Of these morphological parameters were slightly smaller in the frogs fasted for 5 months than in the frogs fasted for 3 weeks, there were no striking differences between them (panel d versus panel b in Fig. 1A). The integrity of the intestinal epithelial layer looked similar in all frogs of the three groups at Day 22. Even in the intestine from frogs fasted for 5 months (panel d in Fig. 1A), we could observe no impairment of the intestinal structure. Digesta was still present in the rectum of all frogs even after 5 months of fasting. Immunoblot analysis indicated that the amounts of proliferating cell nuclear antigen (PCNA) in the intestine homogenates from the fasted frogs were less than those from the fed frogs, and that the amounts in the refed frogs recovered to the levels of the fed frogs (Fig. 1B). The histological staining of intestinal alkaline phosphatase activity revealed that a positive signal was localized in the brush border membranes of the intestinal epithelial layer, and that the signal intensity was lower with fasting than with feeding and recovered partially with refeeding (Additional file 1: Figure S1). The concentrations of glucose, triglycerides and free fatty acids in plasma with fasting at Day 22 declined significantly to 44?4 of those with feeding (Table 1). Although the cholesterol concentration of the fasted frogs was 69 of that of the fed frogs, this decline was not significant. The concentrations of these biochemical parameters in the refed frogs at Day 22 were still low but had recovered slightly to 58?0 of those of the fed frogs. In plasma of the frogs fasted for 5 months, the concentrations of these biochemical parameters except for that of glucose were comparable with those of the frogs fasted for 22 days (Table 1). The activities of intestinal alkaline phosphatase, aminopeptidase, glucoamylase and maltase with fasting at Day 22 decreased to 45, 70, 34 and 58 , respectively, of those of the fed frogs (Fig. 2). However, the activity of these enzymes in the refed frogs had returned to those of the fed frogs within 1 day after refeeding.Tamaoki et al. Cell Biosci (2016) 6:Page 3 ofTable 1 Morphological changes of small intestines and biochemical changes of plasma parameters in fed, fasted and refed Xenopus laevisFed group 22 days Fasted group 22 days 5 months Refed group 1 day after 21 days fasting Sample number of group (n) Body weight (g) Start of experiment End of experiment Intestine Wet weight (g) Length (cm) Diameter (mm) Outer diameter of mucosa/submucosa layer (mm) Circumference of epitherial layer (mm) Muscularis externa width (mm) Number of goblet cells/mm Protein content (mg/g wet whight) Number of throughs in a villus-trough unit Total troughs/section Blood Glucose (mg/dL) Triglyceride (mg/dL) Cholesterol (mg/dL) Free fatty acid (mEq/L) 51.10 ?2.74 55.03 ?3.05 0.54 ?0.06a 5.50 ?0.34 2.64 ?0.27 51.39 ?1.32 48.30 ?1.13 53.75 ?3.01 45.75 ?3.10 0.22 ?0.01 52.69 ?1.33 49.65 ?1.94 0.41 ?0.03c 5.21 ?0.32 2.40 ?0.14 8 8 60.28 ?0.01b 4.80 ?0.29 2.21 ?0.5.05 ?0.2.26 ?0.35.01 ?4.26a 0.19 ?0.02 68.12 ?4.21 4.64 ?0.88a19.83 ?1.67b 0.22 ?0.02 55.06 ?13.42 102.8 ?9.1.76 ?0.1.87 ?0.13.88 ?2.18 0.21 ?0.01 48.2 ?3.1.45 ?0.24.52 ?4.22a, b 0.20 ?0.03 49.15 ?9.2.01 ?0.114.5 ?7.Not determined62.25 ?6.23a 44.55 ?4.08a2.77 ?0.43a30.42 ?5.55b 28.38 ?5.35b2.71 ?0.26.11 ?2.68 41.52 ?3.7.97 ?1.43b99.41 ?8.80.96 ?7.45a 31.02 ?3.25b242.19 ?51.82 173.97 ?27.99 0.93 ?0.08aa107.45 PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/26100631 ?14.30 0.49 ?0.Sitravatinib price 05bb120.57 ?16.