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Le facteur de liberation de la STH a ete caracterise et augmente dans plusieurs especes (homme, porc, bovin, souris). Le mecanisme d'action a ete defini. La cartographie des neurones a STH-LH a ete etablie. Des essais cliniques ont ete mis en route et ont confirme la puissante activite de liberation de STH de la STH-LH chez l'homme. L'effet du peptide sur les taux d'ARNm de la STH a ete decrit et le clonage moleculaire a ete utilise pour etablir les structures de la preproSTH-RH humaine (pancreatique)

SummaryA new method to calculate and analyze results in the McKenzie assay for TSH is presented. It is proposed: 1) to transform the original data (radioactivity counts/ fixed volume/fixed time) in their logarithms (logo10); this applies to both first (control) and second (after TSH) blood samples; 2) a covariance analysis is then applied on the transformed data, the second blood values (dependent variable) being adjusted to the values of the first blood sample (independent variable). This method removes the heteroscedasticity inherent in the original calculations as proposed by McKenzie, thus increasing precision and reliability of the experiments.

SummaryEighty thousand hypothalamus fragments of sheep brains (wet weight 55 kg) were extracted with 2 N acetic acid. The extract was filtered on Sephadex G25 in pyridine acetate 0.1 M, pH 5.6. The TRF-active zone was located by bioassay and further purified by CCD (250 transfers followed by 1,000 transfers) using the system n-butanol-pyridine-acetic acid (5:3:11), ion exchange on IRC-50 equilibrated with ammonium acetate 0.02 M, pH 5.0, and finally thin-layer chromatography on cellulose (butanol-acetic acid-water, 4:1:5). The material obtained (ca 400 μg) at the last stage of purification was active in vivo to stimulate release of TSH at ≤ 0.1 μg dry weight. Highly purified TRF has no LH- or ACTH-releasing activity, Amino acids present in this preparation are reported.

Summaryα- and β-MSH were isolated on preparative scale with high recovery of starting activity. The initial step in purification of both hormones is chromatography on carboxymethylcellulose. β-MSH is further purified (4-5 × 106 U/mg) by use of DEAE cellulose. α-MSH was not completely freed of vasopressin and other contaminants by zone electrophoresis on large vertical column. Countercurrent distribution of concentrate of vasopressin and α-MSH, yields α-MSH with a potency of 1.5 × 107 U/mg, free of vasopressin.

SummaryInjection (iv) of perphenazine, an antipsychotic tranquilizer, into rats produces a 10–fold increase in plasma prolactin levels as measured by radioimmunoassay; a similar response is seen when using adult male or female rats; plasma prolactin levels are increased significantly by 10 min post–injection and a maximal response occurs after 30 min. Ten micrograms of perphenazine is the minimal active dose that will cause an elevation in plasma prolactin levels. Addition of up to 10 μg/ml medium of perphenazine to in vitro cultures of enzymatically dispersed rat pituitary cells does not stimulate secretion of prolactin. Also (ip) injection of 1 mg perphenazine into rats bearing 2 pituitary transplants under the kidney capsule, causes only a marginal increase in prolactin secretion. These data indicate that perphenazine releases prolactin by acting on brain centers above the level of the pituitary.

SummaryA basic peptide with corticotropin releasing activity, no inherent ACTH-like or MSH activity and a pressor activity of 45 u/mg was isolated from pig posterior pituitary glands by the Kamm procedure followed by chromatography on carboxymethylcellulose (CMC), countercurrent distribution and rechromatography on CMC. The amino acid composition showed that the peptide is related to lysine-vasopressin, but with additional amino acids being present; the peptide belongs thus to a group designated β-CRF. The N-terminal and C-terminal amino acid sequences show sequential similarities with those of α-MSH and lysine vasopressin, respectively. This could perhaps explain inherent pressor activity of CRF and CRF activity of LVP and α-MSH analogs (α2-CRF).

SummaryThe adrenocortical response to injected ACTH USP Standard has been studied as a function of time in rats after hypophysectomy or placement of a lesion in median eminence of the hypothalamus. In either case, there is an exponential decrease in sensitivity to ACTH of the adrenal gland, as a function of time. This can be observed in the presence of large adrenal glands, in animals bearing a hypothalamic lesion. The progressive decrease of adrenal sensitivity to ACTH in the lesioned animal makes it desirable to use only an acute preparation as a test for CRF.

SummaryBoth arginine and lysine vasopressin have been obtained in a high degree of purity by means of chromatography on carboxymethyl cellulose using ammonium acetate as a volatile buffer and differential elution gradients. Conditions for the resolution of LVP and AVP by chromatography on this same exchanger are described. By combining efficient recovery of activity, high flow rates for the chromatography, and rapid removal of buffers by lyophilization, a simple means of purifying vasopressin is proposed.

SummaryPurification of the TRF concentrate prepared by gel filtration of acetic acid extracts of hypothalamic tissues on Sephadex G-25 can be achieved following gel chromatography on carboxymethyl-Sephadex C-50 equilibrated in 0.001M pyridine acetate. The TRF activity is quantitatively eluted upon stepwise application of 0.09M pyridine acetate buffer. The method described can be used with small columns (4 × 15 cm) with charges ≤ 1 g TRF concentrate and also with large size preparative columns (15 × 33 cm) with charges up to 25 g of the TRF concentrate.

SummaryMild nonspecific exteroceptive stimuli such as handling, transferring from one room to another, and I.P. injections, lead to a rapid decrease of plasma TSH concentrations which become undetectable within 15 minutes following the beginning of the stressing procedure. There is evidence for a circadian rhythm of plasma TSH levels in opposite phases to those of the variations of plasma ACTH or corticosteroid variations. These observations are considered to be of importance to define resting levels of plasma TSH concentrations. For rats kept at 22°C ± 0.5, rapidly decapitated at 7:00 a.m., resting levels of circulating TSH are between 25–30 mU/100 ml plasma in this laboratory.

SummaryNychthemeral variations in levels of plasma free corticosteroids in the rat have been observed, with highest concentrations of steroid between 4 p.m. and midnight. The magnitude of these cyclic variations is such that they will have to be considered in measurement of “resting levels” of plasma corticosteroids in this species.

SummaryA modified tissue culture technic for rat pituitary was used for assaying the ACTH releasing activity of commercial Pitressin and purified vasopressin. Pitressin increased ACTH release whereas highly purified arginine-vasopressin had no effect. The ACTH hypophysotrope activity of commercial Pitressin is attributed to a contaminant of vasopressin of probable hypothalamic origin.

Summary1) Neurohypophysial extracts of commercial origin were chromatographed on carboxymethylcellulose cation exchange adsorbent under conditions of pH and ionic strength gradient in view of separating CRF. An in vivo assay was used to assess CRF activity. 2) The method described is useful in large scale preparations. Fractions containing CRF were regularly found to emerge before lysine vasopressin and were well separated from oxytocin.

SummarySeveral preparations of highly purified α-MSH were studied for their adrenocorticotropic activity in vivo and in vitro using USP Reference Corticotropin as a Standard. They showed corticotrophic activity by either assay procedure. β-MSH did not demonstrate similar activity. In view of data obtained, it is suggested that the “active core” of ACTH molecule may be no longer than the tridecapeptide from the N-terminus.