Hypothalamic releasing factors

The hypothalamic releasing factors regulate release of the anterior pituitary trophic hormones 844... 

The hypothalamic releasing factors regulate release of the anterior pituitary trophic hormones. As summarized in Figure 52-1, the releasing factors are produced in various neuronal groups within the hypothalamus and are transported to the median eminence for release into the portal circulation to the anterior pituitary. Neurons in the hypothalamus also produce the hormones oxytocin and vasopressin, which are released by the posterior pituitary into the blood. Therefore, it is not surprising that behavior and experience, which influence the hypothalamus, sometimes alter the secretion of these hypothalamic releasing factors and hormones. 

Neuropeptides are often grouped by their structural similarity or tissue source. Among these are the hypothalamic releasing factors (e.g., corticotrophin-releasing factor [CRF], thyrotropin-releasing hormone), anteior pituitary hormones (e.g., adrenocorticotrophic hormone [ACTFI], follicle-stimulating hormone [FSFI]), and posterior pituitary hormones... 

Ascoli, M., and D.L. Segaloff, Adenohy-pophyseal hormones and their hypothalamic releasing factors. In Goodman Gilman s 9" edition. J.E. Hardman and L.E. Limbird, eds. McGraw-Hill, NY. NY, 1996. pp. 1363-82. 

The testes and ovaries synthesize hormones necessary for physical development and reproduction. A single hypothalamic-releasing factor, gonadotropin-releasing hormone, stimulates the anterior pituitary to release the glycoproteins, luteinizing hormone (LH) and... 

Guillemin R. Hypothalamic hormones a.k.a. hypothalamic releasing factors. J Endocrinol. 2005 184 11-28. 

Parker KL, Schimmer BO. Pituitary hormones and their hypothalamic releasing factors. In Brunton LL, et al, eds. The Pharmacological Basis of Therapeutics. 11th ed. New York McGraw-Hill 2006. 

Examples of the use of analytical-scale column systems for the small-scale (i.e., 1 fig to 1 mg) preparative separation of peptides include the extraordinarily potent opoid peptide, dynorphin (I4S) insulin A-, B-, and C-chain peptides (24, 72) j8-chain peptides of the pituitary glycoprotein hormones (8) endorphins (28,60, 126, 137), adrenocorticotropic peptides in plasma, pituitary, and other endocrine glands or secreted from tumor cells iVt vitro (84, I2S, 127, 138, 142. I Si) hypothalamic releasing factors... 

Man) of the pituitat) hormones and their hypothalamic releasing factors are used in diagnosis or therapy. 

Ascoll, M. ef al. (1996) Adenohypophyseal hormones and their hypothalamic releasing factors, in The Pharmacological Basis of Therapeutics. 9th edn, (eds J.G. Hardman et a/.). McGraw-Hill, New York, chapter 55. pp. 1363-1382. 

The role of the hypothalmus in the regulation of the reproductive cycle is coming under increasingly Intensive investigation the action of hormones on this entity has recently been reviewed. Considerable progress is being achieved towards the isolation of the hypothalamic releasing factors for the pituitary hormones. ... 

The anterior pituitary gland receives releasing factors from the hypothalamus in blood via a venous portal system. The releasing factors are hormones that regulate the secretions of the anterior pituitary gland. See Table 6.1 for actions and clinical uses of hypothalamic releasing factors. 

The administration of ji agonists increases the concentration of prolactin in plasma, probably by reducing the dopaminergic inhibition of its secretion. The administration of morphine or P-endorphin has little effect on the concentration of growth hormone in plasma. With chronic administration, tolerance develops to the effects of morphine on hypothalamic releasing factors. Patients maintained on methadone reflect this phenomenon in women, menstrual cycles that had been disrupted by intermittent use of heroin return to normal in men, circulating concentrations of LH and testosterone return to the normal range. 

Adrenal steroids Corticotropin-releasing factor (CRF), a hypothalamic releasing factor, stimulates release of corticotropin (ACTH) from the pituitary gland. ACTH stimulates the adrenal gland to produce corticosteroid hormones (Tables 10.5 - 10.7). Cleavage of the precursor pro-opiomelanocortin... 

In both men and women there is a continuous secretion of the hypothalamic releasing factors so that there is a continuous production of gonadal hormones. In addition, in the female alone, there is superimposed an explosive cyclical release of FSH-RF and LH-RF which are essential for the ovulatory process [5]. In its simplest form it is possible to equate the follicular phase of the menstrual cycle with the preovulatory FSH surge and subsequent rupture of the follicle with mid-cycle LH release. Steroid biogenesis in the testis, in contrast, follows a continuous pattern with no dramatic changes in hormone output. Both ovary and testis utilise cholesterol as raw material for... 

Solid-phase Zincke reaction was applied for the search of activators of the cystic fibrosis transmembrane conductance regulator protein. On the other hand, the tripeptide TRH (pGlu-His-Pro-NH2) was shown to be a hypothalamic releasing factor for the regulation of pituitary function. A solid-phase Zincke reaction was used to prepare analogues of TRH having the central histidine replaced with a 1,4-dihydropyridine unit (such as 48). Compound 48 was expected to cross the hydrophobic blood-brain barrier (BBB) but to be trapped within the central nervous system upon oxidation to the hydrophilic pyridinium form. 

Compared to other hormones we know little about the regulation of the secretion of growth hormone (see regulation of secretion of ACTH and TSH). A hypothalamic releasing factor is supposed to exist, but... 

Burgus, R., Guillemin, R. Hypothalamic releasing factors. Annu. Rev. Biochem. 39, 499-526 (1970)... 

A glycoprotein hormone secreted by the pituitary in response to a specific hypothalamic releasing factor (LH/ FSH-RF). In males it stimulates testosterone secretion by the testis while in females it is responsible for ovulation. LH also acts with FSH in stimulating oestrogen secretion. In females plasma LH levels exhibit a sharp peak in the middle of the menstrual cycle, when ovulation occurs. Although LH can be measured by bioassay, it is now usually estimated by radioimunoassay. 

Recently, several attempts have been made to purify the LRF, using ovine or bovine extracts as the starting material. Gel filtration on Sephadex G-25 was first used by Porath Schally (43) for separation of posterior lobe hormones and has proved to be a good method for purification of the various hypothalamic releasing factors. In our hands, using ovine SME extract and ammonium acetate as the eluting buffer, LRF has been eluted from the Sephadex... 

For many years, the hypothalamic releasing factors were considered to be polypeptides on the basis of various evidence. And indeed it is with the concept that we were dealing with basic polypeptides that CRF, TRF, LRF, etc., were purified by a methodology classically devoted to purification of peptides (8). 

PHYSIOLOGICAL AND BIOCHEMICAL STUDIES ON SOME HIGHLY PURIFIED HYPOTHALAMIC RELEASING FACTORS... 

First, we would like to propose a new nomenclature for hypothalamic releasing factors. Two weeks ago, we made these proposals at the Laurentian Hormone Conference in Canada. We will repeat these proposals for our European colleagure and those who did not attend this Conference. 

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