary gland. Part I. Growth and adrenocorticotropic hormones. Advances in Protein Chem. 11, 102 (1956) Part II. Melanocyte-stimulating and lactogenic hormones. 12, 269 (1957). 

Human growth hormone is a very complex molecule biologically. Several diverse biological activities such as anaboHc, insulin-like, diabetogenic, and lactogenic activities have been ascribed to hGH, which also appears to promote water and salt retention. An in-depth discussion of these activities may be found in several excellent reviews available in the Hterature (34—36). 

The lactogenic hormone of the pituitary is one that has been known for a relatively long time and has been purified. The hormonal control of lactation and of the development of the mammary glands is complicated by several endocrine interactions, but the lactogenic hormone is a potent and highly important agent. 

The difficulties encountered in the analysis of short peptides are reflected by the paucity of publications describing the elucidation of the amino acid sequence of short peptides with the aid of volatile buffers. Such buffers have been employed by Niall et al. 3,54) for their investigations on lactogenic and growth hormone. However, a detailed description of the experimental conditions and the results obtained has yet to be awaited. 

Binding sites for prolactin and other lactogenic hormones are widely distributed in mammalian tissues [26,27]. Discrimination by such binding sites between GH and prolactin is not always complete, and the frequent use of 125I-labelled human GH... 

Fig. 3. Crosslinking of l25I-labelled human growth hormone to lactogenic receptors from rat liver and the Nb2 cell line. Hormone-receptor complexes were cross-linked with disuccinimidyl suberate, fractionated by SDS gel electrophoresis and detected by autoradiography. Lanes 1-4, Nb2 cells lanes 5-8, rat liver. Lines on the left indicate the positions of the hormone-receptor complex for Nb2 cells (102 kDa), rat liver (71 kDa) and uncomplexed hormone (hGH). Numbers on the right are M, values for standards (kDa). Samples were incubated with (lanes 2,4,6,8) or without (lanes 1,3,5,7) unlabelled hGH and electrophoresed under reducing (lanes 1,2,5,6) or non-reducing (lanes 3,4,7,8) conditions. From Ref. 36.

The Nb2 cell line was derived from a rat lymphoma and can be grown in vitro indefinitely. Its growth is dependent on the presence of serum in particular, in the presence of 10% horse serum and 10% fetal calf serum, proliferation of Nb2 cells is rapid, but if the fetal calf serum is omitted proliferation almost ceases. A series of studies showed that the requirement for fetal calf serum could be replaced by prolactin or other lactogenic hormones (human GH has frequently been used) [105], It is not clear that the component in fetal calf serum that provides the stimulant for growth of the cell line actually is prolactin [106], but it is established that under appropriate conditions (presence of horse serum) lactogenic hormones act as specific mitogens for the line (Fig. 8). The response is very sensitive, 1 ng/ml giving a max-... 

A possible involvement of polyamines in the response has been suggested. Prolactin stimulated ornithine decarboxylase activity in Nb2 cells [109]. A specific inhibitor of this enzyme partially blocked the actions of lactogenic hormones on Nb2 cell proliferation [110], and addition of polyamines (putrescine, spermidine or spermine) restored normal growth. However, polyamines alone had no effect on Nb2 cell proliferation, suggesting that they are not the sole or major factors involved in mediating the actions of prolactin on cell growth. 

Gerder, A., Grosclaude, J., Strasburger, C. J., Nir, S., and Djiane, J. (1996). Real-time kinetic measurements of the interactions between lactogenic hormones and prolactin-receptor extracellular domains from several species support the model of hormone-induced transient receptor dimerization. J. Biol. Ghent. 271(40), 24482-24491. 

Shiu R, Kelly P, Friesen H. Radioreceptor assay for prolactin and other lactogenic hormones. Science 1973 180 968-71. 

Tanalta T, Shiu RP, Gout PW, Beer C% Noble RL, Friesen HG. A new sensitive and specific assay for lactogenic hormones Measurement of prolactin and growth hormones in human serum. J Clin Endocrinol Me tab 1980 51 1058-63. 

The placenta produces several protein and steroid hormones (Figure 54-1). The major protein hormones are CG and placental lactogen (PL). The steroids include progesterone, estradiol, estriol, and estrone. The placenta secretes most of its products into the maternal circulation only small amounts reach the fetal circulation. Close proximity of the maternal blood vessels to the site of placental hormone production may explain some of this preferential accumulation of hormones in the maternal blood circulation. Generally, hormone production by the placenta increases in proportion to the increase in placental mass. Therefore concentrations of hormones derived from the placenta, such as PL, increase in maternal peripheral blood as the placenta increases in size CG, which peaks at the end of the first trimester, is an exception. 

Figure 54-1 Schematic representation of steroid and protein hormone production by the placenta. DHEA-S, Dehydro-epiandrosterone sulfate CG, chorionic gonadotropin PL, placental lactogen ACTH, adrenocorticotropic hormone TRH, thyroid-stimulating hormone CT, chorionic thyrotropin GnRH, gonadotropin-releasing hormone CRH, corticotropin-releasing hormone PAPP-A, pregnancy associated plasma protein-A.

M. L. Hogan, et al. Sequence of the pituitary and placental lactogenic and growth hormones evolution from a primordial peptide by gene reduplication. Proc. Natl. Acad. Set U.S.A. 68, 866 (1971).]... 

Trophoblastic expression was evaluated for hCG and its derivatives, leutenizing hormone (EH, LH 3), follicle stimulating hormone (FSH, FSH 3), placental lactogen (PL), and growth hormone (GH-227) in 40 neuroendocrine lung neoplasms, 29 primary pulmonary adenocarcinomas, 20 squamous cell carcinomas, and 1 adenosquamous carcinoma.Trophoblastic hormone immunoreactivity was found in 28 of 90 (31%) of all lung carcinomas but primarily in typical carcinoids. 

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