Biomedical subjects

F Nishimura

Publications and source records attributed to F Nishimura.

At least 55 records · Page 3Linked to original sources

PubMed1998

T cell responses to 53-kDa outer membrane protein of Porphyromonas gingivalis in humans with early-onset periodontitis.

Patients with early-onset periodontitis (EOP) are susceptible to infection with periodontopathic bacteria, such as Porphyromonas gingivalis. Ag53, 53-kDa outer membrane protein of P. gingivalis, evokes strong humoral immune responses in EOP patients. In a first step to clarify how host immune cells recognize Ag53, we established Ag53-specific short-term T cell lines from 22 subjects including 6 EOP patients and 16 healthy donors, using overlapping peptides based on Ag53 amino acid sequences. All T cell lines from active EOP patients recognized a common region (p141-181, especially p141-161) on Ag53, while those from healthy donors showed heterogeneous specificity. p141-181 was not recognized by T cell lines established from EOP patients following therapy. A monoclonal antibody to HLA-DRB 1 inhibited Ag53-induced proliferation of most of the T cell lines. Our observations suggest that, although antigen-presenting molecules are common in EOP patients and in healthy individuals, p141-161 includes a major T cell epitope(s) on Ag53 for active EOP patients but not for healthy individuals or inactive EOP patients.

Adult↗

PubMed1998

Water-absorbent polymer as a carrier for a discrete deposit of antisense oligodeoxynucleotides in the central nervous system.

One of the problems of introducing antisense oligodeoxynucleotides (ODN) into the central nervous system (CNS) is their rapid disappearance from the target site due to their dispersion and diffusion, which results in poor uptake and/or retention in cells (M. Morris, A.B. Lucion, Antisense oligonucleotides in the study of neuroendocrine systems, J. Neuroendocrinol. 7 (1995) 493-500; S. Ogawa, H.E. Brown, H.J. Okano, D.W. Pfaff, Cellular uptake of intracerebrally administrated oligodeoxynucleotides in mouse brain, Regul. Pept. 59 (1995) 143-149) [2,5]. Recently, we adapted a new method using water-absorbent polymer (WAP; internally cross-linked starch-grafted-polyacrylates) as a carrier for antisense ODN. The polymer forms a hydro-gel after absorbing water which is chemically and biologically inert. In these studies, the polymer (powder-form) is fully swollen by physiological saline containing antisense ODN (0.2 micromol/ml) to make 80-fold volume gel. Hydro-gel (1 microliter) is injected into the target site, and water solutes are assumed to be diffused stoichiometrically into CNS from the surface of the gel. Histological studies indicate that 24 h after the injection, antisense ODN (5'biotinylated-S-oligos of 15 mer) are distributed to within 800 micrometer from the edge of the area where the gel is located and then gradually disappear from this area within days, but still remain within 300-micrometer distance 7 days later. Antisense ODN are effectively incorporated by all the cell types examined, i.e., neurons, astrocytes and microglias, and suppress the synthesis of the target protein. This method can be adapted to slow delivery of antisense ODN and other water soluble substances into the CNS.

Absorption↗

PubMed1998

The inhibition of DNA synthesis by prostaglandin E2 in human gingival fibroblasts is independent of the cyclic AMP-protein kinase A signal transduction pathway.

In this study we attempted to clarify the mechanism of the inhibitory effects of PGE2 on DNA synthesis in Gin-1 (fibroblasts derived from healthy human gingiva) from the aspect of the cyclic AMP-dependent protein kinase signal transduction pathway. PGE2 upregulated intracellular cyclic AMP accumulation and inhibited DNA synthesis in Gin-1 in a dose-dependent manner. When the PGE2-induced intracellular cyclic AMP accumulation was further enhanced by treatment with the cyclic AMP-phosphodiesterase inhibitor, IBMX, the inhibitory effect of PGE2 on DNA synthesis was also enhanced. Furthermore, when we examined the effects of forskolin, an activator of cyclic AMP production, on intracellular cyclic AMP accumulation and DNA synthesis, similar results were obtained. However, inhibitors of cyclic AMP-dependent protein kinase (protein kinase A) such as HA1004 did not diminish the inhibitory effect of PGE2 on DNA synthesis in Gin-1. These results suggest that in Gin-1, PGE2-induced cyclic AMP accumulation may not lead to the activation of protein kinase A or protein kinase A activity may not relate directly to the growth inhibitory effect of PGE2, and that PGE2 does not inhibit DNA synthesis through the cyclic AMP-protein kinase A signal transduction pathway in Gin-1.

