Manserin, a secretogranin II-derived peptide, distributes in the rat endocrine pancreas colocalized with islet-cell specific manner.

Manserin is a recently characterized 40-amino acid neuropeptide derived from secretogranin II, a protein belonging to the chromogranin family. Although the physiological roles of manserin have not been elucidated to date, manserin has been shown to distribute in not only the brain but also the endocrine system such as the pituitary and adrenal glands, suggesting its role in the endocrine system. The present study aimed to explore the occurrence and distribution of manserin in the rat pancreas using an immunohistochemical technique with a polyclonal antibody against rat manserin. Immunoreactivity for manserin was readily detected in almost whole islets of Langerhans whereas not at all in the exocrine pancreas. Manserin-expressing cells were not colocalized with the glucagon-secreting cells (alpha cells), whereas they colocalized with insulin-secreting cells (beta cells) and somatostatin-secreting cells (delta cells), although their intracellular distribution was different. These results indicate that manserin, occurring in the endocrine pancreas, may have a potential role in the endocrine system.