Central adenosine A1 and A2A receptors mediate the antinociceptive effects of neuropeptide S in the mouse formalin test

The above findings suggest that: (i) NPS evokes central antinociceptive effects by activating both A1 and A2A receptors during phase 1, but (ii) only the adenosine A2A receptor during phase 2 of the formalin test.