Leucine Supplementation Alleviates Immune and Antioxidant Function Damage in Adult Rats Induced by Early Weaning

Background: Early weaning (EW) can lead to stress and destroy intestinal integrity. Leucine has functional diversity in antioxidant, immune, and metabolic regulation. Objectives: This study aimed to explore the lifelong impact of EW on intestinal, immune, and antioxidant functions of adult rats and the role of leucine supplementation in the alleviation of the damage caused by EW. Methods: In this 211-d study, 36 Sprague Dawley (SD) rat pups were divided into 3 groups: 21-d weaning normal group, 17-d EW group, and 17-d EW group with 2-mo leucine supplementation. The content of amino acids in serum, immune and antioxidant indexes, intestinal morphology, liver transcriptomics, messenger RNA (mRNA), and protein expression of signaling pathway were determined. Results: EW reduced the protein expression level of secretory immunoglobulin A (IgA) and reduced glutathione (GSH) in the jejunum and increased the protein expression concentrations of IgA, IgM, and interleukin 17 (IL-17) in serum, and tumor necrosis factor alpha and IL-1 beta in the jejunum. The impairment by EW was activated via nuclear transcription factor kappa B (NF-kappa B) signal pathway. In terms of antioxidation, EW reduced the concentration of GSH in the jejunum. After leucine supplementation, the damage induced by EW was partially repaired. Conclusions: EW causes long-term damage to the intestinal barrier function, immunity, apoptosis factor, and antioxidant function in rats and leucine supplementation could alleviate the impairment, suggesting a possible approach to EW.