Biomedical subjects

T T Tomura

Publications and source records attributed to T T Tomura.

4 recordsLinked to original sources

PubMed2000

Decrease of endothelial nitric oxide synthase in stroke-prone spontaneously hypertensive rat cerebral cortex.

We reported in our previous study that constitutive nitric oxide synthase (cNOS) activity significantly decreased and oxygen stress increased in the 31-week-old stroke-prone spontaneously hypertensive rat (SHRSP) cerebral cortex (CC). In the present study we examined the protein amount of two cNOS isoforms, the neuronal and the endothelial types, in SHRSP CC using Western blot analysis. Although no significant difference was observed in the amount of neuronal NOS (nNOS) protein, endothelial NOS (eNOS) protein prominently decreased in 31-week-old SHRSP CC compared to age-matched Wistar Kyoto rat and 15-week-old SHRSP. In rats at this age, we also observed a large quantity of albumin in the protein amount. However, the protein amount of heat shock protein 70, which is a molecular chaperon and a marker of injury, showed no significant changes. These results indicate that the alteration of eNOS but not of nNOS protein would be more closely associated with the development of stroke in SHRSP.

Animals↗

PubMed1999

Age-related change of antioxidant capacities in the cerebral cortex and hippocampus of stroke-prone spontaneously hypertensive rats.

Regional distribution and age-related change of Mn-, Cu/Zn-superoxide dismutase (SOD) and constitutive type of nitric oxide synthase (NOS) activities in the brain were determined using stroke-prone spontaneously hypertensive rats (SHRSP). In the hippocampus (HIP), Mn- and Cu/Zn-SOD activities in SHRSP of 31-week-old were significantly lower than those of 15-week-old or normotensive rats (WKY). From Mn-SOD immunohistochemical staining of several subfields of the HIP, our results suggested that SHRSP hippocampal CA1 was more vulnerable to oxidative stress compared with WKY and other subfields. In the 31-week-old SHRSP cerebral cortex (CC), the activities of Mn-, Cu/Zn-SOD and NOS were significantly lower than those in WKY. At this age, most of the SHRSP developed cerebral injuries. These observations indicated that hypertensive vascular disease observed in the SHRSP CC resulted from the decreased antioxidant capacity that is closely associated with the development of stroke and, in turn, shortened life span.

Aging↗

PubMed1997

Induction of manganese superoxide dismutase by thyroid stimulating hormone in rat thyroid cells.

Alterations in the superoxide dismutase (SOD) content of thyroid tissues occurring in association with thyroid dysfunction have been reported. In this study, the Mn-SOD content was found to increase in thyroid tissues of rats administered thyroid stimulating hormone (TSH) and in thyrocytes cultured in medium supplemented with TSH. Furthermore, in the thyroid glands of rats whose serum TSH level was elevated by inhibiting the synthesis of T3 and T4 by 6-methyl-2-thiouracil, the Mn-SOD increased as the TSH concentration increased. In the cultured thyrocytes, the increase in Mn-SOD induced by TSH was inhibited by the C-kinase inhibitor H7. These findings suggest the induction of Mn-SOD by TSH in thyroid cells and point to a role of C-kinase in this process, thereby indicating that a close relationship exists between the serum TSH level and the change in Mn-SOD content in thyrocytes with thyroid dysfunction.

Animals↗

PubMed1995

Regional distribution of superoxide dismutase in the brain and myocardium of the stroke-prone spontaneously hypertensive rat.

1. Enzyme activities and contents of manganese and copper-zinc superoxide dismutase (Mn-, Cu/Zn-SOD) and oxygen free-radical scavengers were determined in the myocardium (right, left ventricle) and brain (cerebral cortex, hippocampus) of 15 and 31 week old stroke-prone spontaneously hypertensive rats (SHRSP). 2. In 15 week old SHRSP myocardium, both Mn- and Cu/Zn-SOD activities were higher but in 31 week old SHRSP, these were lower than that in Wistar-Kyoto (WKY) rats. Further, correlation between Mn-SOD content and activity in 31 week old SHRSP myocardium showed that specific activity was lower than that in WKY. 3. In 15 and 31 week old SHRSP cerebral cortex and hippocampus, SOD content and activity showed a tendency to be lower than that in WKY. 4. These results indicate that enzymatically inactive or low-active Mn-SOD protein exists in SHRSP myocardium, and that the alteration of SOD may be one of the causative factors for the vulnerability of the myocardium and brain against O2-radicals.

Animals↗