PDE inhibition by different compounds increases low-intensity light-induced phase advances and accelerates circadian reentrainment.

<p>A) and B) 50 lux light pulses at CT18 induced a phase advance that was significantly increased by sildenafil, vardenafil or taladafil as compared to vehicle-treated animals. Representative actograms in panel A show vehicle or drug treated-animals; time of injection and LP are indicated by a star and the grey bar shows locomotor activity onsets. Panel B shows the average results, ANOVA-p<0.001- followed by Tukey's Test **p<0,0025. C) Representative actograms showing reentrainment to a 6 h phase advance of the LD cycle for vehicle or drug-treated animals; dark phases are indicated by gray shading and a black bar depicts the transient days until the new phase. Grey horizontal bars indicate computer malfunction. D) Animals injected with PDEs inhibitors entrained significantly faster to a 6-hr advance of the LD cycle than those injected with vehicle. N = 6 per group. ANOVA-P = 0.0011- followed by Tukey's Test *P<0.05, **p<0.0025. All data represented as mean (± SD).