Biomedical subjects

Masahiro Ohsawa

Publications and source records attributed to Masahiro Ohsawa.

9 recordsLinked to original sources

PubMed2005

Modification of kappa-opioid receptor agonist-induced antinociception by diabetes in the mouse brain and spinal cord.

The supraspinal and spinal antinociceptive effects of several kappa-opioid receptor agonists were examined in diabetic and non-diabetic mice using the tail-flick assay. The antinociception induced by intrathecal (i.t.), but not intracerebroventricular (i.c.v.), CI-977, a highly selective kappa(1)-opioid receptor agonist, in diabetic mice was less than that in non-diabetic mice. The antinociceptive effects of ICI-199,441 and R-84760, high potency kappa(1)-opioid receptor agonists, given i.c.v., but not i.t., were attenuated in diabetic mice compared to those in non-diabetic mice. On the other hand, the antinociceptive effects of the new kappa-opioid receptor agonist TRK-820, which has high affinity for kappa(2)- and/or kappa(3)-opioid receptors, injected both i.c.v. and i.t. in diabetic mice were markedly less than those in non-diabetic mice. These results indicate that the antinociceptive effects of those kappa-opioid receptor agonists in diabetic mice are altered in a region-specific manner in the central nervous system (CNS). The dysfunction of kappa-opioid receptor subtypes in diabetic mice may underlie this CNS region-specific variation in the effects of these kappa-opioid receptor agonists.

Analgesics↗

PubMed2005

KiSS-1 expression and metastin-like immunoreactivity in the rat brain.

Metastin, the gene product of metastasis suppressor gene KiSS-1, is the endogenous ligand for the G-protein-coupled receptor GPR54 (or AXOR12, or OT7T175). The expression of KiSS-1 gene and peptide and the distribution of metastin were studied in the rat central nervous system by reverse transcriptase-polymerase chain reaction, Western blotting, and immunohistochemical methods. KiSS-1 gene and peptide expression was higher in the hypothalamus than in the brainstem and spinal cord. In the brain, metastin-like immunoreactivity (irMT) was found mainly in three groups of cells: dorsomedial hypothalamic nucleus, nucleus of the solitary tract, and caudal ventrolateral medulla. Immunoreactive fibers of varying density were noted in bed nucleus of stria terminalis, septal nuclei, nucleus accumbens, caudate putamen, diagonal band, amygdala, hypothalamus, zona incerta, thalamus, periaqueductal gray, raphe nuclei, lateral parabrachial nucleus, locus coeruleus, spinal trigeminal tract, rostral ventrolateral medulla, and medullary reticular nucleus. Preabsorption of the antiserum with metastin peptide fragment (45-54)-NH2 (1 microg/ml) resulted in no staining in any of the sections. The biological activity of metastin was assessed by monitoring intracellular calcium [Ca2+]i in cultured hippocampal neurons, which are known to express GPR54. Metastin increased [Ca2+]i in a population of cultured hippocampal neurons. The results show that metastin is biologically active in rat central neurons, and its anatomical distribution suggests a possible role in nociception and autonomic and neuroendocrine functions.

Animals↗

PubMed2004

Dimensional changes of ring-shaped pattern.

Ring shaped wax patterns, having the same outside diameter and different inside diameters, were invested with a gypsum-bonded cristobalite investment. The wax pattern was eliminated in an electric furnace at 120 degrees C. A fusible alloy with a melting point of 47 degrees C was cast at room temperature. The dimensional deviations between the fusible alloy casting and the wax pattern were calculated using the inside diameter, ring width and outside diameter. On the other series, a gold alloy casting of the same size was fabricated in the usual manner of the dental precise casting procedure, and the dimension was compared with that of the wax pattern. In the comparison of 2 types of patterns, dimensional change by setting expansion was different. Dimensional change of the small inside diameter specimen differed at 3 portions measured, but that of the large inside diameter specimen was comparable at 3 portions. Concerning the resultant gold alloy casting, dimensional change at the outside diameter differed from each other, but those at ring width and inside diameter were comparable to each other. The difference in the inside diameter influenced dimensional change by setting expansion as well as that of the resultant casting.

Analysis of Variance↗

PubMed2004

Sandblasting of inlay margin--marginal abrasion and bond strength.

Specimens (such as metal inlays) with 30 degrees or 45 degrees marginal bevel were prepared by casting with a 12% Au-Pd-Ag alloy or a gold alloy. A form of the marginal bevel was traced on a profile projector before and after sandblasting, and the length of the abraded margin measured. All the blasting conditions abraded the marginal bevel, while the blasting at 20 mm for 2 seconds brought about the least abrasion of approximately 10 microm in the 45 degrees specimen cast with Au-Pd-Ag alloy. The gold alloy specimens were abraded more than the Au-Pd-Ag alloy ones; those with marginal bevel of 30 degrees were abraded more than those of 45 degrees. On the other hand, the effect of different blasting conditions on the bond strength of units bonded with resin cement was evaluated (under selected blasting conditions known to cause relatively less damage to the marginal level). Specimens treated by sandblaster exhibited a comparable tensile bond strength, while specimens without sandblasting but applied with only an alloy primer showed a statistically low value.

Air Abrasion, Dental↗

PubMed2004

Bond durability of resin cements to Au-Pd-Ag alloy under cyclic impact load.

The bond durability of resin cements to a 12% Au-Pd-Ag alloy was studied through cyclic impact tests with different loads. A piece of casting alloy was bonded to a cast block with two types of resin cements, Super Bond C&B and Bistite II. A shear load was applied onto a small piece of alloy until debonding of the specimen, using different weights of plungers, 130 g, 230 g, 330 g and 430 g. The specimen bonded with Super Bond exhibited a higher resistance than that with Bistite II. The fracture modes of the debonded cements were completely different from each other. That is, Bistite II showed a bulk fracture of cement by the crack penetrating through the cement layer. On the other hand, Super Bond showed damages limited to the surface and no bulk fracture. The mode of fracture was dependent not on the loading weight but the types of resin cements used.

