Nematode-induced jejunal inflammation in the ferret causes long-term changes in excitatory neuromuscular responses

Enteric infections in animals and humans have proven the link between mucos al inflammation and gastrointestinal motor dysfunction. The goal of the pre sent investigation was to study the long-term effects of mucosal inflammati on on the neuromuscular functions of the small intestine in a ferret model of primary Trichinella spiralis infection. Myeloperoxidase activity and iso metric contractions of isolated jejunal muscles were studied on days 8, 30, and 60 postinfection (PI). The peak increase in myeloperoxidase activity s een on day 8 PI returned to normal levels by day 60 Pi. Contractions of the longitudinal and circular muscles evoked by electrical field stimulation o f enteric nerves on day 8 PI showed no difference when compared with uninfe cted controls. However, during this enteric phase of the infection, neurall y mediated responses were characterized by a disturbance in the balance bet ween cholinergic and nonadrenergic, noncholinergic (NANC) excitation with b oth a reduction of cholinergic and a reciprocal enhancement of NANC neurotr ansmission. On days 30 and 60 PI the amplitude of neurally mediated respons es and the balance between cholinergic and NANC excitation were restored in the circular but not in the longitudinal muscle. In addition, there were c hanges in the effector function involving smooth muscle hyperresponsiveness to high K+ or carbachol on days 8, 30, and 60 PI. However, a significant r eduction in EC,, for carbachol was found only on day 60 PI. The results dem onstrate that T. spiralis infection results in alterations of muscle contra ctility and enteric neurotransmission that persist after the resolution of mucosal inflammation.