Hormone prolactin and

Lactoferrin is the major whey protein present in breast milk (Teraguchi et ah, 1996) with many microbicidal properties (Leon-Sicairos et ah, 2006). The concentration of lactoferrin in milk has been reported as 1 g/liter in mature milk and 7 g/liter in colostrum (Houghton et ah, 1985). The concentration of lactoferrin in breast milk is controlled by the reproductive hormones prolactin and estrogen (Ward et ah, 2005). Lactoferrin has been demonstrated to resist digestion in the infant gut as it has been recovered intact from the stool of breast-fed infants (Bemt and Walker, 1999). Lactoferrin acts mainly in an iron-free state (apo-lactoferrin) and its microbicidal activity is reported to increase in proportion to its concentration in milk (Leon-Sicairos et ah, 2006). 

Bromocriptine also inhibits the secretion of the hormone prolactin and can be used to treat some problems of male and female infertility and impotence as well as menstrual discomfort. 

Mammary development is under the regulation of a complex set of hormones. Studies involving endocrinectomy (removal of different endocrine organs) show that the principal hormones are oestrogen, progesterone, growth hormone, prolactin and corticosteroids (Figure 1.4). 

Combined cytostatic drug therapy for Hodgkin s disease in childhood often results in abnormal endocrine function, particularly increases in follicle-stimulating hormone, prolactin, and thyroid-stimulating hormone (318). 

Maeda K, Frohman LA (1978) Dissociation of systemic and central effects of neurotensin on the secretion of growth hormone, prolactin, and thyrotropin. Endocrinology 103 1903-1909. 

The tumors are positive for synaptophysin, chromogranin, and neuron-specific enolase and may express a variety of hormones (growth hormone, prolactin, TSH, ACTH, and FSH). A few are hormone negative and are designated as null-cell adenomas. Almost all are positive for CAM 5.2, either focally or diffusely, and about half are positive for AE 1/3. They are negative for cytokeratin 7, 19, and 20, as well as S-100 protein. Pituitary transcription factor-1 is selectively expressed in tumors that express growth hormone, prolactin, and TSH. No diagnostic molecular markers are currently in use for sporadic pituitary lesions. ... 

Horseman ND Yu-Lee LY (1994) Transcriptional regulation by the helix bundle peptide hormones growth hormone, prolactin, and hematopoietic cytokines. Endocrinol Rev, 15 627-649. 

Paksy K, Oiajos F, Toth BF, Nahay M, Tatrail F and Huszar L (1999) Uptake and distribution of cobalt in rat ovaries and pituitary acute ffects of cobalt on preovulatory luteinizing hormone, foUide stimulating hormone, prolactin and progesterone levels, and on ovulation in rats. CFJOFM 5 313 — 323. 

Beck, W., and W. Wuttke. 1979. Annual rhythms of luteinizing hormone, follicle stimulating hormone, prolactin and testosterone in the serum of male rhesus monkeys. Journal of Endocrinology 83 131-139. 

ENDOCRINE SYSTEM A number of endocrine tissues respond to PGs. In a number of species, the systemic administration of PGE increases circulating concentrations of adrenocorticotropic hormone (ACTH), growth hormone, prolactin, and gonadotropins. Other effects include stimulation of steroid production by the adrenals, stimulation of insulin release, and thyrotropinlike effects on the thyroid. The critical role of PGF in parturition relies on its ability to induce an oxytocin-dependent decline in progesterone levels. PGE works as part of a positive-feedback loop to induce oocyte maturation required for fertihzation during and after ovulation. 

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... 

Thus far, to the extent that our observations include the same parameters as those published, PPP(H) appears to be identical with the "human placental lactogen", "chorionic growth hormone-prolactin" and "placental protein". 

The prolactin receptor, PER, which regulates milk production in mammals, belongs to the same receptor class as the growth hormone receptor. In addition to binding the hormone prolactin, PER also binds and is activated by growth hormone. The extracellular domain of PER forms a very stable 1 1 complex with growth hormone in solution this complex has been crystallized and its structure determined (Figure 13.21). We shall compare this structure with the 1 2 complex of the same hormone with GHR. 

Figure 13.22 Hormone-receptor interactions involving the domain-domain linker region in the receptor, (a) Interactions between the growth hormone (red) and the growth hormone receptor (blue) linker region. Glu 127 of the receptor forms a salt bridge to Arg 167 in the hormone, (b) The same interaction area in the growth hormone (red)-prolactin receptor (green) complex. The displacement of the linker region due to differences in the domain orientations have brought Asp 124 in the prolactin receptor into contact with Arg 167 of the hormone. (Adapted from W. Somers et al.. Nature 372 478-481, 1994.)...

There are five known classes of enzyme-linked receptors (1) receptor tyrosine kinases, which phosphorylate specific tyrosine residues on intracellular signaling proteins (2) tyrosine kinase-associated receptors, such as the prolactin and growth hormone receptors we have already discussed, which... 

Cannabimimetics are also shown to affect reproductive and metabolic functions indirectly by hormonal modulation through the hypothalamic and pituitary regulatory centers. They are found to reduce serum levels of the luteinizing hormone, prolactin, growth hormone, and thyroid-stimulating hormone, and to increase corticotropin (Murphy, 1998). 

Yet different elaboration of the same molecule affords a compound (162) that acts as an inhibitor to the pituitary peptide hormone prolactin, the factor responsible for supporting lactation. As such the drug has found use in suppressing lactation and in the treatment of prolactin-dependent breast tumors. 

---