Acute salivary gland hypofunction in the duct ligation model in the absence of inflammation

Abstract

OBJECTIVE: The commonly associated aetiology of salivary gland inflammation and salivary hypofunction has led to the widely held belief that inflammation causes salivary gland hypofunction. Indeed, our own recent study seemed to support this contention. Here, we tested the hypothesis that, in an acute duct ligation model, eliminating inflammation the submandibular gland would recover normal function. MATERIALS AND METHODS: Ligation of the rat submandibular gland excretory duct for 24 h was used to induce inflammation and salivary gland hypofunction. A group of duct ligated rats was compared with a second group given dexamethasone, on the day of duct ligation. Twenty-four hours later salivary gland function was assessed and salivary glands were collected. RESULTS: Histology and myeloperoxidase activity assay revealed a profound decrease in inflammatory cell infiltration of ligated glands from rats given dexamethasone, compared with ligated glands in the absence of dexamethasone. Salivary flow rate evoked by methacholine was decreased (P < 0.01) by approximately 56% (ligated vs control, 79 ± 9 ll min )1 g )1 vs 177 ± 11 ll min )1 g )1 ) and salivary flow from ligated dexamethasone-treated and ligated glands was similar. CONCLUSION: Despite eliminating the inflammatory reaction in the ligated gland, salivary hypofunction was not reversed, suggesting that other mechanisms must be at work in the ligation-induced salivary hypofunction. Oral Diseases (2008) 14, 520-528

P2X7 receptor activation induces inflammatory responses in salivary gland epithelium

“…Studies (10,15,31,49,81,89) of duct-ligated salivary glands have demonstrated a progressive atrophy of acinar cells, loss of saliva flow, and infiltration of immune cells within 24 h of ligation. Results from the current study demonstrate that BzATP perfusion of the main SMG excretory duct before a 24-h duct ligation induces significant immune cell infiltration, a response mediated by the P2X7R since it is absent in SMG of P2X7R Ϫ/Ϫ mice (Fig.…”

“…The induction of acute salivary gland inflammation by ligation of the primary SMG excretory duct has been used by our group and others (2,10,15,31,49,81,89,98) for many years as an in vivo model of salivary gland dysfunction. Studies (10,15,31,49,81,89) of duct-ligated salivary glands have demonstrated a progressive atrophy of acinar cells, loss of saliva flow, and infiltration of immune cells within 24 h of ligation.…”

“…Moreover, the use of P2X7R antagonists in clinical trials for rheumatoid arthritis and inflammatory bowel disease underscores the importance of this receptor in chronic inflammatory diseases (3). To investigate the role of P2X7R activation in salivary gland inflammation in vivo, we utilized the mouse model of unilateral SMG excretory duct ligation, a commonly used model of acute salivary gland inflammation (2,10,15,31,49,81,89,98). To activate the P2X7R in vivo, 20 l of 3 mM BzATP were perfused into the main SMG excretory duct of wild-type and P2X7R Ϫ/Ϫ mice followed by duct ligation and after 24 h the glands were histologically analyzed, as described in MATE-RIALS AND METHODS.…”

Proton change of parotid glands after gustatory stimulation examined by magnetic resonance imaging

“…Normal parotid gland function relies on the success of serial steps, including autonomic nervous control, blood supply, acinar cellular function, especially the function of aquaporin‐5, and patency of Stenson's duct . Evaluation of parotid gland function requires thoughtful examination of each of the aforementioned steps.…”

A mouse model linking viral hepatitis and salivary gland dysfunction

“…These findings in combination with equal susceptibility in TH1-deficient BALB ⁄ c-Rel ) ⁄ ) mice are evidence that the early phase of MCMV-induced salivary gland dysfunction occurs independently from inflammation or viral replication in the salivary gland. Recently, ischemic injury to the salivary gland via ligation was also shown to induce transient saliva deficiency in the absence of inflammation (Correia et al, 2008).…”