Analysis of Variance↗

PubMed2003

Beacon/ubiquitin-like 5-immunoreactivity in the hypothalamus and pituitary of the mouse.

Beacon is a 73-amino acid peptide encoded by a novel gene in the hypothalamus of Israeli sand rat Psammomys obesus. Reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemical techniques were used to investigate the presence of beacon mRNA and the distribution of beacon-immunoreactivity (irBC) in the hypothalamus of ICR mice. RT-PCR experiments revealed beacon mRNA in the mouse hypothalamus. Using a rabbit polyclonal antiserum directed against the synthetic C-terminal peptide fragment (47-73), irBC was detected in the mouse hypothalamus and pituitary. In the hypothalamus, irBC was concentrated in perikarya of the supraoptic (SO), paraventricular (PVH) and accessory neurosecretory nuclei and in cell processes of the median eminence and pituitary stalk. In the pituitary, irBC was noted mainly in the posterior lobe. Double-labeling the hypothalamic sections with guinea-pig vasopressin-antiserum or mouse monoclonal oxytocin-antibody and beacon-antiserum revealed that <30% of vasopressin-immunoreactive neurons and nearly all oxytocin-immunoreactive neurons in the PVH and SO were irBC. The result shows the presence of beacon mRNA in the mouse hypothalamus, and the distribution of irBC is distinctively different from that reported in the hypothalamus of Psammomys obesus, but similar to that of the Sprague-Dawley rats described in our earlier study. More interestingly, Blast search uncovered a 73-amino acid peptide, human ubiquitin-like 5, which has the same exact sequence as beacon. Thus, irBC observed in the mouse brain could be that of ubiquitin-like 5.

Animals↗

PubMed2003

Involvement of beta-arrestin-2 in modulation of the spinal antinociception induced by mu-opioid receptor agonists in the mouse.

Beta-arrestins have been suggested to regulate mu-, delta-, and kappa-opioid receptor-mediated responses. In the present study, we examined the effects of pretreatment with beta-arrestin-2 antibody on tail-flick inhibition induced by opioid receptor agonists in the mouse spinal cord. Intrathecal (i.t.) pretreatment with beta-arrestin-2 antibody potentiated the antinociception induced by i.t.-administered mu-opioid receptor agonists [D-Ala(2),NMePhe(4),Gly-ol(5)]enkephalin (DAMGO) and endomorphin-1, but not endomorphin-2, the delta-opioid receptor agonist [D-Ala(2)]deltorphin II or the kappa-opioid receptor agonist U50,488H. The present result suggests that beta-arrestin-2 may tonically down-regulate a selected population of mu-opioid receptors activated by endomorphin-1 or DAMGO in the mouse spinal cord.

Analgesics↗

PubMed2002

Apelin-immunoreactivity in the rat hypothalamus and pituitary.

With the use of an antiserum against human apelin-36, apelin-immunoreactivity (irAP) was detected in neurons and cell processes of the supraoptic nucleus (SO), paraventricular nucleus (PVH), accessory neurosecretory nuclei (Acc) and suprachiasmatic nucleus. Strongly labeled cells/processes were noted in the internal layer of the median eminence, infundibular stem, anterior and posterior pituitary. Double-labeling the sections with goat polyclonal neurophysin I-antiserum and rabbit polyclonal apelin-antiserum revealed a population of magnocellular neurons in the PVH, SO and Acc expressing both irAP and neurophysin I-immunoreactivity (irNP), the latter being a marker of oxytocin-containing neurons. By inference, the AP-positive but irNP-negative magnocellular neurons could be vasopressin-containing. The presence of irAP in certain hypothalamic nuclei and pituitary suggests that the peptide may be a signaling molecule released from the hypothalamic-hypophysial axis.

Animals↗

PubMed2002

Modulation of nociceptive transmission by pituitary adenylate cyclase activating polypeptide in the spinal cord of the mouse.

Superficial layers of the dorsal horn receive a dense plexus of nerve fibers immunoreactive to pituitary adenylate cyclase activating polypeptide (PACAP). In vivo experiments were conducted in the mice to evaluate the effects of PACAP-38, herein referred to as PACAP, PACAP receptor antagonist PACAP(6-38) and PACAP-antiserum on nociceptive behaviors induced by radiant heat, intrathecally administered N-methyl-D-aspartate (NMDA) or intraplantarly administered formalin. PACAP (0.05-0.5 microg) dose-dependently decreased the paw-withdrawal latencies induced by thermal stimulation and enhanced the aversive licking and biting behaviors induced by intrathecally injected NMDA. Pretreatment with the PACAP receptor antagonist PACAP(6-38) (0.5-2 microg) or PACAP-antiserum (1:500-2,000 dilution) dose-dependently attenuated the second phase, but not the first phase, of nociceptive responses to formalin. Next, the effects of PACAP on NMDA- and kainate-induced currents evoked in single dorsal horn neurons were studied. Whole-cell patch recordings were made from superficial dorsal horn neurons of spinal cord slices from 14- to 20-day-old mice. PACAP at the concentrations of 100 and 200 nM, which caused no significant change of holding currents, increased NMDA-but not kainate-induced currents in superficial dorsal horn neurons. Our results suggest that exogenously applied PACAP sensitizes the dorsal horn neurons to formalin stimulation, and facilitates NMDA receptor-mediated nociceptive response. As a corollary, PACAP, which may be released from primary afferent fibers potentiates nociceptive transmission to the dorsal horn by interacting primarily with NMDA receptors.

Animals↗