Solubilization of unconjugated bilirubin by bile salts

Summary Freshly precipitated uncojugated bilirubin (UCB) is solubilized rapidly and to a large extent by the sodium salts of di- and trihydroxy bile acids. The solubilization effect depending on bile salt concentration, pH and ionic strength is based on micellar mechanisms.     

Solubilization of unconjugated bilirubin by bile salts.

Freshly precipitated unconjugated bilirubin (UCB) is solubilized rapidly and to a large extent by the sodium salts of di- and trihydroxy bile acids. The solubilization effect depending on bile salt concentration, pH and ionic strength is based on micellar mechanisms.     

Solubilization of human red cell membranes by lysolecithins of various chain lengths

Summary Red cells and membranes prepared from them were treated with graded amounts of palmitoyl, myristoyl and lauroyl lysolecithins. There was no release of phospholipids from the intact red cells in the absence of hemolysis. The solubilization pattern of lipid and protein from the red cell membranes by lysolecithins varies with their chain length.The skillful technical assistance of Mrs Isca Levy is gratefully acknowledged.     

Changes in the differentiation of the sea urchin larva by action of a detergent upon the unsegmented egg

Résumé Le traitement de l'uf d'oursin, quelques secondes après la fertilisation, par un détergent, le lauryl sulfate de sodium, provoque l'hyperdéveloppement des structures ectodermiques chez les larves (animalisation). Cet effet n'est plus observé lorsqu'on intervient plusieurs minutes après le fécondation. On suggère que le lauryl sulfate inactive ou solubilise un matériel, peut être de nature protéique, localisé à l'intérieur ou à la surface de la membrane plasmatique de l'uf fécondé. Ce matériel serait responsable de la différenciation de l'entomésoderme des larves.     

Reduction of body fat stores by inhibition of prolactin secretion

Reductions of prolactin secretion by bromocriptine treatment for 24 days reduced fat stores (abdominal and epididymal fat depots) in hamsters by 25-49% compared with control animals. However, body weights and food consumption were not affected. These results further substantiate an important role for prolactin in regulation of fat metabolism and indicate that bromocriptine might be used to decrease fat stores.     

Reduction of body fat stores by inhibition of prolactin secretion

Summary Reductions of prolactin secretion by bromocriptine treatment for 24 days reduced fat stores (abdominal and epididymal fat depots) in hamsters by 25–49% compared with control animals. However, body weights and food consumption were not affected. These results further substantiate an important role for prolactin in regulation of fat metabolism and indicate that bromocriptine might be used to decrease fat stores.     

Serum prolactin levels and maintenance of progeny by prenatally-stressed female offspring

Summary Prenatal stress significantly reduced the number of progeny born to 47% of the female offspring and significantly increased the incidence of low birthweight young. None of these litters survived by the tenth postpartum day when serum prolactin levels were significantly reduced. Upon autopsy, these females had twice as many uterine implantation sites than the number of fetuses they bore, suggesting that a) the reduced postpartum serum prolactin most likely was the cause rather than the effect of the neonatal mortality and b) major hormonal deficiencies (possibly gonadotropic-related) were present even before giving birth.     

Effect of sulpiride on prolactin release by rat pituitaries in vitro

Résumé La sulpiride stimule la libération de la prolactine de l'hypophise après 4 h d'incubation. L'addition d'extraits hypothalamiques l'inhibe, mais la sulpiride ajoutée en même temps aux extraits hypothalamiques permet l'inversion de cet effet d'inhibition. Il semble evident que la sulpiride peut modifier la libération de la prolactine en agissant directement sur l'hypophise du rat, in vitro.     

Somatic growth in hypophysectomized pituitary-homografted rats is promoted by prolactin

Summary Hypophysectomized male rats bearing a homograft of two adenopituitaries under the kidney capsule showed a significant increase in b.wt as compared to hypophysectomized non-homografted animals. Radiommunoassay of growth hormone (GH), ACTH, -MSH,-endorphin and prolactin (PRL) revealed that only the latter was highly increased in the plasma of hypophysectomized homografted rats. These animals showed also increased levels of plasma corticosterone. However, daily injection of corticosterone failed to promote somatic growth in hypophysectomized non-homografted rats. These results suggest that PRL, and not other hormonal factors, promotes somatic growth in hypophysectomized homografted rats, and stress the concept that only PRL is secreted in significant amounts by pituitary homografts.     

