The Effects Of Neuropeptide S Microinjected Into Substantia Nigra On The Locomotor Activity Of Mice

Neuropeptide S (NPS), a bioactive peptide identified in2002, was reported to be involved in regulating arousal, anxiety, locomotion, learning and memory. It is reported that NPSR protein has some expression in basal ganglia of rats which plays a crucial role in the regulation of locomotion. Here, we first performed immunohistochemical analysis in the basal ganglia of the mouse brain using polyclonal anti-NPSR antibodies. The result shows that NPSR protein of mouse was identified in the substantia nigra, subthalamic nucleus and globus pallidus. Then, we confirmed that the microinjections of NPS in lateral globus pallidus and substantia nigra could significantly and dose-dependently increase the locomotor activity of mice in open field. SHA68, a selective NPS receptor antagonist, exerts functionally opposing respouses, indicating that endogenous NPS is involved in the regulation of locomotor. We also found that the CRF1receptor antagonist (antalarmin) could counteract the stimulant effects elicited by NPS. Finally, we observed the expression of c-fos protein in the mouse brain after the microinjection of NPS in substantia nigra. The result suggests that the expression of c-fos in the substantia nigra was significantly increased. In conclusion, these results indicated that NPS may promote the locomotor activity witch may be mediated by CRF1system by regulating the activity of the basal ganglia through NPS-NPSR system.