Effects of treadmill running and swimming on plasma and brain vasopressin levels in rats

The influence of treadmill or swimming exercise on resting values of plasma and brain arginine vasopressin (AVP), and plasma sodium, potassium, osmolality and proteins was studied after 5 weeks of training using female Wistar rats. The duration of daily training sessions was progressively increased to reach 6 h/day for swim training (S) and 3 h/day for treadmill running (T). Compared to their untrained controls, treadmill and swim training were respectively associated with: a significant lower body weight; a decreased plasma AVP (36.4% for T and 47.4% for S) and hypothalamic AVP (20% for T and 16% for S); a higher hypophyseal AVP (145% for T and 36.3 for S); a decreased plasma osmolality (6.7% for T and 6.1% for S), sodium (1.2% for both) and potassium (15% for T and 22.4% for S); and no change in protein concentration. For T, rectal temperature increased (38.5 +/- 0.20 to 39.7 +/- 0.5) and for S rectal temperature decreased from 38.6 +/- 0.12 to 37.74 +/- 0.10). The differences observed in AVP contents of the pineal and Harderian glands (enhanced only in the treadmill groups) could be explained by the supposed role of these glands in thermoregulation. Two conclusions could be drawn from this study: there are no parallel changes in the hypothalamo-hypophyseal system (where AVP plays its endocrine role) and the brain (where AVP is a neurotransmitter); plasma changes could be explained by an extracellular fluid expansion with Na and K loss leading to a decrease in AVP secretion.     

Acute cardiorespiratory responses of hypertensive rats to swimming and treadmill exercise

The acute cardiorespiratory responses of spontaneously hypertensive rats (SHR) to swimming and running exercise was investigated because SHR populations are hyperresponsive to external stimuli, of the paucity of existing data, and of the uncertainty on the role of exercise stimuli for training adaptations to occur. Male rats were assigned to one of five groups (n = 5-6/group) and designated as controls (C), inexperienced or naive free swimmers (NFS), experienced free swimmers (FS), experienced weighted swimmers (WS) (attached weights equal to 2% of their body weight) or experienced runners (R) who ran at an intensity of 75% of their VO2max. After 75 min in the water, all groups were acidotic and hypercapnic with the WS experiencing the greatest changes. Heart rate (HR) was increased in all swimmers during the initial 10 min, but declined thereafter, and after 75 min, the HR of WS (348 +/- 1 beats/min) was significantly lower than the C group (416 +/- 22 beats/min). At the same time interval, mean arterial blood pressure (MAP) was decreased in all swimming groups to values lower than the C animals. In addition, an exaggerated diving reflex was frequently noted when the rats were submerged. When the magnitudes of the changes were evaluated in the swimming animals they were directly associated with their submergence times, i.e., during 65-75 min of the swim, NFS, FS, and WS were submerged for 43, 46, and 66% of their total swim time, respectively. In sharp contrast to the swimmers, the runners exhibited increases in HR and MAP with their blood gas measurements being indicative of hyperventilation. We concluded that swimming as an exercise mode for hypertensive rats is best served to study the combined effects of excitement, prolonged submergence, and the consequences of the diving reflex.     

Effect of acute swimming exercise on lactate levels and its relation with zinc in pinealectomized rats

It is argued that melatonin secreted from the pineal gland regulates the levels of zinc, which is an important trace element. Decreases in zinc levels of pinealectomized rats supports this relationship. There is an increasing amount of evidence suggesting that the pineal gland can have important effects on physical activity. The objective of the present study was to explore the changes in serum lactate levels in pinealectomized rats subjected to acute swimming exercise and its relation with zinc. Forty adult male rats of Spraque Dawley strain were equally allocated to four groups. Group 1: General Control Group. Group 2: Pinealectomized Control Group. Group 3: Swimming Control Group. Group 4: Pinealectomized Swimming Group. Serum zinc, melatonin and lactate levels were determined in the blood samples collected from the animals by a decapitation method. Zinc and melatonin levels were higher in Group 1 than in Groups 2, 3 and 4 (p < 0.01), higher in Group 3 than in Groups 2 and 4 (p < 0.01) and higher in Group 2 than in Group 4 (p < 0.01). The highest lactate levels were found in Group 4 (p < 0.01). Lactate levels in Group 3 were higher than those in Groups 1 and 2 (p < 0.01), while the levels in Groups 1 and 2 did not differ. Pinealectomy results in a significant increase in lactate levels in rats subjected to an acute swimming exercise. This increase in lactate levels may be associated with the decrease observed in zinc levels after pinealectomy.     

