Background
Polycystic liver disease (PLD) is a hereditary liver disease with progressive enlargement of fluid-filled liver cysts, which causes abdominal discomfort and worsens quality of life. Long-term exercise has beneficial effects in various organs, but the effects of long-term exercise on PLD are unclear. Therefore, the aim of this study was to investigate whether long-term exercise inhibits liver cyst formation and fibrosis.
Methods
Polycystic kidney (PCK) rats, a model of PLD, were randomly divided into a sedentary group and a long-term exercise group, which underwent treadmill running for 12 wk (28 m·min−1, 60 min·d−1, 5 d·wk−1). Sprague–Dawley (SD) rats were set as a control group. After 12 wk, exercise capacity, histology, and signaling cascades of PLD were examined.
Results
Compared with control SD rats, PCK rats showed a low exercise capacity before exercise protocol. After 12 wk, the exercise improved the exercise capacity and ameliorated liver cyst formation and fibrosis. The exercise significantly decreased the number of Ki-67-positive cells; the expression of cystic fibrosis transmembrane conductance regulator, aquaporin 1, transforming growth factor β, and type 1 collagen; and the phosphorylation of extracellular signal–regulated kinase, mammalian target of rapamycin and S6. It also increased the phosphorylation of AMP-activated protein kinase in the liver of PCK rats.
Conclusions
The present results indicated that long-term moderate-intensity exercise ameliorates liver cyst formation and fibrosis with the inhibition of signaling cascades responsible for cellular proliferation and fibrosis in PCK rats.
Background
High‐fructose diet (HFr) induces hypertension and renal damage. However, it has been unknown whether the HFr‐induced hypertension and renal damage are exaggerated in subjects with salt sensitivity. We tested impacts of HFr in Dahl salt‐sensitive (DS) and salt‐resistant (DR) rats.
Methods and Results
Male DS and DR rats were fed control diet or HFr (60% fructose) with normal‐salt content. After 12 weeks, plasma and urinary parameters, renal histological characteristics, and renal expression of renin‐angiotensin system components were examined. Furthermore, effects of renin‐angiotensin system inhibitors were also examined in DS rats fed the HFr. HFr elevated blood pressure in DS rats but not in DR rats. HFr increased urinary albumin and liver type fatty acid binding protein excretions in both rats, but the excretions were exaggerated in DS rats. HFr increased plasma lipids and uric acid in both rats, whereas HFr increased creatinine clearance in DS rats but not DR rats. Although HFr decreased plasma renin activity in DS rats, HFr‐induced glomerular injury, afferent arteriolar thickening, and renal interstitial fibrosis were exaggerated in DS rats. HFr increased renal expression of angiotensinogen, renin, (pro)renin receptor, angiotensin‐converting enzyme, and angiotensin II type 1 receptor in DS rat, whereas HFr increased only angiotensin‐converting enzyme expression and decreased renin and angiotensin II type 1 receptor expressions in DR rats. Enalapril and candesartan attenuated the HFr‐induced hypertension, albuminuria, glomerular hyperfiltration, and renal damage in DS rats.
Conclusion
HFr‐induced hypertension and renal damage are exaggerated in DS rats via renal renin‐angiotensin system activation, which can be controlled by renin‐angiotensin system inhibitors.
Background Polycystic liver disease (PLD) is hereditary liver disease in which the number of cysts increases over time, causing various abdominal symptoms and a poor quality of life. Although effective treatment for PLD has not been established, we recently reported that long-term exercise ameliorated liver cyst formation and fibrosis with activation of AMP-activated protein kinase (AMPK) in polycystic kidney (PCK) rats, a PLD model. Therefore, the aim of this study was to investigate whether metformin, an indirect AMPK activator, was effective in PCK rats. Methods PCK rats were randomly divided into a control (Con) group and a metformin group (Met group). The Met group was treated orally with metformin in drinking water. After 12 weeks, liver function, histology and signaling cascades of PLD were examined in the groups. Results Metformin did not affect body weight or liver weight, but it reduced liver cyst formation, fibrosis and Ki-67-positive cells around the cyst. Metformin increased the phosphorylation of AMPK and decreased the phosphorylation of mammalian target of rapamycin and extracellular signal-regulated kinase and the expression of cystic fibrosis transmembrane conductance regulator, aquaporin I, transforming growth factor-β and type 1 collagen in the liver. Conclusions Metformin slows the development of cyst formation and fibrosis with activation of AMPK and inhibition of signaling cascades responsible for cellular proliferation and fibrosis in the liver of PCK rats.
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