Changes in Cocaine- and Amphetamine-Regulated Transcript-Like Immunoreactive (CART-LI) Nerve Structures of the Porcine Descending Colon During Proliferative Enteropathy

The distribution pattern of CART- like immunoreactive (CART-LI) nerve structures was studied by a double immunofluorescence technique in the circular muscle layer, myenteric (MP), outer submucous (OSP), and inner submucous plexuses (ISP), as well as in the mucosal layer of porcine descending colon under physiological conditions and during proliferative enteropathy (PE). In control animals, CART-LI perikarya have been shown to constitute 3.18 ±0.51%, 3.44 ±0.6%, and 3.33 ±0.72% in MP, OSP, and ISP, respectively. PE caused a decrease in the number of CART - LI neurons in MP and ISP. In OSP, the observed changes were not statistically significant. During PE, the number of CART-LI perikarya amounted to 2.18 ±0.27%, 3.07 ±0.06%, and 0.07 ±0.02% within MP, OSP, and ISP, respectively. Moreover, PE caused an increase in the number of CART-LI nerve fibers in the colonic circular muscle and mucosal layers as well as in MP. This study describes for the first time changes in CART-LI nerve structures of the porcine descending colon during Lawsonia intracellularis infection, and suggests the participation of this neuropeptide in the regulation of gut functions, not only under physiological conditions, but also during pathological processes.