| Objective:To study the effects of hyperglycemia on proliferation and differentiation of precursor cells in discrete regions of rats, and further study to explore whether insulin signal and Wnt signal have been implicated in these processes above mentioned.MethodsStreptozotocin (STZ) (65 mg/kg) was once injected through femoral vein after 24 hours fasting in rats. Three days later, plasma glucose was measured, and≥250mg/dL were used for fellowing experiments. Rats were administrated with 5-bromodeoxyuridine (Brdu, 35mg/kg/d, ip) once a day for four consecutive days before they were sacrificed. Brains were removed and cut serial cornal sections after the post-fixing. The different cell-phenotypes were analysis with different markers including Ki67+, Brdu+, GFAP+, DCX+, GFAP+/Brdu+, DCX+/Brdu+ Immunohistochemistry or immunofluorescence was used to detect different phenotypic cells in SVZ and SGZ. The expressions of IR-β,Pho-GSK-3βandβ-Catenin in hippocampus or cortex were measured by Western blotting.Result:1. Ki67 positive cells of SVZ significantly decrease in DM-group (148.6±11.2) compared to the age-matched control group (205±10.8, P<0.05), Brdu positive cells of SVZ (120.3±23.2) are less in diabetic rats than that of the age-matched rats (202.2±10.8, P<0.05).2. Type A cells in SVZ (12.6±7.4) significantly decrease in DM-group compared to the age-matched control group (18.9±12.8, P<0.05); Type B cells (24.4±8.5) in SVZ also decrease in DM-group compared to the age-matched control group (53.8±15.5, P<0.05).3. The precursor in SVZ differentiated into less numbers of DCX+/Brdu+ positive cells in diabetic rats (2.8±2.48) than that of age-matched control rats (4.6±3.89, P<0.05). And the GFAP+/Brdu+ positive cells in SVZ also decrease in DM-group (6.4±4.9) compared to the age-matched control group (16.6±8.3, P<0.05).4.The expression of P-GSK-3β,IR-βandβ-catenin were decreased in cortex of diabetic rats by 40%,27% and 18% compared to the age-matched control group.5. Ki67 positive cells of SGZ significantly decrease in DM-group (1.31±4.9) compared to the age-matched control group (2.38±9.8, P<0.05).6. The precursor in SGZ differentiated into less numbers of DCX+/Brdu+ positive cells in diabetic rats (12.7±9.9) than that of age-matched control rats (20.1±14.1, P<0.05). And the GFAP+/Brdu+positive cells in SGZ also decrease in DM-group (13.6±8.5) compared to the age-matched control group (20.7±11.5, P<0.05).7. The expression of P-GSK-3β,IR-βandβ-catenin were decreased in hippocapus of diabetic rats by 36%,25% and 27% compared to the age-matched control groupConclusions:1. Sustained high glucose inhibits the proliferation of precursor oriented SVZ with the methods of Brdu and Ki67, respectively.2. Persistant high glucose represses the differentiation of progenitor cells oriented SVZ.3. Sustained high glucose causes desensitivity of insulin signaling, and inhibits the activity of GSK3-β, further increase the degradation ofβ-catenin in cortex, which may contribute to the decline of proliferation of precursor cells in SVZ.4. Sustained high glucose inhibits the proliferation of precursor oriented SGZ with the methods of Brdu and Ki67, respectively5. Persistant high glucose represses the differentiation of progenitor cells oriented SGZ.6. Sustained high glucose causes desensitivity of insulin signaling, and inhibit the activity of GSK3-β, further increase the degradation ofβ-catenin in cortex, which may contribute to the decline of proliferation of precursor cells in SGZ.
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