Hyperammonemia leads to intestinal barrier function impairment and gut microbiota dysbiosis associated with PERK signaling pathway-induced endoplasmic reticulum stress

Background/Objective: L-Ornithine L-aspartate (LOLA) can effectively alleviate hepatic encephalopathy by reducing blood ammonia levels. Recent studies have shown that amino acids can affect via the gut‒liver axis has a significant effect on the progression of various liver diseases, but the effects of LOLA on the intestine have not been reported. Methods Rats were given intraperitoneal injections of 0.5% N‒E dimethylnitrosamine (DMN) at 10 mg/kg while being simultaneously administered LOLA (1000 mg/kg) via gavage three times per week for 4 weeks, after which the animals were euthanized. Serum was collected to assess liver function. Rat feces were collected for 16S rRNA sequencing of the microbiota, and biochemical and histological evaluations of ileal damage were performed.The expression of tight junction proteins (ZO-1), lysozyme (Lyz), and endoplasmic reticulum stress (ER) pathway-related markers were detected in the rat ileal epithelium. Results LOLA gavage did not significantly restore gut microbiota diversity or the abundance of dominant intestinal bacteria such as Prevotella, but it significantly reduced the abundance of harmful bacteria such as Clostridium. Additionally, LOLA gavage increased ZO-1 expression in the rat small intestinal mucosa, reduced plasma DAO and LPS levels, and restored Lyz secretion. Furthermore, the expression of ER stress pathway-related markers (BIP, p-PERK, p-eIF2a, ATF4, and CHOP) decreased after LOLA gavage. Conclusion LOLA may ameliorate gut microbiota dysbiosis in cirrhotic rats by affecting the ER stress response and restoring intestinal barrier function, revealing a new mechanism by which LOLA controls liver disease.