Effect of Adenosine Receptor Antagonists on Adenosine-Pretreated PC12 Cells Exposed to Paraquat.

Previous studies evaluated the adenosine receptor antagonists alone to determine their effects on oxidative stress, but little is known about adenosine's protective efficacy when oxidative injury occurs in vivo. Adenosine is a crucial signaling molecule recognized by four distinct G-protein-coupled receptors (GPCRs) (i.e., A1R, A2AR, A2BR, and A3R) and protects cells against pathological conditions. The present study was performed to evaluate the role of antagonist modulation in the setting of paraquat toxicity with adenosine pretreatment. First, PC12 cells were exposed to paraquat (850 µM) and adenosine (30 µM) to develop an in vitro model for the antagonist effect assay. Second, we found that the A1R antagonist DPCPX enhanced the viability of paraquat-induced PC12 cells that underwent adenosine pretreatment. Moreover, the A2AR antagonist ZM241385 decreased the viability of paraquat-induced PC12 cells that underwent adenosine pretreatment. Our findings indicate that adenosine protection requires a dual blockade of A1R and activation of A2AR to work at its full potential, and the A2B and A3 adenosine receptor antagonists increased paraquat-induced oxidative damage. This represents a novel pharmacological strategy based on A1/A2A interactions and can assist in clarifying the role played by AR antagonists in the treatment of neurodegenerative diseases.

AdoR-1 (Adenosine Receptor) Contributes to Protection against Paraquat-Induced Oxidative Stress in Caenorhabditis elegans.

AdoR-1, the single adenosine receptor homolog in Caenorhabditis elegans, which belongs to the superfamily of G-protein coupled receptors (GPCRs), mediates most of the physiological effects of extracellular adenosine. Adenosine has been proved to improve the survival rate of C. elegans in oxidative stress conditions. However, the potential mechanism of adenosine's protective effect against oxidative stress via AdoR-1 has not been studied. In this study, C. elegans were divided into three groups: two groups with paraquat treatment, one in the presence and one in the absence of adenosine, and an untreated control group. Results indicate that many differentially expressed genes were found to be enriched significantly in neural-related signaling pathways among transcriptome data of three groups. Further gene network analysis showed that some important genes well known to be involved in promoting the acetylcholine release pathway, such as dop-1, egl-30, and unc-13, and those involved in promoting the neuropeptide release pathway, such as kin-1, were upregulated by paraquat induction but downregulated after adenosine treatment. Meanwhile, a completely opposite trend was observed for the goa-1 gene that inhibits the acetylcholine-release and neuropeptide-release pathway. Additionally, some biochemical assays including SOD, GSSG, GSH, and AChE were measured to identify the potential protection of adenosine against oxidative stress between wild-type strain N2 and ador-1 gene knockout strain EG6890. Conclusively, our study revealed series of adenosine receptor-mediated genes in C. elegans that might act as regulators of paraquat-induced oxidative stress and may indicate adenosine's promising protective effects.

Optimization of In Vitro Culture Conditions for Production of Cordyceps bassiana Spores (Ascomycetes) and the Effect of Spore Extracts on the Health of Caenorhabditis elegans.

Cordyceps bassiana, an entomogenous fungus, has been used as a dietary therapeutic in traditional Chinese medicine for several millennia. However, naturally occurring C. bassiana is notably scarce in the field, especially at the spore stage. To date, there are few comprehensive studies on the biological characteristics and pharmacological attributes of C. bassiana spores. In this study, an isolate of C. bassiana (Bs1112) was identified as the teleomorph of Beauveria bassiana using morphology and rDNA internal transcribed spacer sequences. In vitro solid substrate fermentation parameters were evaluated; a rice substrate with 0.01% K+ achieved the maximum spore yield. High-performance liquid chromatography analysis of the bioactive components of C. bassiana spore powder (BC-CBSP), which was extracted using alcohol, showed that concentrations of adenosine were higher than concentrations of inosine, uridine, and cordycepin. The pharmacological impact of BC-CBSP was elucidated in a live animal model, Caenorhabditis elegans, at a range of concentrations from 0.145 to 14.5 mg/mL. The reproductive rate, frequency of head swinging and body bending (indicative of C. elegans locomotion), and lifespan of C. elegans were determined and compared with untreated populations. At the lowest concentration of BC-CBSP, reproduction was slowed but the number of eggs was not reduced. However, at both of the higher concentrations (1.45 and 14.5 mg/mL), BC-CBSP reduced the total number of eggs produced during the 8-day observation period. Furthermore, 0.145 mg/mL of BC-CBSP significantly increased the frequency of head swinging/body bending and the lifespan of C. elegans. This is the first report on the pharmacological effects of C. bassiana spores. Results suggest that low concentrations of BC-CBSP have no negative effects on the reproduction rate of C. elegans but could enhance nervous system activity and extend their lifespan.

The Protective Effect of Adenosine-Preconditioning on Paraquat-Induced Damage in Caenorhabditis elegans.

Adenosine plays an important role in the physiological and pathological conditions of the body by combining different types of adenosine receptors widely distributed in various tissues in the body. In present study, an acute model for paraquat-poisoning in Caenorhabditis elegans was established for quantitative assessment via a time-dose-mortality (TDM) modeling technique with various paraquat doses over 8 hours. Adenosine was first used to precondition at high, medium, and low concentrations and the survival rate of C. elegans was recorded to evaluate adenosine antistress protection against paraquat damage. The results revealed that the TDM model was good for the quantitative assessment of paraquat-poisoning on C. elegans based on the Hosmer-Lemeshow test for homogeneity of modeling (P = .38). The survival rates of adenosine-preconditioned C. elegans have a dose-dependent association with adenosine concentration. At 3000 µM (high concentration) and 300 µM (medium concentration), adenosine-preconditioned C. elegans still had survival rates of 5.38% ± 1.68% and 5.0% ± 1.19% in the subsequent 8 hours observation period. On the contrary, the survival rates of those receiving 30 µM (low concentration) and the 0 µM (unpreconditioned treatment) were zero. To conclude, adenosine preconditioning had protective effects on C. elegans intoxicated with paraquat by decreasing its mortality rate.