Salivary Secretion In Rats Research Articles

Paradoxical sleep deprivation induces oxidative stress in the submandibular glands of Wistar rats.

Paradoxical sleep deprivation has been associated with impaired salivary secretion in rats. However, the mechanism that underlies this is not known. Therefore, this study assessed salivary and serum oxidative stress levels following paradoxical sleep deprivation in rats. Twenty-one male Wistar rats randomly divided into three groups of seven rats each as; Control (C); partialsleep-deprived (PSD); and total sleep-deprived (TSD) wereused. Malondialdehyde (MDA) concentration, Superoxide dismutase (SOD), and catalase activities were evaluated insaliva, serum, and submandibular glands after seven daysof sleep deprivation. Data were expressed as mean±standard error of the mean and analyzed using one-way ANOVA, Tukey HSD post hoc, and Pearson's correlation tests. Serum MDA levels were significantly higher in both the TSD and PSD groups compared to the control group whereas only the TSD group showed higher submandibular MDA levels compared to the PSD group and the control group. Submandibular SOD activity was significantly lower in both the TSD and PSD groups compared to the control group. Serum catalase activity was significantly lower in the TSD group only compared to the control group. These results have demonstrated for the first time that paradoxical sleep deprivation was associated with changes in the oxidant/antioxidant defense system in the submandibular salivary glands of male Wistar rats which may contribute to impairment in salivary secretion.

Association Between N-Desmethylclozapine and Clozapine-Induced Sialorrhea: Involvement of Increased Nocturnal Salivary Secretion via Muscarinic Receptors by N-Desmethylclozapine.

Clozapine-induced sialorrhea (CIS) is a common side effect of clozapine. There is no established standard treatment of CIS since the underlying mechanism remains unknown. This study aimed to elucidate the mechanisms involved in CIS. In our clinical study, a prospective observational study evaluated the association between serum and saliva concentrations of clozapine or its metabolites and Drooling Severity and Frequency Scale (DSFS) score. In our in vivo study, we first developed a new CIS animal model; subsequently, we measured salivary secretion and concentrations of clozapine or its metabolites in the animal model. In our in vitro study, we measured the calcium ion (Ca2+) response to evaluate the effect of clozapine or its metabolites on human salivary gland cell line (HSY cells) and then examined whether their effect was inhibited by atropine. In our clinical study, serum and saliva N-desmethylclozapine concentrations were significantly correlated with nocturnal DSFS score. In our in vivo study, daily single oral administration of 100 mg/kg clozapine for 7 days significantly increased salivary secretion in rats. Furthermore, N-desmethylclozapine concentrations in serum and submandibular glands of the rats were higher than clozapine concentrations. In our in vitro study, N-desmethylclozapine only elicited an increase in the intracellular Ca2+ in HSY cells. N-desmethylclozapine-induced Ca2+ responses were inhibited by atropine. These results suggest that N-desmethylclozapine is implicated in CIS by increasing nocturnal salivation via the muscarinic receptors. Moreover, our developed animal model that reflects CIS in clinical condition plays a key role as a bridge between basic and clinical research. SIGNIFICANCE STATEMENT: Clozapine-induced sialorrhea (CIS) is a severe and frequent adverse reaction, but the mechanism underlying CIS is less well understood. This paper reports that N-desmethylclozapine, a metabolite of clozapine, is implicated in CIS by increasing nocturnal salivation via the muscarinic receptors and that oral administration of clozapine at 100 mg/kg once daily for 7 days to rat is the optimum method for establishing the new animal model reflecting the clinical scenario of CIS.

