External perturbation manifested system size resonance in a mesoscopic hormone signaling model

In mesoscopic reaction systems that contain only finite number of reactants, molecular fluctuation (or the so called internal noise), which can be characterized by the system size, plays an important role in nonlinear systems. In this work, the effect of internal noise is studied in a mesoscopic hormone signaling model with the presence of external perturbations (noise or signal). Simulation results reveal that the internal noise can play a constructive role to optimize the regularity of the noise induced internal signal only when external perturbation is present. This is a novel external perturbations induced system size resonance, which indicates that in complex mesoscopic systems, the system can automatically avoid the destructive environmental effects by tuning its size. Such kind of nontrivial cooperative effect may attribute to the fact that external perturbations broadened the regulation scope of the key mutual feedback. Therefore, current finding is of practical significance for similar physiological systems where the intercellular regulation plays the dominate role for signaling.