【Animal Modeling】-Miniature Pig Parotid Gland Atrophy Model

  Due to the effects of radiation therapy for head and neck tumors, Sjogren’s syndrome and salivitis, the large salivary glands of the human body will experience gland atrophy and decreased salivary secretion, which will have serious effects on the patient’s physiology and psychology. However, there is currently no effective treatment. How to treat salivary gland atrophy and promote the recovery of gland function has attracted increasing attention. Because the structure and function of the parotid gland of miniature pigs are very similar to that of humans, Xia Dengsheng and others established a model of parotid gland atrophy using miniature pigs.

  The experiment selected 10 Chinese experimental miniature pigs, 6 months old, and weighing 30-35kg. After conventional anesthesia, insert the special salivary gland imaging cannula into the main parotid duct about 2cm, inject 4ml of 1% methyl violet water solution, and leave the cannula in the duct for 30 minutes. Methyl violet is a cationic chemical substance that can bind to the negatively charged hydroxyl groups of the protein on the cell membrane, causing protein denaturation, interfering with the normal function of the cell membrane, and affecting the normal metabolism of the cell, leading to cell pyknosis. Methyl violet destroys the parotid acini, causing parotid glands to shrink.

  This experiment also measured changes in oral flora and saliva flow rate of parotid atrophy pigs. The miniature pigs were fasted for 12 hours. Under anesthesia, the bacteria-removing ring (a 0.25mm stainless steel ligature wire bent into a 1.0mm diameter ring) was used to collect the front and rear subgingival plaques of the miniature pigs, and immediately put them into the sterile 1ml In the 0.9% NaCl bottle, transfer to the bacteria operation room and dilute with 0.9% NaCl times. The mixed saliva was collected by subcutaneous injection of pilocarpine (1mg/10kg) to promote saliva secretion, and then the miniature pig was placed prone on the operating table with its head drooping naturally. Collect the mixed saliva for 10 minutes from the beginning of saliva secretion and record the total amount. Draw 1.0ml of mixed saliva, immediately put it into a sterile bottle with stopper, and transfer it to the bacteria operation room, and dilute it with 0.9% NaCl.

  Results The number of main pathogenic bacteria in different parts of the oral cavity after bilateral parotid gland destruction and atrophy in miniature pigs showed different changes in the 12-24 months after atrophy. Among them, the number of bacteria in the posterior subgingival plaque changed the most, and the change in saliva was the smallest. The saliva flow rate decreased by 40% after bilateral parotid gland atrophy. With the increase of parotid gland atrophy time, the pH of the mixed saliva gradually increased, which was statistically different from the control group (P<0.05), while the pH of the mixed saliva of the healthy control group only slightly increased with the age of miniature pigs. After bilateral parotid gland atrophy in the experimental group, the number of main pathogenic bacteria in different parts of the oral cavity changed. Except for aerobic bacteria in the posterior subgingival plaque, the number of other bacteria was significantly higher than that of the healthy control group after parotid gland atrophy . In the anterior subgingival plaque, the number of aerobic bacteria and Fusobacterium sclerotium was significantly higher in the experimental group than in the healthy control group, while the number of Streptococcus mutans decreased slightly. The number of Fusobacterium nuclei in saliva was significantly higher than that in the healthy control group after atrophy, while the number of black-producing bacteria was lower than that in the healthy control group after atrophy, and the number of other bacteria remained unchanged.