Pharmacological characterization of DA-8010, a novel muscarinic receptor antagonist selective for urinary bladder over salivary gland

Several antimuscarinics have been commonly used for overactive bladder patients, but dry mouth as a major anticholinergic side effect remains a shortcoming to limit long-term use. The aim of this study was to elucidate the pharmacological properties of DA-8010, a novel muscarinic receptor antagonist selective for urinary bladder over salivary gland. DA-8010 exhibited a high binding affinity for human muscarinic M3 receptor with pKi of 8.81 ± 0.05 and great potencies for human M3 receptor and rat bladder preparation. The potency of DA-8010 for bladder smooth muscle cells was 3.6-fold higher than that for salivary gland cells isolated from mice. Intravenous administration of DA-8010 dose-dependently inhibited rhythmic urinary bladder contractions induced by distension in rats, indicating the most potent activity (ID30 = 0.08 mg/kg) among the antimuscarinics tested. Taken together with the inhibitory effects of DA-8010 and other antimuscarinics on carbachol-induced salivary secretion in rats, the in vivo functional selectivity of DA-8010 for urinary bladder over salivary gland was 3.1-fold, 3.2-fold and 5.2-fold greater than those observed for solifenacin, oxybutynin and darifenacin, respectively. Furthermore, oral administration of DA-8010 in mice resulted in more selective and persistent binding for muscarinic receptors in the bladder rather than in the submaxillary gland, in comparison with other antimuscarinics. These findings suggest that DA-8010 is a potent muscarinic M3 receptor antagonist to be highly selective for bladder over salivary gland, which might be a promising agent with greater efficacy and less dry mouth in the treatment of overactive bladder.

Tu1249 - Rikkunshito, a Kampo Medicine, Prevents the PH of Oral Fluid from Decreasing by Promoting Salivary Secretion in Rats with Gastroesophageal Reflux Disease

Tu1249 - Rikkunshito, a Kampo Medicine, Prevents the PH of Oral Fluid from Decreasing by Promoting Salivary Secretion in Rats with Gastroesophageal Reflux Disease

Differential involvement of two cortical masticatory areas in submandibular salivary secretion in rats

To evaluate the role of the masticatory area in the cerebral cortex in the masticatory-salivary reflex, we investigated submandibular salivary secretion, jaw-movement trajectory and electromyographic activity of the jaw-opener (digastric) and jaw-closer (masseter) muscles evoked by repetitive electrical stimulation of the cortical masticatory area in anesthetized rats. Rats have two cortical masticatory areas: the anterior area (A-area) in the orofacial motor cortex, and the posterior area (P-area) in the insular cortex. Our defined P-area extended more caudally than the previous reported one. P-area stimulation induced vigorous salivary secretion (about 20µl/min) and rhythmical jaw movements (3–4Hz) resembling masticatory movements. Salivary flow persisted even after minimizing jaw movements by curarization. A-area stimulation induced small and fast rhythmical jaw movements (6–8Hz) resembling licking of solutions, but not salivary secretion. These findings suggest that P-area controls salivary secretion as well as mastication, and may be involved in the masticatory-salivary reflex.

Effects of α1-adrenoceptor antagonists on phenylephrine-induced salivary secretion and intraurethral pressure elevation in anesthetized rats

α1-Adrenoceptor antagonists are widely used for the treatment of voiding dysfunction associated with benign prostatic hyperplasia. Activation of α1-adrenoceptors is reported to induce salivary secretion in rats and humans. However, the effects of α1-adrenoceptor antagonists on salivary secretion remain unknown. Here, we investigated the effects of the α1-adrenoceptor antagonists prazosin, silodosin, tamsulosin and urapidil on phenylephrine-induced salivary secretion and compared the results with the effects on phenylephrine-induced intraurethral pressure (IUP) elevation in anesthetized rats. All antagonists inhibited phenylephrine-induced salivary secretion and IUP elevation in a dose-dependent fashion. Comparison of DR10 values (the dose required to shift the dose–response curve 10-fold to the right) in both tissues showed that the inhibitory effect of silodosin was significantly more potent in the salivary gland than in the urethra (18-fold), but tamsulosin (2.3-fold), prazosin (1.7-fold) and urapidil (1.1-fold) did not show comparable tissue selectivity. These results suggest that α1-adrenoceptor antagonists inhibit not only urethral contraction but also salivary secretion, and that high tissue selectivity for the salivary gland over the urethra as shown by silodosin may contribute to the incidence of dry mouth.

