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 assess the involvement of apoptotic factors, cytokeratins and metalloproteinase- 9 in the histogenesis of both Epithelialized Gingival Lesions (EGL) and Periapical Lesions (PAL). 55 consecutive patients, 30 with PAL and 25 with EGL, were selected for the study after clinical and radiological examinations. The PAL patients had severe periapical lesions and tooth decay with exposure of the pulp chamber. All PAL and EGL biopsies were surgically extracted, fixed in 10% buffered formalin, and processed for routine light microscopy. Ten biopsies of each category were processed for immunohistochemistry (IHC). Serial paraffin sections were stained by IHC with appropriate antibodies to detect cytokeratins (CKs) 1, 5, 8, 10 and 14, caspase-3 and -9, metalloproteinase-9, and for PCNA and TUNEL assays. Both PAL and EGL showed a high expression of the cytokeratin 1, 5 and 8 with higher expression in EGL. Moreover, CK10 was markedly less intense expressed in EGL compared to PAL, while CK14 was almost three times stronger expressed in EGL. The expression of caspase-3 and -9 was stronger in PAL compared to EGL, however, the difference was only significant for caspase-9. In PAL apoptosis detected by TUNNEL method and the expression of MMP-9 were higher than in EGL, whereas PCNA was significantly more expressed in EGL. The results clearly suggest that both lesions have exclusively an epithelial origin and that epithelial proliferation was correlated with the degree of apoptosis in both entities. PAL and EGL presented mostly similar cytokeratin expression except for CK10 and CK14, though with marked differences in the distribution and intensity of IHC reactions. Finally, the degradation of extracellular matrix in both lesions could be partially attributed to the strong presence of MMP-9. (Folia Histochemica et Cytobiologica 2012, Vol. 50, No. 4, 497–503)

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.