Exposure to heat stress alters the structural integrity of the enteric nervous system in the broiler chicken ileum

Authors: CAPUTI, VALENTINA - University Of Arkansas; Robinson, Kelsy; ARSI, KOMALA - University Of Arkansas; Donoghue, Ann; Lyte, Joshua

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/28/2022
Publication Date: 7/11/2022
Citation: Caputi, V., Robinson, K., Arsi, K., Donoghue, A.M., Lyte, J.M. 2022. Exposure to heat stress alters the structural integrity of the enteric nervous system in the broiler chicken ileum. Meeting Abstract.

Interpretive Summary:

Technical Abstract: Heat stress (HS) in broiler chickens severely affects their gastrointestinal (GI) tract, increasing intestinal permeability and inflammation, and favoring the colonization of bacterial foodborne pathogens. The enteric nervous system (ENS) is the intrinsic innervation of the GI tract, and plays a fundamental role in regulating secretion, absorption, and motility, as well as host immune surveillance against pathogenic bacteria. The effect of HS on broiler chicken ENS integrity is unknown, and this represents a novel research approach for reducing foodborne pathogens in poultry through the investigation of the neurobiological mechanisms of stress-induced perturbations of gut health. Therefore, the present study evaluates whether HS determines structural alterations in broiler chicken ENS. Experimental design: Male broiler chicks were randomly divided into control or HS groups, placed in pens and kept under standard environmental conditions. At 6 weeks of age, a 12-h daily cyclic HS (35°C) was applied for either 1 day or 6 consecutive days to the HS group, whereas control chickens were maintained under standard age-appropriate conditions. Birds were euthanized following either 1 day or 6 days of HS. Birds from the control group were sacrificed on the same days and age as those from the HS group. Methods: The distribution of HuC/D (pan-neuronal marker) and neuronal nitric oxide synthase (nNOS; nitrergic neurons marker) was assessed in ileum wholemount preparations (N=6 birds/group) by performing tissue clearing and double-labelling confocal immunofluorescence. The integrity of glial fibrillary acidic protein (GFAP; enteric glial marker) and ionized calcium binding adaptor molecule 1 (Iba1; enteric muscular macrophages marker) was determined by confocal microscopy in ileal frozen sections. Statement of statistical analyses: Data were analyzed using two-tailed unpaired Student’s t test with Welch’s correction. Results: HS caused a marked distortion of the dendritic and axonal processes of nNOS-containing neurons with no changes in the number of HuC/D+ neuronal cells in the myenteric ganglia of broiler chickens exposed to HS for 1 or 6 days. In the neuromuscular compartment of 1-day HS chickens the density of GFAP+ processes was significantly increased (p<0.05), and these changes persisted after 6 days of HS. The immunoreactivity of Iba-1 was not affected by HS in chicken ileum. Conclusions: HS caused structural alterations of enteric neurons and glial cells in the broiler chicken ileum. These findings warrant future studies aimed at identifying ENS-related biomarkers of stress-induced susceptibility to intestinal inflammation and foodborne pathogen colonization in poultry.