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Published on: September 30, 2019
Interleukin-18 expression in pig salivary glands and salivary content changes during acute immobilization stress
Y Muneta1, Y Minagawa, T Nakane
1Research Team for Advanced Biologicals, National Institute of Animal Health, National Agriculture and Food Research Organization, 3-1-5, Kannondai, Tsukuba, Ibaraki, Japan. ymuneta@affrc.go.jp
Abstract:
Interleukin-18 (IL-18) has recently been considered a promising marker of stress responses. In this study, to evaluate IL-18 as a noninvasive stress marker in pigs, we investigated the expression of IL-18 in porcine salivary glands and its presence in saliva, and its dynamics during acute immobilization stress in pigs. IL-18 mRNA was detected robustly in the pig salivary glands by RT-PCR. Immunohistochemical staining of IL-18 protein expression revealed that the expression patterns differed among the three types of salivary glands (parotid, submandibular, and sublingual gland). IL-18 was also detected in pig saliva by ELISA, and a diurnal rhythm with a peak in the afternoon was observed. The IL-18 concentration in saliva was significantly increased during a 60-min acute immobilization stress in thirteen 5-month-old pigs. These results are the first evidence of a stress-related change of IL-18 in pig saliva. Salivary IL-18 may thus become a useful noninvasive marker for the evaluation of acute stress in pigs.
