Fig. 4

Immunohistochemistry for the EP₁ receptor in the colonic muscle layer. Cryostat sections (10 μm thick) of the rat middle colon were stained with rabbit anti-EP₁ receptor and mouse anti-α-smooth muscle actin primary antibodies. EP₁ and α-smooth muscle actin IR were visualized by secondary antibodies conjugated with Alexa594 (a, red) and Alexa488 (b, green), respectively. The nuclei were stained with DAPI (blue). α-smooth muscle actin was used a marker for intestinal smooth muscle. c Merged image of (a) and (b). d Magnified image of the longitudinal muscle in (c). Arrows in (d) indicate EP₁ IR on the nuclei of smooth muscle cells. Bars 10 μm. LM longitudinal muscle, CM circular muscle, mg myenteric ganglion (arrowheads)