Effects of cevimeline on excitability of parasympathetic preganglionic neurons in the superior salivatory nucleus of rats.

The superior salivatory nucleus (SSN) contains parasympathetic preganglionic neurons innervating the submandibular and sublingual salivary glands. Cevimeline, a muscarinic acetylcholine receptor (mAChR) agonist, is a sialogogue that possibly stimulates SSN neurons in addition to the salivary glands themselves because it can cross the blood-brain barrier (BBB). In the present study, we examined immunoreactivities for mAChR subtypes in SSN neurons retrogradely labeled with a fluorescent tracer in neonatal rats. Additionally, we examined the effects of cevimeline in labeled SSN neurons of brainstem slices using a whole-cell patch-clamp technique. Mainly M1 and M3 receptors were detected by immunohistochemical staining, with low-level detection of M4 and M5 receptors and absence of M2 receptors. Most (110 of 129) SSN neurons exhibited excitatory responses to application of cevimeline. In responding neurons, voltage-clamp recordings showed that 84% (101/120) of the neurons exhibited inward currents. In the neurons displaying inward currents, the effects of the mAChR antagonists were examined. A mixture of M1 and M3 receptor antagonists most effectively reduced the peak amplitude of inward currents, suggesting that the excitatory effects of cevimeline on SSN neurons were mainly mediated by M1 and M3 receptors. Current-clamp recordings showed that application of cevimeline induced membrane depolarization (9/9 neurons). These results suggest that most SSN neurons are excited by cevimeline via M1 and M3 muscarinic receptors.

Vagal afferent activation induces salivation and swallowing-like events in anesthetized rats.

The aim of this study was to clarify the effect of vagal afferent activation on salivation and swallowing-like events. Salivation is part of a reflex induced by stimulation of the oral area during feeding or chewing. Recently, we reported that nausea induced by gastroesophageal reflux (GER) activation produced salivation and swallowing in humans. Here, we investigated the ability of visceral sensation to enhance salivation and swallowing in rodents in order to inform the mechanism of GER-mediated stomatognathic activation. First, we administered LiCl to anesthetized male rats to induce nausea. LiCl significantly increased salivation and increased the activity of the vagal afferent nerve. Next, we simultaneously recorded salivation and swallowing using an electrode attached to the mylohyoid muscle during vagal afferent stimulation in a physiological range of frequencies. Vagal afferent stimulation significantly increased salivation and swallowing-like events in a frequency-dependent manner. A muscle relaxant, vecuronium bromide, diminished the swallowing-like response but did not affect salivation. These results indicate that visceral sensation induces salivation and swallowing-like events in anesthetized rodents through vagal afferent activation.

The role of ghrelin in patients with functional dyspepsia and its potential clinical relevance (Review).

Functional dyspepsia (FD) is a functional gastrointestinal disorder (FGID). According to the Rome III consensus, FD is divided into 2 subgroups: epigastric pain syndrome (EPS) and postprandial distress syndrome (PDS). Although multiple mechanisms of FD pathogenesis have been suggested, its underlying etiology and pharmacological therapy remain unclear. Ghrelin is a gut-derived peptide found in the stomach. It plays a role in the regulation of gastric motility and appetite. The ghrelin gene encodes 3 molecular forms, acyl ghrelin, des-acyl ghrelin and obestatin. Acyl ghrelin acts as an endogenous ligand for growth hormone secretagogue receptor; furthermore, it is orexigenic, with effects on food intake, energy homeostasis and gastrointestinal motility. Des-acyl ghrelin exerts an opposite effect to acyl ghrelin. Obestatin exerts an inhibitory effect on the motor activity of the antrum and duodenum in fed animals. These peptides exert differential effects on gut motility and food intake. The therapeutic potential of ghrelin has attracted attention due to its varied bioactivities. Certain studies have shown that total ghrelin levels are significantly lower in patients with FD compared with healthy volunteers and that the acyl ghrelin levels of patients with FD are higher compared with healthy volunteers. However, a recent study demonstrated that acyl ghrelin levels in patients with PDS were lower compared with healthy volunteers; the association between FD and other ghrelin family gene products also remains unclear. Although certain studies have demonstrated the beneficial effects of acyl ghrelin administration and its agonist in patients with FD, only a few clinical reports exist. Further studies are required in order to examine the effects of ghrelin on FD.

