Effect of laminarin on the expression of GRP78 and GRP94 in rat after unilateral ureteral obstruction.

Objective: The objective of this study was to determine the effect of laminarin on the expression of kidney endoplasmic reticulum molecular chaperones (GRP78 and GRP94) in rats with renal interstitial fibrosis.

Material and methods: A renal interstitial fibrosis model in rats was developed by unilateral ureteral obstruction (UUO). Rats were randomly divided into control group, model group, enalapril group, laminarin high-dosage group, laminarin median-dosage group and laminarin low-dosage group. The rats were killed 7 days after surgery and blood samples were collected. Serum creatinine (SCr) and blood urea nitrogen (BUN) levels were determined. Renal tubular damage index was determined by hematoxylin and eosin staining. The percentage of areas with renal interstitial fibrosis collagen was determined by the Masson staining method. Expression of kidney tissue endoplasmic reticulum stress (ERS) protein GRP78 and molecular chaperone GRP94 was determined by Western blotting.

Results: Tubulointerstitial injury index, renal interstitial fibrosis, SCr level, BUN level and expressions of GRP78 and GRP94 were significantly different between the model group and treatment groups (p < 0.01). Expressions of GRP78 and GRP94 in rat nephridial tissue was increased (p < 0. 05), tubulointerstitial injury and renal interstitial fibrosis degree were decreased (p < 0.05) and renal function, SCr and BUN were decreased (p < 0.05) compared to those in the laminarin medium-dosage group.

Conclusions: The results demonstrate that UUO activated the reaction of ERS and increased the expression of GRP78 and GRP94 in the early period after laminarin was applied, which helped the refolding, assembling and membrane transportation of denatured proteins. Consequently, the ERS signal transduction pathway was blocked, apoptosis was prevented and the development of renal interstitial fibrosis was reduced.