[Effect of fibroblast growth factor 1 on the proliferating cell nuclear antigen expression in submandibular gland of diabetic mice].

Objective: To examine the proliferating cell nuclear antigen (PCNA) expression in submandibular gland of diabetic mice and to investigate the influence of fibroblast growth factor 1 (FGF-1) on PCNA expression and its possible mechanism. Methods: Sixteen db/db diabetic male mice were randomly divided into diabetic group and diabetic-FGF-1 group (n=8). Eight age-matched db/m mice served as a control group. After FGF-1 was administered intraperitoneally to diabetic-FGF-1 group continuously for 16 weeks, blood glucose and body weight of each mouse in the three groups were detected at 0, 4, 8, 12, 16 weeks. Then the flow rate of saliva in three groups was compared at 0, 8, 16 weeks. At 16 week, bilateral submandibular glands were resected. Then HE staining was performed to observe the histological morphology of submandibular gland and PCNA expression was examined by immunohistochemical staining. Results: Four weeks after administration, the blood glucose in diabetic-FGF-1 group decreased markedly, close to the control group (P>0.05). Weight loss in diabetic-FGF-1 group was noticeable at 8 weeks after administration, but still higher than that in the control group (P<0.05). The flow rate of saliva in diabetic-FGF-1 group increased gradually after administration, which was higher at 8, 16 weeks ([260.1±43.3], [308.5±34.0] mg·min(-1)·kg(-1)) respectively than that in the diabetic group at the same time point ([181.8±37.5], [194.9±49.8] mg·min(-1)·kg(-1)) (P<0.05). Compared with the control group, submandibular glands in diabetic group significantly atrophied and the glandular atrophy in diabetic-FGF-1 group was alleviated. The submandibular gland index in the control group, diabetic group and diabetic-FGF-1 group were (7.45±0.63), (2.23±0.26), (3.97±0.15) mg/g, respectively (P<0.05). HE staining showed that the histological morphology of submandibular gland in diabetic-FGF-1 group was clearer, and acinar and ductal atrophy were less significant than diabetic group. Immunohistochemistry showed that the rate of PCNA-positive cells in the control group, diabetic group and diabetic-FGF-1 group were (45.23±7.78)%, (11.50±1.69)%, (36.98±6.53)% respectively (P<0.05). Conclusions: FGF-1 can up-regulate the expression of PCNA in submandibular gland of diabetic mice. This effect may be one of the important mechanisms of FGF-1 reversing the structural atrophy and dysfunction of submandibular gland caused by diabetes mellitus.