Effect of treadmill exercise on bone mass in female rats.

Increasing peak bone mass at skeletal maturity, minimizing bone loss during middle age and after menopause, and increasing bone mass and preventing falls in advanced age are important measures for preventing osteoporotic fractures in women. Exercise has generally been considered to have a positive influence on bone health. This paper reviews the effects of treadmill exercise on bone in young, adult, ovariectomized, and osteopenic female rats. Treadmill exercise increases cortical and cancellous bone mass of the tibia as a result of increased bone formation and decreased bone resorption in young and adult rats. The increase in lumbar bone mass seems to be more significant when long-term exercise is applied. Treadmill exercise prevents cancellous bone loss at the tibia as a result of suppressed bone resorption in ovariectomized rats, and increases bone mass of the tibia and mechanical strength of the femur, as a result of suppressed bone resorption and increased bone formation in osteopenic rats after ovariectomy. Treadmill exercise transiently decreases the serum calcium level as a result of accumulation of calcium in bone, resulting in an increase in serum 1,25-dihydroxyvitamin D(3) level and a decrease in serum parathyroid hormone level. We conclude that treadmill exercise may be useful to increase bone mass in young and adult rats, prevent bone loss in ovariectomized rats, and increase bone mass and bone strength in osteopenic rats, especially in the long bones at weight-bearing sites. Treadmill exercise may have a positive effect on the skeleton in young, and adult, ovariectomized, and osteopenic female rats.     

Effect of exercise on plasma interferon levels

The effect of exercise on plasma interferon activity was studied on eight male subjects before and after exercise on a bicycle ergometer for 1 h at 70% of their maximal O2 consumption (VO2 max). Acid-labile interferon, alpha-type according to immunological characterization, rose significantly from a preexercise value of 3 +/- 1 to 7 +/- 2 IU/ml postexercise. Negligible changes were recorded for plasma protein, lipid, and glucose concentrations, whereas blood lactate slightly increased only at the end of exercise. According to hematocrit and plasma protein values before and after exercise, hemoconcentration did not occur. These data provide evidence that plasma interferon activity increased following a bout of submaximal exercise.     

Effect of acute exercise on plasma neurotensin levels

Neurotensin (NT) levels were examined in five aerobically untrained females aged 20-36 engaged in acute graded exercise testing. In addition to radioimmunoassay measurements, high pressure liquid chromatography was performed to further characterize plasma NT-like immunoreactivity (NTLI). Epinephrine (E), norepinephrine (NE), and lactate (L) responses were also determined. Exercise testing consisted of one hour of treadmill running subdivided into three 20-minute segments representing 50, 60, and 70%, respectively, of the previously determined maximal aerobic capacity. Mock testing established baseline values for each subject. Three components of NTLI were evaluated: NT(1-13), NT(1-8), and NT(1-11). Resting NT(1-13) concentrations averaged 5.8 +/- 4.2 fmol/ml, while mean NT(1-8) values were 13.0 +/- 5.2 fmol/ml, and NT(1-11) averaged 5.8 +/- 3.2 fmol/ml. Peak exercise values were: for NT(1-13), 5.4 +/- 2.0 fmol/ml, for NT(1-8), 13.5 +/- 2.8 fmol/ml, and for NT(1-11), 5.9 +/- 0.5 fmol/ml. Analysis of variance with repeated measures detected no changes in these levels with exercise. Four-fold increases in E (36 +/- 3 pg/ml to 121 +/- 51 pg/ml), NE (340 +/- 95 pg/ml to 1431 +/- 319 pg/ml), and L (0.8 +/- 0.1 mM to 4.3 +/- 1.7 mM) confirmed the stress of exercise on the body in general, and the sympatho-adrenal system in particular. While other research has associated peripheral NT metabolite elevations with stressful stimuli in laboratory animals, the results of the present study suggest either that NT is not released from the human adrenal medulla during exercise, or that peripheral sampling precludes detection of any increases in NT from the adrenal medulla with currently available radioimmunoassay systems.     

