Effect of cilostazol on the neuropathies of streptozotocin-induced diabetic rats

OBJECTIVES: This study examined the effect of cilostazol, a potent phosphodiesterase inhibitor, on the progression of neuropathies associated with streptozotocin-induced diabetes mellitus in Sprague-Dawley rats. METHODS: Eight weeks after streptozotocin treatment, a pelleted diet containing 0.03% cilostazol (15 mg/kg body weight) was given for four weeks. Body weight, blood glucose level, motor nerve conduction velocity (MNCV), myelinated fiber density and size distribution of sciatic nerves were compared between age-matched normal rats (Group 1), control diabetic rats (Group 2) and cilostazol-treated diabetic rats (Group 3). RESULTS: Body weight was significantly reduced and blood glucose level was significantly increased in diabetic rats (Group 2 and 3) compared to normal rats. MNCV and cAMP content of sciatic nerves were significantly reduced in diabetic rats 12 weeks after streptozotocin treatment. Myelinated fiber size and density were also significantly reduced, and thickening of the capillary walls and duplication of the basement membranes of the endoneural vessels were observed in the diabetic rats. Whereas both body weight and blood glucose level of Group 3 did not differ significantly from those of Group 2, cilostazol treatment significantly increased MNCV and cAMP content of sciatic nerves in Group 3 but not to the levels observed in Group 1. MNCV positively correlated with cAMP content of sciatic nerves (r = 0.86; p < 0.001). Cilostazol treatment not only restored myelinated fiber density and size distribution but reversed some of the vascular abnormalities. CONCLUSION: These findings suggest that a reduced cAMP content in motor nerves may be involved in the development of diabetic neuropathy, and that cilostazol may prevent the progression of diabetic neuropathy by restoring functional impairment and morphological changes of peripheral nerves.

The Effect of Equilibration Temperature and Exposure Time on the Ultrarapid Freezing of 1-cell Mouse Zygote / 대한불임학회지

The present study was to assess the effect of ultrarapid freezing on the development of 1-cell mouse zygote using cryoprotectants, DMSO (dimethyl sulfoxide) or PROH (1,2-propanediol). We investigated the effect of the type and concentration of cryoprotectant, and of the temperature and time of prefreezing equilibration on their capacity to develop to the blastocyst stage in vitro. The concenration, the equilibration temperature, and the exposure time seemed to serve as an important factor in ultrarapid freezing of 1-cell mouse zygotes. In addition to the exposure time and the concentration of cryoprotectant appeared to play a key role in the development of the embryo. In general, the development of the embryo was more effective at 3degrees C than 23degrees C and 4.5 M than 3 M for 3 to 5 minutes. At 23degrees C the development of the embryo was stimulated by DMSO while at 3degrees C it was stimulated by PROH. Thus it has been suggested that there exists a correlation between the concentration of cryoprotectants and exposure time in the development of the embryo. In conclusion, we found that for ultrarapid freezing of mouse 1-cell embryos in DMSO, or PROH-based solution, viability shown optimum depending on the cryoprotectant, the concentration of the cryoprotectant and on the temperature and the duration of equilibration.

A Morphological Study on Migration and Proliferation of Smooth Muscle Cells by Endothelial Cells in Full Layer Vascular Wall Model

To study the biology of the endothelium and the media of the vascular wall, full layer vascular wall model was constructed in vitro. In the experimental vascular wall model, endothelial cell (EC)s were grown on a collagen lattice containing multilayers of smooth muscle cell (SMC)s and a EC-free portion was made by a cloning ring on the culture disc. As conditioned culture media of ECs-SMCs contain biologic mediators that may promote the growth of SMCs, the availability of this vascular wall model promptly us to examine the extent to which ECs regulate the migration and proliferation of SMCs when these cells are maintained with or without covering EC lining in coculture. Morphologic characteristics of full layer vascular wall model was a whitish, non-transparent membrane. Outer boundaries and the zone of no EC were thicker than that of central portion. By light microscope imaging, luminal surface was composed of EC monolayer, and SMCs and collagen fibers were distributed between the polyethylene terephtalate (PET) membrane and EC monolayer. SMCs and collagen fibers were mainly located near the PET membrane. Venous SMCs were densely infiltrated as compared to arterial SMCs. By scanning electron microscopy, EC monolayer and dense collagen fibers in the zone of no EC were clearly shown. On the effects of platelet derived growth factor (PDGF) in the proliferation of SMCs and modeling of full layer vascular wall model, no effect on SMC in the zone of EC covering was seen however, active migration and proliferation of SMCs were noted in the zone of no EC. Wall thickness was two times greater than that of control. On the effects of EGF, it was observed that EGF markedly stimulated migration of SMCs with or without EC coverings in contrast to the control group. On the effects of FGF, results were similar to the PDGF group. Results on the effect of IGF-1 were similar to the PDGF group. As conclusions, full layer vascular wall model in this study was proved to be a good laboratory model for basic vascular research. And SMCs migration and proliferation were more active in venous SMCs compared to arterial SMCs. The collagen fibers were also richer and the wall was more thickened. EGF was most the potent SMC stimulator. PDGF, FGF, and IGF-1 were moderate SMC stimulator in the zone of no EC covering. These results strongly support why intimal hyperplasia eventually occured in autogenous venous bypass graft.