Heat exposure affects jejunal tight junction remodeling independently of adenosine monophosphate-activated protein kinase in 9-day-old broiler chicks

Abstract

Dysfunction of the intestinal epithelial barrier under elevated temperatures is assumed to prompt pathological conditions and to eventually impede chickens' growth, resulting in massive economic losses in broiler industries. The aims of this research were to determine the impact of acute heat stress on the intestinal tight junction network of broiler chicks (Gallus domesticus L.) and to elucidate whether adenosine monophosphate-activated protein kinase (AMPK) was involved in the integrated response of the broiler's gastrointestinal tract to heat stress. A total of 80 9-day-old Arbor Acres chicks were subjected to temperature treatment (thermoneutral versus heat stress) and AMPK inhibition treatment (5 mg/kg body weight intraperitoneal injection of compound C vs. sham treatment) for 72 h. In addition to monitoring growth performance, the mRNA and protein levels of key tight junction proteins, target components of the AMPK pathway, and biomarkers of intestinal inflammation and oxidative stress were assessed in the jejunum under both stressors at 24 and 72 h. An increase of the major tight junction proteins, claudin-1 and zonula occludens-1, was implemented in response to an exacerbated expression of the AMP-activated protein kinase. Heat stress did not affect zootechnical performance but was confirmed by an increased gene expression of heat shock proteins 70 and 90 as well as heat shock factor-1. In addition, hyperthermia induced significant effects on tight junction proteins, although it was independent of AMPK.

l-Arginine alleviates heat stress-induced intestinal epithelial barrier damage by promoting expression of tight junction proteins via the AMPK pathway

“…To further investigate how l-arginine was involved in the regulation of gene expression and signaling pathways under heat stress, we analyzed the transcriptome in IEC-6 cells of the various groups. Some studies have demonstrated that heat stress leads to the elevation of HSPs [11][12][13]. This study obtained similar results with higher expression levels of HSPs in HS and ARG groups (Fig.…”

“…Dorsomorphin induced a significant increase in HSF-1 after heat stress, reflecting the oxidative stress response in IEC-6 cells and the intestines. This result is in line with a study by Uerlings et al [13]. l-Arginine, which had the same effect as AICAR, markedly elevated the expression levels of HSP70 and HSP90 (Figs.…”

“…Nalli et al [41] reported that AMPK is a negative regulator of MLCK and is responsible for the contractility of intestinal muscles. Uerlings et al [13] also found that AMPK inhibition causes an increase in MLCK gene expression. Therefore, it is conceivable that the MLCK expression level was significantly increased in rat intestines by dorsomorphin treatment following 3 days of heat stress.…”

“…Hao et al, found that heat stress increases HSP70 expression in the small intestine [12]. Uerlings et al demonstrated that gene expression of HSF1, HSP70, and HSP90 is elevated under HS [13].…”

Dietary L-Citrulline supplementation modulates nitric oxide synthesis and anti-oxidant status of laying hens during summer season

“…Under normal conditions, eNOS and iNOS expression were observed in heart tissues of broilers (24), although heat exposure induced increased expressions (25). Also, heat stress induced iNOS protein expression has been related to cardioprotective functions (26,27). These NOS enzymes isoforms actively catalyze the conversion of L-arginine to nitric oxide and L-Citrulline (L-Cit) (23).…”