Normal prolactin content of rat pituitary may be maintained by Nebenkern formations

Summary We have observed Nebenkern formations in mammotrophs of normal male rats. The ultrastructural appearance of these formations suggests that they may be part of a mechanism which by the process of autophagy disposes of older prolactin granules.     

Serum prolactin levels and maintenance of progeny by prenatally-stressed female offspring.

Prenatal stress significantly reduced the number of progeny born to 47% of the female offspring and significantly increased the incidence of low birthweight young. None of these litters survived by the tenth postpartum day when serum prolactin levels were significantly reduced. Upon autopsy, these females had twice as many uterine implantation sites than the number of fetuses they bore, suggesting that a) the reduced postpartum serum prolactin most likely was the cause rather than the effect of the neonatal mortality and b) major hormonal deficiencies (possibly gonadotropic-related) were present even before giving birth.     

Rat mammary cancer inhibition by a prolactin suppressor, 2-bromo-α-ergokryptine (CB 154)

Zusammenfassung 2-Br--Ergokryptin (=CB 154) wurde täglich während 80–100 Tagen, beginnend mit der Carcinogenapplikation, DMBA - (5 mg i.v.)-behandelten weiblichen Ratten in der Dosis 6 mg/kg i.p. verabreicht. CB 154 bewirkte ein verzögertes Erscheinen und ein langsameres Wachsen der Mamma-Tumoren sowie eine verminderte Todesrate der carcinogenbehandelten Ratten.     

Intensification of amphetamine-induced excitation by methysergide,a serotonergic receptor blocker

Summary Methysergide, a serotonergic receptor blocker, was studied to determine its effects against d-amphetamine-induced excitation as measured by convulsions elicited by handling in mice. Significant intensification (p<0.01) of the action of d-amphetamine was observed in mice. These results indicate that reduction in serotonergic activity in the central nervous system enhances excitation induced by d-amphetamine.This work was supported by the Pharmaceutical Manufacturer Association Starter Grant, No. 5 S01 RR 05654-06 and the Air Force Office of Scientific Research Grant. The authors are grateful to Ben Wiggins, Michael Wallace, Maria Salazar, and Sanford Futterman for their technical assistance. The authors are also grateful to Dr Boris Tabakoff for supplying the formula of the CSF used in this experiment and we are indebted to San Antonio College for the use of their computer facilities. Dr Blum is a Career Teacher in drug addiction sponsored by NIDA, grant No. 1-T01-DA00290-01.     

Regulation of receptor function by cholesterol

Cholesterol influences many of the biophysical properties of membranes and is nonrandomly distributed between cellular organelles, subdomains of membranes, and leaflets of the membrane bilayer. In combination with the high dynamics of cholesterol distribution, this offers many possibilities for regulation of membrane-embedded receptors. Depending on the receptor, cholesterol can have a strong influence on the affinity state, on the binding capacity, and on signal transduction. Most important, cholesterol may stabilize receptors in defined conformations related to their biological functions. This may occur by direct molecular interaction between cholesterol and receptors. In this review, we discuss the functional dependence of the nicotinic acetylcholine receptor as well as different G protein-coupled receptors on the presence of cholesterol.     

Influence of dopamine infusion on plasma prolactin released by kidney capsule transplanted anterior pituitaries

Summary The infusion of dopamine into the renal artery resulted in decreased prolactin release from 3 anterior pituitary glands transplanted under the kidney capsule. Prolactin levels continually decreased over a 5 min period after DA infusion was terminated and thereafter approached preinfusion levels by the end of 10 min.Supported by NSF Research, grant No. 74-17332.The authors wish to express their appreciation to Mrs Cynthia Van De Walle for her outstanding technical assistance in the performance of the prolactin RIA and the statistical analyses. We also appreciate receiving as a gift from the National Institute for Arthritis, Metabolism and Digestive Diseases the rat prolactin used for iodination (RP-I₂) and standards (RP-1).     

In vitro stimulation of chicken pituitary growth hormone and prolactin secretion by chicken hypothalamic extract

Summary The effect of an acid extract of chicken hypothalami on the in vitro secretion of prolactin and growth hormone (GH) by dispersed chicken pituitary cells has been investigated. Both prolactin and GH release were stimulated in a dose related manner in the presence of the hypothalamic extract (HE). Somatostatin had no effect on the basal or HE stimulated release of prolactin although it did inhibit the HE induced release of GH.