Involvement of alteration of CD36 expression on pilocarpine-induced salivation in mouse parotid gland

Dry mouth is observed commonly in middle-aged and elderly patients. Although the deterioration of parotid gland (PG) function in those patients is considered, the relationship between aging and hyposecretion has been unclear. We hypothesized that the reduction in expression of fatty acid translocase FAT/CD36, which facilitates the transport of fatty acids, induced dry mouth through the hyposecretion in PG. In this study, the level of CD36 expression was detected by real-time RT-PCR in male 8- and 48-weeks BALB/c mice. Also, effect of CD36 inhibitor sulfosuccinimidyl oleate (SSO) on salivary secretion of male 48-weeks BALB/c mice was assessed. Moreover, the involvement of PG CD36 in the salivary secretion of male 48-weeks senescence-accelerated mouse (SAM) was investigated. The RNA expression level of CD36 in PG was superior to other salivary glands in BALB/c mice. SSO reduced pilocarpine-induced salivation in BALB/c mice. Compared with SAM resistant 1 (SAMR1), the pilocarpine-induced salivation in age-matched SAM prone 1 (SAMP1) was significantly decreased. In addition, the CD36 protein expression in PG was investigated by western blotting, and the expression of CD36 of SAMP1 was significantly lower than that of SAMR1. These results suggest that the CD36 plays an important role in the aging-induced hyposecretion of PG.