DAO and obesity due to melanocortin 4 receptor deficiency: A number of obesity- and gut epithelial barrier integrity-related parameters were recorded at eighth week, including the weights of epididymis fat and the liver (Figure 4c), H & E staining of epididymis fat (Figure 4d), adipocyte size of epididymis fat (Figure 4e), liver morphology (Figure 4f), fasting blood glucose and insulin (Figure 4g,h), serum levels of GLP-2, diamine oxidase (DAO), and D-lactate (Figure 4i-k), H&E and AB-PAS stainings of intestinal tissue sections (Figure 4l,m).