慢性不可预知性应激刺激后大鼠行为学的改变

目的:建立长期慢性不可预知性应激刺激大鼠动物模型,观察大鼠在应激后行为学的改变。方法:雄性SD大鼠20只,5周龄,饲养3周后随机分为实验组和对照组,每组10只。实验组进行为期5周的随机应激刺激,建立慢性不可预知性应激动物模型,对照组不施加任何刺激,正常饲养。两组大鼠每周都要进行体质量测量、矿场行为学测验以及糖水偏好测试,将两组的测试结果进行比较。结果:两组大鼠在体质量方面无明显差异,而矿场实验,实验组与对照组从第14天就开始出现显著差异(t=-2.420,P=0.016);糖水测验两组出现显著差异则出现在21天时(t=5.854,P=0.000)。结论:大鼠的行为活动在长期慢性不可预知性应激刺激后明显改变,说明大鼠长期处在应激刺激下,正常的行为活动会出现障碍。     

Prolonging lateral hypothalamic anorexia by tube-feeding

Male rats sustaining lateral hypothalamic (LH) lesions were anorexic for approximately one week following surgery. They then maintained their body weight at a reduced level (approximately 20% below controls) for the remainder of an 8-week postlesion period of observation. By tube-feeding another group of LH animals, their body weight was held at a control level for the first week postlesion. Following tube-feeding, these animals were anorexic for several weeks while their body weights declined to the same reduced level as that of the LH animals not tube-fed. For both groups of LH animals, achievement of a lowered weight level, rather than a time-dependent recovery process, appeared to underlie the return of food intake to levels sufficient for maintaining body weight. By impeding the loss of body weight, tube-feeding can thus prolong the duration of LH anorexia.     

Cardiac remodeling and function following exercise and angiotensin II receptor antagonism

The purpose of this study was to test the impact of chronic exercise training combined with selective angiotensin II receptor (AT1) antagonism on systolic blood pressure (SBP) and the left-ventricular pressure–volume relationship in normotensive, non-infarcted rat hearts. Wistar rats (N = 19) were randomly assigned to either a sedentary control group (N = 8) or an exercise-trained group (N = 11). Losartan was administered to individually caged rats via the drinking water (10 mg/kg/d). Exercise training consisted of running on a motorized driven treadmill for 6 weeks at 30 m/min, 60 min/day, 5 days/week. Tail cuff SBP was measured weekly. Left ventricular performance was assessed in an ex vivo Langendorff isovolumic mode. One week of losartan treatment significantly reduced SBP in both groups by 13% relative to baseline (P < 0.05). SBP was lower in exercise-trained animals versus sedentary animals in the later weeks of the protocol (P < 0.05) Body weight was significantly lower in exercise-trained animals versus sedentary animals, but heart weight, heart to body weight ratio, atrial weight, and absolute left ventricular mass and length were similar between groups. The LV systolic pressure–volume relationship (PV) and systolic elastance were significantly greater in exercise-trained animals versus sedentary controls (P < 0.05). The left ventricular end-diastolic PV and diastolic stiffness were similar between exercise-trained and sedentary animals. These data suggest that chronic aerobic exercise training can improve the Starling response in the presence of AT1 receptor blockade without altering absolute cardiac size.     

Isoflavone-supplemented soy yoghurt associated with resistive physical exercise increase bone mineral density of ovariectomized rats

OBJECTIVE: To determine the effects produced by the ingestion of a fermented soy product (soy yoghurt), supplemented with isoflavones and associated with a resistive exercise program, on the bone metabolism of mature ovariectomized (Ovx) and sham-ovariectomized (sham-Ovx) rats. METHODS: A total of 56 rats were used. They were divided into 2 sedentary control groups, the Ovx control group (C-Ovx) and the sham-Ovx control group (C-Sovx), each with 7 sedentary animals, and 2 treated groups, Ovx and sham-Ovx, with 21 animals each. These two treated groups were subdivided into three subgroups of seven animals each, which received the following treatments: consuming the soy yoghurt+sedentary, only subjected to resistive exercise, and consuming the soy yoghurt+resistive exercise. Both the program of resistive exercise and the consumption of soy yoghurt (at 3 mL/(kg body weight day)) continued for 12 weeks. The soy yoghurt was supplemented with isoflavones at 50mg/100g of product. The animals were sacrificed and their right-side femurs and tibias removed and assessed for bone mineral density (BMD). The alkaline phosphatase activity (AP) was determined in the blood serum. RESULTS: There was a significant increase in both femur and tibia BMD values and in serum alkaline phosphatase activity in all the treated subgroups, compared with the control groups (p<0.05). CONCLUSION: The ingestion of the soy yoghurt supplemented with isoflavones was capable of preventing a loss of bone mass in Ovx rats and of increasing bone mass in sham rats, whilst the resistive exercise program was effective in augmenting the bone mass in sham and Ovx rats.     

