First Author: M.Nagaya JAPAN
Co Author(s): H. Kaneko A. Suzumura H. Terasaki
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Various effects such as anti-inflammatory and cytoprotective effect by omega-3 fatty acids have recently been reported, and therapeutic effects against diabetic complications are also expected. Therefore we produced diabetic rats by Streptozotocin (STZ) and examined the effects of omega-3 fatty acid: eicosapentaenoic acid (EPA) on retinal disorders and complications.
Kyouritsu General Hospital, Nagoya University Graduate School of Medicine
8-week-old female SD rats were divided into 3 groups (control group, DM group, DM+EPA group). STZ (65 mg/kg) was intraperitoneally administered to DM group and DM+EPA group, and only rat with blood glucose level of 350 mg/dl or more was used on the third day. The DM + EPA group was fed diet with EPA (5%), and the same amount of sunflower oil was administered to the control group and DM group as subjects. After 8 weeks, blood glucose level・HbA1c measurement and Scotopic electroretinogram (ERG) were carried out. Before ERG measured, rats were anesthetized with an intramuscular injection of ketamine and xylazine after at least two hours of dark adaptation. The pupils were dilated with topical 0.5% tropicamide and 0.5% phenylephrine. ERGs were recorded with a gold wire loop electrode on the cornea and a gold wire reference electrode placed on the sclera. Strobe flash stimuli were presented in a Ganzfeld bowl. Scotopic ERGs were measured with stimulus intensity of 1.0 log cd-s/m2. As a statistical analysis method, a Kruskal-Wallis test was conducted between the 3 groups, and when the P value was less than 0.05, the P value between the groups was examined by the Steel-Dwass method.
HbA1c in the rats 8 weeks after STZ was administered were significantly elevated in the DM group, and DM+EPA group relative to the control group, but no significant difference was found between DM group, and DM+EPA group. ERG results showed that the b/a ratio were 2.74±0.10 in the control group (n =12), 2.33 ± 0.10 in DM group (n = 13) and 2.36 ± 0.09 in the DM+EPA group (n = 13). There was a significant decrease in the DM group relative to the control group (P = 0.03), but no significant difference was found between the DM group and DM+EPA group (P = 0.92). On the other hand, the OP waves were 1208.1 ± 73.6 µV in the control group (n = 12), 441.2 ± 50.2 μV in the DM group (n = 13) and 639.0 ± 50.4 μV in the DM + EPA group (n = 13). It was significantly decreased in the DM group compared to the contorl group (P = 0.0001), but was significantly recovered in the DM + EPA group compared to the DM group (P = 0.04).
These results indicated that EPA possibely preserve retinal function in diabetic retinopathy.