Site-specific autonomic vasomotor responses and their interactions in rat gingiva.

Blood flow in the gingiva, comprising the interdental papilla as well as attached and marginal gingiva, is important for maintaining of gingival function and is modulated by risk factors such as stress that may lead to periodontal disease. Marked blood flow changes mediated by the autonomic (parasympathetic and sympathetic) nervous system may be essential for gingival hemodynamics. However, differences in autonomic vasomotor responses and their functional significance in different parts of the gingiva are unclear. We examined the differences in autonomic vasomotor responses and their interactions in the gingiva of anesthetized rats. Parasympathetic vasodilation evoked by the trigeminal (lingual nerve)-mediated reflex elicited frequency-dependent blood flow increases in gingivae, with the increases being greatest in the interdental papilla. Parasympathetic blood flow increases were significantly reduced by intravenous administration of the atropine and VIP antagonist. The blood flow increase evoked by acetylcholine administration was higher in the interdental papilla than in the attached gingiva, whereas that evoked by VIP agonist administration was greater in the attached gingiva than in the interdental papilla. Activation of the cervical sympathetic nerves decreased gingival blood flow and inhibited parasympathetically induced blood flow increases. Our results suggest that trigeminal-parasympathetic reflex vasodilation 1) is more involved in the regulation of blood flow in the interdental papilla than in the other parts of the gingiva, 2) is mediated by cholinergic (interdental papilla) and VIPergic systems (attached gingiva), and 3) is inhibited by excess sympathetic activity. These results suggest a role in the etiology of periodontal diseases during mental stress.

Differences in the regulatory mechanism of blood flow in the orofacial area mediated by neural and humoral systems.

Marked blood flow (BF) changes mediated by the autonomic neural and humoral systems may be important for orofacial hemodynamics and functions. However, it remains questionable whether differences in the autonomic vasomotor responses mediated by neural and humoral systems exist in the orofacial area. This study examined whether there are differences in changes in the BF and vascular conductance (VC) between the masseter muscle and lower lip mediated by autonomic neural and humoral systems in urethane-anesthetized rats. Electrical stimulation of the central cut end of the lingual nerve elicited BF increases in the masseter (mainly cholinergic) and lower lip (mainly non-cholinergic), accompanied by an increase in arterial blood pressure (ABP), while cervical sympathetic trunk stimulation consistently decreased BF at both sites. The lingual nerve stimulation induced a biphasic change in the VC in the masseter, consisting of an initial decrease and a successive increase. This decrease in VC was positively correlated with changes in ABP and diminished by guanethidine. Cervical vagus nerve stimulation also induced BF increases at both sites; the increases were greater in the masseter than in the lower lip. Adrenal nerve stimulation and isoproterenol administration induced BF increases in the masseter but not in the lower lip. These results indicate that cholinergic parasympathetic-mediated hemodynamics evoked by trigeminal somatosensory inputs are closely related to ABP changes. The sympathetic nervous system, including the sympathoadrenal system and visceral inputs, may be more involved in hemodynamics in the muscles than in epithelial tissues in the orofacial area.

Nasogastric Tube Knotted Around a Nasal Endotracheal Tube in the Nasopharynx: Possible Cause.

A nasogastric tube is often used along with a nasal endotracheal tube during oral surgery or dental treatment under general anesthesia. Although the insertion of a nasogastric tube is a simple procedure, it can be associated with complications that lead to potentially serious consequences. The knotting of a nasogastric tube around an endotracheal tube is rare. Here, we report a case in which the nasogastric tube became knotted around the nasal endotracheal tube in the nasopharynx. We compare this case with 4 previous similar cases and provide a theory of how the nasogastric tube might have become knotted.

Effect of the parasympathetic vasodilation on temperature regulation via trigeminal afferents in the orofacial area.

The skin temperature (Tm) of the orofacial area influences orofacial functions and is related to the blood flow (BF). Marked increases in BF mediated by parasympathetic vasodilation may be important for orofacial Tm regulation. Therefore, we examined the relationship between parasympathetic reflex vasodilation and orofacial Tm in anesthetized rats. Electrical stimulation of the central cut end of the lingual nerve (LN) elicited significant increases in BF and Tm in the lower lip. These increases were significantly reduced by hexamethonium, but not atropine. VIP agonist increased both BF and Tm in the lower lip. The activation of the superior cervical sympathetic trunk (CST) decreased BF and Tm in the lower lip; however, these decreases were significantly inhibited by LN stimulation. Our results suggest that parasympathetic vasodilation plays an important role in the maintaining the hemodynamics and Tm in the orofacial area, and that VIP may be involved in this response.

Post-ischemic Intravenous Administration of Allogeneic Dental Pulp-Derived Neurosphere Cells Ameliorated Outcomes of Severe Forebrain Ischemia in Rats.

BACKGROUND: Transplantation of bone marrow or adipose-derived mesenchymal stem cells (MSCs) for various neurological disorders has yielded promising results in models of focal cerebral ischemia. Dental pulp stem cells (DPSCs) are a type of MSC. In serum-free culture, they can form neurospheres that contain nestin-positive neuronal progenitor cells. We hypothesized that transplantation of dental pulp-derived neurosphere cells would ameliorate outcomes of global cerebral ischemia, the pathophysiology of which is known to resist conventional treatments. We also hypothesized that transplantation of dental pulp-derived cells would provide some neuroprotection in this pathology due to the presence of DPSCs. METHODS: Using adult rats, ischemia was induced by two-vessel occlusion of both carotid arteries in combination with systemic hypotension. Allogeneic dental pulp cells from juvenile rats were cultured in advance in serum-free medium to obtain neurospheres. Dental pulp-derived neurosphere cells or dental pulp-derived cells were intravenously administered at 3 h after ischemic insult, with normal saline as a control. Animals were observed for 14 days after ischemia. Neurological outcome was assessed using the water-maze test and neuromotor test. Histological outcome was measured by counting the percentage of dead neurons in the hippocampal CA1 and CA3 regions. RESULTS: Transplantation of both dental pulp-derived neurosphere cells and dental pulp-derived cells significantly improved survival rate and water-maze test results. Neurosphere cell transplantation was related to significantly better neuromotor test and histological outcomes, as indicated by the reduced percentage of dead neurons in CA1. CONCLUSIONS: Transplantation of dental pulp-derived neurosphere cells ameliorated outcomes of global cerebral ischemia. It was also demonstrated that dental pulp-derived cell administration provided some neuroprotection.