Effects of wobble board training on weight distribution on the lower extremities of sedentary subjects

Inequality of weight distribution on the lower extremities affects the posture and gait performance of an individual. The effect of wobble board training on weight distribution on the lower extremities is presently unknown. The purpose of this study was to investigate the effects of a six week wobble board exercise training program on the weight distribution in the lower extremities. Subjects (n = 16) in the wobble board group were trained three times a week for the period of six weeks. The subjects in the control group (n = 13) did not receive any training. Weight distribution symmetry scores improved by 9% and 2% in the wobble board and control groups, respectively, no significant difference was found between the two groups' pre-training weight distribution on the lower extremities. The two-ways repeated analysis of variance revealed a significant F ratio between the two groups (P < 0.001). LSD post hoc analysis showed significant improvements in the symmetry of the weight distribution at the 4th and 6th week of training compared to pre-training value within the wobble board group, while no significant improvement was recorded within the control group. Our findings implied that the wobble board exercise program could be used to improve the symmetry of weight distribution on the lower extremities in sedentary subjects.     

心理应激和体力运动对大鼠海马NE及其合成酶TH、代谢酶MAOA的影响

目的： 本研究通过比较慢性心理应激（以下简称应激）和长期体力运动（以下简称运动）2种过程对大鼠海马去甲肾上腺素（NE)水平及其合成酶酪氨酸羟化酶（TH）和代谢酶单氨氧化酶A（MAOA）的影响,探讨体力运动减缓海马应激损伤的相关机制。方法：动物分别施予自愿跑轮动物模型4周和慢性束缚应激模型3周后,高效液相色谱法比较海马NE变化;蛋白免疫印迹法检测NE合成酶TH、代谢酶MAOA蛋白表达变化。结果：与对照组相比,应激大鼠体重增长缓慢,糖水偏嗜量明显降低,NE水平明显降低［（303.46±24.36) ng/g,P<0.05］,TH、MAOA蛋白表达升高,分别为(1.35±0.94）倍和（2.22±0.62)倍（P<0.05）;运动组大鼠NE水平明显升高｛（418.53±70.64) ng/g,P<0.05］,TH、MAOA蛋白表达亦升高,分别为(1.22±0.59)倍和(1.85±0.36)倍（P<0.05）。结论：结果提示NE水平变化可能与运动减缓应激性海马损伤的关系密切,NE水平的改变与NE的合成与代谢关系不密切,可能存在其它机制。     

Effect of exercise on blood pressure in rats with chronic NOS inhibition

Regular training lowers blood pressure in hypertensive humans and other animals. We investigated the response to 4 weeks of treadmill exercise training in hypertensive male Wistar rats receiving the nitric oxide synthase inhibitor N ^ω-nitro-L-arginine methyl ester (L-NAME). The rats were on either a short- (4 weeks) or long-term (10 weeks) L-NAME treatment protocol and were subjected to running exercise that started concomitantly in the short-term group and in the 6th week in the long-term group. Four weeks of exercise training induced a fall in mean arterial pressure in both the short- [mean (SEM) 137.6 (4.0) mmHg] and long-term hypertensive groups [161.4 (2.3) mmHg] compared to their sedentary hypertensive controls [160.4 (3.3) mmHg and 176.8 (8.9) mmHg, respectively]. Exercise also increased muscle nitric oxide synthase activity in both of the trained hypertensive groups. Muscle nitrite levels were higher in the exercising short-term hypertensive group compared to both the sedentary control and the sedentary hypertensive groups, and were not different between the sedentary and exercising long-term hypertensive groups. Increased wall thickness of the aortic and mesenteric vessels was observed in the hypertensive groups, but was prevented in the exercising long-term hypertensive group. In rat, exercise reduces the elevated blood pressure in L-NAME-induced hypertension via increasing nitric oxide synthase activity. Changes in vessel structure with exercise training may also be involved in the blood-pressure-lowering effects. Electronic Publication     