1-Methyl-3-isobutylxanthine↗

PubMed1998

Periodontal disease as a complication of diabetes mellitus.

Based on our clinical observations that patients with insulin-dependent diabetes mellitus (IDDM) are subject to periodontal disease, we developed the hypothesis that hyper- or hypoglycemia might contribute to the pathogenesis of diabetic periodontitis. In this article, experimental facts that substantiate this hypothesis are presented on the basis of our studies and then discussed. Hyperglycemia progressively glycates body proteins, forming advanced glycation end products (AGE), which stimulate phagocytes to release inflammatory cytokines such as TNF-alpha and IL-6. In this context, to understand the effects of hyperglycemic episodes on periodontal health, 24 adolescent IDDM patients were examined for their periodontal status, and 3 of them were found to have periodontitis. Laboratory analyses on these 3 patients revealed that 2 had elevated serum TNF-alpha levels. These results may partly support the current hypothesis of a mechanism of diabetic complications in which abnormal cytokine levels induced by AGE could exacerbate inflammatory responses. In IDDM patients, the diabetes is often accompanied not only by hyperglycemic episodes but also by iatrogenic hypoglycemia. Periodontal ligament cells (PDL) cultured under hyperglycemic conditions were impaired in such biological functions as adhesion and motility, while cells cultured under hypoglycemic conditions (10 mg/dL) gradually dissociated from their anchor and underwent cell death. These phenomena correlated well with the expression profile of fibronectin receptor. Interestingly, these changes due to the different glucose levels were observed more intensively in PDL than in other fibroblastic cells, suggesting that the biological functions of PDL are easily led to impairment by variation or rapid fluctuation of glucose levels. These observations suggest that hyperglycemia could indirectly exacerbate inflammatory tissue destruction through the body's scavenger system against AGE, and that both hyper- and hypoglycemia might directly impair the biological functions of periodontal connective tissues through cell-matrix interactions.

Adolescent↗

PubMed1998

[Mechanical properties of titanium casting obtained using short-time cast procedure].

The purpose of this study was to investigate the mechanical properties of titanium casting obtained using short-time cast procedure. A commercial phosphate-bonded investment for titanium casting were used. And dumbbell-shaped specimens with phi 2 mm x 14 mm parallel portion were cast according to manufacture instruction and by way of three different short-time cast procedures. Then, micro vickers hardness test and tensile test were performed with these specimens. In the hardness test, the micro vickers hardness of 50 approximately 250 microns deep location from specimen surface was ranged from 192.8 to 259.0 Hv; there were significant difference among both the location factor and the casting procedure factor by the two-way ANOVA (p < 0.05). In the tensile test, tensile strength, yield strength, elastic modulus and elongation were obtained: these tensile properties of short-time cast procedures were not significantly different from those of manufacture instruction. These results indicated that the short-time cast procedure for titanium casting was available in the point of mechanical properties. It was, however, not obvious that how the short-time cast procedures effected the dimensional accuracy of titanium casting. Therefore, further investigation was needed for the practical usage of this method.

Dental Casting Technique↗

PubMed1997

Occurrence of paralytic shellfish poison in the starfish, Asterias amurensis in Kure Bay, Hiroshima Prefecture, Japan.

In May 1996, during surveillance on the toxicity of invertebrates such as bivalves inhabiting the coasts of Hiroshima Bay, the starfish Asterias amurensis collected in the estuary of the Nikoh River was found to contain toxins which showed strong paralytic action in mice; the maximum toxicity (as paralytic shellfish poison, PSP) was 8.0 MU/g for whole body and 28.7 MU/g for viscera throughout the monitoring period, March to July 1996. Attempts were made to identify the paralytic toxins in the starfish. They were extracted with 80% ethanol acidified with acetic acid, followed by defatting with dichloromethane. The aqueous layer obtained was treated with activated charcoal and then applied to a Sep-Pak C18 cartridge. The unbound toxic fraction was analyzed by high-performance liquid chromatography techniques. The starfish toxin was rather unexpectedly identified as PSP. It was comprised of high toxic components (gonyautoxin-1; GTX1, GTX2, GTX3, GTX4, decarbamoyl-GTX3; dcGTX3 and dcSTX) as the major components, which accounted for approximately 77 mole% of all components, along with protogonyautoxin-1, 2, 3 and 4 (PX1-4), which are N-sulfocarbamoyl derivatives. Of the high toxic components, GTX1 was present in the largest amounts. It was concluded that the toxin of starfish collected in the estuary of Nikoh River in May 1996 consisted of PSP, which supposedly came via the food chain from toxic bivalves living in the same area. To our knowledge, this is the first report of the occurrence of PSP in starfish.