Reduced methacholine-induced submandibular salivary secretion in rats with experimental periodontitis

ObjectiveSaliva is the first barrier to the entry of bacteria and viruses into the body and is considered a necessary instrument in oral health. Intraperitoneal injection of lipopolysaccharide endotoxins results in submandibular gland (SMG) hyposalivation. The objective of present studies was to assess if periodontitis, a chronic inflammatory disease caused by oral bacteria, alters cholinergic-induced SMG salivary secretion. DesignAn experimental periodontitis model (EP) (cotton thread ligature around the neck of the first lower molars) was used. Male Wistar rats (300–380g) were randomly divided into 3 groups: control, 7 days-bilateral EP and 7 days-unilateral EP (to study if there were different effects at the ipsilateral and contralateral side). The following determinations were performed in SMG: (1) dose–response curves to the cholinergic agonist methacholine, (2) prostaglandin E (PGE) content, (3) inducible nitric oxide synthase (iNOS) activity and (4) histology of gland sections. ResultsThe molars with EP, no matter the group, exhibited significant and similar bone loss (p<0.001). Bilateral EP reduced methacholine-induced salivary secretion (p<0.05, dose 1μg/kg; p<0.001, dose 3–30μg/kg), increased PGE content (p<0.01), stimulated iNOS activity (p<0.05). Ipsilateral glands of unilateral EP animals presented lower methacholine-induced salivary secretion (p<0.05, dose 3μg/kg; p<0.001, dose 10–30μg/kg), and higher PGE content than contralaterals (p<0.001). In turn, at 3 and 10μg/kg of methacholine, contralateral glands showed significantly lower secretion than control animals (p<0.001). Histological studies of glands revealed partial loss of secretor granular material and periductal oedema in the bilateral and unilateral EP groups as compared to controls. ConclusionsAs far as we know, the present results demonstrate for the first time that EP reduces methacholine-induced SMG salivary secretion.

N‐Desmethylclozapine exerts dual and opposite effects on salivary secretion in the rat

N-Desmethylclozapine is a major metabolite of the atypical antipsychotic drug clozapine, used in the treatment of therapy-resistant schizophrenia. Patients under clozapine treatment report a troublesome sialorrhea. Recent experiments show clozapine to exert mixed agonist/antagonist actions on salivary secretion in rats. The present study was performed to define the secretory role of N-desmethylclozapine and to compare it with that of its parent compound. N-Desmethylclozapine evoked secretion by acting directly on the muscarinic acetylcholine M1-receptors of 'silent' duct-cannulated parotid and submandibular glands of the anaesthetized rat. In chronic surgically denervated glands, the secretory response was enlarged. The methacholine-evoked secretion, as well as the parasympathetic nerve-evoked secretion, were reduced by N-desmethylclozapine and involved blockade of M3-receptors, while the sympathetic nerve-evoked response was reduced, involving blockade of alpha(1)-adrenergic receptors. Synergistic interactions between N-desmethylclozapine and the beta-adrenergic receptor agonist, isoprenaline, occurred. Compared with clozapine, the excitatory efficacy of N-desmethylclozapine was higher and the inhibitory efficacy was lower (parasympathetic activity) or about the same (sympathetic activity). Theoretically, in humans treated with clozapine, an increase in the N-desmethylclozapine : clozapine ratio would contribute to salivation during the night and at rest, and, furthermore, the magnitude of the reduction in the reflexly elicited secretion is likely to diminish.

Effect of the Scent from Grapefruit Oil on Salivary Secretion in Rats

Effect of the Scent from Grapefruit Oil on Salivary Secretion in Rats

Anandamide injected into the lateral ventricle of the brain inhibits submandibular salivary secretion by attenuating parasympathetic neurotransmission

