Abstract

Background: Diabetic neuropathy (DN) is a major complication of diabetes. Although it is wellestablished that DN targets sensory and autonomic nerves, little is known about its influence on motor disorders.
Methods: This study investigated morphological alterations inabdominal (Abd) motoneurons and muscles of experimental type I diabetic rats. Alterations in the number and size of Abd motoneurons were studied using retrograde labeling techniques in diabetic rats 6 or 14 weeks after injection of streptozotocin (diabetic group). Age-matched control animals were labeled at 6 or 14 weeks after saline injection (control group). Further, the thicknesses of the external oblique, internal oblique, transversus abdominis (TA), and rectus abdominis muscles were similarly examined and the cross-sectional area of the TA myocytes was measured.
Results: The number and mean size of cell bodies significantly decreased in Abd motoneurons in the diabetic group compared with the control group (P < 0.05). As diabetes progressed, there was a clear decrease in the number and mean motoneuron size (P < 0.05). In the diabetic group, the thickness of Abd muscles was reduced, as was the cross-sectional area of the TA myocytes (P < 0.05). Moreover, there was a clear decrease in muscle thickness and in the cross-sectional area of the myocytes (P < 0.05).
Conclusion: We suggest that hyperglycemia induceda reduction in the number and size of Abd motoneurons and atrophy of Abd muscles at 6 and 14 weeks after induction of diabetes by streptozotocin. Therefore, Abd muscular disorders caused by hyperglycemia may relate to a wide range of disorders, such as those involved with expiratory, defecation function, and trunk movement.