Identification and androgen regulation of egasyn in the mouse epididymis.

The expression and androgen regulation of egasyn, the endoplasmic reticulum-targeting protein of beta-D-glucuronidase, was examined in the mouse-epididymis. The proximal (caput) and distal (corpus & cauda) epididymal tissue extracts were prepared by homogenization and sonication in buffered Triton X-100 solution, and high speed centrifugation. The supernatant when resolved by 2D-PAGE under non-denaturing conditions and stained for esterase activity showed that the distal (but not proximal) epididymis of the normal mouse contain several specific forms of esterases. These forms include a series of four variants (pI 5.2-5.75) with high mobility (HM) and esterase activity, and three faintly staining variants (beginning at pI 6.0) with low mobility (LM). Several lines of evidence indicate that the specific esterases seen in the corpus/cauda epididymidis are egasyn-esterases. Firstly, these molecular forms were not seen in the distal epididymal extracts from the egasyn-deficient mouse. Secondly, the HM forms can be immunoprecipitated with anti-egasyn antibody, suggesting the presence of free egasyn. Finally, the LM forms disappeared after heat treatment (56 degrees C for 8 min), a condition known to dissociate egasyn:beta-D-glucuronidase complex. This result indicates that a small amount of egasyn is complexed with beta-D-glucuronidase. Immunoblotting (Western blot) studies (using anti-egasyn antibody) following resolution of egasyn released from the egasyn:beta-D-glucuronidase complex revealed a single band of an apparent molecular weight 64 kDa in the distal (but not proximal) epididymis, indicating that the mouse epididymal egasyn is identical or very similar to the liver egasyn. Castration of mice lead to the appearance of free and complexed egasyn forms in the proximal epididymis. Testosterone supplementation to the castrated mice resulted in the disappearance of the induced egasyn forms from the caput epididymidis. Taken together, these results indicate that the expression of egasyn in the epididymis is region-specific and is differentially regulated by androgens.

Characterization of glycoconjugates in the epididymal epithelium and luminal fluid during postnatal development of the mouse.

The qualitative nature and distribution of glycoproteins in the mouse epididymis during postnatal development was examined by using lectin cytochemical procedures on paraffin sections and lectin blots on electrophoretically separated luminal fluid polypeptides transferred onto nitrocellulose. Histochemical results revealed the presence of glycoproteins with terminal alpha-D-mannose, N-acetyl-D-glucosamine and neuraminic acid in the principal cells along the epididymis during early stages of development (1st week), and glycoproteins containing terminal alpha-L-fucose, N-acetyl-D-galactosamine and alpha-D-galactose in specific regions of the duct during the differentiation state (2nd-3rd week). Lectin staining localized in the Golgi region and at the apical surface increased during development. Specific changes occurred with age and between cell types. Examination of the epididymal luminal fluid glycopeptides by lectin blot analysis revealed the presence of a large number of glycoproteins with various saccharide moieties at 7 days of age. Epididymal differentiation was accompanied either by the disappearance of some glycoproteins (apparent molecular mass: 16, 17.5, 22, 28, 30 and 74 kDa) or the appearance of new glycoproteins in the proximal (23, 13 kDa) and distal regions (29, 20.5, 19 and 14.4 kDa), or along the entire epididymal duct (26 kDa). The main changes occurred in the epididymis of 21-day-old mice and were completed before spermatozoa reached the epididymal lumen.

Histochemistry of oxidative metabolism in epididymal epithelium of mouse.

The activities of cytoplasmic and mitochondrial dehydrogenases were assessed histochemically in the lining epithelia of five segments of the proximal part and the medial and distal parts of the mouse epididymis. The cytochemical evaluation of enzyme activities revealed by nitro BT or tetranitro BT was well supported by the relative transmittance values. In the principal cells of the proximal part, the activities of dehydrogenases differed according to histological segmentation. In the medial and distal parts of the duct, a progressive increase in the intensity of all the reactions was observed. The "goblet cells" with apical nuclei in the proximal part and the "clear cells" in the medial and distal parts showed higher activities than the adjacent principal cells.

[Morphological and histochemical behavior of arterial tissue in normal and spontaneously hypo- or hypercholesterolemic rats on a normal or hyperlipidic diet]. / Comportement morphologique et histochimique du tissu artériel de rats génétiquement normo, hypo et hypercholestérolémiques à l'état normal et après régime hyperlipémiant.

Hypo and hypercholesterolemic rats strains were selected (Lyon) and compared to a normocholesterolemic one issued from the same race (Sprague-Dawley). The arterial tissue of these three strains at three ages (10-19-25 months) and their reactivity to an hyperlipidic diet (2 and 6 month duration) were studied using histological and histochemical technics. There were neither histological nor histochemical differences between the three strains whatever the ages. Therefore, at the present stage of selection, the genetic differences have not changed the arterial metabolism or its evolution during ageing. However the arterial reactivity of hypo and hypercholesterolemic strains towards an hyperlipidic diet was different: indeed both strains developed hypercholesterolemia, liver steatosis and diffuse intimal lipoidosis, but on the other hand the hypercholesterolemic rat alone demonstrated arterial cell proliferation. These data suggest that a same genetic trait can give rise to both a spontaneous hypercholesterolemia and an arterial hyperactivity against a superimposed hyperlipemia.