Our objective was to determine the effect of arachidonylethanolamide (anandamide, AEA) injected intracerebroventricularly (icv) into the lateral ventricle of the rat brain on submandibular gland (SMG) salivary secretion. Parasympathetic decentralization (PSD) produced by cutting the chorda tympani nerve strongly inhibited methacholine (MC)-induced salivary secretion while sympathetic denervation (SD) produced by removing the superior cervical ganglia reduced it slightly. Also, AEA (50 ng/5 microL, icv) significantly decreased MC-induced salivary secretion in intact rats (MC 1 microg/kg: control (C), 5.3 +/- 0.6 vs AEA, 2.7 +/- 0.6 mg; MC 3 microg/kg: C, 17.6 +/- 1.0 vs AEA, 8.7 +/- 0.9 mg; MC 10 microg/kg: C, 37.4 +/- 1.2 vs AEA, 22.9 +/- 2.6 mg). However, AEA did not alter the significantly reduced salivary secretion in rats with PSD, but decreased the slightly reduced salivary secretion in rats with SD (MC 1 microg/kg: C, 3.8 +/- 0.8 vs AEA, 1.4 +/- 0.6 mg; MC 3 microg/kg: C, 14.7 +/- 2.4 vs AEA, 6.9 +/- 1.2 mg; P < 0.05; MC 10 microg/kg: C, 39.5 +/- 1.0 vs AEA, 22.3 +/- 0.5 mg; P < 0.001). We showed that the inhibitory effect of AEA is mediated by cannabinoid type 1 CB1 receptors and involves GABAergic neurotransmission, since it was blocked by previous injection of the CB1 receptor antagonist AM251 (500 ng/5 microL, icv) or of the GABA A receptor antagonist, bicuculline (25 ng/5 microL, icv). Our results suggest that parasympathetic neurotransmission from the central nervous system to the SMG can be inhibited by endocannabinoid and GABAergic systems.

Acupuncture as an alternative to stimulate salivary secretion in rats

Acupuncture as an alternative to stimulate salivary secretion in rats

In vivo demonstration of muscarinic receptor binding activity of N-desethyl-oxybutynin, active metabolite of oxybutynin

The present study was undertaken to characterize in vivo muscarinic receptor binding of N-desethyl-oxybutynin (DEOB), active metabolite of oxybutynin (anticholinergic agent), in the bladder, submaxillary gland, heart and colon of rats, in relation to the plasma concentrations and inhibition of salivation. In the in vitro experiment, DEOB, as well as oxybutynin, inhibited the concentration-dependently specific [ 3H]N-methylscopolamine (NMS) binding in rat tissues and the affinity of DEOB in the rat bladder, submaxillary gland and colon was significantly (about 2 times) greater than that of oxybutynin. Following i.v. injection of DEOB (2.73–27.3 μmol/kg), there were dose- and time-dependent increases in the apparent dissociation constant (Kd) for specific [ 3H]NMS binding in the bladder, submaxillary gland, heart and colon of rats, compared with control values, and the effect was similar to that by i.v. injection of oxybutynin (2.54–25.4 μmol/kg). Plasma concentrations of DEOB and oxybutynin in these rats showed dose- and time-dependent increases. The pilocarpine-induced salivary secretion in rats was equipotently reduced by the i.v. injection of DEOB and oxybutynin. In conclusion, it has been shown that intravenously injected DEOB, as well as oxybutynin, binds significantly to muscarinic receptors in rat tissues including the bladder and salivary gland and the receptor binding activity of DEOB is roughly similar to that of oxybutynin.

DEMONSTRATION OF BLADDER SELECTIVE MUSCARINIC RECEPTOR BINDING BY INTRAVESICAL OXYBUTYNIN TO TREAT OVERACTIVE BLADDER

The current study was done to elucidate the in vivo mechanism of action of intravesical instillation of oxybutynin to treat overactive bladder. In rats receiving oral and intravesical oxybutynin we measured muscarinic receptors in the bladder and other tissues by radioligand binding assay using [3H]NMS ([N-methyl-3H] scopolamine methyl chloride) with the simultaneous measurement of plasma concentrations of oxybutynin and its active metabolite N-desethyl-oxybutynin. Pilocarpine induced salivary secretion was also measured. Following oral administration of oxybutynin there was a significant increase in the apparent dissociation constant (Kd) for specific [3H]NMS binding in the bladder, submaxillary gland, heart and colon of rats at 1 and 3 hours with a consistent decrease in the maximal number of binding sites (Bmax) in the submaxillary gland. Furthermore, a marked and prolonged decrease in pilocarpine induced salivary secretion in rats was observed by oral oxybutynin. In contrast, intravesical instillation of oxybutynin produced a significant increase in Kd for specific [3H]NMS binding in the bladder of rats at 0.5 to 4 hours later and also in the submaxillary gland only at 0.5 hours later. The enhancement in Kd was much larger and longer lasting in the bladder than in the submaxillary gland. Moreover, intravesical oxybutynin had little muscarinic receptor binding activity in the heart and colon, and little significant suppression of pilocarpine induced salivation in rats. The plasma concentrations of oxybutynin and N-desethyl-oxybutynin were much higher in rats receiving oxybutynin orally than intravesically. Intravesical oxybutynin in rats may cause selective binding of bladder muscarinic receptors via a direct local effect, while oral oxybutynin may exert predominant binding of salivary gland receptors.

