To evaluate the effects of early regular exercise and to assess the electrophysiological and histopathological findings of the rat tail nerve in relation to the timing of exercise training for swimming exercise in rats with diabetic neuropathy.
We used 70 Sprague-Dawley male rats, and the experimental group comprised 60 rats, and the control group comprised 10 rats. Diabetes was induced by intraperitoneal injection of streptozotocin. Blood glucose concentrations were measured in tail vein blood samples. The experimental group was divided into 6 subgroups according to insulin treatment and swimming exercise: group 1, diabetic control; group 2, insulin treated; group 3, insulin untreated with early swimming exercise; group 4, insulin treated and early swimming exercise; group 5, insulin treated and late swimming exercise; and group 6, insulin untreated with late swimming exercise. Sensory and motor nerve conduction studies were performed weekly up to the 13th week using rat tail nerves. The effect on structural diabetic neuropathy was assessed by morphometry and ultrastructural examination of the rat tail nerve fiber at the 14th week.
An exercise effect was observed in the insulin treated groups, but it was not observed in the insulin untreated groups. The sensory nerve conduction study in the rat tail revealed significantly prolonged latency and decreased amplitude in groups 1 and 6, and a further delay was observed in group 5 when compared to group 4. Decreased thickness of myelin was found in groups 1 and 6 through morphometry.
Early regular exercise programs in addition to conventional insulin treatment may retard the progression of diabetic peripheral neuropathy.
Citations
Objective: This study was designed to see the effect of swimming exercise in the rats after experimental contusive spinal cord injury.
Method: Twenty six Sprague-Dawley rats (weight, 300 to 350 g) were divided into control (n=9) and experimental swimming groups (n=17). With the Spinal Cord Dropping Device (NYU, U.S.A.), contusive injury to the spinal cord was induced at the eighth thoracic level in both groups. Rats of the experimental group put to swim for 5 minutes a day during the second week and then swimming times a day were increased in one number to each week. But the other ten rats were remained without swimming exercise as the control. Functional recovery of the hind limb was evaluated by the inclined board plane test, the Bassoe Beattie Bresnahan (BBB) locomotor rating scales and histological findings of injured spinal cord.
Results: 1) Upward maximal angles of the inclined plane test were significantly greater in experimental group than control group after 10 days post-injury (p＜0.05). 2) BBB scores were higher in experimental group than control group at 14 days after injury (p＜0.05).
Conclusion: This study suggests that swimming applied from the early phase after spinal cord injury be beneficial in the early recovery of motor function.
Objective: To determine the effect of exercise in the early phase of reinnervation after sciatic nerve injuries in the rat.
Method: Thirty six rats, Sprague-Dawley (weight, 200 to 220 g), were divided into the normal control and experimental groups. Using a haemostatic forceps, crushing injuries to the bilateral sciatic nerves were induced in the experimental group. The experimental group was further divided into exercise groups by the duration of daily swimming and initiation (duration since injury) of exercise after nerve injury (A, 2 hours/day and day 1; B, 30 minutes/day and day 1; C, 2 hours/day and week 2; D, 30 minutes/day and week 2) and non-exercise group (E). After completion of 5-week program the test results were evaluated by 1) sciatic nerve motor conduction study recorded at the gastro-soleus muscles, 2) measurement of soleus muscle tension, and 3) hematoxylin-eosin stain & alkaline ATPase stain (pH 9.4) of the soleus muscles.
Results: Nerve conduction study revealed significantly prolonged latency in group C and decreased amplitude in the group C, D. Peak twich tension decreased significantly in group C, D & E. Maximal tetanic tension was increased significantly in the group A compared to C. Both type I and II muscle fibers atrophied significantly in all the experimental groups compared to the normal control group with no changes of the composition of two muscle fibers.
Conclusion: Swimming applied from the early phase after sciatic nerve injury may be beneficial in early recovery of muscle tension. Overexercise in the early stage of reinnervation, however, may hamper the functional return of the damaged muscle by nerve injury.
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