Effects of Inflammation and Axotomy on Expression of Acetylcholine Transferase and Nitric Oxide Synthetase within the Cocaine- and Amphetamine-regulated Transcript-immunoreactive Neurons of the Porcine Descending Colon

This study reports changes in expression of acetylcholine transferase (AChT) and nitric oxide synthetase (NOS) in neurons immunoreactive for cocaine- and amphetamine-regulated transcript (CART) peptides during chemically-driven inflammation and axotomy in the porcine descending colon. The co-localization of the neurotransmitters with CART was studied by double immunofluorescence in the myenteric plexus (MP) and outer submucosal plexus (OSP) of the porcine descending colon under physiological and selected pathological conditions. In control animals, neurons expressing CART also expressed AChT in 25.37 ± 0.98% and 26.73 ± 0.96% in the MP and OSP, respectively. Neuronal co-expression of CART with NOS occurred in 90.66 ± 2.13% and 88.09 ± 2.96% in the MP and OSP, respectively. Following axotomy the number of neurons co-expressing CART and AChT decreased to 16.50 ± 3.20% in the MP and increased to 35.49 ± 2.04% in the OSP, while the number of neurons co-expressing CART and NOS increased to 96.66 ± 2.38% in the MP and 97.46 ± 2.22% in the OSP. Experimentally-induced colitis resulted in an increase in the number of neurons co-expressing CART and AChT to 42.40 ± 2.28% in the MP and 63.62 ± 1.83% in the OSP. Similarly, in these animals the number of neurons co-expressing CART and NOS increased to 93.9 ± 2.58% in the MP and 90.43 ± 2.09% in the OSP. Sham-operated controls showed expression levels of 26.22 ± 0.66% (MP) and 27.02 ± 1.73% (OSP) for simultaneous CART and AChT expression and 94.18 ± 0.93% (MP) and 88.21 ± 0.81% (OSP) for CART and NOS co-localization. These data confirm that the examined neurotransmitters have a role in traumatic and inflammatory responses of enteric neurons.