Investigating the Dichotomous Nature of Nitric Oxide During the Enteral Phase of Trichinella spiralis Infection in Mice: An Experimental Study

The exact role of nitric oxide (NO) in the complex interplay between the host and Trichinella spiralis (T. spiralis) parasite remains uncovered. While much has been revealed about the role of the inducible isoenzyme (iNOS) in different parasitic infections, research is slowly progressing toward understanding the neuronal enzyme (nNOS)-derived impacts on trichinosis. This study aims to clarify the dual nature of (NO) during the enteral phase of experimental trichinosis by examining the participation of both iNOS and nNOS in T. spiralis-infected mice. The experimental design included 48 male Swiss albino mice divided into six groups: (G1) negative control, (G2) infected control, (G3) infected–Albendazole-treated, (G4) infected-infected–L-arginine-treated, (G5) infected–Aminoguanidine-treated, and (G6) infected–7-Nitroindazole-treated. On the seventh day post-infection, the study groups underwent parasitological (adult worm count), histopathological, immunohistochemical, and biochemical assessments. Our results showed that (nNOS) predominance during the enteral phase of trichinosis enhanced parasitic clearance. Conversely, NO produced by iNOS was not essential for worm expulsion but contributed to T. spiralis-mediated enteropathy. Nitric oxide seems to play a puzzling role in T. spiralis infection. While (iNOS) is known for eliminating numerous infections, this is the first example we are aware of where the activity of the neuronal isoform (nNOS) is required in trichinosis.