The xerogenic potency and mechanism of action of tramadol inhibition of salivary secretion in rats

Tramadol is a centrally acting analgesic with weak opioid agonist properties, which also has monoaminergic activity, exerted via inhibition of neuronal uptake of serotonin and norepinephrine. Tramadol is generally well tolerated and the most common adverse events are nausea, dizziness, drowsiness, sweating, vomiting and dry mouth. Currently it was examined by which principal mechanism tramadol induces oral dryness. The effects of intravenous administration (+/-)-tramadol were studied in rats on the flow of saliva in response to a peripheral cholinergic stimulus or to reflex activation involving the relay of impulses in the central nervous system. In pentobarbitone-anaesthetized rats, the salivary secretion to acetylcholine (0.1-10 micromol/kg IV) was increased by up to 110% by tramadol (1-5 mg/kg IV) and the protein concentration therein by up to 400%. The administration alpha- and beta-adrenoceptor antagonists resulted in almost identical acetylcholine-evoked responses as in the absence of tramadol. The secretory response to the application of citric acid on the tongue of the rat was reduced by 38% and by 64%, respectively, at 5 and 10 mg/kg IV of tramadol (p < 0.05-0.01). Thus, tramadol exerts its principal xerogenic effect by activating inhibitory pathways in the central nervous system and has no anticholinergic effect on the salivary glands at dosages that may be clinically relevant. Furthermore, the tramadol-induced increase of the acetylcholine-evoked secretion occurred at a glandular level and depended most likely on a release of noradrenaline from glandular nerve terminals.

Nizatidine and cisapride increase salivary secretion in rats.

Saliva is a neurally induced solution with buffering capacity against acidic solutions. Salivation therefore plays an important role in defending the esophageal mucosa against refluxed gastric acid and is evoked by cholinergic stimulation. Both nizatidine and cisapride are reported to increase acetylcholine concentrations in the postganglionic cholinergic synapses. We performed this study to clarify the effect of administration of nizatidine and cisapride on salivary secretion. Eight-week-old male Sprague-Dawley rats were used for the experiments. Histamine-stimulated gastric acid secretion was measured after intraduodenal administration of nizatidine or famotidine to determine the equipotent acid-suppressing doses. Salivary secretion was then measured for 3 hr after intraduodenal administration of nizatidine (30 mg/kg), famotidine (3 mg/kg), or cisapride (1 mg/kg). Both nizatidine and famotidine dose-dependently inhibited histamine-stimulated gastric acid secretion. Total salivary secretion was significantly increased by nizatidine (P = 0.02) and cisapride (P = 0.02) but not by famotidine (P = 0.50) compared with controls.

Suppression of reflex saliva from rat parotid gland following intracerebroventricular injection of hypertonic NaCl and sucrose

These effects were studied in conscious rats. Salivary volume and flow rate induced by eating solid diet were decreased by both the hypertonic solutions, compared with the effects of normal saline. This finding suggests that central osmotic perception affects parotid salivary secretion in rats.

Selective muscarinic antagonists. II. Synthesis and antimuscarinic properties of biphenylylcarbamate derivatives.

A novel series of biphenylylcarbamate derivatives were synthesized and evaluated for binding to M1, M2 and M3 receptors and for antimuscarinic activities. Receptor binding assays indicated that biphenyl-2-ylcarbamate derivatives had high affinities for M1 and M3 receptors and good selectivities for M3 receptor over M2 receptor, indicating that the biphenyl-2-yl group is a novel hydrophobic replacement for the benzhydryl group in the muscarinic antagonist field. In this series, quinuclidin-4-yl biphenyl-2-ylcarbamate monohydrochloride (8l, YM-46303) exhibited the highest affinities for M1 and M3 receptors, and selectivity for M3 over M2 receptor. Compared to oxybutynin, YM-46303 showed approximately ten times higher inhibitory activity on bladder pressure in reflexly-evoked rhythmic contraction, and about 5-fold greater selectivity for urinary bladder contraction against salivary secretion in rats. Moreover, selective antagonistic activity was also observed in vitro. Further evaluation of antimuscarinic effects on bradycardia and pressor in pithed rats, and on tremor in mice, showed that YM-46303 can be useful for the treatment of urinary urge incontinence as a bladder-selective M3 antagonist with potent activities and fewer side effects.

