Inhibition of heme oxygenase attenuates cGMP concentrations during guanosine enhanced NGF-dependent neurite outgrowth in PC12 cells

<p><b>Copyright information:</b></p><p>Taken from "Guanosine stimulates neurite outgrowth in PC12 cells via activation of heme oxygenase and cyclic GMP"</p><p></p><p>Purinergic Signalling 2005;1(2):161-172.</p><p>Published online Jan 2005</p><p>PMCID:PMC2096532.</p><p></p> PC12 cells were cultured on plates coated with poly--ornithine for 72 h. Cells were then grown in serum-reduced medium (3% heat-inactivated) fetal calf serum and 3% heat-inactivated horse serum) for 12 h, and were treated with guanosine (G, 300 µM) or NGF (N, 40 ng/ml) or guanosine (300 µM) plus NGF (40 ng/ml) (G + N), or with no added treatments (C) as described in Figure . The selective inhibitor of heme oxygenase, zinc protoporphyrin-IX (100 nM), was added to some cultures prior to the addition of guanosine, or NGF, or guanosine plus NGF. Cells were lysed after 12 h and cGMP concentrations were determined by a competitive enzyme immunoassay. Open bars: no zinc protoporphyrin-IX added, closed bars: zinc protoporphyrin-IX added. Statistical analysis was performed using a one-way ANOVA followed by Fischer's LSD post-hoc comparison test (** < 0.01, relative to control); (ΔΔ < 0.01, relative to NGF); (○ < 0.05, relative to treatment without zinc protoporphyrin-IX). Data presented represent the mean relative optical density T SEM obtained in six independent experiments