Quercetin Alleviates Inflammation and Energy Deficiency Induced by Lipopolysaccharide in Chicken Embryos

SIMPLE SUMMARY: Energy deficiency causes multiple organ dysfunctions in the lipopolysaccharide (LPS)-induced model. Quercetin is a flavonoid found in many plants including herbal medicines; nevertheless, the protective effects of quercetin in alleviating LPS-induced energy deficiency remain unclear. In the present study, an in ovo LPS-induced inflammation model was established in chicken embryos. Quercetin attenuated the increase in glycogen and lipid contents in the liver after LPS stimulation when compared with the control group. Quercetin could downregulate the mRNA expressions of AMPKα1 and AMPKα2 in the duodena, ceca, and livers when compared with the LPS group; quercetin decreased the immunoreactivity to AMPKα2 in the duodena and livers. The LPS-induced high mRNA expressions of PPARα and SGLT1 were blocked by quercetin in the duodena, ceca, and livers. Quercetin improved the APOA4 decrease in the duodena, ceca, and livers after LPS induction. Quercetin could downregulate the mRNA expression of PEPT1 in the duodena and ceca increased after LPS challenge. These data demonstrate that quercetin improves the energy deficiency induced by LPS in chicken embryos. ABSTRACT: Energy deficiency causes multiple organ dysfunctions after LPS induction. Quercetin is a phenolic compound found in herbal medicines. However, the effects of quercetin in alleviating LPS-induced energy deficiency remain unclear. In the present study, an in vivo LPS-induced inflammation model was established in chicken embryos. Specific pathogen-free chicken embryos (n = 120) were allocated to control, PBS with or without ethanol, quercetin (10, 20, or 40 nmol, respectively), and LPS (125 ng/egg) with or without quercetin groups. Fifteen day old embryonated eggs were injected with the abovementioned solutions via the allantoic cavity. On embryonic day 19, the tissues of the embryos were collected for histopathological examination using frozen oil red O staining, RNA extraction, real-time quantitative polymerase chain reaction, and immunohistochemical investigations. The glycogen and lipid contents in the liver increased after LPS stimulation as compared with the PBS group, whereas quercetin decreased the accumulation as compared with the LPS group. The mRNA expressions of AMPKα1 and AMPKα2 in the duodena, ceca, and livers were upregulated after LPS induction as compared with the PBS group, while quercetin could downregulate these expressions as compared with the LPS group. The immunopositivity of AMPKα2 in the villus, crypt, lamina propria, tunica muscularis, and myenteric plexus in the duodena and in the cytoplasms of hepatocytes significantly increased after LPS induction when compared with the PBS group (p < 0.01), whereas the immunopositivity to AMPKα2 in the quercetin treatment group significantly decreased when compared with the LPS group (p < 0.01 or p < 0.05). The LPS-induced high expressions of transcription factor PPARα and glucose transporter (SGLT1) were blocked by quercetin in the duodena, ceca, and livers. Quercetin treatment improved the LPS-induced decrease in APOA4 in the duodena, ceca, and livers. The mRNA expression of PEPT1 in the duodena and ceca increased after LPS challenge, whereas quercetin could downregulate PEPT1 gene expression. These data demonstrate that quercetin improved the energy deficiency induced by LPS in chicken embryos. The LPS-induced inflammation model was established to avoid the effect of LPS exposure from the environment and intestinal flora. The results form the basis the administration of quercetin pretreatment (in ovo infection) to improve the energy state of chicken embryos and improve the inflammation response.