Animals↗

PubMed1997

Comparison of in vitro proliferative capacity of human periodontal ligament cells in juvenile and aged donors.

OBJECTIVE: The aim of this study is to compare the in vitro proliferative capacity of periodontal ligament (PDL) cells from aged and juvenile donors. MATERIALS AND METHODS: Flow-cytometric analysis of the cell cycle was used to compare the length of each cell cycle, and the ratio of the cells progressing through the cycles between four PDL cells from juvenile donors and four cells from aged donors. Then, replicative capacity of the PDL cells from three juvenile and three aged donors was compared by serial cultures. Finally, expression of c-fos was compared between cells proliferating and cells which had reached senescent. RESULTS: Flow-cytometric analysis of the cell cycle had revealed that although there were no differences in the length of each phase of the cell cycle, significant differences were found in the ratio of the cells entering from Gap I to DNA synthesis phase of the cell cycle (P < 0.025). Replicative capacity was much longer in two cells from juvenile donors (about 20 population doublings), while all cells from aged donors showed short dividing abilities (less than eight population doublings), hence entered senescent phases shortly. Additionally, no c-fos was detected in cells which had reached senescence upon stimulation with serum. CONCLUSIONS: It is generally believed that aged humans have an impaired wound healing ability. We believe that more fibrotic PDL tissues seen in aged humans might be the reason for this, and suggest that this phenomena might be due to the progressive accumulation of senescent cell populations.

Adolescent↗

PubMed1997

Host defensive, immunological, and microbiological observations of an early-onset periodontitis patient with virus-associated hemophagocytic syndrome.

Virus-associated hemophagocytic syndrome (VAHS) is a disorder characterized by benign generalized histiocytic proliferation and marked hemophagocytosis associated with systemic viral infection. An immunodeficiency which includes an extremely decreased leukocyte and platelet count together with abnormalities in the CD4/CD8 ratio are the most common features of VAHS. Here we report an early-onset periodontitis (EOP) patient with VAHS from the standpoint of host-parasite interaction to understand the effect of this systemic disorder which might possibly influence susceptibility to periodontal disease. The patient is a 16-year-old Japanese male clinically diagnosed as having generalized EOP with slight gingival inflammation and moderate bone loss. This patient manifested VAHS at 3 years of age, and then had an unusual 4 recurrences (at 5, 7, 11, and 14 years old). Laboratory tests conducted include: 1) complete blood analyses: 2) peripheral neutrophil functions (chemotaxis, phagocytosis, superoxide production, and adherence); 3) peripheral lymphocyte subpopulations and functions, T-cell proliferative activity and productivity of cytokines (interleukin-2 [IL-2], interferon gamma [IFN-gamma], and tumor necrosis factor alpha [TNF-alpha]); 4) serum cytokine levels (IL-1 beta, IL-2, soluble IL-2 receptor [sIL-2R], IL-4, IL-6, IFN-gamma, and TNF-alpha; 5) serum immunoglobulin G (IgG) antibody titers against periodontopathic bacteria; 6) serological human leukocyte antigen (HLA) typing; and 7) determination of bacterial flora of the periodontal pockets. The results indicated that the patient's neutrophil chemotaxis and random migration were below the normal range. In lymphocyte examinations, T-cell proliferative activity, IL-2, and IFN-gamma productivity were elevated. Serum IFN-gamma level was also significantly higher than normal range. No specific periodontopathic bacteria were predominant in the periodontal pockets, however, the serum IgG titer against Porphyromonas gingivalis was elevated throughout the examination period. It is suggested that VAHS might be a possible risk factor for periodontal disease, and hence may serve as a model in understanding the role of host defense mechanisms in the establishment of inflammatory periodontal disease.

Adolescent↗

PubMed1997

Dental students' understanding of titanium.

The understanding of titanium by students in the dental faculty of Tokyo Medical and Dental University was surveyed from 1990 to 1996. A seven-item questionnaire was used in the survey conducted during the first lecture of the dental materials and science course. The students' basic understanding of titanium was not very good and did not improve with time. However, their understanding improved significantly after the lecture and laboratory instructions.

