Influence of Best Available Technique (BAT) farming systems on the enteric nervous system (ENS) of fattening pigs’ ileum

The enteric nervous system (ENS) is part of the autonomic nervous system and consists of two types of intramural ganglia1: 1) the muscular ganglia (MG) which create the myenteric plexus (MP) between the circular and longitudinal muscular fibers in the muscular layer of the intestine; 2) the submucous ganglia (SG) located in the submucosal layer forming the submucous plexus (SP)2. These neuronal cells are involved in the regulation of a large variety of gastrointestinal tract functions, both from a physiological point of view and in terms of adaptive responses to systemic and gastrointestinal disorders and to the impact of harmful substances 3–7. Given these premises, the aim of this study was to evaluate whether two different farming systems (Best Available Techniques (BAT)- system vs not-BAT system) act differently on the enteric nervous system. To do this, six pig enteric traits per group (experimental group (EG) vs control group (CG) reared in non-BAT and BAT systems respectively) were collected at the slaughterhouse (University Ethical approval: OPBA 58_2016). Through histological and immunofluorescence analysis, we evaluated the number of neurons, the number of plexuses and the ratio between the area of the plexuses and the area of the section, as well as the thickness of the mucous layer that covers the intestinal epithelium. In EG, both the number of neurons and the number of plexuses increased in the muscular and in the submucosal layers. The area occupied by neuronal cells, evaluated thought Protein Gene Product 9.5 (PGP9.5), increased in SP but did not have any significant variation in MP. The area occupied by glial-like cells, evaluated through Glial Fibrillary Acidic Protein (GFAP), increased both in the SP and in MP. There was no significant change in mucus secretion in the two experimental groups. These data suggest that pigs reared in no BAT solutions during perinatal life exhibit increased vulnerability to ENS. Moreover, these findings mimic some of the pathophysiologic findings in human gut disorders, thus suggesting that the pig could be a valuable sentinel for human environmental exposure. [1] Makowska K, Gonkowski S. Bisphenol A (BPA) Affects the Enteric Nervous System in the Porcine Stomach, Animals, 10(12):2445, 2020. [2] Makowska K, Obremski K, Gonkowski S. The impact of T-2 toxin on vasoactive intestinal polypeptide-like immunoreactive (VIP-LI) nerve structures in the wall of the porcine stomach and duodenum, Toxins (Basel), 10(4), 2018. [3] Szymanska K, Makowska K, Gonkowski S. The influence of high and low doses of bisphenol a (BPA) on the enteric nervous system of the porcine ileum, International Journal of Molecular Sciences, 19(3), 2018. [4] Furness JB. The enteric nervous system and neurogastroenterology, Nature Reviews Gastroenterology & Hepatology, 9(5):286-294, 2012. [5] Furness JB et al. The enteric nervous system and gastrointestinal innervation: Integrated local and central control, Advances in Experimental Medicine and Biology, 817:39-71, 2014. [6] Palus K, Całka J. Influence of acrylamide administration on the neurochemical characteristics of enteric nervous system (ENS) neurons in the porcine duodenum. International Journal of Molecular Sciences, 21(1), 2020. [7] Vasina V et al. Enteric neuroplasticity evoked by inflammation, Autonomic Neuroscience: Basic and Clinical, 126-127:264-272, 2006.