There are local renin-angiotensin systems (RAS) in regions such as the kidney and heart, and dysfunction of these systems may lead to changes in the regulation of blood pressure. It is likely that all components of the RAS are present in the brain, and local production of angiotensin peptides has been shown in several brain areas. Stimulation of brain RAS leads to increases in blood pressure, attenuation of the baroreceptor heart-rate reflex, stimulation of drinking, and release of various hormones including vasopressin. Nucleus tractus solitarius (NTS), located within the dorso-medial medulla, is the site of termination for primary afferent fibers originating from a wide variety of peripheral organs and tissues and is essential in the integration of autonomic nervous system functions. Several demonstrations suggest that the NTS contains all of the components of the RAS including angiotensinogen, angiotensin-converting enzyme (ACE), AngiotensinII (AngII) and AngII receptors. This review reports the role of AngII in NTS.

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Leptin, a hormone secreted by adipocytes, acts on the hypothalamus to reduce appetite and inhibit body weight gain. Leptin has pleiotropic actions on bone, gonadal hormone secretion, the pancreas, immune tissues, and vascular organs. Leptin-deficient (ob/ob) mice, used in many studies defining leptin actions, have low bone mineral density (BMD) and retarded femoral growth. Loss of leptin function contributes to aberrant regulation of renal 25-hydroxyvitamin D₃ metabolism by increasing the gene expression of renal 1α-hydroxylase, which catalyzes 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃] synthesis and thus elevates serum 1,25(OH)₂D₃ concentrations. Excess 1,25(OH)₂D₃ results in increased calcium absorption in the intestine and stimulates bone resorption, resulting in reduced BMD, especially in long bones. Finally, leptin deficiency increases serum calcium concentrations; excess calcium in blood is excreted in urine.

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GABA_A receptors are a family of ligand-gated ion channels that are pentamer composed predominantly of α, β and γ subunits. They are the major target of the endogenous inhibitory neurotransmitter (GABA, γ-aminobutyric acid) and maintain the majority of fast inhibitory ion currents in the central nervous system, in addition to being drug targets for benzodiazepines, barbiturates, alcohols, neurosteroids, and some anesthetics. Moreover, modifications in GABA_A receptor function are crucial in central nervous system diseases such as anxiety disorders, sleep disturbances, and seizure disorders. Therefore it is very important to understand the molecular mechanisms underlying the maintenance of functional inhibitory synapses including GABA_A receptors. We have first isolated PRIP (phospholipase C-related, but catalytically inactive protein) as a novel inositol 1,4,5-trisphosphate binding protein, and subsequently found GABARAP (GABA_A receptor associated protein) as one of binding partners that binds to γ2 subunit of the receptor and thus is implicated in the clustering and trafficking of the receptor to synaptic membrane. Further studies revealed that PRIP binds β subunit of the receptors and PP1c (catalytic subunit of protein phosphatase 1). These findings have prompted us to explore the possible involvement of PRIP in modulation of GABA_A receptor signaling. Here we summarize our current understanding regarding how PRIP is involved in the modification of GABA_A receptor signaling on the basis of the characteristics of these interacting molecules.

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Tooth development is regulated by sequential and reciprocal interaction between the oral ectoderm and mesenchyme. Glycolipids regulate the signaling of growth factor receptor and cell adhesion to extracellular matrix; however, the role of glycolipids in ameloblast differentiation is scarcely understood. GD3 synthase is a glycolipid synthase. The GD3 synthase gene was highly expressed during the embryonic stage of dental epithelium, but not in dental mesenchyme. Dental epithelium transiently transfected with the GD3 synthase gene was shown to enhance its proliferation and inhibit enamel matrix expression. These results may indicate regulatory roles of glycolipids in cell proliferation and the differentiation of ameloblasts.

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Membrane-type 1 matrix metalloproteinase (MT1-MMP) has been implicated in tumor invasion and metastasis. Degradation of the extracellular matrix (ECM) and cell migration are critical steps in tumor invasion. MT1-MMP stimulates a cascade for ECM degradation on the surface of tumor cells, and promotes cell migration and focal adhesion turnover by activating extracellular signal-regulated kinase (ERK) and by processing various biologically important cell-surface molecules. Moreover, MT1-MMP promotes tumor cell proliferation in the 3-dimensional (3-D) ECM but not in 2-D ECM culture system. Studying the biological function of MT1-MMP would appear to be important for better understanding of the mechanisms of tumor invasion and progression.

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The change in the secretory immunoglobulin A (sIgA) level in saliva has received remarkable attention in recent years as an index of mental stress. Here, we examined its utility for assessing the stress caused by dental treatment. To achieve this, we measured salivary sIgA levels in children before and after dental treatment, and assessed their levels of stress by analyzing the change in salivary sIgA following treatment. Overall, 83% of the subjects showed a decrease in their salivary sIgA after treatment. Furthermore, the overall level of sIgA decreased significantly following dental treatment (p<0.01), suggesting that the children suffered increased stress following treatment, since increased stress results in decreased salivary sIgA. The level of sIgA was significantly decreased after prolonged treatment time (=20 min; p<0.01), the use of infiltration anesthesia (p<0.01) and surgical operation (p<0.01). Moreover, the level of salivary sIgA was significantly lower in children who showed cooperative behavior during treatment (p<0.01), indicating that stress may be reduced, in part, by uncooperative behavior. These results indicate that changes in the salivary sIgA level may represent an index for monitoring the stress of dental treatment, which changes following treatment. Taken together, as a non-invasive and convenient method for evaluating the stress caused by dental treatment, the level of salivary sIgA represents a promising clinically relevant marker.

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Localization of motoneurons of the transverse mandibular muscle (TM) was examined by a retrograde tracing method (horseradish peroxidase (HRP) and wheat germ agglutinin-HRP (WGA-HRP) ) in the rat (rodent), house musk shrew (Suncus murinus, insectivore) and miniature pig (even-toed, ungulate). In the injection of HRP solution into the TM of the rat, labeled neurons with HRP appeared at the lateral and ventral margins of the dorsolateral division in the rostral two-thirds level of the trigeminal motor nucleus. This distribution area was close to or overlapped that of medial pterygoid and lateral pterygoid motoneurons. TM motoneurons of the shrew and pig were located in the ventromedial part of the dorsolateral division at the rostral half level of the nucleus. The distribution patterns of each masticatory muscle motoneuron in the rat were also confirmed for comparison with those of TM motoneurons. Electromyography during feeding in the rat showed that TM activity almost synchronized with the activities of both jaw-closer and jaw-opener muscles.

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Using low viscous silicone impression material, we made a mold of the dorsal surface of living human tongues and successfully made precise replicas of lingual papillae with epoxy resin. Following a paradium coating, the epoxy resin replica was examined under a scanning electron microscope (SEM) and the images were compared with close-up photographs of the dorsal surface of the same tongue. Distribution patterns of fungiform papillae of the apical surface of the tongue varied in each individual. In epoxy resin replicas, bundles of fine slender protrusions of filiform papillae as well as taste pores of fungiform papillae of both living and fixed human tongues became apparent and easily distinguishable under an SEM.

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