Parotid salivary secretion induced by stimulation of periodontal regions with toothbrush in humans

The act of brushing teeth induces salivary secretion (1). However, there is no evidence to show which particular regions of the teeth and oral cavity in brushing induces the most effective salivary secretion. We investigated the effects of tooth brushing in different oral regions on parotid salivary secretion in humans. Saliva was collected using a modified Lashley cup. Brushing of the gingival margin was performed according to the Bass method, which may stimulate periodontal mechanoreceptors. The occulsal surface of the molars, gingiva, tongue, and palatal rugae were also brushed with a toothbrush. Compared to the flow rate of saliva from the unstimulated parotid gland, the salivary flow rates were enhanced when every oral region was brushed. The flow rate produced by brushing the palatal gingival margin of the ipsilateral maxillary molars was greater than that produced by brushing the occlusal surface of ipsilateral maxillary molars and palatal gingiva beside the molars. The flow was also significantly greater than that produced by brushing the palatal gingival margins of the contralateral maxillary molars, the maxillary/mandibular incisors, the dorsum of tongue and the palatal rugae. No significant difference was observed between brushing the gingival margins of the ipsilateral maxillary versus mandibular molars. These data indicate that brushing the gingival margin of molars is the most effective region to stimulate parotid saliva secretion. This likely activates periodontal mechanoreceptors, and this technique may be a simple way to improve salivary secretion in oral rehabilitation. The degree of salivary secretion caused by brushing the teeth is specific to particular oral regions. Brushing of the gingival margins is the most effective location to induce parotid salivary secretion

Effects of pilocarpine and cevimeline on Ca2+ mobilization in rat parotid acini and ducts

Previous reports suggested that there is no significant difference in the binding affinity of pilocarpine and cevimeline on muscarinic receptors (1). However, in vivo studies from our laboratory suggested that pilocarpine-induced salivation from the parotid gland is greater than that induced by cevimeline in rats (2, 3). Therefore, in the present study, sialogogue-induced intracellular Ca2+ mobilization was investigated in isolated parotid gland cells in vitro. Pilocarpine and cevimeline increased the intracellular Ca2+ concentration of parotid gland acinar and duct cells over 1 μM in a dose-dependent manner. Pilocarpine-induced responses were higher than cevimeline-induced responses. Ca2+ responses to both agents were completely blocked by 1 μM 4-DAMP, an M3 muscarinic receptor antagonist. In the absence of extracellular Ca2+, both sialogogues induced transient Ca2+ increase in parotid gland acinar cells. These results suggest that the sialogogues stimulate some common routes via the Ca2+ signaling in parotid gland acinar cells. We also report a significant difference of Ca2+ responses in concentration between pilocarpine and cevimeline in parotid gland acinar cells. The different Ca2+ responses between the sialogogues would explain the different saliva volumes from the parotid gland between them that we have observed in previous in vivo studies (2, 3)

Ca2+ mobilization by nicotine through synaptic activation in rat parotid acini

Nicotine has been reported to increase the intracellular Ca2+ concentration ([Ca2+]i) in sublingual acini due to neurotransmitter release from nerve terminals associated with the cell preparation (1). However, it is unclear whether or not the same reaction exists in parotid cells. Therefore, we investigated effect of nicotine on Ca2+ mobilization in digested parotid acini from rats. After removing the parotid gland from Wistar rats, the tissues were minced and digested with collagenase. Then, the intracellular Ca2+ indicator fura-2 was added to the preparation, and the change in [Ca2+]i was monitored using fluorescent microscope. In many but not all parotid acini, K+ stimulation induced transient increases in [Ca2+]i. The K+-induced Ca2+ response in parotid acini was completely blocked by Cd2+-containing solution. These results suggest that the parotid cell preparation has nerve terminals. In all high-K+-sensitive parotid acini, over 3μM of nicotine increased [Ca2+]i, and the response was blocked by a Cd2+-containing solution and nicotinic receptor antagonists. All high-K+-insensitive acinar cells were resistant to the effect of nicotine on Ca2+ mobilization. These results suggest that nicotine induces increases in [Ca2+]i in parotid acini due to neurotransmitter release from associated nerve terminals

Ca2+ mobilization by nicotine through synaptic activation in rat parotid acini

Nicotine has been reported to increase the intracellular Ca2+ concentration ([Ca2+]i) in sublingual acini due to neurotransmitter release from nerve terminals associated with the cell preparation (1). However, it is unclear whether or not the same reaction exists in parotid cells. Therefore, we investigated effect of nicotine on Ca2+ mobilization in digested parotid acini from rats. After removing the parotid gland from Wistar rats, the tissues were minced and digested with collagenase. Then, the intracellular Ca2+ indicator fura-2 was added to the preparation, and the change in [Ca2+]i was monitored using fluorescent microscope. In many but not all parotid acini, K+ stimulation induced transient increases in [Ca2+]i. The K+-induced Ca2+ response in parotid acini was completely blocked by Cd2+-containing solution. These results suggest that the parotid cell preparation has nerve terminals. In all high-K+-sensitive parotid acini, over 3μM of nicotine increased [Ca2+]i, and the response was blocked by a Cd2+-containing solution and nicotinic receptor antagonists. All high-K+-insensitive acinar cells were resistant to the effect of nicotine on Ca2+ mobilization. These results suggest that nicotine induces increases in [Ca2+]i in parotid acini due to neurotransmitter release from associated nerve terminals

Proteome analysis for rat saliva

Proteome analysis is a popular method to discover biomarkers for the prevention and diagnosis of diseases. Since saliva is a non-invasively available body fluid, gathering of saliva causes minimal harm to patients. Therefore, detection of proteins for the prevention and diagnosis from the saliva sample may be the preferred method, especially for children and elderly people. However, the abundance of salivary proteins and contaminant proteins from food and mouth bacteria obscure identification of proteins present in the saliva at low concentrations. To address this problem, we developed a shotgun proteomic method using two-dimensional nano-flow LC tandem mass spectrometry. We report here that our method is able to detect proteins quantitatively even in small sample volumes of saliva