间断低氧大鼠谷胱甘肽过氧化物酶及还原型谷胱甘肽的变化

动态测定了常压间断低氧大鼠全血和肺组织谷胱甘肽过氧化物酶(GSH-PX)活性及还原型谷胱甘肽(GSH)含量。结果发现随低氧时间延长,肺动脉压逐渐升高的过程中有全血及肺组织GSH-PX活性及GSH含量的显著降低。维生素E和山莨菪碱有部分保护作用。提示间断低氧过程中活性氧自由基生成增多,消耗了较多的抗氧化酶(剂)。氧自由基生成增多可能在其肺动脉高压的发生中起一定作用。     

Glutathione and ascorbic acid metabolism and antioxidative enzyme activity in tissues of vitamin E-deficient rats

Vinnitsa Medical Institute. All-Union Cardiologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR I. K. Shkhvatsabaya [deceased]. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 107, No. 4, pp. 437–438, April, 1989.     

The mechanism of cell-damaging reactive oxygen generation by colloidal fullerenes

Because of the ability to induce cell death in certain conditions, the fullerenes (C₆₀) are potential anticancer and toxic agents. The colloidal suspension of crystalline C₆₀ (nano-C₆₀, nC₆₀) is extremely toxic, but the mechanisms of its cytotoxicity are not completely understood. By combining experimental analysis and mathematical modelling, we investigate the requirements for the reactive oxygen species (ROS)-mediated cytotoxicity of different nC₆₀ suspensions, prepared by solvent exchange method in tetrahydrofuran (THF/nC₆₀) and ethanol (EtOH/nC₆₀), or by extended mixing in water (aqu/nC₆₀). With regard to their capacity to generate ROS and cause mitochondrial depolarization followed by necrotic cell death, the nC₆₀ suspensions are ranked in the following order: THF/nC₆₀>EtOH/nC₆₀>aqu/nC₆₀. Mathematical modelling of singlet oxygen (¹O₂) generation indicates that the ¹O₂-quenching power (THF/nC₆₀nC₆₀nC₆₀) of the solvent intercalated in the fullerene crystals determines their ability to produce ROS and cause cell damage. These data could have important implications for toxicology and biomedical application of colloidal fullerenes.     

Glutathione protects human airway proteins and epithelial cells from isocyanates

BACKGROUND: Glutathione (GSH), one of the major anti-oxidants of the lung, has been linked to the human response to isocyanate exposure. However, the ability of GSH to modulate key chemical reactions, thought to be central to the development of human isocyanate allergy, has not been directly analyzed under biologic exposure conditions. OBJECTIVE: To better understand the potential role of GSH in the response to occupational isocyanate exposure, we evaluated its effects on two processes thought to be involved in the development of isocyanate allergy, isocyanate-protein conjugation and epithelial cell toxicity. METHODS: The effects of GSH on (1) isocyanate conjugation with albumin, its major target in the airway fluid and (2) isocyanate-induced toxicity to human airway epithelial cell lines, A549 and NCI-H292, were tested using two different in vitro models. For protein conjugation studies, a newly described vapour exposure system was used to model the air/liquid interface at the surface of the epithelial fluid in the airways. Epithelial cell exposures were performed in fluid phase to mimic the in vivo exposure of airway cells covered by epithelial lining fluid. RESULTS: Reduced GSH prevented hexamethylene diisocyanate (HDI) conjugation to albumin in a dose-dependent manner, while oxidized GSH (GSSG) conversely increased conjugation rates. GSH levels equivalent to those found in normal human airway fluid (100 microm) provided >90% protection against HDI-protein conjugation when albumin was exposed to HDI vapour levels 10-fold above permissible occupational limits. Physiologic levels of GSH, but not GSSG, also reduced HDI toxicity to human airway epithelial cells in a dose-dependent manner, when present extracellularly, however, drugs that modulate intra-cellular GSH levels did not significantly alter isocyanate toxicity. CONCLUSIONS: Together with previously reported genetic and toxicity studies, the data suggest that airway GSH plays an important role in protection against HDI exposure and may help prevent the development of allergic sensitization and asthma.     

