Prosaposin and its receptors are differentially expressed in the salivary glands of male and female rats
Salivary glands produce various neurotrophins that are thought to regulate salivary function during normal and pathological conditions. Prosaposin (PSAP) is a potent neurotrophin found in several tissues and various biological fluids and may play roles in the regulation of salivary function. However, little is known about PSAP in salivary glands. As the functions of salivary glands are diverse based on age and sex, this study examines whether PSAP and its receptors, G protein-coupled receptor 37 (GPR37) and GPR37L1, are expressed in the salivary glands of rats and whether sex and aging affect their expression. Immunohistochemical analysis revealed that PSAP and its receptors were expressed in the major salivary glands of rats, although their expression varied considerably based on the type of gland, acinar cells, age and sex. In fact, PSAP, GPR37 and GPR37L1 were predominantly expressed in granular convoluted tubule cells of the submandibular gland and the intensity of their immunoreactivity was higher in young adult female rats than age-matched male rats, which was more prominent at older ages (mature adult to menopause). On the other hand, weak PSAP, GPR37 and GPR37L1 immunoreactivity was observed mainly in the basal layer of mucous cells of the sublingual gland. Triple label immunofluorescence analysis revealed that PSAP, GPR37 and GPR37L1 were co-localized in the basal layer of acinar and ductal cells in the major salivary glands. The present findings indicate that PSAP and its receptors, GPR37 and GPR37L1, are expressed in the major salivary glands of rats and their immunoreactivities differ considerably with age and sex.
KeywordsProsaposin Salivary glands Aging Sex Rat
We would like to thank D. Shimizu for his technical support with confocal imaging. The English in this document has been checked by at least two professional editors, both native speakers of English. For a certificate, please see: http://www.textcheck.com/certificate/zXYQdv
This work was supported in part by grants to M.S.I.K. from the Japan Society for the Promotion of Science Grant-in-Aid for Young Scientists (No. 15K20005), and to S.M., from the Ministry of Education, Culture, Sports, Science and Technology of Japan (No. 22591637).
Compliance with ethical standards
All experimental procedures were accomplished in accordance with the ethical regulations and the guide for animal experimentation at Ehime University School of Medicine, Japan.
Conflict of interest
The authors declare that they have no conflict of interest.
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