Lab Anim Res.  2011 Sep;27(3):189-195. 10.5625/lar.2011.27.3.189.

Differential effects of treadmill exercise on cyclooxygenase-2 in the rat hippocampus at early and chronic stages of diabetes

• Nam SM
• Yi SS
• Yoo KY
• Park OK
• Yan B
• Song W
• Won MH
• Yoon YS
• Seong JK

• KMID: 1850045
• DOI: http://doi.org/10.5625/lar.2011.27.3.189

Abstract

Cyclooxygenase-2 (COX-2) is believed to be a multifunctional neural modulator that affects synaptic plasticity in the hippocampus. In the present study, we investigated the differential effects of treadmill exercise on COX-2 immunoreactivity in the dentate gyrus in early and chronic diabetic stages in Zucker diabetic fatty (ZDF) rats and lean control (ZLC) rats. To this end, ZLC and ZDF rats at 6 or 23 weeks of age were put on a treadmill with or without running for 1 h/day for 5 consecutive days at 16-22 m/min for 5 weeks or 12-16 m/min for 7 weeks, respectively. Treadmill exercise in prediabetic and chronic diabetic rats significantly reduced blood glucose levels. In particular, exercise in the prediabetic rat blocked the onset of diabetes. COX-2 immunoreactivity was mainly detected in the granule cell layer of the dentate gyrus and stratum pyramidale of the CA3 region in all groups. COX-2 immunoreactivity was significantly increased in these regions of ZLC and ZDF rats after treadmill exercise in the early diabetic stage. However, COX-2 immunoreactivity was not changed in these regions in ZDF rats after treadmill exercise in the chronic stage. These results suggest that treadmill exercise in diabetic animals in the chronic stage has limited ability to cause plasticity in the dentate gyrus.

Keyword

Cyclooxygenase-2; diabetic stages; type 2 diabetes; treadmill exercise; Zucker diabetic rat

MeSH Terms

Animals
Blood Glucose
Cyclooxygenase 2
Dentate Gyrus
Hippocampus
Plastics
Rats
Running
Blood Glucose
Cyclooxygenase 2
Plastics

Figure

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  Figure 1 Change in blood glucose levels in 12-week-old Zucker lean control (ZLC) and Zucker diabetic fatty (ZDF) rats in the sedentary groups (Co12-ZLC and Co12-ZDF), in the 12-week-old rats in the exercised groups (Ex12-ZLC and Ex12-ZDF), in the 30-week-old rats in the sedentary groups (Co30-ZLC and Co30-ZDF), and in the 30-week-old rats in the exercised groups (Ex30-ZLC and Ex30-ZDF rats; n=5 per group; aP<0.05, significantly different from control group; bP<0.05, significantly different from the ZLC group; cP<0.05, significantly different from 12-week-old age group). The bars indicate the SEM.

• 

  Figure 2 Cyclooxygenase-2 (COX-2) immunoreactivity in the dentate gyrus of Co12-ZLC (A), Co12-ZDF (B), Ex12-ZLC (C), Ex12-ZDF (D), Co30-ZLC (E), Co30-ZDF (F), Ex30-ZLC (G) and Ex30-ZDF (H) rats. COX-2 immunoreactivity is mainly detected in the granule cell layer (GCL, asterisk) of the dentate gyrus. Note that COX-2 immunoreactivity is strong in the exercised group except in the Ex30-ZDF group. PL, polymorphic layer; ML, molecular layer. Scale bar=100 µm.

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  Figure 3 COX-2 immunoreactivity in the hippocampal CA3 region of Co12-ZLC (A), Co12-ZDF (B), Ex12-ZLC (C), Ex12-ZDF (D), Co30-ZLC (E), Co30-ZDF (F), Ex30-ZLC (G) and Ex30-ZDF (H) rats. COX-2 immunoreactivity is observed in the stratum pyramidal (SP, asterisk). Note that COX-2 immunoreactivity is strong in most exercised groups except the Ex30-ZDF group. SO, stratum oriens; SR, stratum radiatum. Scale bar=100 µm.

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  Figure 4 Relative optical densities (ROD) as percentage values of COX-2 in the dentate gyrus (A), and CA3 (B) of Co12-ZLC, Co12-ZDF, Ex12-ZLC, Ex12-ZDF, Co30-ZLC, Co30-ZDF, Ex30-ZLC and Ex30-ZDF rats. Differences among the means were analyzed statistically by two-way analysis of variance followed by Duncan's new multiple range method (n=5 per group; aP<0.05, significantly different from control group; bP<0.05, significantly different from the ZLC group; cP<0.05, significantly different from the 12-week-old group). Bars indicate the SEM.

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