NO-synthase activity and generation of reactive oxygen species in the brain in old rats: Association with individual behavior

NO synthase activity and the generation of reactive oxygen species (ROS) were measured in different brain regions of old rats separated in an “emotional resonance” test into two groups: passive rats (those preferring a dark space) and active ones (those preferring a lighted space). In both groups, NO synthase activity and ROS generation were at the highest level in the cerebellum. In the tested brain regions of active rats, NO synthase activity was lower and ROS generation more strongly marked than in the respective regions of passive rats. Interregional positive linear correlations were discovered both for NO synthase activity and for ROS generation. When the two groups were considered together, negative correlations were detected between NO synthase activity and ROS generation. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 8, pp. 145–147, August, 1995 Presented by I. P. Ashmarin, Member of the Russian Academy of Medical Sciences     

Shivering and nonshivering thermogenesis in exercised cold-deacclimated rats

Summary Norepinephrine (NE)-induced increase in oxygen consumption ( ) and colonic temperature (Tc) was greater in cold-acclimated rats housed at 4° C for 4 weeks (CA) than warm-acclimated controls housed at 24° C for 4 weeks (WA). On the other hand, shivering activity measured at 4° C was less in CA than in WA, while propranolol administration eliminated the difference between these two groups by enhancing shivering in CA. Wet weight and protein content of interscapular brown adipose tissue (IBAT) were greater in CA than in WA. Following cold acclimation, CA were deacclimated at 24° C for 5 weeks. During deacclimation, half of this latter group were forced to run (15 m·min^–1 for 1 h) every day (CD-T) while the remaining rats remained sedentary (CD-S). Shivering activity assessed at 4° C 4 weeks after commencing cold deacclimation was significantly less in CD-T than in CD-S and the difference disappeared following propranolol injection. and Tc responses to NE injection measured 1, 2 and 5 weeks after commencing cold deacclimation did not differ between CD-S and CD-T. Although IBAT weight was lighter in CD-T than in CD-S, its total protein content was not different between the latter two groups of rats. These results suggest that a greater degree of NE-independent nonshivering thermogenesis (NST) is retained in rats that are exercised during the process of deacclimation as compared with animals that are sedentary. This difference in NST would not seem to be directly related to BAT thermogenic capacity.     

Effect of AF64A on cerebral oxygen consumption in young and old rats

Regional brain O2 consumption was determined in conscious Fischer-344 rats 3- and 33-months of age after intrahippocampal injection of the selective presynaptic cholinergic neurotoxin AF64A to investigate the influence of acetylcholine on this parameter. Regional cerebral blood flow (rCBF) was determined with 14[C]-iodoantipyrine. Regional arterial and venous oxygen saturation was measured microspectrophotometrically. Regional cerebral oxygen consumption was calculated by multiplying rCBF and cerebral oxygen extraction. Systemic hemodynamic and blood gas parameters were not altered by aging or AF64A. Aging or sham injection per se did not have any significant effect on rCBF, oxygen extraction and cerebral oxygen consumption. In 3-month-old AF64A-treated rats, rCBF, oxygen extraction or cerebral oxygen consumption were significantly lower than in the control group of the same age. Old AF64A-treated animals demonstrated a significant decrease in rCBF and cerebral oxygen consumption but not in cerebral oxygen extraction when compared to the sham-lesioned group of the same age. Oxygen consumption was significantly decreased by AF64A in each examined region of both young and old groups of rats, although the decreases were less severe in the older rats. This may be related to the lesser influence of the cholinergic system on cerebral oxygen consumption in old animals or a decreased toxicity of AF64A in older animals.     

Comparison of oxygen kinetics in young and old subjects

Summary Five older men (aged 60–69 yr) and five young men (aged 21–29 yr) with approximately equal levels of age-corrected max were compared with respect to oxygen kinetics at equal absolute workloads (100 watts) and at equal relative workloads (45% max) on a cycle ergometer. At 45% max, half times for response to instantaneous transition from unloaded pedalling were 30.0 s and 27.4 s for old and young respectively (t=0.260,p<0.80). No significant differences were found in the response and by inference none existed in O₂ extraction. Mean half times for heart rate responses at a workload of 100 W were 24.2 s and 20.6 s for old and young groups respectively (t=0.722,p<0.49). Mechanical efficiency estimated from steady state data at 100 W was 19.8% and 20.5% for old and young groups respectively (t=0.574). The close similarity in responses to submaximal work in old and young subjects of equivalent fitness suggests caution in the interpretation of agewise decrements observed in physiological variables which may be sensitive to physical fitness status.     