Kallikrein and salivary secretion in rats during heat exposure

RP 67580, a NKI receptor antagonist, inhibited the sialogogic effect of Substance P (SP). Heat-induced salivation was indirectly measured through the changes in body weight. Thermolytic salivation was reduced by atropine and RP 67580 and thus would be mainly controlled by acetylcholine and tachykinins. This salivation was associated with a large depletion of kallikrein in submaxillary glands. This depletion was not inhibited by atropine and RP 67580. Feeding has been reported to reduce amylase activity in parotid glands but did not modify the kallikrein content in submaxillary glands. Heat exposure did not modify amylase activity. There is a dissociation between the releases of amylase and kallikrein from salivary glands.

Involvement of the central nervous system in the salivary secretion induced by pilocarpine in rats.

The effect of rats of an anteroventral third ventricle (AV3V) electrolytic lesion on salivary secretion induced by intraperitoneal (i.p.) or intracerebroventricular (i.c.v.) injection of a cholinergic agonist (pilocarpine) was investigated. Sham- or AV3V-lesioned rats anesthetized with urethane and with a stainless steel cannula implanted into the lateral ventricle (LV) were used. The amount of salivary secretion was studied over a seven-minute period after i.c.v. or i.p. injection of pilocarpine. In sham-operated rats, i.p. injection of pilocarpine (1 mg/kg b.w.) (after 6 h, 2, 7, and 15 days) produced salivary secretion (486 +/- 21, 778 +/- 85, 630 +/- 50, and 560 +/- 55 mg/7 min, respectively). This effect was reduced 6 h, 2, and 7 days after an AV3V lesion (142 +/- 22, 113 +/- 32, and 290 +/- 62 mg/7 min, respectively), but not 15 days after an AV3V lesion (516 +/- 19 mg/7 min). I.c.v. injection of pilocarpine (120 micrograms in 1 microL), in sham-operated rats after 6 h, 2, 7, and 15 days also produced salivary secretion (443 +/- 20, 417 +/- 81, 496 +/- 14, and 427 +/- 47 mg/7 min, respectively). The effects of i.c.v. pilocarpine were also reduced 6 h, 2, and 7 days after an AV3V lesion (143 +/- 19, 273 +/- 14, and 322 +/- 17 mg/7 min, respectively), but not after 15 days (450 +/- 28 mg/7 min). The results demonstrate that the central nervous system, and particularly the AV3V region, is important for the effect of pilocarpine on salivary secretion in rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Modes of action of local hypothalamic and skin thermal stimulation on salivary secretion in rats.

1. In urethane or ketamine-anaesthetized rats, salivary secretion was observed when local brain sites or trunk skin were stimulated thermally or electrically. 2. Salivary secretion was facilitated by bilateral local brain warming. Sensitive sites were restricted to the preoptic area and anterior hypothalamus, but in a region distinct from a previously reported sensitive site for producing saliva-spreading behaviour. 3. Unilateral warming of the preoptic area produced greater salivary secretion from the ipsilateral submandibular/sublingual salivary glands than from the contralateral glands. Electrical stimulation of the same sites elicited salivation only from the ipsilateral glands. 4. Trunk skin, not including the scrotum, was unilaterally cooled when spontaneous salivary secretion was observed in a hot environment. Salivary secretion from both sides was equally suppressed in response to the unilateral skin cooling. 5. We conclude that efferent signals from the anterior part of the hypothalamus project dominantly to the ipsilateral salivary gland for thermally induced salivary secretion. Thermal signals from the skin of either side of the trunk, on the other hand, appear to be integrated and to affect salivary secretion bilaterally.