Studies of persistent infection by Chlamydia trachomatis serovar K in TPA-differentiated U937 cells and the role of IFN-gamma

To investigate the effects of adenosine A1 receptor activation on energy metabolism and RNA and protein biosynthesis in central neurons, cultured neurons from the rat forebrain were exposed for 1 hr to 72 hr to various concentrations (10 nM-100 microM) of the selective A1 receptor agonist 2-chloro-N6-cyclopentyladenosine (CCPA) or the A1 receptor antagonist 8-cyclopentyltheophylline (CPT). At all concentrations tested, the adenosinergic compounds did not affect cell viability within 72 hr of treatment, except for CPT, which reduced viability by 19.7% when used at the concentration of 100 microM. Energy metabolism was analysed by studying the specific uptake of 2-D-3H]deoxyglucose (3H]2DG). Rates of RNA and protein biosynthesis were assessed by the measurement of 3H]uridine and 3H]leucine incorporation, respectively. Neuronal 3H]2DG uptake was increased by 16% (P < 0.01) after 8 hr in the presence of 100 microM CCPA, whereas 100 microM CPT for 24 hr also increased 3H]2DG uptake (8%, P < 0.01). At these concentrations, both ligands inhibited 3H]uridine incorporation after a 3-hr treatment by 92% and 30%, respectively. CCPA never altered 3H]leucine incorporation when compared to controls, and CPT significantly inhibited protein synthesis only at 10-100 microM. Additional experiments to analyse the influence of A1 ligands on the transport of 3H]2DG, 3H]leucine and 3H]uridine suggested that CCPA and CPT, which interact functionally with adenosine receptors by regulating cyclic AMP production in this model, are able to alter energy metabolism and RNA synthesis in central neurons in a nonspecific manner by interacting with glucose and uridine transporters.