The role of zinc in the treatment of taste disorders.

In the 1990s the number of patients diagnosed with taste disorders in the USA and Japan was over one million people each year, and the number is increasing annually. Taste disorders are caused by several factors such as genetic disease, head trauma, structural changes, glossodynia, cancer, change of lifestyle, and more. The role of zinc in the treatment of taste disorders has been studied since the oral administration of zinc by patients was reported to improve their taste disorders. Carbonic anhydrase (CA), a zinc metalloenzyme, has also been studied in association with taste disorders, since the regulation of serum CA levels was shown to influence the effect of orally administrated zinc in the treatment of taste disorders. Zinc is an essential trace element that contributes to the active center of approximately 300 enzymes. Studies have revealed that zinc is involved in various physiological functions. Moreover, some medications have been shown to induce a zinc deficiency, which has been associated with a variety of clinical conditions. Hence, since the relationship between taste disorder and serum zinc concentration has been discussed for long time, taste disorder may be useful in diagnosing zinc deficiency. Moreover, it appears that medicines of the zinc-containing supplement type contribute to the treatment of taste disorders caused by zinc deficiency. Orally administered zinc has been shown to directly stimulate food intake via neuropeptide in the hypothalamus. Therefore, zinc administration may potentially be used to treat taste disorders, as well as several other diseases by stimulating feeding. The article presents some promising patents on the role of zinc in the treatment of taste disorders.

The roles of salivary secretion, brain-gut peptides, and oral hygiene in obesity.

Obesity has a prevalence of 15-30% among European and American populations. It is an incurable chronic disease associated with considerable mortality and co-morbidity. The co-morbidity risk can be reduced substantially by a moderate weight loss of 5-15%. Notably, additional weight gain exacerbates the morbidity of any concurrent disease. Obesity is also recognized as the basis for metabolic syndrome. Recent research has shown that adipocytes secrete various hormones and cytokines that contribute to obesity. Leptin is an adipostatic hormone that acts on receptors in the hypothalamus to suppress food intake and increase energy consumption. Reduced sensitivity to this molecule can trigger the onset of obesity. Neuropeptides such as leptin also affect salivary secretion. Various neuropeptides have been identified in saliva; the associated receptors are located in the salivary glands or in the nerves innervating the salivary glands. Obesity is associated with hyposalivation and thereby related to several aspects of oral health, such as caries and periodontitis. Hyposalivation is a severe morbidity that can lead to a precipitous decline in oral hygiene, which further leads to multifocal dental caries and periodontitis, or even cardiac disorders. In this article, we review the relationship between salivary secretion and neuropeptides known to play a role in obesity.

The role of ghrelin, salivary secretions, and dental care in eating disorders.

Eating disorders, including anorexia and bulimia nervosa, are potentially life-threatening syndromes characterized by severe disturbances in eating behavior. An effective treatment strategy for these conditions remains to be established, as patients with eating disorders tend to suffer from multiple relapses. Because ghrelin was originally discovered in the stomach mucosa, it has been widely studied over the past decade in an effort to uncover its potential roles; these studies have shed light on the mechanism by which ghrelin regulates food intake. Thus, studying ghrelin in the context of eating disorders could improve our understanding of the pathogenesis of eating disorders, possibly resulting in a promising new pharmacological treatment strategy for these patients. In addition, early detection and treatment of eating disorders are critical for ensuring recovery of young patients. Oral symptoms, including mucosal, dental, and saliva abnormalities, are typically observed in the early stages of eating disorders. Although oral care is not directly related to the treatment of eating disorders, knowledge of the oral manifestations of eating disorder patients may aid in early detection, resulting in earlier treatment; thus, oral care might contribute to overall patient management and prognosis. Moreover, ghrelin has also been found in saliva, which may be responsible for oral hygiene and digestion-related functions. This review discusses the pharmacological potential of ghrelin in regulating food-intake and the role of saliva and oral care in young patients with eating disorders.

