Immunohistochemical Assessment of GDNF and Chromogranin A Expression in Erosive and Granulomatous Lesions in Glandular Region of Equine Stomach

The equine stomach consists of two separate non-glandular and glandular sections. Despite the incidence of most lesions in the non-glandular region, both stomach parts are prone to lesions. In this study, 41 hybrid-native horses, including 24 stallions and 17 mares, were examined over five years. In total, 27 horses (65.85%) that were sampled had lesions, including erosion, granuloma, or both on the glandular region of the stomach. Occurrence of gastric erosive and granulomatous lesions had no significant relationship with the age and gender of horses or the sampling season (P>0.05). Moreover, parasites Gastrophilus and Habronema were mainly the primary cause of gastric erosive and granulomatous lesions respectively. In Periodic Acid Schiff (PAS) stained tissue sections, the inflammation severity in granulomatous lesions was higher and statistically significant, compared to erosive lesions (P<0.05). Immunohistochemistry revealed negative expression of glial cell line-derived neurotrophic factor in gastric lesions, while its expression was relatively positive in normal stomachs. Interestingly, based on counting cells and evaluation of expression intensity, Chromogranin A expression in neuroendocrine glandular cells had a significant relationship with the increase of severity and depth of the lesions (P<0.05). The results indicated that the glial cell line-derived neurotrophic factor does not affect the pathogenesis of equine gastric lesions while confirming the role of increment of gastric neuroendocrine cells in lesion progress. Furthermore, the increased expression of Ki67 and p53 proteins in granulomatous lesions, compared to other groups, may be associated with the proliferation and control process of the cells in measures regarding the formation and healing of the lesion.