c-Fos immunohistochemical staining in periaqueductal grey. Photomicrographs and quantification of immunohistochemical staining for c-Fos in periaqueductal grey (PAG) (week 10). A. Few stained nuclei are evident in naïve rat. B. Significantly more c-Fos labeled nuclei are evident in animals with diet-induced pancreatitis and application of vehicle, or (C) in animals with diet-induced pancreatitis and application of HSV-β-gal. D. Little or no staining for c-Fos is evident in animals given the diet and application of HSV-ENK.