Phenyl N-t-butylnitrone, a reactive oxygen species scavenger, reduces zymosan-induced visceral pain in rats

To examine a possible involvement of reactive oxygen species (ROS) in visceral pain, the levels of ROS in the colon and the effect of a ROS scavenger phenyl N-t-butylnitrone (PBN) on pain were examined in zymosan-induced colitis rats. Zymosan was instilled into the colon of adult rats. The electromyograms (EMGs) of abdominal muscle contractions in response to colorectal distension (CRD) were recorded as an indicator of visceral pain. After zymosan treatment, the rats showed enhanced EMG and elevated levels of H2O2 in the colon. PBN treatment (intraperitoneal, intrathecal or intracolonic) significantly reduced the enhanced EMGs induced by zymosan. The results suggest that elevated ROS in the spinal cord and the colon are involved in visceral pain.     

Single unit activity in frontal cortex and caudate nucleus of young and old rats

Spontaneous neuronal activity was recorded extracellularly from isolated single units in frontal neocortex and caudate nucleus of young and aged F344 rats anesthetized with urethane. Average firing rates, mean interspike intervals (ISI)±standard deviations, and ISI frequency histograms were computed and analyzed by microprocessor. For frontal cortex cells (N=226), there was a nonsignificant trend toward slower average discharge rates in the old group. However, a significantly longer mean ISI and proportionally more very slow firing cells (<I Hz) were observed in old rats. A laminar analysis of frontal cortex unit activity in young animals showed average discharge rates to be distributed somewhat evenly throughout the cortical mantle with the exception of the zone 1200–1400 μ beneath brain surface. This depth corresponds approximately to layer V where a 50% increase in mean firing rate in young animals was observed. In aged animals, this increased cell firing in layer V was absent, while mean discharge rates in other laminae remained essentially the same in the young and old rat groups. Caudate nucleus cells (n=70) showed a significant shift towards fewer fast discharging cells in old rats, with the average firing rate diminished by one-third. Although more brain regions need to be examined in a similar fashion, the consistency of the present results with those previously reported for the brainstem and cerebellum suggests that slower firing rates and longer ISIs are likely to be wide-spread throughout the brains of aged rats.     

The effects of joint immobilization on articular cartilage of the knee in previously exercised rats

Studies have determined the effects of joint immobilization on the articular cartilage of sedentary animals, but we are not aware of any studies reporting the effects of joint immobilization in previously trained animals. The objective of the present study was to determine whether exercise could prevent degeneration of the articular cartilage that accompanies joint immobilization. We used light microscopy to study the thickness, cell density, nuclear size, and collagen density of articular cartilage of the femoral condyle of Wistar rats subjected to aerobic physical activity on an adapted treadmill five times per week. Four groups of Wistar rats were used: a control group (C), an immobilized group (I), an exercised group (E), and an exercised and then immobilized group (EI). The right knee joints from rats in groups I and EI were immobilized at 90 °C of flexion using a plastic cast for 8 weeks. Cartilage thickness decreased significantly in group I (mean, 120.14 ± 15.6 μm, P < 0.05), but not in group EI (mean, 174 ± 2.25), and increased significantly in group E (mean, 289.49 ± 9.15) compared with group C (mean, 239.20 ± 6.25). The same results were obtained for cell density, nuclear size, and collagen density (in all cases, P < 0.05). We concluded that exercise can prevent degenerative changes in femoral articular cartilage caused by immobilization of the knee joint.     

Pharmacokinetics of hexobarbital in young and old rats

Hexobarbital is a drug widely used to study the capacity of the liver to metabolize drugs. The pharmacokinetics of hexobarbital in 3- and 30-month-old male BN/BiRij rats were studied. The half-life of hexobarbital in 30-month-old rats (34.9 ± 4.1 min) was significantly higher than that of 3-month-old ones (21.3 ± 3.8 min). The volume of distribution (ml·kg⁻¹ body weight) did not change with age. The intrinsic clearance, expressed as ml·min⁻°kg⁻¹ body weight, or hexobarbital in 30-month-old rats (2-.2 ± 6.6) was half that of the 3-month-old ones (39.5± 7.6). Further studies will be performed to investigate the effect of age on the intrinsic clearance of S(+)- and R(−) — hexobarbital.     