Enzymatic changes in hypertrophied fast-twitch skeletal muscle

Summary Fast-twitch plantaris muscles of female rats were subjected to unilateral compensatory overload, induced by partial excision of synergistic muscles. One group of rats remained sedentary whereas another was subjected to a supplemental program of treadmill exercise consisting of walking 3 m/min, 65% grade, 2 h/day, 5 days/week. Groups of rats were sacrificed after 1, 2, 4, and 8 weeks and their muscles were weighed and analyzed for protein, citrate synthase, phosphofructokinase (PFK) and myofibril ATPase. Absolute and relative (muscle weight/body weight) muscle weights were much greater in both overloaded groups as compared to contralateral controls. However, treadmill exercise also increased the absolute and relative muscle mass of control plantaris muscles in the exercising group as compared to normal sedentary contralateral controls. Citrate synthase activity was decreased in overloaded, sedentary muscles as compared to contralateral controls, but after 8 weeks of exercise, it returned to normal levels. PFK was decreased in both sedentary and exercised overloaded muscles througout the 8 week period. Myofibril ATPase showed a tendency to be reduced in sedentary, overloaded muscles, and was significantly reduced in overloaded, exercising muscles. These results collectively suggest that certain fibers of overloaded fast-patterns take on similar in certain aspects to that normally seen in differentiated slow-twitch muscle fibers.     

Effect of exercise on Hepatic cholesterof of rats fed diets high in saturated or unsaturated fats

Summary Rats have been fed diets containing 24.2% coconut or corn oil or an equal mixture of each for 14–18 weeks. Half of the animals in each dietary group were exercised by running in motor-driven work wheels throughout the entire experimental period. During the final 10–14 weeks, these exercised animals ran continuously for 60 min at 1.0 mph or faster each day. Comparisons between sedentary groups revealed that hepatic cholesterol and excretion of digitonin precipitated sterols in the feces increased (P < 0.01) as the per cent of unsaturated fat (corn oil) in the ingested food increased. In contrast, total liver lipid decreased (P < 0.01) as the consumption of corn oil increased. No change in plasma cholesterol occurred in the sedentary rats in response to the three diets. Hepatic cholesterol of the exercised groups was significantly less (P < 0.05–P < 0.01) than that of their respective control groups (same diet). However, the group fed the corn oil diet had a significantly higher (P < 0.01) liver cholesterol after exercise than did the exercised group fed the coconut oil diet. Liver lipid was reduced (P < 0.01) by exercise in the corn oil and mixed corn-coconut oil fed groups. Plasma cholesterol and sterol excretion were unchanged by the exercise program.This investigation supported by Research Grant HE 08262 from the National Heart Institute, National Institutes of Health, U.S. Public Health Service.     

Prepro-galanin messenger RNA levels are increased in rat locus coeruleus after treadmill exercise training

The effects of treadmill exercise training on prepro-galanin (GAL) and tyrosine hydroxylase (TH) gene expression in the locus coeruleus (LC) were examined. Male Fischer-344 rats (n=9) were assigned to 6 weeks of treadmill running. An additional group of animals comprised the sedentary home cage control group (n=9). Levels of GAL and TH messenger RNA (mRNA) in the LC were measured using in situ hybridization histochemistry with autoradiography. Levels of GAL mRNA were higher in treadmill trained animals compared to sedentary animals, but there was no effect of treadmill running on TH mRNA. These results suggest that gene expression for galanin is responsive to repeated exercise stress and may have a neuromodulatory role in LC-noradrenergic adaptation to treadmill exercise training.     

Exercise and the development and persistence of dietary obesity in male and female rats

Adult male and female hooded rats were housed in sedentary conditions or were given free access to a running wheel. Exercising and sedentary rats received either a palatable, mixed, high energy diet with chow (experimental group) or only chow (control group). Exercise reduced the weight gain of the males but not of the females. All experimental groups preferentially selected the palatable foods. Both exercising and sedentary females and the sedentary males became obese compared to their controls, but the exercising males did not. The mixed diet was withdrawn after 10 weeks: thereafter the male and female sedentary experimental groups maintained the elevated body weight. The exercising experimental females showed significant weight loss. Analysis of x-ray photographs indicated that elevated body weight in the experimental rats probably reflected increased deposition of fat and not skeletal growth. The results show that the effect of exercise on the development of dietary obesity is different in males and females, and that sedentary male and female rats can both show persistent dietary obesity after withdrawal of the palatable foods.     

