Motoko Kawai

Bromocriptine protects mice against 6-hydroxydopamine and scavenges hydroxyl free radicals in vitro

Pretreatment with bromocriptine (5 mg/kg, i.p., 7 days) completely protected against the decrease in mouse striatal dopamine and its metabolites induced by intraventricular injection of 6-hydroxydopamine after intraperitoneal administration of desipramine, but similar pretreatment with L-DOPA/carbidopa (75/7.5 mg/kg, i.p., 7 days) showed only partial protective effect. Furthermore, in an in vitro system that generated.OH from FeSO4-H2O2, bromocriptine dose-dependently reduced the number of .OH radicals. These findings indicate that bromocriptine has a neuroprotective effect against neurotoxins such as 6-hydroxydopamine, probably due, in part, to its hydroxyl radical scavenging activity and inhibiting effect on dopamine turnover rate. This suggests that early introduction of bromocriptine in the therapy of Parkinsons disease may be superior to treatment with L-DOPA alone.

Free radicals and superoxide dismutase in blood of patients with Alzheimer's disease and vascular dementia

We measured hydroxyl radical (.OH) levels in blood, superoxide dismutase (SOD) activity in red blood cells (RBC) relative to both total protein (RBC-SOD/P) and Cu,Zn-SOD protein (RBC-SOD/SOD), SOD activity in plasma (plasma-SOD), and Cu,Zn-SOD protein relative to total RBC protein (Cu,Zn-SOD/P) in 22 patients with probable dementia of the Alzheimer type (DAT group, mean age 74.8+/-9.4 years), 16 with probable vascular dementia (VAD group, mean age 76.9+/-6.7 years) and 19 non-demented controls (control group, mean age 73.5+/-6.2 years). Levels of .OH in the DAT and VAD groups were significantly (P<0.01 and P<0.001, respectively) higher, whereas the values of RBC-SOD/P and RBC-SOD/SOD in these two groups (both P<0.001) and Cu,Zn-SOD/P in the DAT group (P<0.001) were significantly lower than the corresponding control values. Members of the VAD group with risk factors for stroke (RF+ group) showed significantly higher .OH levels than members of the VAD group without risk factors (RF- group; P<0.01) and the control group (P<0.001). RBC-SOD/P and RBC-SOD/SOD values in the RF+ group were significantly (both P<0.01) lower than the corresponding control values. There were no significant differences among the VAD, RF+ and control groups with respect to Cu,Zn-SOD/P values, or between the RF- and control groups for any measured parameter. We conclude that oxidative stress plays a role in the brain damage seen in both DAT and VAD, and that the causes of decreased SOD activity in RBC differ between DAT and VAD patients.

Free radicals, lipid peroxides and antioxidants in blood of patients with myotonic dystrophy.

We studied the levels of free radicals, lipid peroxides and antioxidants, as well as superoxide dismutase (SOD) activity in the blood of six patients with myotonic dystrophy (MyD) (mean age 52.8, SD 5.0 years) and seven controls (mean age 48.8, SD 6.3 years). Electron spin resonance was used to assess the free radicals by the spin-trapping method using 5,5-dimethyl-l-pyrroline-l-oxide. The levels of C centre radical (P < 0.05) and H radical (P < 0.05) in blood from the six MyD patients were significantly higher than those in the seven controls. The SOD activities in red blood cells and serum from the six MyD patients showed no significant difference from those in the seven controls. The serum lipid peroxide concentration was increased in five of the MyD patients and tended to increase further as the disease progressed. The serum vitamin E level was low in two patients and in the low normal range in three. Serum coenzyme Q10 was decreased in four patients. The serum selenium level was decreased in two patients and that of serum albumin was decreased in three. Therefore we conclude that increased levels of free radicals and lipid peroxides and decreased antioxidant levels play an important role in the pathogenesis of MyD.

