Preliminary Study On The Regeneration Of Parotid Tissue After Ligation And Recanalization Of Main Duct On Rats

Purpose To study the regenerative ability of the parotid gland at different time points of recanalization after ligated the ducts in rats.To explore the role of water channel protein 5(Aquaporin 5 AQP5)and programmed cell death molecule 5(Programmed cell death 5,PDCD5)in the process of parotid gland regeneration.Methods 84 SPF female Wistar rats at 8 weeks olds as the research.(Purchased in Ji’nan Peng Yue experimental animal breeding weight(250 +10g)).randomly divided into three groups(27 for each group).A group,B group and C group were recanalization respectively after seventh,fourteenth,twenty-first days of ligation.It was divided into 0,1,3,5,7,10,14,21,28 day groups according to the catheter recanalization(respectively as A0,Al...A28,B0,B1...B28,C0,C1...C28).The remaining 3 rats were used as the sham operation control group,which the parotid duct was only free from the ligation of the parotid gland during the operation.After sampling,some fresh specimens were cryopreserved for Western Blot at protein level and real-time fluorescence quantitative PCR(real timePCR)at gene level to detect the expression of AQP5 and PDCD5 in the regenerated parotid tissues.The other part for formalin fixed,paraffin section,Using hematoxylin eosin staining(HE staining)and alcian blue periodic acid Schiff staining(AB-PAS staining),immunohistochemical staining,to observe histological changes in morphology of tissue.Results Glandular regeneration occurred in the three groups after reopen the dominant parotid duct.In group A and group B,the morphology and secretory function returned to normal at 14 days and 21 days after recanalization.C group did not return to normal level until 28th days after recanalization.HE staining and AB-PAS staining showed that after the recanalization of the parotid main duct,the acinar cells were regenerated,the ductal structure gradually decreased,the morphology of the glandular lobules gradually resumed,the ability to secrete saliva increased gradually,and the saliva in acinus and ductal increased.The morphology and secretion function of glands in group A and group B could be restored to no difference from those in normal group.The glandular structure and secretion ability of C group were significantly different from those in normal group after 28 days.AQP5、PDCD5 immunohistochemistry,Western Blot and real time PCR results showed that the expression of AQP5 increased gradually after recanalization of the 7 day and 14 days of ligation,which could be restored to normal level fourteenth days and twenty-first days after recanalization,and 21 days after ligation,it still failed to recover completely after 28 days of recanalization.PDCD5 tended to increase as apoptosis of ductal like structure.The three groups reach the highest level respectively at 5th day、10th day、14th day after reopening the main duck.A group and B group respectively in 14th day,21th day returned to normal levels,C group failed return to normal the level until 28th day.Conclusions The rat parotid gland has the ability to regenerate after injury,and the strength of its regenerative ability depends on the degree of tissue damage.The longer the ligation of the parotid leading tube,the more serious the damage of the parotid gland,the worse the regenerative ability of the parotid gland.Expression of AQP5 is an important indicator of the functional recovery of parotid gland.PDCD5 is an indicator of apoptosis.During the process of regeneration of the gland,the structure of the ductal structure is apoptosis.