Pituitary lactogenic hormone

Chorionic Somatomammotropin. Three genes encode human chorionic somatomammotropin [11085-36-2] (hCS). These are located within a cluster of genes on human chromosome 17 which code for pituitary growth hormone [12629-01 -5] (GH-N), placental GH [109675-94-7J (GH-V), and three hCS molecules, ie, hCS-A, hCS-B, and hCS-V (1 3), also referred to as human placental lactogens. All of these molecules ate closely related to GH in stmcture (Fig. 1). Placental lactogens also exist in rodents and mminants however, these hormones are more closely related to prolactin than GH. 

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. 

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). 

Wallis, M. The molecular evolution of pituitary growth hormone, prolactin and placental lactogen a protein family showing variable rates of evolution. J. Mol. Evol. 16, 10-18 (1981) Zahner, H., Drautz, H., Weber, W. Novel approaches to metabolite screening. In Bioactive Microbial Products Search and Discovery (J. D. Bu Lock, L, J, Nisbet. D. J. Winstanley, eds,), pp. 51-70. Spec. Publ. Soc, Gen. Microbiol. 6, Academic Press, New York 1982... 

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). 

The pituitary, as well as the hypothalamic hormones, also contribute to VN development. A transient prolactin receptor (PRLR) is expressed in the late foetal rat. At El8, there is positive staining for this binding protein along the lumenal border the reaction is restricted to the medial (sensory) zone [Freemark et al, Fig. 6(d), 1996]. These sites possibly function in the detection of endogenous lactogenic ligands such as PL-I and PL-II. The VNORs also occupy microvillous sites in this area, but the precise developmental role of PRLR in the early AOS is unknown. The modulatory influence of prolactin is well established after puberty in mammals as a reproductive determinant (Chap. 5). In a more central role, it acts on the EOG recorded from the accessory area of the bulb in newts (Toyoda, 2000). 

Anterior pituitary hormones are classihed into three families the somatomammotropin family (GH and PRL), the glycoprotein hormones (LH, FSH, and TSH), and the opiomelanocortin family (ACTH, /i-endorphin, and related peptides). These three families appear to have evolved from three separate ancestral polypeptides homologous members of each family occur in other parts of the body. For example, human placental lactogen (hPL) is somatomammotropic, human chorionic gonadotrophin (hCG) is a glycoprotein hormone, and the brain and gut produce substances related to endorphins (enkephalins and dynorphin). 

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).]... 

Insulin did not react as an accelerator but exerted its effects only under the conditions specified above. The Coris proposed that in diabetic tissue the inhibitory reactions of adrenocortical extracts depend on the presence of a substance of pituitary origin. Highly purified extracts of adrenotropic, lactogenic, and growth hormones were ineffective as inhibitors in conjunction with adrenocortical extracts. The Coris inhibitory substance had unusual lability, since (1) the initial inhibition effect on the hexokinase reaction is relieved by time, and (2) complete destruction of the inhibitory factor is observed by aging of extract for 45 to 120 minutes at 0°C. 

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