Manda, a Fermented Natural Food, Suppresses Lipid Peroxidation in the Senescent Rat Brain

The level of lipid peroxidation reflects the degree of free radical-induced oxidative damage in brain tissue of the elderly. We examined the effects of Manda, a product prepared by yeast fermentation of several fruits and black sugar, on lipid peroxidation in the senescent rat brain as model of aging. Senescent rats were provided with a diet containing 50 g/100 g Manda for 8 days, supplemented on day 8 with an intragastric administration of Manda (6.0 g/kg body wt.) twice daily. The hydroxyl radical scavenging activity was generated by the FeSO4-H2O2 system and analyzed by electron spin resonance spectrometry. Using this method, the addition of Manda (2.88 mg/ml) to brain homogenates of adult rats (0.06 mg/ml) had an additive inhibitory effect on lipid peroxidation compared with control adult rats not treated with Manda. Incubation of brain homogenates with Manda for 2 h and 3 h, significantly inhibited the increase in lipid peroxides (malondialdehydes and 4-hydroxyalkenals) levels in aged rats due to auto-oxidation. In addition, oral administration of Manda significantly suppressed the age-related increase in lipid peroxidation in the hippocampus and striatum, although such change was not observed in the cerebral cortex. Although Manda contains trace level of α-tocopherol, the level of α-tocopherol in Manda did no correlate with its antioxidant effect. Our results suggest that Manda protects against age-dependent oxidative neuronal damage caused by oxidative stress and that this protective effect may be due, in part, to its scavenging activity against free radicals.

Free radical scavenging by brain homogenate: Implication to free radical damage and antioxidant defense in brain

To study the mechanisms of free radical-induced brain damage and the antioxidant defense in the brain, we quantified the superoxide and hydroxyl radical scavenging effects of brain homogenate using electron spin resonance spectrometry. Brain homogenate was found to scavenge both superoxide and hydroxyl radicals in concentration-dependent fashion. Heat denaturation significantly decreased these scavenging effects. The ability of brain homogenate to scavenge free radicals implies that brain damage can be induced by free radicals since they are known to react virtually with any type of molecule such as nucleic acids, membrane lipids, and proteins in the brain. On the other hand, some molecules which can be regenerated or repaired after free radical scavenging are considered to be antioxidants which include both enzymatic and non-enzymatic antioxidants. Measurement of the decrease in antioxidant activity following heat denaturation suggests that the contribution of enzymatic antioxidants is about 20-40% in scavenging superoxide radicals and about 10-20% in scavenging hydroxyl radicals.

Superoxide dismutase and free radicals in sporadic amyotrophic lateral sclerosis: relationship to clinical data

We studied the relationships between the superoxide dismutase (SOD) activity, free radical (FR) levels and clinical data in patients with sporadic amyotrophic lateral sclerosis (SALS). The SOD activities and blood FR levels of 16 patients with SALS (mean age 58.6 +/- 10.2 years), 11 with other neurological disease, including myotonic dystrophy (ND, mean age 53.5 +/- 9.1 years), and 15 normal control subjects (mean age 56.2 +/- 7.3 years) were measured. The mean levels of FR in blood from the patients with SALS and ND and the SOD activities in red blood cells (RBC) from those with ND were significantly higher than the corresponding control values. There was a positive correlation between the SOD activities in RBC and blood hydroxyl radical levels in the patients with ND, but neither the patients with SALS nor the controls showed such a correlation. The SALS patients without pyramidal signs showed slow disease progression and their mean RBC SOD activity was significantly higher than the corresponding control value. We compared the FR levels and SOD activities of 8 patients who needed a respirator within 40 months after the onset of SALS (SALS40, mean age 58.7 +/- 9.4 years), 3 who needed a respirator over 100 months after the onset of SALS (SALS100, mean age 58.3 +/- 15.9 years) and the controls. The mean blood FR levels of the SALS40 and SALS100 patients were significantly higher than the corresponding control values. The mean SOD activity in RBC from the SALS100 group was significantly higher than the SALS40 and control group values. Therefore, we concluded that elevated blood FR levels do not induce RBC SOD in SALS patients and that the disease progressed more rapidly in SALS patients with low than high RBS SOD activities.

