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Ethanol metabolism in the liver induces oxidative stress and altered cytokine production preceding myofibroblast activation and fibrogenic responses. The purpose of this study was to determine how ethanol affects the fibrogenic response in precision-cut liver slices (PCLS). PCLS were obtained from chow-fed male Wistar rats (200-300 g) and were cultured up to 96 h in medium, 25 mM ethanol, or 25 mM ethanol and 0.5 mM 4-methylpyrazole (4-MP), an inhibitor of ethanol metabolism. Slices from every time point (24, 48, 72, and 96 h) were examined for glntathione (GSH) levels, lipid peroxidation [thiobarbituric acid-reactive substance (TBARS) assay], cytokine production (ELISA and RT-PCR), and myofibroblast activation [immunoblotting and immunohistochemistry for smooth muscle actin (SMA) and collagen]. Treatment of PCLS with 25 mM ethanol induced significant oxidative stress within 24 h, including depletion of cellular GSH and increased lipid peroxidation compared with controls (P < 0.05). Ethanol treatment also elicited a significant and sustained increase in interleukin-6 (IL-6) production (P < 0.05). Importantly, ethanol treatment accelerates a fibrogenic response after 48 h, represented by significant increases in SMA and collagen 1[alpha](I) production (P < 0.05). These ethanol-induced effects were prevented by the addition of 4-MP. Ethanol metabolism induces oxidative stress (GSH depletion and increased lipid peroxidation) and sustained IL-6 expression in rat PCLS. These phenomena precede and coincide with myofibroblast activation, which occurs within 48 h of treatment. These results indicate the PCLS can be used as in vitro model for studying multicellular interactions during the early stages of ethanol-induced liver injury and fibrogenesis. smooth muscle actin; collagen; IL-6; oxidative stress doi: 10.1152/ajpgi.00287.2009.

Animal social systems come in a wide range of forms characterized by different types of group-living relationships. Species that express facultative group-living behaviours, where individuals only associate under certain conditions or at certain times, are especially interesting for studying social evolution. We investigated the social structure of the western black widow spider (Latrodectus hesperus Chamberlin and Ivie, 1935) over 5 years in a coastal British Columbia habitat, and present the first comprehensive evidence of facultative group living in the genus Latrodectus Walckenaer. 1805. Latrodectus hesperus have a flexible social structure that varies seasonally, whereiti individuals (mostly females) either form groups or live solitarily. In the fall and early winter, females spontaneously form groups of 2-8 individuals, but live alone during the oviposition season in the spring and summer. When living in groups spiders share large webs and are tolerant of each other, although they appear to forage individually. We also report on the relationships between different ecological factors and the social structure of L. hesperus, including the interaction of these spiders with two co-occurring species of introduced spiders (Tegenaria agrestis (Walckenaer, 1802) and Tegenaria duellica Simon, 1875). Our findings suggest that L. hesperus is a good model system with which to explore the mechanisms involved in the evolution of sociality. Le regne animal offre une grande diversite d'organisations sociales, chacune presentant differents niveaux de relations entre les membres d'un groupe. Les especes chez qui la vie en groupe est facultative, des groupes ne se formant que sous certaines conditions ou a certaines periodes, sont particulierement propices a l'etude de l'evolution de la socialite. Durant 5 ans nous avons examine la structure sociale de la veuve noire de l'ouest (Latrodectus hesperus Chamberlin et Ivie, 1935) dans un habitat littoral de la Colombie-Britannique, et nous presentons les premieres preuves detaillees de vie en groupe facultative dans le genre Latrodectus Walckenaer, 1805. Latrodectus hesperus a une structure sociale flexible qui varie de facon saisonniere: les individus (en particulier les femelles adultes) vivent soit en groupe, soit seuls. De l'automne au debut de l'hiver les femelles s'associent spontanement en groupes de 2 a 8 individus, mais vivent isolees au printemps et en ete, durant leur periode de ponte. Au sein d'un groupe les araignees partagent une vaste toile et se tolerent mutuellement, mais semblent chasser en solitaires. Nous montrons egalement les relations entre la structure sociale de la veuve noire de l'ouest et differents facteurs ecologiques, y compris leur interaction avec deux especes d'araignees recemment introduites et qui partagent leur habitat (Tegenaria agrestis (Walckenaer, 1802) et Tegenaria duellica Simon, 1875). Notre etude indique que L. hesperus est un bon modele pour explorer les mecanismes lies a l'evolution de la socialite., Introduction Various animals associate with conspecifics to satisfy specific needs (e.g., prey capture, predator protection) that would neither be met by an individual on its own nor achieved as profitably. [...]