Liver growth factor induces testicular regeneration in EDS-treated rats and increases protein levels of class B scavenger receptors.

The aim of the present work was to determine the effects of liver growth factor (LGF) on the regeneration process of rat testes after chemical castration induced by ethane dimethanesulfonate (EDS) by analyzing some of the most relevant proteins involved in cholesterol metabolism, such as hormone sensitive lipase (HSL), 3ß-hydroxysteroid dehydrogenase (3ß-HSD), scavenger receptor SR-BI, and other components of the SR family that could contribute to the recovery of steroidogenesis and spermatogenesis in the testis. Sixty male rats were randomized to nontreated (controls) and LGF-treated, EDS-treated, and EDS + LGF-treated groups. Testes were obtained on days 10 (T1), 21 (T2), and 35 (T3) after EDS treatment, embedded in paraffin, and analyzed by immunohistochemistry and Western blot. LGF improved the recovery of the seminiferous epithelia, the appearance of the mature pattern of Leydig cell interstitial distribution, and the expression of mature SR-BI. Moreover, LGF treatment resulted in partial recovery of HSL expression in Leydig cells and spermatogonia. No changes in serum testosterone were observed in control or LGF-treated rats, but in EDS-castrated animals LGF treatment induced a progressive increase in serum testosterone levels and 3ß-HSD expression. Based on the pivotal role of SR-BI in the uptake of cholesteryl esters from HDL, it is suggested that the observed effects of LGF would facilitate the provision of cholesterol for sperm cell growth and Leydig cell recovery.

In vitro and in vivo characterization of neural stem cells.

Neural stem cells are defined as clonogenic cells with self-renewal capacity and the ability to generate all neural lineages (multipotentiality). Cells with these characteristics have been isolated from the embryonic and adult central nervous system. Under specific conditions, these cells can differentiate into neurons, glia, and non-neural cell types, or proliferate in long-term cultures as cell clusters termed "neurospheres". These cultures represent a useful model for neurodevelopmental studies and a potential cell source for cell replacement therapy. Because no specific markers are available to unequivocally identify neural stem cells, their functional characteristics (self-renewal and multipotentiality) provide the main features for their identification. Here, we review the experimental and ultrastructural studies aimed at identifying the morphological characteristics and the antigenic markers of neural stem cells for their in vitro and in vivo identification.

Immunohistochemical detection of the retinoid acid receptors (RXR-alpha, -beta, -gamma) and Farnesoid X-activated receptor (FXR) in the marbled newt along the annual cycle.

Retinoid acid receptors (RXR-alpha, -beta, -gamma) and Farnesoid X-activated receptor (FXR) expression in the testis of the marbled newt were investigated with special attention to the changes during the annual testicular cycle, using light microscopy immunohistochemistry and Western blot analysis. The annual testicular cycle of the marbled newt (Triturus marmoratus marmoratus) comprises three periods: (a) proliferative period (germ cell proliferation from primordial germ cells to round spermatids, April-June); (b) spermiogenesis period (July-September); and (c) quiescence period (interstitial and follicular cells form the glandular tissue, October-April). In the proliferative period, primordial germ cells and primary spermatogonia immunostained intensely to the three types of RXRs and also to FXR. In the other periods, immunostaining to these antibodies was weak or absent. Secondary spermatogonia stained weakly to the four antibodies in the proliferative period, and only to FXR, also weakly, in the spermiogenesis period. Immunoreactive primary spermatocytes were weakly labeled with the RXR antibodies in the proliferative period. Spermatids and spermatozoa did not stain to any antibody in any period. Follicular cells only immunostained to RXR-gamma and only in the quiescence period when they are forming the glandular tissue, together with the interstitial cells. As follicular cells, interstitial cells only immunostained in the quiescence period; however, they immunoreacted to the three types of RXRs. These findings suggest that in the newt, RXRs and FXR are involved in spermatogenesis control by regulating the proliferation of primordial germ cells and spermatogonia. In addition, RXR-gamma seems to be also involved in the development of the glandular (steroidogenic) tissue.