Exercise improves biomarkers of health and stress in animals fed ad libitum

Voluntary and forced exercise decrease morbidity and mortality in laboratory animals. Caloric restriction has similar effects on health and unique benefits on life span. Nonetheless, in most experiments, animals do not have access to physical activity and are fed ad libitum (AL). We hypothesized that with regular access to either unlimited running wheel exercise (EX) or limited physical activity (PA), key biomarkers of health would be enhanced enough to counter some consequences of a sedentary AL lifestyle. This 16-month study compared body weight, tumor number and size, tissue lesions, oxidative stress, and reactive stress in (1) sedentary animals with no access to physical activity (SED); (2) animals with access to hour-long, twice weekly activity in a large box (PA); and (3) animals with access every other day to a running wheel (EX). At the end of the study, EX body weight was 8-9% lower than PA and SED. In addition, EX had no kidney lesions versus 50% in PA and SED, and had smaller tumor size (10+/-2 vs. 14+/-4 and 30+/-4 mm). Exhaustive exercise lowered glutathione/oxidized glutathione ratio in EX and PA, but in SED, the ratio was depressed even in resting animals. In all treatments, prolactin (PRL) levels were lower in resting animals than in acutely exercised animals. In conclusion, EX had the most favorable health biomarkers while SED had the least. PA did not confer gross health benefits different than the SED group, but was biochemically more similar to EX animals.     

Effect of the detraining status on high-fat diet induced fat accumulation in the adipose tissue and liver in female rats

The purpose of the present study was to investigate the effects of a high-fat diet (HFD) in previously trained rats that have been detrained for different periods. Two groups of female rats were, first, either treadmill trained for 8 weeks or remained sedentary (Sed). Trained animals, thereafter, remained inactive for 4 weeks (Inact-4 weeks), while fed a standard diet, before being submitted to a high-fat diet (42% kcal of fat) for an additional 2 or 6 weeks. The order was reversed in a 3rd group in which rats were first kept sedentary for 4 weeks before being submitted to the same 8-week training program that ended with the initiation of the HFD (Inact-0 week). Fat accumulation in the mesenteric depot (P<0.05) and in the sum of 3 intra-abdominal (urogenital, retroperitoneal, and mesenteric; P=0.065) tissues in response to the HF feeding was higher in trained rats kept inactive for 4 weeks than in Sed and Inact-0 week animals. Liver triacylglycerol accumulation also showed a tendency to be higher (P<0.07) in Inact-4 weeks than in Inact-0 week rats. These changes were not associated with significant changes in fat cell diameter and number in the mesenteric adipose tissue. When rats in all groups were subdivided into obesity prone (OP) and obesity resistant (OR) on the basis of the change in body weight gain in response to the HFD, liver lipid infiltration was higher (P<0.01) in OP Inact-4 weeks rats than in all other groups. The present results indicate that previously trained rats that have been inactive for a while maintain higher body adiposity in response to a HFD than in freshly inactive and sedentary rats.     

Responses of rat myocardial antioxidant defences and heat shock protein HSP72 induced by 12 and 24‐week treadmill training