SYNTHESIS AND EVALUATION OF DMPO-TYPE SPIN TRAPS

The spin traps substituted with some groups at the 4-position of dimethyl-1-pyrroline N-oxide(DMPO) were compared with DMPO itself regarding their abilities as spin traps and their physical properties. 4,5,5-Trimethyl-1-pyrolline N-oxide (4MDMPO) and 5,5-dimethyl-4-phenyl-1-pyrolline N-oxide (4PDMPO) were synthesized by the Bonnett method, and 5,5-dimethyl-4-hydroxymethyl-1-pyrolline N-oxide (4HMDMPO) was made by a unique method from 2(5H)-furanone. The melting points of 4MDMPO, 4PDMPO and 4HMDMPO were higher than that of DMPO. The magnitude of hydrophilicity was in the order of 4HMDMPO, DMPO, 4MDMPO, and 4PDMPO based on the partition coefficient experiments in a 1-octanol--water system. Several radicals, O2-., HO., .CH3, .CH2OH, .CH(CH3)OH, (CH3)3CO. and H. radicals, were trapped with these DMPO derivatives for comparison with the trapping by DMPO itself. Spin adducts of O2-. with the three DMPO derivatives showed ESR spectra similar to that of DMPO. In spite of the formation of diastereomers arising from spin trapping, the line-width enlargement was very small. The intensities and the decay rates of the spectra of 4MDMPO-O2-, 4PDMPO-O2-, 4HMDMPO-O2- and DMPO-O2- were almost equal. In the trapping of the .OH radical by 4MDMPO, 4PDMPO and 4HMDMPO, the eight-line ESR spectra observed were different from the well-known four-line spectrum of DMPO-OH.

Free radicals in the cerebrospinal fluid are associated with neurological disorders including mitochondrial encephalomyopathy

The free radical levels in the cerebrospinal fluid of 8 patients with neurological diseases and 9 undergoing lumbar anesthesia for surgery were measured. The ascorbate free radical level 10 min after lumbar puncture showed a positive correlation with the hydroxyl radical level. In the patient with mitochondrial encephalomyopathy, the levels of hydroxyl and ascorbate free radicals increased upon discontinuation of treatment and decreased upon its resumption, and the ascorbate free radical levels without therapy fell after lumbar puncture. The free radical levels in the cerebrospinal fluid may reflect the degree of oxidative stress in the central nervous system.

Manda suppresses emotional stress-induced stomach ulcers in rats

Manda, a natural product made by yeast fermentation of many fruits and black sugar, has antioxidant activity. In the present study, manda prevented stomach ulcers caused by immobilization-induced emotional stress. Manda [5% manda solution (w/v)] and saline as control, were administered by a canula into the stomach of each experimental animal subsequently after 1, 2, 3, 4, and 5 hours from the start of the emotional stress. We classified the severity of gastric lesion formation induced by immobilization with each rat lying on its back for 6 hours at room temperature on a five-grade scale. The control rats all showed congestion and some degree of bleeding in the mucosa of the stomach. However, of the experimental rats, one showed no hemorrhagic lesions only congestion in four cases, and slight or moderate bleeding in eight cases with no massive bleeding cases. The distribution of these data significantly differ from that of the control rats, which suffered the greater damage (X2=10.589,p<0.05). In light microscopic examinations, the control rats showed necrosis in the gastric mucous membranes, desquamation, and bleeding of gastric mucosa. However, the rats treated with manda showed only congestion and did not show erosion or hemorrhage. These results suggest that manda or manda metabolite(s) was absorbed from the stomach and may have produced these action. In the meantime, we are analyzing manda components to try to isolate the active ingredient(s)