糖尿病モデル動物における間歇的圧刺激による微小血管の形態変化

microvasculature

北海道歯学会

北海道歯学雑誌

Recently, the number of adults and elderly people seeking orthodontic treatment has increased and we frequently encounter opportunities to treat patients with diabetes and of the diabetic corps. However, regarding tissue changes associated with orthodontic force to move teeth, much is still unclear about differences in the responsiveness of microvasculature to mechanical stimulus for those with hyperglycemia. In this study, we focused on intermittent pressure of shorter loading periods because the fragility of microvasculatures tends to advance in hyperglycemia. Thus far, it is clear that monocyte lineage cells are stimulated to migrate outside of blood vessels when capillaries are dilated to the width of post capillary venules by mechanical pressure in normoglycemia. However, there is no report examining microvascular changes in response to weak pressure stimulation, and in particular intermittent pressure, in hyperglycemia. The purpose of this study is to observe microvascular changes with intermittent pressure and to examine the load conditions under which sufficient vasodilation occurred with vascular structure maintained by streptozotocininduced diabetic hamsters. Non-diabetic male Syrian golden hamsters (6 weeks old) are termed “normal group” (unloading) and streptozotocin-induced diabetic hamsters (5 weeks old) are divided into “control group” (unloading) and three loading groups. The three loading groups were alternately repeated loading and unloading. The duration for loading/unloading was 1sec/19secs (T20), 1sec/39secs (T40), and 1sec/59 secs (T60). Each animal was fitted with a specially-designed, purpose-built dorsal skinfold chamber with a loading device capable of exerting an intermittent pressure of 100 g/cm2. Intermittent pressure was applied to the three loading groups. From day 1 until day 5, microvascular changes were observed with a stereoscopic microscope and a fluorescence microscope, and differences between the groups were observed with the following results. 1. Under loaded conditions, capillary diameters for the T20 and T40 groups were significantly higher than for the control group. 2. Under loaded conditions, the T20 group exhibited significantly stronger bleeding tendency than the control group. 3. Regarding disappearance rates of capillaries, the loss rate for the T20 group was significantly higher than for the other groups. The above results suggest that through the application of intermittent orthodontic force in intervals consisting of one second of pressure followed by 39 seconds of rest, it may be possible to bring about dilation of the capillaries of diabetic hamsters while their structure is maintained in periodontal tissue.