Aim: The purpose of this study was to determine the effects of both a short (12 weeks) and a long‐term (24 weeks) endurance treadmill‐training programme on the levels of oxidative stress markers, the activity of the enzymatic antioxidants, and the content of the 72 kDa heat shock protein (HSP72) in rat myocardium. Methods: Thirty male Wistar rats were randomly assigned to exercise trained (n = 16) and sedentary (n = 14) groups. After 12 week of training, eight rats were killed while the remaining eight continued the training programme until 24 week. Results: Seven sedentary controls were killed together with each trained group. Levels of thiobarbituric acid‐reactive substances (TBARS), protein carbonyls, and total and oxidized glutathione (tGSH and GSSG) in myocardial homogenates were unchanged by training irrespective of the protocol duration. However, an increased content of the oxidative stress biomarkers was detected in hearts from both the 24‐week trained rats and their sedentary controls when compared with their corresponding 12‐week groups. The antioxidant enzymatic activities total and mitochondrial superoxide dismutase (tSOD and mtSOD, respectively), glutathione peroxidase (GPX) and glutathione reductase (GR), remained unchanged after the 12‐week training period whereas a significant increase in tSOD and mtSOD activities (18%, P < 0.05) was observed in heart homogenates of 24‐week trained animals as compared with their sedentary controls. HSP72 expression levels were not significantly modified after 12 week of training but a threefold increase was detected after 24 week (P < 0.05). Conclusion: These results demonstrate that a long‐term endurance training (24 weeks) induced discrete increases in antioxidant enzyme activities in rat myocardium and elicited a marked enhancement in HSP72 expression levels. However, a shorter training programme (12 weeks), was not effective in increasing heart antioxidant defences.     

Responses of rat myocardial antioxidant defences and heat shock protein HSP72 induced by 12 and 24-week treadmill training

AIM: The purpose of this study was to determine the effects of both a short (12 weeks) and a long-term (24 weeks) endurance treadmill-training programme on the levels of oxidative stress markers, the activity of the enzymatic antioxidants, and the content of the 72 kDa heat shock protein (HSP72) in rat myocardium. METHODS: Thirty male Wistar rats were randomly assigned to exercise trained (n = 16) and sedentary (n = 14) groups. After 12 week of training, eight rats were killed while the remaining eight continued the training programme until 24 week. RESULTS: Seven sedentary controls were killed together with each trained group. Levels of thiobarbituric acid-reactive substances (TBARS), protein carbonyls, and total and oxidized glutathione (tGSH and GSSG) in myocardial homogenates were unchanged by training irrespective of the protocol duration. However, an increased content of the oxidative stress biomarkers was detected in hearts from both the 24-week trained rats and their sedentary controls when compared with their corresponding 12-week groups. The antioxidant enzymatic activities total and mitochondrial superoxide dismutase (tSOD and mtSOD, respectively), glutathione peroxidase (GPX) and glutathione reductase (GR), remained unchanged after the 12-week training period whereas a significant increase in tSOD and mtSOD activities (18%, P < 0.05) was observed in heart homogenates of 24-week trained animals as compared with their sedentary controls. HSP72 expression levels were not significantly modified after 12 week of training but a threefold increase was detected after 24 week (P < 0.05). CONCLUSION: These results demonstrate that a long-term endurance training (24 weeks) induced discrete increases in antioxidant enzyme activities in rat myocardium and elicited a marked enhancement in HSP72 expression levels. However, a shorter training programme (12 weeks), was not effective in increasing heart antioxidant defences.     

Effects of ageing and endurance exercise training on alpha-actinin isoforms in rat plantaris muscle

Aim: We recently reported that α‐actinin adaptation occurs at the isoform level. This study was undertaken to clarify the effects of: (1) ageing‐induced shift of myosin heavy chain (MyHC) composition and (2) endurance exercise training on α‐actinin isoforms in rat plantaris muscle. Methods: Adult (18 mo) and old (28 mo) male Fischer 344 rats were assigned to either sedentary control or endurance exercise training groups. Animals in the training groups ran on a treadmill for 8 week with training intensity adjusted to be equal for adult and old groups. After the training was completed, the plantaris muscles were taken for analyses of α‐actinin‐2, α‐actinin‐3, and MyHC composition and metabolic enzyme activities. Results: The proportion of type IIb MyHC was lower, and that of type I MyHC was higher in old animals than in adult animals. α‐actinin‐3 was significantly lower in old animals than in adult animals. No significant difference was found in α‐actinin‐2 and citrate synthase (CS) activity between adult and old animals. Citrate synthase activity was higher in trained animals than in sedentary animals. Endurance training produced a fast‐to‐slow shift within type II MyHC isoforms in both adult and old animals. α‐actinin‐2 was significantly higher in trained animals than in sedentary animals. No significant difference was found in α‐actinin‐3 between trained and sedentary animals. Conclusion: These results support the α‐actinin adaptation at the isoform level and show that the α‐actinin‐3 expression depends on the amount of type II MyHC, whereas α‐actinin‐2 expression is associated with improvement of muscular aerobic capacity.     