几种反应性氧代谢物逆转剂免疫佐剂作用的比较

目的 分析比较硫普罗宁(TIP)、还原型谷胱甘肽(GSH)、二氢氯组胺(DHT)3种反应性氧代谢物(ROM)逆转剂抗白血病细胞免疫治疗中的增效作用.方法 在K562细胞、NK细胞的混合培养系中分别加入单核细胞和白细胞介素-2,然后分别加入TIP、GSH、DHT,观察ROM水平及K562细胞抑制率(KIR)的变化.结果 加入E/MO=10/2、10/5、10/10三种浓度的MO,ROM水平分别为(389.79±43.83)U/L,(456.74±42.77)U/L,(601.42±21.92)U/L,KIR分别为82.36%,81.36%,48.09%:加入TIP、GSH或DHT后,当E/MO=10/2时,ROM水平从(389.79±43.83)U/L,分别减至(-1.20±60.70)U/L、(-3.58±9.49)U/L和(50.21 4-22.4)U/L(P＜0.05),随着TIP、GSH或DHT浓度的增加ROM水平逐渐减少,KIR从82.53%分别升至96.09%、96.39%和94.64%(P＜0.05).结论 TIP、GSH逆转ROM的效应强于DHT,提高NK细胞对K562的抑制率,其效应强度与DHT相似,但毒副作用轻微,两者均可能成为更理想的抗白血病的免疫佐剂.     

Levels of plasma and aortic lipids in young exercised rats with a diminished weight gain

Summary Young exercised rats with a diminished weight gain had a decrease in high density lipoprotein (HDL) cholesterol and phospholipid levels in the plasma and augmented free cholesterol and phosphatide in the aorta. When the weight gain in the trained rats paralleled the gain in non-exercised animals, the values of these lipids were not altered. The levels of aortic free cholesterol in the non-exercised and exercised groups were inversely associated with concentrations of HDL-cholesterol, but were not related to the activities of lecithin cholesterol acyltransferase. In addition, the total cholesterol and phospholipid contents in the aorta negatively correlated with HDL-cholesterol concentrations. We propose that in young exercised rats with a diminished weight gain, the removal of aortic lipids is hampered due to a reduction in HDL-cholesterol.     

Effects of 60% oxygen inhalation on the survival and antioxidant enzyme activities of young and old rats

Under 60% oxygen, both the 50% and maximum survival times of old rats were markedly shortened, and the maximum survival time of young rats did not change although the 50% survival time was shortened. In addition, the mean body weight of the old rats decreased rapidly, while that of the young rats increased very slowly after the small decrease. In lungs of the young and old rats, the activities of catalase and Mn superoxide dismutase (SOD) were increased, while those of CuZn SOD and glutathione peroxidase remained unchanged. In the liver of the young rats, the activities of Mn SOD and glutathione peroxidase were increased. In the lungs of the old rats, the messenger RNA (mRNA) levels of these antioxidant enzymes were markedly increased. The oxygen-dependent mRNA induction did not correspond to the augmentations of the activities of antioxidant enzymes. The protein levels and activity of CuZn SOD did not changed by 60% oxygen inhalation although the mRNA level was increased to 4.7-fold at 2 weeks of oxygen exposure. Translational efficiency of antioxidant enzymes in old rats might be reduced under oxidative stress. These results indicate that old rats are less tolerant to the oxidative stress of 60% oxygen than young rats because antioxidant enzyme activities are less induced due to low translational efficiency, and suggest that the activities of antioxidant enzymes, not only in the lung but also in the liver, may contribute to the tolerance to oxidative stress.     

Skeletal muscle and heart antioxidant defences in response to sprint training

Although endurance training enhances the antioxidant defence of different tissues, information on the effect of sprint training is scanty. We examined the effect of sprint training on rat skeletal muscle and heart antioxidant defences. Male Wistar rats, 16–17 weeks old, were sprint trained on a treadmill for 6 weeks. Total glutathione levels and activities of glutathione peroxidase, glutathione reductase, glutathione S-transferase and superoxide dismutase in heart and various skeletal muscles were compared in trained and control sedentary animals. Lactate dehydrogenase and citrate synthase enzyme activities were measured in muscle to test the effects of training on glycolytic and oxidative metabolism. Sprint training significantly increased lactate dehydrogenase activity in predominantly fast glycolytic muscles and enhanced total glutathione contents of the superficial white quadriceps femoris, mixed gastrocnemius and fast-glycolytic extensor digitorum longus muscles. Oxidative metabolic capacity increased in plantaris muscle only. Compared with the control group, glutathione peroxidase activities in gastrocnemius, extensor digitorum longus muscles and heart also increased in sprint trained rats. Glutathione reductase activities increased significantly in the extensor digitorum longus muscle and heart. Glutathione S-transferase activity was also higher in the sprint trained extensor digitorum longus muscle. Sprint training did not influence glutathione levels or glutathione-related enzymes in the soleus muscle. Superoxide dismutase activity remained unchanged in skeletal muscle and heart. Sprint training selectively enhanced tissue antioxidant defences by increasing skeletal muscle glutathione content and upregulating glutathione redox cycle enzyme activities in fast and mixed fibre leg muscles and heart.     