Education, Dental↗

PubMed1996

Changes in responsiveness to serotonin on rat ventromedial hypothalamic neurons after food deprivation.

The effects of food deprivation on responsiveness of neurons in the ventromedial nucleus of the hypothalamus (VMH) to serotonin (5-HT), norepinephrine (NE), gamma-aminobutyric acid (GABA), and neuropeptide Y (NPY) were investigated using brain slices in vitro along with behavioral changes in vivo during fasting. Adult male rats were fasted for 48 h starting at the beginning of the dark phase (lights on: 0700-1900 h). The animals showed a significant loss of body weight on the second day of fasting and an increase in food consumption on the first day of refeeding. During fasting, voluntary locomotor activity was significantly increased in the light phase but not during the dark phase. Plasma catecholamine levels were not affected by fasting. In vitro electrophysiological study showed that, in normally fed rats, 5-HT and NE induced both excitatory and inhibitory responses, while GABA and NPY intensively suppressed unit activity in the VMH. Food deprivation for 48 h significantly changed the responsiveness of VMH neurons to 5-HT, for instance, the ratio of neurons whose activity was facilitated by 5-HT was significantly decreased. The responsiveness of VMH neurons to NE, GABA, and NPY was not affected by food deprivation. These results suggest that food deprivation decreases the facilitatory response of VMH neurons to 5-HT, and that this change in responsiveness to 5-HT is at least partially involved in the increase in food intake motivation and locomotor activity during fasting.

Animals↗

PubMed1996

Comparative study of the chemotactic responses of periodontal ligament cells and gingival fibroblasts to polypeptide growth factors.

Selective recruitment of periodontal ligament cells to a previously exposed root surface is believed to enhance periodontal regeneration. It has been hypothesized that competition from gingival fibroblasts may reduce the potential of periodontal regeneration. We compared the migratory responses of PDL cells and gingival fibroblasts to a variety of biologicals. Parallel experiments designed to examine the directed migration responses of both periodontal ligament cells (PDL cells) and gingival fibroblasts (GF) isolated from the same donors were conducted using Platelet Derived Growth Factor (PDGF), Insulin Like Growth Factor-I, -II (IGF-I, -II), Epidermal Growth Factor (EGF), Transforming Growth Factor-beta (TGF-beta), and the chemotactic factor derived from the conditioned culture media of PDL cells (termed PDL-CTX) as attractants. Both PDL cells and GF exhibited dose-dependent migratory responses when challenged with PDGF, IGF-I, IGF-II, EGF, and TGF-beta. However, when these cells were challenged with PDL-CTX, only PDL cells migrated in a specific dose-dependent manner, while GF were refractive to PDL-CTX stimulation. Additionally, concentrated conditioned culture media from cultures of gingival fibroblasts did not stimulate PDL cell migratory responses. In other experiments, antibody directed against PDGF, FGF, TGF-beta, IGF-I, IGF-II, NGF, and EGF did not inhibit the PDL-CTX-elicited response in PDL cells. Previous studies have suggested that success of periodontal therapy depends on the specific attachment, migration, and proliferation of selected periodontal ligament cells. The data presented in this manuscript suggest that both PDL cells and gingival fibroblasts respond to a multitude of growth factors. PDL-CTX was found to be PDL-cell-specific for directed migration. Thus, we conclude that any biological therapeutic regime for periodontal regeneration should include PDL-cell-specific agents.

Cells, Cultured↗

PubMed1996

Periodontal ligament cells are chemotactic to fibroblast collagenase.

Periodontal ligament (PDL) cell motility and the passage of PDL cells along a root surface are important components of tissue remodeling during periodontal regeneration. Proteolytic enzymes, including fibroblast collagenase, have been demonstrated to play an important role in tissue remodeling. Previous studies have shown that PDL cells chemotactically respond to a variety of matrix and growth factors. We therefore studied the effects of type I collagen fragments and fibroblast collagenase on PDL cell migration, since PDL cells have been shown to adhere preferentially to partially demineralized root surfaces with exposed type I collagen. Gingival epithelial cells were used as a control cell population. We report that PDL cells but not gingival epithelial cells preferentially migrate in a dose-dependent manner to both fibroblast collagenase and to type I collagen degradation products. Epithelial cell migration to fibroblast collagenase and type I collagen fragments was observed. Antibody to type I collagen inhibited the type I collagen fragment-mediated migration. Collagenase pre-treatment of PDL cells enhanced PDL cell migration to type I collagen fragments. In other assays, enzyme inhibitors were shown to decrease the collagenase-mediated PDL cell motility. Epithelial cells were shown to migrate preferentially to 92-kDa type IV collagenase and type IV collagen degradation products. Antibody to type IV collagen inhibited type IV collagen-induced epithelial cell migration. Taken together, these data suggest a role for collagenase in the fine control of PDL cell migration in tissue remodeling during periodontal regeneration.