Running reduces stress and enhances cell genesis in aged mice

Cell proliferation and neurogenesis are diminished in the aging mouse dentate gyrus. However, it is not known whether isolated or social living affects cell genesis and stress levels in old animals. To address this question, aged (17–18 months old) female C57Bl/6 mice were single or group housed, under sedentary or running conditions. We demonstrate that both individual and socially housed aged C57Bl/6 mice have comparable basal cell proliferation levels and demonstrate increased running-induced cell genesis. To assess stress levels in young and aged mice, corticosterone (CORT) was measured at the onset of the active/dark cycle and 4 h later. In young mice, no differences in CORT levels were observed as a result of physical activity or housing conditions. However, a significant increase in stress in socially housed, aged sedentary animals was observed at the onset of the dark cycle; CORT returned to basal levels 4 h later. Together, these results indicate that voluntary exercise reduces stress in group housed aged animals and enhances hippocampal cell proliferation.     

Effects of chronic caffeine intake and low-intensity exercise on skeletal muscle of Wistar rats

Caffeine can affect muscle cell physiology and the inflammatory response during exercise. The purpose of this study was to analyse muscle damage markers and inflammatory cell infiltration into the soleus muscle of sedentary and exercised animals submitted to chronic caffeine intake. Thirty-two male Wistar rats were divided into the following four groups (n = 8 per group): sedentary control (SCO); sedentary + caffeine (SCAF); trained control (TCO); and trained + caffeine (TCAF). The animals were housed in individual cages and received tap water or caffeine (1 mg ml(-1)); they were maintained at rest or submitted to swimming for up to 40 min day(-1) with a 4% load, five times per week for 30 days. Blood samples were collected for analysis of serum lactate, creatine kinase and calcium. The right soleus muscle and the epididymal fat depot were weighed, and the muscle was submitted to histological analysis. Training and caffeine did not change body or muscle weight, food and liquid intake or serum calcium levels among groups. Decreased fat tissue (P < 0.05) was observed in the SCAF (4.05 ± 1.03 g), TCO (4.14 ± 0.78 g) and TCAF groups (4.02 ± 1.02 g) compared with the SCO group (5.31 ± 1.06 g). Serum creatine kinase activity was significantly reduced in the SCAF (787.3 ± 230.3 U l(-1)), TCO (775.3 ± 232.3 U l(-1)) and TCAF groups (379.5 ± 110.5 U l(-1)) compared with the SCO group (1610.2 ± 276.5 U l(-1)). Few damaged muscle fibres (P < 0.05) were found in SCAF (16.7 ± 12.8%) and TCAF groups (17.3 ± 11.7%) compared with the SCO group (53.6 ± 13.9%). The SCAF group presented fewer fields with inflammatory cells (7.6 ± 8.7 fields) compared with the SCO group (123 ± 146 fields). The results suggest that the chronic intake of caffeine, as well as chronic low-intensity exercise, decreased muscle damage and inflammatory infiltration into skeletal muscle.     

Anaerobic exercise reduces tumor growth, cancer cachexia and increases macrophage and lymphocyte response in Walker 256 tumor-bearing rats

Here, we investigated the effect of jump exercise on tumor growth, cancer cachexia, lymphocyte proliferation and macrophage function in Walker 256 tumor-bearing rats. Male Wistar rats (60 days) were divided into sedentary (C) and exercised (E) groups. Jump training consisted of six sets of 10 jumps in water with overload of 50% of body mass with 1 min of resting, four times per week for 8 weeks. After 6 weeks of training, half of each group was inoculated with 2 × 10⁷ cells of Walker 256 tumor. Sedentary tumor-bearing and exercised tumor-bearing are referred to as T and TE, respectively. Tumor weight in the T group was 25 g. These animals display loss of weight, hypertriacylglycerolemia, hyperlacticidemia, depletion of glycogen stores and increase in PIF expression. Jump exercise (TE) induced a significant lower tumor weight, preserves liver glycogen stores, partly prevented the hypertriacylglycerolemia, hyperlacticidemia and, prevented the fall in body weight and reduced PIF expression. Lymphocyte was increased by tumor burden (T) and was higher by including exercise (TE). The same was observed regarding phagocytosis and lysosomal volume. Anaerobic exercise decreases tumor growth, cancer cachexia and increases innate and adaptative immune function.