A preliminary therapeutic study of the effects of molecular hydrogen on intestinal dysbiosis and small intestinal injury in high-fat diet-loaded senescence-accelerated mice

OBJECTIVES

Aging and excessive fat intake may additively induce dysbiosis of the gut microbiota and intestinal inflammatory damage. Here, we analyzed microbiota dysbiosis and intestinal injury in high-fat diet-loaded senescence-accelerated mice (SAMP8). Additionally, we examined whether treatment with molecular hydrogen could improve the intestinal environment.

METHODS

SAMP8 and SAMR1 (control) mice were first fed a normal diet (ND) or high-fat diet (HFD) for 10 wk (n = 10 each group). Subsequently, HFD was supplemented with a placebo jelly or hydrogen-rich jelly (HRJ) for 4 wk. After treatment, isolated small intestinal tissues were used for hematoxylin and eosin staining, immunofluorescence staining, and thiobarbituric acid reactive substances (TBARS) assay. Furthermore, we analyzed alterations in the microbiota composition in cecal feces using 16S rRNA gene analysis for microbiota profiling. Statistical analyses were performed using unpaired Student's t tests or one-way analysis of variance and Tukey's post hoc test for multiple comparisons.

RESULT

HFD feeding reduced the expression of caudal-related homeobox transcription factor 2 (CDX2) and 5-bromo-2'-deoxyuridine (BrdU) and enhanced malondialdehyde (MDA) levels in the small intestine of SAMP8. HRJ treatment improved the reduction in CDX2 and BrdU and enhanced MDA levels. We performed a sequence analysis of the gut microbiota at the genus level and identified 283 different bacterial genera from the 30 samples analyzed in the study. Among them, Parvibacter positively correlated with both HFD intake and aging, whereas 10 bacteria, including Anaerofustis, Anaerosporobacter, Butyricicoccus, and Ruminococcus were negatively correlated with both HFD and aging. HRJ treatment increased Lactinobactor and decreased Akkermansia, Gracilibacter, and Marvinbryantia abundance.

CONCLUSION

Our findings suggest that treatment with molecular hydrogen may affect microbiota profiling and suppress intestinal injury in HFD-loaded SAMP8.

Npr2 mutant mice show vasodilation and undeveloped adipocytes in mesentery

Objective

The biological importance for the signaling of C-type natriuretic peptide (CNP) and natriuretic peptide receptor B (NPR-B) has been recognized. However, the details remain unclear and are debatable. The Npr2 is a gene of NPR-B, and we previously reported a unique phenotype of a spontaneous mutant mouse lacking Npr2 (Npr2^slw/slw), such as severe ileus-like disorder with bloodless blood vessels. In this study, we analyzed the bloodless mesenteric vascular morphology of Npr2^slw/slw by histological observation to clarify the effects of the CNP/NPR-B signal deficiency.

Results

Blood vessels in the mesentery were clearly dilated in the preweaning Npr2^slw/slw mice. Additionally, in the Npr2^slw/slw mice, the lacteals were partially dilation or randomly direction mucosal epithelial cells in villi, and mesenteric adipocytes were undeveloped. These findings provide important information for understanding the role of CNP/NPR-B signals on intestine with mesentery.