To Detect The Influence Of Phenylephrine Pretreatment On The Expression Of P-JNK In Radiation-induced Impairment Of Salivary Gland Of Rat In Early Phase

Radiotherapy has been one of the most important treatments for oral, head andneck cancers. It is inevitable to result in radiation-induced impairment of salivary glandfunction, because of the special sites of salivary glands and salivary glands’ exquisiteradiosensitivity. Although the survival rates of these patients has been improved, theradiotherapy left them with permanently impaired quality of life. What is worse,salivary glands’ hypofunction to be recovered, no effective modalities are available yet.So, it is extremely urgent to explore the mechanisms of radiogenic damage deeply, andfind practical and effective approaches in order to augment patients’ life quality afterradiotherapy. It is demonstrated that phenylephrine can protect the submandibular glandof rats from the damage which is produced by irradiation, enriching the secretion ofsubmandibular glands, but the scientists have not understanded the specific processes.c-Jnk NH2-terminal kinases(JNK) is reported that the activation of it may initiate andpromote apoptosis. However what effect JNK plays in radiogenic injury insubmandibular glands of rats and what relation with phenylephrine is unclear till now. In this study, we detected the relative effects of pre-treated PE on the expression of JNKand p-JNK in rat submandibular gland during early phase after radiation.Materials and methods Twenty-seven Wistar rats were divided into three groups bychance,and then respectively named: the control group,the simple irradiated group,andthe irradiated group with pretreated phenylephrine, the treatment of the last group isdifferent, proper dosage of phenylephrine (5mg/kg) was injected into the rats throughintraperitoneal30minutes before radiation.20Gy X-ray irradiation was delivered to thesubmandibular region by applying a medical linear accelerator, and submandibularglands were removed on seven days after irradiation. The distribution and expression ofp-JNK was then detected by immunohistochemical assay, and Western blot was appliedto detect the expression of p-JNK and JNK.Results The expresssion of p-JNK was mainly founded in the cytoplasm and nucleusof both serous acinar and ductal cells in the control group, compared with the first group,it was significantly increased in the simple irradiated group, and in the last group thedistribution was markedly decreased. Also, results from Western blot demonstrated thatthere is not outstanding difference of the expression of JNK between the three groups;the expression of p-JNK was up-regulated40.14%(P＜0.05) in the simple irradiatedgroup compared with the control group, butWas down-regulated45.02%(P＜0.05) in the irradiated group with pretreatedphenylephrine compared with the simple irradiated group.Conclusion The expression of p-JNK in the rat submandibular gland could beincreased after irradiation early stage and could be decreased by phenylephrinepretreatment. These results suggested that the activation of а1-adrenocepter receptorsignal pathway might be involved in the mechanism of function regulation insubmandibular gland after irradiated injury,which might provide a new strategy inpreventing and renewing salivary gland irradiated damage.