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.

The expressions of some metabolic hormones (leptin, ghrelin and obestatin) in the tissues of sheep tongue

“…Similar to previous research, it was determined that the peptide hormones investigated in the present study were expressed at varying intensity in the luminal epithelial and glandular and ductal epithelial cells of the sheep tongue (Leone et al, ). In agreement with the reports of Alnema et al () and Ohta et al () for human oral epithelial cells, the present study demonstrated moderate ghrelin, obestatin and leptin expression in the luminal epithelial cells of the sheep tongue.…”

“…Feeding mechanisms are an important factor that defines the success of the environmental adaptation of vertebrates (Roth & Wake, ). It is well known that food digestion starts in the mouth under the control of the secretion of the major and minor glands localized to the mucosa of the oral cavity and the oropharyngeal organs (Leone et al, ). The results of the present study demonstrated that, in sheep, the tongue, which has a vital role in nutrition together with other organs of the digestive system (i.e., the stomach and intestines), is also a source of the peptide hormones leptin, ghrelin and obestatin.…”

“…Recent research has shown that, in humans, the endometrium, the alveolar and ductal epithelium of the mammary glands (Grönberg et al, ; Ishikawa, Kitayama, & Nagawa, ; Jeffery et al, ; Leone et al, ; Tanaka & Umesaki, ), the stomach and intestines (Gesmundo, Gallo, Favaro, Ghigo, & Granata, ; Grönberg et al, ; Hardwick, Van Den Brink, Offerhaus, Van Deventer, & Peppelenbosch, ; Leone et al, ; Mix et al, ) and the alveolar epithelium of the lungs express leptin, ghrelin and obestatin (Vernooy et al, ), whilst, in sheep, the alveolar and ductal epithelium of the mammary glands expresses leptin (Bonnet, Gourdou, Leroux, Chilliard, & Djiane, ). Furthermore, it has been demonstrated that, in humans, rats, sheep and cows, rather than in the mucous glandular epithelial cells of the major salivary glands, leptin and ghrelin are expressed in the serous glandular and ductal epithelial cells of the parotid, submandibular and sublingual glands, at varying intensity (Gröschl et al, ; Leone et al, ; Li et al, ). In mice, leptin and ghrelin expression has been demonstrated in the gustatory cells of the epithelium lining the taste buds (Kawai et al, ; Shin et al, ).…”

“…Immunohistochemical staining was repeated to prove the validity of the results obtained. Leptin, ghrelin and obestatin immunoreactivities were measured using a semiquantitative scoring method based on the intensity of staining (IS; Leone et al, ). IS reflected the intensity of positive staining in the membrane, cytoplasm and nucleus of the cells.…”

“…It has been reported that, in mice, leptin and ghrelin are expressed in the gustatory buds of the epithelium lining the gustatory papillae on the dorsal lingual surface (Dun et al, ; Kawai, Sugimoto, Nakashima, Miura, & Ninomiya, ). According to literature review, previous studies have mostly focussed on the expression of leptin and ghrelin in the salivary glands of humans (De Matteis, Puxeddu, Riva, & Cinti, ; Li et al, ), cows, sheep and rats (Leone et al, ). To our knowledge, no information is available on the localization and expression of obestatin in the organs of the oral cavity.…”