Are Saunas Beneficial or Harmful for Autosomal Dominant Polycystic Kidney Disease? Examination with Model Mouse / 日本温泉気候物理医学会雑誌

ABSTRACT

  Background: Heat shock proteins (Hsps), expression of which are induced by thermal treatment, function in the protection of kidneys by suppressing apoptosis and maintaining renal tubular viability. Moreover, recently, it has been indicated that the expression of Hsps can be a therapeutic target for autosomal dominant polycystic kidney disease (ADPKD). We investigated the effect of dry sauna therapy on ADPKD model mice.  Methods and Results: The mice (male DBA/2FG-pcy mice) were categorized into three groups controls, TS pcy mice subjected to prolonged sauna with administered water containing 4% sucrose, SW pcy mice administered water containing 4% sucrose. The TS group was subjected to sauna sessions twice a week for four weeks. The TS group attained and were maintained at rectal temperatures of approximately 39.0°C, until they were carefully removed from the far infrared-ray device. After 4 weeks of sauna treatment, creatinine and blood-urea-nitrogen (BUN) levels determined by an enzymatic method. The heat shock protein (HSP) or cell growth and size related proteins were analyzed by western blotting. The TS group exhibited marginally higher creatinine and BUN levels than did the control and SW groups, however, the differences were not significant. However, cyst enlargement in the TS group reduced significantly compared to that of the control group. HSP90 expression was slightly decreased in the TS and SW groups relative to the control group (p < 0.01 or p < 0.001, vs. control), as was Erk expression, which is linked to cyst development and proliferation (p < 0.05, TS vs. control). Hsp27 expression and phosphorylation level in the SW group were comparable with that of the control group. However, the TS group had increased levels of Hsp27 and phosphorylation (NS). The expression of pro-caspase-3 in the TS group was marginally lower than that in the control group. However, the activity of caspase-3 in all groups showed no differences.  Conclusion: The findings of this study indicated that 4 weeks of sauna treatment could cause transient dehydration and related renal dysfunction and led to the risk of stimulating cyst growth by increased Hsp27 expression. Moreover, we concluded that prevention of dehydration and cyst growth could be suppressed by taking an appropriate amount of water directly after sauna treatment.