ABSTRACT
Gap junctions mediate direct communication between cells; however, toxicological cascade triggered by nonessential metals can abrogate cellular signaling mediated by gap junctions. Although cadmium (Cd) is known to induce apoptosis in organs and tissues, the mechanisms that underlie gap junction activity in Cd-induced apoptosis in BRL 3A rat liver cells has yet to be established. In this study, we showed that Cd treatment decreased the cell index (a measure of cellular electrical impedance) in BRL 3A cells. Mechanistically, we found that Cd exposure decreased expression of connexin 43 (Cx43), increased expression of p-Cx43 and elevated intracellular free Ca2+ concentration, corresponding to a decrease in gap junctional intercellular communication. Gap junction blockage pretreatment with 18β-glycyrrhizic acid (GA) promoted Cd-induced apoptosis, involving changes in expression of Bax, Bcl-2, caspase-3 and the mitochondrial transmembrane electrical potential (Δψm). Additionally, GA was found to enhance ERK and p38 activation during Cd-induced activation of mitogen-activated protein kinases, but had no significant effect on JNK activation. Our results indicated the apoptosis-related proteins and the ERK and p38 signaling pathways may participate in gap junction blockage promoting Cd-induced apoptosis in BRL 3A cells.
Subject(s)
Animals , Rats , Apoptosis/drug effects , Cadmium/toxicity , Calcium/metabolism , Cell Communication/drug effects , Connexin 43/genetics , Enzyme Activation/drug effects , Gap Junctions/drug effects , Gene Expression Regulation/drug effects , Hepatocytes/cytology , Signal Transduction/drug effectsABSTRACT
Objective_To study the effect of human insulin on cell cycle progression and apoptosis of rat liver cell line BRL-3A in vitro.Methods_MTT method was used to observe the effect of insulin on cell activity, and flow cytometry was used to detect cell apoptosis and cell cycle.qRT-PCR was used to evaluate the expression of related genes.Results_Human insulin induced the proliferation of BRL-3A cells in a dose-dependent manner ( P<0.05 or P<0.01);After 3 days treated by human insulin (500 nmol/L), the proportion of cells in G0/G1 phases re-markably decreased (P<0.05).Moreover, pro-apoptotic BAX was down-regulated (P<0.05), while cell prolif-eration-related gene CCNA2 was up-regulated (P<0.05).Conclusions_Human insulin may inhibit the apoptosis of BRL-3 A cell line and induce proliferation due to the down-regulated expression of BAX and up-regulated expres-sion of CCNA2 .
ABSTRACT
The aim of the present study was to determine the preventive effects of the polysaccharide of Larimichthys crocea swim bladder (PLCSB) on CCl4-induced hepatic damage in ICR mice. The in vitro preventive effects of PLCSB on CCl4-induced liver cytotoxic effect were evaluated in BRL 3A rat liver cells using the MTT assay. The serum levels of AST, ALT, and LDH in mice were determined using commercially available kits. The levels of IL-6, IL-12, TNF-α, and IFN-γ were determined using ELISA kits. The pathological analysis of hepatic tissues was performed with H and E staining, and the gene and protein expressions were determined by RT-PCR and Western blotting, respectively. PLCSB (20 μg·mL(-1)) could increase the growth of BRL 3A rat liver cells treated with CCl4. The serum levels of AST, ALT, and LDH were significantly decreased when the mice were treated with two doses of PLCSB, compared with the control mice (P < 0.05). PLCSB-treated groups also showed reduced levels of the serum pro-inflammatory cytokines IL-6, IL-12, TNF-α, and IFN-γ. PLCSB could decrease the liver weight, compared to the CCl4-treated control mice. The histopathology sections of liver tissues in the 100 mg·kg(-1) PLCSB group indicated that the animals were recovered well from CCl4 damage, but the 50 mg·kg(-1) PLCSB group showed necrosis to a more serious extent. The 100 mg·kg(-1) PLCSB group showed significantly decreased mRNA and protein expression levels of NF-κB, iNOS, and COX-2, and increased expression of IκB-α compared with the CCl4-treated control group. In conclusion, PLCSB prevented from CCl4-induced hepatic damage in vivo.