Antibodies↗

PubMed1996

Glucose-mediated alteration of cellular function in human periodontal ligament cells.

Because diabetic patients are easily led to manifest severe periodontitis, we wanted to determine whether various glucose levels interfere with normal cellular function. Human periodontal ligament (PDL) cells were cultured in glucose-free medium, or in medium containing either 1100 mg/L of glucose (normal-glucose medium) or 4500 mg/L of glucose (high-glucose medium). Cells cultured in glucose-free medium changed their morphology from spindle-shaped to round, and incorporated trypan blue in a time-dependent manner. The incorporation rate was much faster in cells with shorter cell cycles than in those with longer cycles, suggesting the involvement of cell-cycle progression in cell death. However, fragmented DNA, which suggests apoptotic cell death, was not observed in these cells. We reasoned that initial cell rounding and detachment from the culture plate might be due to the conformational changes in cell-surface receptors to fibronectin, a major extracellular matrix for fibroblasts. Western blot analysis revealed that cells cultured in glucose-free medium lost their fibronectin receptor in a time-dependent manner. In addition, fibronectin receptor expression was much higher in cells cultured in high-glucose medium than in cells cultured in normal-glucose medium. Furthermore, the over-expression of the fibronectin receptor resulted in a suppressed chemotactic response of these cells to platelet-derived growth factor. On the basis of these data, it was hypothesized that a high glucose level induced over-expression of these receptors. This might be the mechanism by which a high glucose level compromises wound healing in diabetic patients and, at least in part, might be the reason diabetic patients are subject to severe periodontal destruction.

Blotting, Western↗

PubMed1996

Immunological, genetic, and microbiological study of family members manifesting early-onset periodontitis.

From the standpoint of host-parasite interactions, family studies help us understand the host defensive factors and the molecular mechanisms involved in the periodontal immune response. In this study, we report the immunological profile of host-defensive functions, human leukocyte antigen (HLA) phenotypes, and the microflora of a mother (rapidly progressive periodontitis), an older son (periodontally healthy), a younger son (localized juvenile periodontitis), and a daughter (localized juvenile periodontitis). We examined the peripheral neutrophil functions, phenotypic and functional analysis of peripheral lymphocytes, serum immunoglobulin G (IgG) antibody titers against periodontopathic bacteria, serological type of HLA class II antigens, and bacterial flora in all periodontal pockets. The results showed that Actinobacillus actinomycetemcomitans was dominant in the pockets of all subjects. The mother and two sons showed a depressed neutrophil chemotaxis to N-formyl-methionyl-leucyl-phenylalanine. All subjects except the older son exhibited low T4/T8 ratios. The mother and daughter had raised levels of IgG titers to Porphyromonas gingivalis. All subjects had HLA phenotypes of DRw52 and DQ1 in common. We found that the family members had similar disorders in certain defensive functions. This family has been a model for our understanding of the host defensive factors in the development of early-onset periodontitis.

Adolescent↗

PubMed1996

Host defensive functions in a family manifesting early-onset periodontitis.

Family case studies help us identify host risk factors in periodontal disease. In this study we examine a family consisting of a mother (40 years old, with rapidly progressive periodontitis), her elder daughter (14 years old, with localized juvenile periodontitis), and younger daughter (13 years old, with simple gingivitis). We examined 1) the peripheral neutrophil functions (chemotactic migration, phagocytosis, superoxide production); 2) lymphocyte functions (proliferative activity and cytokine productivity of T cells, immunoglobulin [Ig] M productivity of B cells when stimulated with pokeweed mitogen); 3) phenotypic analyses of peripheral lymphocyte subpopulations; 4) serum IgG antibody titers against periodontopathic bacteria; and 5) serological type of HLA class II. All the subjects exhibited high T4/T8 ratios due to high percentage of CD4-positive cells, showed high IgG titers to Actinobacillus actinomycetemcomitans, and had a HLA DQw1 in common. The mother showed a slight deficiency of neutrophil chemotactic migration to N-formyl methyonyl leucyl phenylalanin (fMLP), raised interleukin-2 productivity of T cell, and high levels of IgG titers to Porphyromonus gingivalis and Fusobacterium nucleatum. Both daughters showed weak T cell proliferative response to anti-CD3 monoclonal antibody and low IgM productivity. Low lymphocyte responsiveness may be involved in the pathogenesis of periodontal disease of these daughters; therefore, the lymphocyte dysfunctions shown should be considered in relation to the progression of periodontal disease.

