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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 49 (1983), S. 300-306 
    ISSN: 1432-1106
    Schlagwort(e): Choroid plexus ; Lactogen ; Radioautography ; Receptor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Prolactin binding sites have been demonstrated previously in rat choroid plexus using in vivo radioautography (Walsh et al. 1978). In the present study we have employed this procedure to characterize further the binding specificity of these sites. Following the injection of 125 I-hGH or 125I-oPRL an intense radioautographic reaction was observed over the choroid plexus. The reaction was significantly reduced by coinjecting excess unlabeled hGH or oPRL but not bGH. The specific binding of 125I-oPRL to choroid plexus from rat, rabbit, sheep and pig was demonstrated by in vitro assays. Subsequently a survey of 125I-oPRL specific binding in a number of regions of pig brain indicated that the highest binding was in choroid plexus. A detailed study of the characteristics of 125I-oPRL binding to pig choroid plexus was undertaken. Specific binding increased with choroid plexus homogenate protein to a maximum of 30% (3.0 mg protein/tube). Binding was maximum at 4 ° C by 30–40 h of incubation. During the incubation the integrity of 125I-oPRL in the incubation medium declined steadily to 50% after 20 h and 35–40% after 48 h. Radioactivity eluted from binding sites was fully intact as judged by rebinding to lactogen receptor-enriched membranes. Binding showed a broad pH optimum of 5.5–7.5. On cell fractionation of choroid plexus binding sites were enriched in microsomes. The binding of 125I-oPRL and 125I-hGH was inhibited in a dose-dependent manner by unlabeled lactogens and was of high affinity. hGH and oPRL were equipotent inhibitors of the binding of both radioligands whereas bGH and a variety of structurally unrelated peptides were noninhibitory. These studies indicate rat choroid plexus binds lactogens other than prolactin as do other wellcharacterized lactogen receptors. Furthermore, the in vitro binding studies on pig brain have demonstrated notable enrichment of lactogen binding sites in choroid plexus and have indicated that they have characteristics of lactogen receptors. The physiologic significance of our findings is unknown but the presence of lactogen receptors in choroid plexus raises the possibility of its being a target organ for prolactin. It is also possible that the receptors play a role in transporting prolactin from the blood to the CSF.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1573-2568
    Schlagwort(e): GALLBLADDER MUCOSA ; MUCOSAL FLUID ABSORPTION ; LIPID ABSORPTION ; CHOLESTEROL GALLSTONES ; OBESITY
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Gallbladder mucosal absorption of fluid duringfasting is a well-known process. Indirect in vivo andrecent in vitro evidence for physiologically relevantgallbladder absorption of cholesterol and phospholipids from bile has been observed in humans. Thepresent study explored and compared by indirect meansthe relative efficiences of human gallbladder mucosalabsorption of fluid and lipids in health and disease. Biliary lipids and pigment content weremeasured in fasting gallbladder bile samples obtainedfrom gallstone-free controls and from four study groups:multiple and solitary cholesterol gallstone patients, and morbidly obese subjects with and withoutgallstones. Bile salts and pigment content weresignificantly greater in gallstone-free controls than inall other disease study groups. This was interpreted as evidence of more effective gallbladdermucosal fluid absorption in nonobese gallstone-freecontrols compared to that in all other groups.Correlation plot analyses of biliary lipids showed lowerconcentrations of phospholipids than expected from the indexbile salt concentrations. The same was found forcholesterol concentrations but only in supersaturatedsamples. These findings were much more pronounced in gallstone free-controls and were accordinglyinterpreted as evidence of more efficient gallbladderabsorption of both phospholipids and cholesterol incontrols compared with that found in each of the disease study groups. Moreover, impaired gallbladdermucosal function, while invariably associated withcholesterol gallstone disease, was not found to be anecessary consequence of the physical presence ofstones. It is concluded that efficient gallbladdermucosal absorption of both fluid and apolar lipids frombile is a normal physiological process that is oftenseriously impaired in the presence of either cholesterol gallstone disease or at least one of itsprecursor forms.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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