The dopamine D1 receptor is expressed and induces CREB phosphorylation and MUC5AC expression in human airway epithelium

Background Dopamine receptors comprise two subgroups, Gs protein-coupled “D1-like” receptors (D1, D5) and Gi-coupled “D2-like” receptors (D2, D3, D4). In airways, both dopamine D1 and D2 receptors are expressed on airway smooth muscle and regulate airway smooth muscle force. However, functional expression of the dopamine D1 receptor has never been identified on airway epithelium. Activation of Gs-coupled receptors stimulate adenylyl cyclase leading to cyclic AMP (cAMP) production, which is known to induce mucus overproduction through the cAMP response element binding protein (CREB) in airway epithelial cells. We questioned whether the dopamine D1 receptor is expressed on airway epithelium, and whether it promotes CREB phosphorylation and MUC5AC expression. Methods We evaluated the protein expression of the dopamine D1 receptor on native human airway epithelium and three sources of cultured human airway epithelial cells including primary cultured airway epithelial cells, the bronchial epithelial cell line (16HBE14o-), and the pulmonary mucoepidermoid carcinoma cell line (NCI-H292) using immunohistochemistry and immunoblotting. To characterize the stimulation of cAMP through the dopamine D1 receptor, 16HBE14o- cells and NCI-H292 cells were treated with dopamine or the dopamine D1 receptor agonists (SKF38393 or A68930) before cAMP measurements. The phosphorylation of CREB by A68930 in both 16HBE14o- and NCI-H292 cells was measured by immunoblot. The effect of dopamine or A68930 on the expression of MUC5AC mRNA and protein in NCI-H292 cells was evaluated by real-time PCR and immunofluorescence staining, respectively. Results The dopamine D1 receptor protein was detected in native human airway epithelium and three sources of cultured human airway epithelial cells. Dopamine or the dopamine D1-like receptor agonists stimulated cAMP production in 16HBE14o- cells and NCI-H292 cells, which was reversed by the selective dopamine D1-like receptor antagonists (SCH23390 or SCH39166). A68930 significantly increased phosphorylation of CREB in both 16HBE14o- and NCI-H292 cells, which was attenuated by the inhibitors of PKA (H89) and MEK (U0126). Expression of MUC5AC mRNA and protein were also increased by either dopamine or A68930 in NCI-H292 cells. Conclusions These results suggest that the activation of the dopamine D1 receptor on human airway epithelium could induce mucus overproduction, which could worsen airway obstructive symptoms

Chronic Orofacial Pain in Dental Patients: Retrospective Investigation over 12 years

Orofacial pain is often difficult to diagnose and treat. However, there have been few reports on the clinical observation of dental patients with orofacial pain. We retrospectively investigated the characteristics of 221 dental patients who had suffered from persistent orofacial pain. Data were collected from the outpatient medical records in our clinic over the past 12 years. More than half of the patients (53.8%) had suffered with pain for more than 6 months from pain onset until the first visit to our clinic. The main diagnoses were neuropathic pain (30.3%), myofascial pain (23.5%), psychogenic pain (20.4%), odontogenic toothache (17.2%), and others (7.7%) such as temporomandibular disorders and glossitis. The treatments included pharmacotherapy, splint therapy, and others such as nerve block, dental treatment, physiotherapy, and/or psychotherapy. Excluding the patients (52 of 221 initially enrolled patients) with unknown responses to treatment, 65.7% showed remission or a significant improvement in pain in response to treatment. Although only a small group of patients had odontogenic toothache, the rate of improvement was highest for this disorder. In conclusion, early consultation with a dentist is useful to prevent chronicity of odontogenic pain and to make a differential diagnosis in patients with orofacial pain

Effects of glucose-insulin infusion during major oral and maxillofacial surgery on postoperative complications and outcomes

Abstract Background Secretion of hormones, which antagonize the action of insulin, is facilitated in response to surgery, and acute resistance to the action of insulin develops. Our aim is to elucidate the effects of intraoperative glycemic control by glucose-insulin (GI) infusion on postoperative complications and outcomes in major oral and maxillofacial surgery. Findings Thirty patients aged ≥ 60 years undergoing a radical operation of oral malignant tumors with tissue reconstruction (≥ 8 h) were analyzed. In the GI group, regular insulin was continuously applied with glucose-added acetate Ringer’s solution (5–10 g glucose per 500 mL). Blood glucose was adjusted within the target concentration of 80–120 mg/dL. In the control group, combination of acetate Ringer’s solution containing 1% (W/V) glucose and lactate Ringer’s solution, which contains no glucose, was employed. Perioperative clinical parameters, incidence of hypoalbuminemia, and postoperative complications, i.e., surgical site infection, necrosis of a reconstructed flap, bacteremia, hypotension, or pneumonia, were compared. Both serum total protein and albumin concentrations (postoperative day 1 [Day1]) were higher in the GI group. The mean infusion rate of glucose during surgery (mg/kg/h) was independently associated with the decrease in both serum total protein and albumin concentrations from the control to Day1. No difference was found between the groups in the incidence of postoperative complications and the days required until discharge, except less incidence of hypoalbuminemia in the GI group. Conclusions Application of additional glucose during major oral and maxillofacial surgery preserved serum albumin concentration. However, it did not lead to less postoperative complications and less days until discharge

Role of the Hyperpolarization-Activated Cation Current (Ih) in Pacemaker Activity in Area Postrema Neurons of Rat Brain Slices

To clarify the functional properties of the hyperpolarization-activated cation current (Ih) as a pacemaker current in area postrema neurons, whole-cell recordings were made in visually identified cells in rat brain slices. The activation of Ih was identified in approximately 62 % of area postrema neurons tested. The cells displaying Ih showed a depolarizing ‘sag’ in responses to hyperpolarizing current injection in current-clamp mode. The reversal potential for the Ih was −36 mV, and this was shown to depend on the external concentration of Na+ and K+ ions. Extracellular Cs+ ions (2 mM) and ZD7288 (100 μm), a potent selective Ih channel antagonist, blocked Ih and induced a membrane potential hyperpolarization, suggesting the sustained activation of Ih near the resting potential and a contribution from Ih to membrane potential maintenance at more depolarized levels. In contrast, extracellular Ba2+ ions caused a depolarization of the membrane potential, suggesting the blockade of inward rectifier K+ currents. ZD7288 decreased the spontaneous discharge rate by prolonging the slow depolarization between two spikes, with minimal effect on the amplitude of the afterhyperpolarization or action potential waveforms. Ih stabilized the latency of rebound action potentials. Ih was weakly activated by external 8-bromoadenosine 3′,5′ cyclic monophosphate (1 mM) or forskolin (50-100 μm), indicating that the Ih channel subtypes in area postrema cells could be modulated by intracellular cAMP. Our findings indicate that Ih contributes to the subthreshold membrane and firing properties of rat area postrema neurons and may regulate their resting membrane potential and firing patterns