Adolescent↗

PubMed1996

Effect of frozen storage and boiling on tensile strength of bovine dentin.

Bovine teeth are used for dental research as a substitute for human teeth. In the present study the effects of storage on the tensile strength of bovine dentin were investigated. Storage conditions selected were frozen storage for 1 week, 4 weeks, and 1 year. Boiling in water for 45 minutes was also employed to clarify the effect of heat. Dumbbell-shaped specimens were prepared from teeth of each condition and tensile tests were performed immediately. The same tests were also performed on specimens, as a control, prepared from bovine teeth within 8 hours of extraction. The tensile strength of the control was 76.1 MPa; 1 week frozen storage, 78.7 MPa; 4 weeks, 79.9 MPa; 1 year, 79.0 MPa. The tensile strength of bovine dentin remained unchanged during one year frozen storage. On the other hand, the tensile strength of bovine dentin after boiling was 70.3 MPa, showing that tensile strength had decreased.

Analysis of Variance↗

PubMed1996

Clinical evaluation of a dental rinse containing aluminum lactate for treatment of dentinal hypersensitivity.

The effectiveness of a dental rinse containing aluminum lactate, which was used as a daily home treatment for dentinal hypersensitivity, was evaluated in a 6-week, double-blind study. Fifty-six subjects who complained of cold and/or tactile hypersensitivity were randomly divided into two groups: one given a dental rinse containing 2.18% aluminum lactate (test group) and the other a vehicle control dental rinse (control group). Subjects in both groups were instructed to rinse with the assigned dental rinse and to brush their teeth twice daily. The hypersensitivity levels of the affected teeth were assessed at baseline and at 4 and 6 weeks by application of tactile, cold air and cold water stimuli, and scored against baseline. All hypersensitivity scores in both groups were decreased significantly at weeks 4 and 6 compared to the baseline (p < 0.001). The hypersensitivity scores for tactile, cold air and cold water stimuli in the test group were significantly lower at weeks 4 and/or 6 compared to those in the control group (p < 0.05). Furthermore, on the analysis for the teeth with apparent pain (score 2 or 3) at the baseline, the reduction rates of hypersensitivity scores for cold air and cold water stimuli in the test group were significantly greater than those in the control group (p < 0.05). These findings suggest that daily home use of a dental rinse containing aluminum lactate is effective for treatment of dentinal hypersensitivity.

Adult↗

PubMed1995

Excitability of neurons in the ventromedial nucleus in rat hypothalamic slices: modulation by amino acids at cerebrospinal fluid levels.

Free amino acid composition of cerebrospinal fluid (CSF) in the rat was measured to examine if electrical activity of neurons in the ventromedial nucleus of the hypothalamus (VMH) is modulated by amino acids at CSF levels. In CSF collected through a cannula in the cerebromedullary cistern of freely moving rats, the total concentration of amino acids was 979 microM, while that in plasma was 3.50 mM. Glutamine was the major (60%) component and each of other amino acids was less than 8.0% (lysine) of total. Among neutral amino acids, concentrations of serine, threonine and alanine were much higher than those of others. Although concentrations of basic amino acids such as lysine and arginine were also relatively high, those of acidic amino acids such as glutamate and aspartate were very low. Spontaneous firing rates of 73% of the neurons in the VMH in brain slices in vitro were facilitated by changing the perfusion medium from artificial CSF (ACSF) without amino acids to one containing each amino acid close to CSF levels (AA-ACSF). Glutamine (600 microM) alone similarly facilitated the activity in 64% of VMH neurons, though the facilitatory effect of amino acids was blocked by simultaneous application of neither AP-5 nor CNQX, antagonists for NMDA or non-NMDA receptors, respectively, to AA-ACSF at 100 microM.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