Muscarinic receptor immunoreactivity in the superior salivatory nucleus neurons innervating the salivary glands of the rat.

The superior salivatory nucleus (SSN) contains preganglionic parasympathetic neurons to the submandibular and sublingual salivary glands. Cevimeline, a muscarinic acetylcholine receptor agonist, stimulates the salivary glands and is presently used as sialogogue in the treatment of dry mouth. Since cevimeline passes through the blood-brain barrier, it is also able to act on muscarinic acetylcholine receptors in the central nervous system. Our preliminary experiment using the whole-cell patch-clamp technique has shown that cevimeline excites SSN neurons in rat brain slices, suggesting that SSN neurons have muscarinic acetylcholine receptors; however, it is unclear which subtypes of muscarinic acetylcholine receptors exist in SSN neurons. In the present study, we investigated immunohistochemically muscarinic acetylcholine receptor subtypes, M1 receptor (M1R), M2R, M3R, M4R, and M5R in SSN neurons. SSN neurons innervating the salivary glands, retrogradely labeled with a fluorescent tracer from the chorda-lingual nerve, mostly expressed M3R immunoreactivity (-ir) (92.3%) but not M1R-ir. About half of such SSN neurons also showed M2R- (40.1%), M4R- (54.0%) and M5R-ir (46.0%); therefore, it is probable that SSN neurons co-express M3R-ir with at least two of the other muscarinic receptor subtypes. This is the first report to show that SSN neurons contain muscarinic acetylcholine receptors.

Cevimeline enhances the excitability of rat superior salivatory neurons.

Cevimeline, a therapeutic drug for xerostomia, is an agonist of muscarinic acetylcholine receptors (mAChRs), and directly stimulates the peripheral mAChRs of the salivary glands. Since cevimeline is distributed in the brain after its oral administration, it is possible that it affects the central nervous system. However, it is unknown how cevimeline affects the superior salivatory (SS) neurons, which control submandibular salivation. In the present study, we examined the effects of cevimeline on the SS neurons using the whole-cell patch-clamp technique in brain slices. In Wistar rats (6-10 days), the SS neurons were retrogradely labeled by Texas Red applied to the chorda-lingual nerve. Two days after injection, whole-cell recordings were obtained from the labeled cells, and miniature excitatory postsynaptic currents (mEPSCs) were examined. Cevimeline induced the inward currents dose-dependently and increased the frequency of mEPSCs. Therefore, it is suggested that cevimeline enhances the excitability via post- and presynaptic muscarinic receptors in the rat SS neurons. In conclusion, cevimeline may enhance the excitability of the SS neurons.

Gemcitabine plus UFT combination chemotherapy as second- or third-line therapy in non-small cell lung cancer: a pilot study.

BACKGROUND: Gemcitabine plus UFT combination chemotherapy are highly effective and less toxic in the first line setting in patients with non-small cell lung cancer (NSCLC). The purpose of the study is to confirm the feasibility of this regimen as second- or third-line therapy in NSCLC. METHODS: Fifteen patients with performance status of 0-1 were enrolled. UFT (tegafur 250 mg/m(2)/day) was administered orally twice a day from days 1-14, and gemcitabine of 900 mg/m(2) was administered intravenously on days 8 and 15 every three weeks on an outpatient setting. The treatment was repeated for at least 3 cycles and continued unless the disease progressed. RESULTS: The response rate and the disease control rate were 6.7% and 66.7%, respectively. Grade 3-4 toxicities included neutropenia in one patient and elevation of transaminases in one patient. The mean relative dose intensity of gemcitabine and UFT were 0.93 and 0.97, respectively. CONCLUSION: High disease control rate and less toxicity suggested the potential of gemcitabine and UFT combination chemotherapy as second- or third-line therapy in NSCLC.

