7779. Prolactin

Nomenclature

CAS number: 9002-62-4
Pituitary lactogenic hormone; adenohypophysial luteotropin; anterior pituitary luteotropin; lactogen; galactin; mammotropin; luteotropic hormone; luteotropin; LTH; Ferolactan (Bioindustria).

Description and references

Polypeptide hormone of mol wt about 23,000; active principle of adenohypophysial gland essential in the induction of lactation in mammals at parturition. Its synergistic action with estrogen promotes mammary gland proliferation. Also brings about the release of progesterone, q.v. from lutein cells which renders the uterine mucosa suited for the imbedding of the ovum, should fertilization occur. Isoln procedures from adenohypophyseal tissue or whole pituitary glands of ox, sheep, and swine: Lyons, Cold Spring Harbor Symp. Quant. Biol. 5, 198 (1937); Li et al., J. Biol. Chem. 146, 627 (1942); White et al., ibid. 143, 447 (1942). Isoln from sheep pituitaries: Reisfeld et al., J. Am. Chem. Soc. 83, 3719 (1961); from other mammalian pituitaries: Nelson; Eppstein, US 3265580 and US 3317392 (1966, 1967, both to Upjohn); from human pituitaries: Lewis et al., Biochem. Biophys. Res. Commun. 44, 1169 (1971). Amino acid sequence of ovine prolactin: Li et al., Nature 224, 695 (1969); Li, Dixon, Arch. Biochem. Biophys. 146, 233 (1971). Review of structural studies of human prolactin and relationship to somatotropin, q.v.: H. D. Niall et al., Recent Prog. Horm. Res. 29, 387 (1973). Amino acid sequence of human prolactin: B. Shome, A. F. Parlow, J. Clin. Endocrinol. Metab. 45, 1112 (1977). Effects of prolactin on the murine immune system: E. Nagy et al., Acta Endocrinol. 102, 351 (1983). Symposium on clinical endocrinology: Horm. Res. 22, 129-252 (1985). General reviews: Li, Evans, Hormones 1, 631 (1948); White, Vitam. Horm. 7, 253 (1949); Voss, Arzneim.-Forsch. 4, 467 (1954); Apostalakis, Vitam. Horm. 26, 197 (1968). Books: Prolactin vols. 1-8, D. F. Horrobin, Ed. (Eden Press, Quebec, 1973-1981); Prolactin: Physiology, Pharmacology and Clinical Findings, O. Hutzinger et al., Eds. (Springer-Verlag, New York, 1982) 224 pp; Prolactin and Prolactinomas, G. Tolis et al., Eds. (Raven Press, New York, 1983) 478 pp.

Properties

Crystals. Isoelectric point 5.73. [α]D25 -40.5° (c = 1 in phosphate buffer of pH 7). Practically insol in water (0.102 g/l) unless electrolytes are present. Forms a water-soluble hydrochloride. Sol in abs methanol or ethanol, if a small amount of acid is present. These data apply to prolactin obtained from ox glands. Prolactin from sheep glands is slightly different: In 0.357M NaCl at pH 2.25 the sheep hormone has a soly of 0.506 g/l, while the soly of the ox hormone is only 0.316 g. In citrate buffer (1M, pH 6.36) and in alcohol the ox protein is more sol than the sheep protein. In the absence of salt, prolactin shows little loss of potency after boiling for one hour at pH 8.0 or at 60° for 5 hours; in the presence of salts complete destruction may occur. An 0.04% soln was stable in a boiling water bath for 15 minutes at pH 1 to 9, but lost activity rapidly at pH 11 and 13. As a rule the hormone is more stable in acid than in alkaline solns. 1 mg = 30 I.U.

Therapeutic Category

Lactation stimulating hormone.

Keywords

Lactation Stimulating Hormone