Pituitary and hypothalamic concentration of met-enkephalin in young and old rats

Anterior pituitary and hypothalamic concentration of met-enkephalin was measured by a specific radioimmunoassay in old (22–24 months) and young (4–6 months) rats. The old rats were reproductively abnormal and based on their vaginal cytology, they were further classified under pseudopregnant, irregular cycle and constant estrus groups. All old rats had significantly higher concentration of met-enkephalin in the anterior pituitary gland when compared with young rats in estrus. Pseudopregnant rats had the highest concentration of met-enkephalin (7.38 ± 1.72 ng met-enkephalin/mg protein, mean ± SEM) followed by rats with irregular cycles (3.07 ± 1.54) and old rats exhibiting constant estrus (2.22 ± 0.47). Young rats in estrus had a mean concentration of 0.13 ± 0.08 ng met-enkephalin/mg protein in the anterior pituitary gland. However, there was no significant difference in the hypothalamic concentration of met-enkephalin of old animals when compared with young animals.     

Pituitary and hypothalamic concentration of met-enkephalin in young and old rats

Anterior pituitary and hypothalamic concentration of met-enkephalin was measured by a specific radioimmunoassay in old (22–24 months) and young (4–6 months) rats. The old rats were reproductively abnormal and based on their vaginal cytology, they were further classified under pseudopregnant, irregular cycle and constant estrus groups. All old rats had significantly higher concentration of met-enkephalin in the anterior pituitary gland when compared with young rats in estrus. Pseudopregnant rats had the highest concentration of met-enkephalin (7.38 ± 1.72 ng met-enkephalin/mg protein, mean ± SEM) followed by rats with irregular cycles (3.07 ± 1.54) and old rats exhibiting constant estrus (2.22 ± 0.47). Young rats in estrus had a mean concentration of 0.13 ± 0.08 ng met-enkephalin/mg protein in the anterior pituitary gland. However, there was no significant difference in the hypothalamic concentration of met-enkephalin of old animals when compared with young animals.     

EEG delta power during sleep in young and old rats

Delta EEG power density, which has been viewed as a measure of intensity of NREM sleep, declines across the lifetime in humans, cats, and hamsters, but data in rats have been unclear. It is also uncertain whether older rats differ from younger animals in the degree of change in delta power during recovery sleep following short-term sleep deprivation. We have examined delta power density in NREM sleep under baseline conditions and following 48 h of sleep deprivation in young (3 months), middle-aged (12 months), and older (24 months) rats. The presence or absence of age effects was highly dependent on the method of normalizing the data. When expressed as a fraction of total NREM EEG power, there was no age effect on baseline delta power density, or on the change from baseline to recovery conditions. When expressed as a multiple of delta power in REM under the same condition, the younger rats had higher delta power density than the middle-aged and older rats. For all the ages combined, there was an increase in delta power density in the recovery condition. When examined by age, the younger rats (which started from a higher level of delta power density than the other groups) did not have an increase in delta during recovery; the middle-aged rats tended to, and the older rats (which started from lower baseline levels) significantly increased delta power density in the recovery condition. This suggests that the lower delta power seen during baseline in older rats is not due to decreased ability to generate delta activity.     

Physical Activity and Quality of Life: Assessing the Influence of Activity Frequency,Intensity, Volume,and Motives

In the present study, the authors investigated the impact of exercise frequency, intensity, and volume along with exercise motives on quality of life (QOL) reports. The authors assessed exercise habits with the Godin Leisure Time Activity Scale and measured exercise motives with the Reasons for Exercise Inventory. The Quality of Life Inventory assessed satisfaction in 16 domains including health, work, and recreation. High-frequency exercisers reported significantly higher health, helping, and community-related QOL than those who exercised less frequently. The authors noted significantly higher healthrelated QOL in the heavy volume group compared with the other volume groups. Multiple regression tests revealed that activity intensity and exercise motives significantly predicted QOL reports. The strongest bivariate correlations with QOL existed for mild activity and exercising for fitness and health reasons. Thus, high-frequency activity of mild intensity that produces high kcal utilization and is performed to improve health and fitness has the strongest influence on QOL reports.