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An examination of the occurrence and distribution of phthalate esters in the alimentary canal of a polyhybrid of Tilapia gave evidence of different and selective patterns of distribution in the organ tissues: the phthalate esters were shown to be concentrated in the stomach and anterior intestine. The restricted distribution of phthalate esters can have implications for the physiology of the digestive system. The phthalates, stored in the oxyntic cells of the gastric tubular glands, probably interfere with the digestive process. The strategic location of the enterocytes in the anterior intestine implies that they can hamper the reabsorption of digestion products. The endocrine disrupting effects known for these chemicals are probably related to the absorption of them via the alimentary canal. Copyright 2002 The Fisheries Society of the British Isles. Published by Elsevier Science Ltd. All rights reserved. [Copyright &y& Elsevier]

Exposure of the Py1a rat osteoblastic cells to butyl benzyl phthalate (BBP)and dibutyl phthalate (DBP) showed that these endocrine disrupting chemicals(EDC) strongly and reversibly affect the cytoplasmic fibroblast growth factor-2(FGF-2) translocation into the nucleus in a dose-dependent and time-relatedmanner. Stimulation of cells with high concentrations of BBP or DBP for shorttiming gave results comparable to those of cells treated with low concentrationsfor long timing. By confocal laser scanning microscope (CLSM) analysis itwas found that the first relevant effect resulted in an accumulation of FGF-2near the nuclear envelope, sometimes in the shape of clusters; the growthfactor was then translocated into the nucleus and, finally, after long periodsof exposure, the basal nuclear and cytoplasmic binding, typical of unstimulatedcells, was re-established. In addition it was found that phthalate estersdid not affect the FGF receptor 2 (FGFR-2) but decreased Con A binding indicatinga possible inhibition of collagen fiber assembly. The different concentrationsand timing of exposure of BBP and DBP affected the FGF-2 modulation in a similarway. Noticeable cumulative effects of BBP and DBP were not observed. [ABSTRACT FROM AUTHOR]

Calpastatin, the endogenous inhibitor of calcium-activated neutral proteases (calpains; EC 3.4.22.17), was studied in the rabbit vastus lateralis muscle by means of immunochemical and immunohistochemical techniques. Immunoaffinity chromatography using an antibody raised against the 34-kDa monomer of the 68-kDa dimeric inhibitor allowed us to isolate three main proteins (130-, 100- and 80-kDa). These proteins strongly inhibited calpain activity in muscle homogenate (I at about 50 μg/ml). Immunohistochemical experiments showed that calpastatin-related immunoreactivity was present in all fibre types (oxidative, glycolytic, oxidative-glycolytic) at both surface and cytoplasmic level. However, a few (20%) of the slow-twitch, oxidative fibres (5% of the total fibres), did not contain the cytoplasmic inhibitor. Specific immunoreactivity for calpastatin was also associated with the interstitial connective tissue. These results suggest that (i) calpastatin in skeletal muscle, as in other tissues, is present as a mixture of proteins of various molecular weights and (ii) the inhibitor may act not only in the cytoplasm but also at the surface or extracellular level. [ABSTRACT FROM AUTHOR]

The possible effect of proopiomelanocortin-derived peptide, β-endorphin on frog gonadotrope cells was investigated. Binding and internalization of β-endorphin to pituitary pars distalis cultured cells were visualized by immunofluorescence and analyzed by means of confocal laser scanning microscopy. Using biotinylated endorphin, the time-course of β-binding showed that this opioid was internalized through receptor-mediated endocytosis, the mechanism in which actin and clathrin were involved; then, the lysosomal degradation program occurred at later stages. The β-endorphin binding was well antagonized by Naloxone, the opiate receptor antagonist, and up-regulated since more rapid response was obtained in the previously primed cells. The double immunostaining reaction for β-endorphin and LH β-subunit revealed that half the β-endorphin labeled cell population was positively immunostained for LH β-subunit, and β-endorphin was able to induce an increasing trend of LH secretion in cultured pars distalis cells. Therefore, it seems that β-endorphin acts directly on pituitary pars distalis and influences gonadotropin secretion through the interaction with its own receptor. [Copyright &y& Elsevier]