Hormonal, pH, and calcium regulation of connexin 43-mediated dye transfer in osteocytes in chick calvaria.

UNLABELLED: Gap junctional intercellular communication among osteocytes in chick calvaria, their natural 3D environment, was examined using FRAP analysis. Cell-cell communication among osteocytes in chick calvaria was mediated by Cx43 and was regulated by extracellular pH, extracellular calcium ion concentration, and PTH. INTRODUCTION: The intercellular network of communication among osteocytes is mediated by gap junctions. Gap junctional intercellular communication (GJIC) is thought to play an important role in integration and synchronization of bone remodeling. We hypothesized that extracellular pH (pH(o)) and extracellular calcium ion concentration ([Ca2+](e)), both of which are dynamically altered by osteoclasts during bone remodeling, affect GJIC among osteocytes. Using fluorescence replacement after photobleaching (FRAP) analysis, we examined the effect of changes in pH(o) and [Ca2+](e) and addition of PTH on GJIC in osteocytes in chick calvaria. Additionally, we examined the role of intracellular calcium on the regulation of GJIC among osteocytes. MATERIALS AND METHODS: Anti-Connexin43 (Cx43) immunolabeling was used to localize gap junctions in chick calvaria. GJIC among osteocytes in chick calvariae was assessed using FRAP. RESULTS: Cx43 immunoreactivity was detected in most of the osteocyte processes. FRAP analysis showed dye-coupling among osteocytes in chick calvariae. In untreated osteocytes, fluorescence intensity recovered 43.7 +/- 2.2% within 5 min after photobleaching. Pretreatment of osteocytes with 18 alpha-GA, a reversible inhibitor of GJIC, significantly decreased fluorescence recovery to 10.7 +/- 2.2%. When pH(o) was decreased from 7.4 to 6.9, fluorescence recovery significantly decreased from 43.3 +/- 2.9% to 19.7 +/- 2.3%. Conversely, when pH(o) was increased from 7.4 to 8.0, fluorescence recovery was significantly increased to 61.9 +/- 4.5%. When [Ca2+](e) was increased from 1 to 25 mM, fluorescence recovery was significantly decreased from 47.0 +/- 6.1% to 16.1 +/- 2.1%. In bone fragments exposed to 1.0-10 nM rPTH for 3 h, replacement of fluorescence was significantly increased to 60.7 +/- 7.2%. Chelating intracellular calcium ions affected GJIC regulation by [Ca2+](e) and PTH. CONCLUSIONS: Our study of cell-cell communication between osteocytes in chick calvaria showed for the first time that GJIC among osteocytes is regulated by the extracellular environment and by hormonal stimulation during bone remodeling. This method may be more biologically relevant to living bone than current methods.

[A case of recurrent small cell lung cancer with symptoms improved by nogitecan hydrochloride].

A 68-year-old woman with recurrent advanced small cell lung cancer (SCLC), previously treated with 7 courses of carboplatin + etoposide, 4 courses of cisplatin + irinotecan and radiotherapy (primary site and whole brain irradiation), received 3 courses of a single nogitecan hydrochloride i.v. bolus with 4 consecutive days of administration, for a total dose of 7.5 mg. MR-imaging revealed a response in the brain metastasis, and tumor markers (NSE and ProGRP) were improved after the first course. Headache, her main complaint, was also alleviated. These observations suggest that nogitecan hydrochloride alone might be useful for treatment of recurrent SCLC in cases of poor performance status (PS), especially when the patient requires remission of symptoms.