Lysosome dysfunction alters intestinal morphology and lipid metabolism in early neonatal piglets

Neonatal piglets possess lysosome-rich foetal-type enterocytes that facilitate uptake and intracellular processing of maternally provided nutrients. However, the role of lysosomes in early-life growth and intestinal maturation remains unclear. Therefore, this study was conducted to determine the role of lysosomes in the development of neonatal intestine in piglets. For 1-day-old neonatal piglets, a total of 12 piglets (Duroc × (Landrace × Large Yorkshire)) were divided into 2 groups using a split-litter design. To initiate malfunction in lysosomes, newborn piglets were subjected to oral gavage with imipramine (25 mg/kg bodyweight) once daily for 7 days. For 21-day-old piglets, a total of 12 piglets were divided into two groups, and each group received the same treatment as described above.

Piglets receiving imipramine demonstrated significantly stunted growth at 7 days of age, but not at 27 days. By postnatal day 7, the foetal-type enterocytes of untreated piglets were restricted in the mid to upper ileal villus and contained several large lysosomal vacuoles. In contrast, marked changes in ileal morphological and histological structure were observed following imipramine treatment, as evidenced by reduced degree of vacuolation, decreased lysosomal count, as well as pronounced mitochondrial swelling; however, no vacuolated enterocytes were found in 27-day-old piglets. Furthermore, signaling pathways associated with lipid transport and metabolism were significantly enriched, and the related hub genes were identified by bioinformatic analysis after imipramine administration. These findings were further confirmed by biochemical analysis demonstrating that serum levels of total cholesterol (TC) and apolipoprotein A1 (ApoA1) were significantly increased while serum ApoB was decreased in 7-day-old piglets receiving imipramine treatment. Additionally, there was an opposite trend in levels of ApoA1and ApoB in ileal mucosa compared to serum.

These results demonstrate that lysosome dysfunction induced by imipramine resulted in significant growth retardation, pronounced morphological and ultrastructural alterations in ileal enterocytes, along with disrupted lipid metabolism in early postnatal piglets; however, no such effect was observed in 27-day-old piglets. These findings enhance understanding of lysosomal functions and intestinal maturation in neonatal piglets.