Immunohistochemical expression and distribution of orexin, orphanin and leptin in the major salivary glands of some mammals

Abstract

The aim of the study was to determine by immunochemistry the expression of leptin, orexin A and
orphanin FQ in the major salivary glands (parotid, submandibular and sublingual) of rat, sheep and cow. These
peptides, originally synthesized in central nervous system, adipose tissue and peripheral tissues including gastrointestinal
tract, play an orexigenic (orphanin and orexin) or anorexigenic (leptin) roles in the intricate neuronal
network appointed to the control of nutritional homeostasis. Peptide-specific immunoreactivity was present
in the studied salivary glands with various intensities in different species, in the ductal epithelium, sometimes in
the acinar epithelium, and in nervous trunks spread in connective tissue stroma. The obtained data show that
salivary glands present an unexpected source of orexigenic and anorexigenic peptides which with their autocrine,
paracrine, and endocrine mechanisms of action may participate in the control of salivary gland function.