Abstract
The aim of the present study was to investigate the effect of streptozotocin-induced
diabetes mellitus and lipoic acid treatment on serum paraoxonase-1 and paraoxonase-3
protein levels and paraoxonase, arylesterase and lactonase activities.
36 rats were equally and randomly divided into 4 groups as control, lipoic acid, diabetes
and diabetes+lipoic acid. To induce diabetes, a single dose of streptozotocin (40 mg/kg)
was injected intraperitoneally to diabetes and diabetes+lipoic acid groups. Lipoic
acid (10 mg/kg/day) was injected intraperitoneally for 14 days to lipoic acid and
diabetes+lipoic acid groups. Serum PON1 and PON3 protein levels were measured by western
blotting. Serum paraoxonase, arylesterase and lactonase activities were determined
by the measuring initial rate of substrate (paraoxon, phenylacetate and dihydrocoumarin)
hydrolysis.
Streptozotocin-induced diabetes mellitus caused a significant decrease whereas lipoic
acid treatment caused a significant increase in serum PON1 and PON3 protein levels
and paraoxonase, arylesterase and lactonase activities. The increase percent of serum
PON3 protein was higher than that of serum PON1 protein and the increase percent of
serum lactonase activity was higher than that of serum paraoxonase and arylesterase
activities in diabetes+lipoic acid group.
We can report that, like PON1 protein, PON3 protein and actually its lactonase activity
may also have a role as an antioxidant in diabetes mellitus and lipoic acid treatment
may be useful for the prevention of the atherosclerotic complications of diabetes
by increasing serum PON1 and PON3 protein levels and serum enzyme activities.
Key words
streptozotocin-induced diabetes mellitus - lipoic acid - paraoxonase 1 - paraoxonase
3 - arylesterase - lactonase