运动干预对衰老模型大鼠血清炎性因子水平的影响

目的:探讨6周跑台运动对D-半乳糖致衰老模型大鼠血清炎性因子水平的影响,以此阐明运动延缓衰老的部分机制。方法:将雄性SD大鼠随机分为正常对照组(NC组)、衰老对照组(AC组)、衰老训练组(AE组),每组8只。AC和AE组大鼠每日腹腔注射1次D-半乳糖125 mg/kg,NC组注射等量生理盐水,持续6周。同时,AE组进行6周中小强度跑台训练。6周后,各组大鼠腹主动脉取血,分离血清检测血清中白细胞介素-6(IL-6)、白细胞介素-10(IL-10)、肿瘤坏死因子-α(TNF-α)的含量。结果:与正常对照组比较,衰老模型组大鼠血清IL-6、TNF-α水平明显升高(P＜0.01);与衰老模型组比较,衰老训练组大鼠血清IL-6、IL-10和TNF-α水平明显减少(P＜0.01),表明6周中小强度跑台训练有助于降低衰老机体促炎症因子的分泌,减弱体内炎症反应。结论:6周中小强度跑台训练在一定程度上可以纠正衰老机体内的炎性因子网络紊乱状况,起到干预炎性衰老的目的。     

Immunomodulations induced in rats by exercise on a treadmill

Various regimens of treadmill exercise (0% slope) were used with rats: 60 min at 15 m/min (T-15), 180 min at 10 m/min (T-10), and 60 min/day at 15 m/min for 6 consecutive days (T-15-6). Exercise resulted in 1) decreases in the absolute number of mononuclear spleen cells in T-10 rats, 2) significant increases in in vitro splenic T-cell blastogenesis in response to phytohemagglutinin in T-10 rats, and 3) significant decreases in T-cell blastogenesis in T-15-6 rats. T-15-6 rats were given aminoglutethimide per os before exercise sessions to study the role of corticosteroids in the alteration of splenic T-cell blastogenesis. Aminoglutethimide significantly increased the T-cell blastogenesis in these T-15-6 rats compared with those not given aminoglutethimide, whereas it had no effect on immune parameters of sedentary rats. These results show that immunomodulations in the rat depend on the treadmill exercise regimen employed. If the mechanisms of the immunomodulation induced by isolated exercise of long duration are not elucidated, these data suggest that corticosteroids are involved in the alteration in T-cell blastogenesis induced by chronic muscular exercise.     

Stress biomarkers in rats submitted to swimming and treadmill running exercises

The objective of the present work was to compare stress biomarkers (serum ACTH and corticosterone hormones) during known intensity swimming and treadmill running exercises performed by rats. Adult Wistar rats (n=41) weighing 320-400 g at the beginning and 420-500 g at the end of the experiment, previously adapted to exercise and with Maximal Lactate Steady State (MLSS) already determined were used. The animals were divided into the following subgroups: (1) sacrificed shortly after session of 25 min of exercise (swimming or treadmill) at the MLSS intensity or (2) sacrificed after exhaustive exercise (swimming or treadmill) at intensity 25% higher than MLSS. For comparison, a control group C was sacrificed at rest. Two-way ANOVA was used to identify differences in the stress parameters (P<0.05). At both exercise intensities serum ACTH concentrations were significantly higher for the swimming group compared to running and control groups, while serum corticosterone concentrations in swimming and running groups were significantly higher than in the control group. The differences were more pronounced at the higher intensity (25% higher than MLSS). The swimming group showed higher concentrations for both hormones in relation to the running group. Only acute swimming exercise induced activity of the hypothalamic-pituitary-adrenal axis responses expected to stress: elevations in the serum ACTH and corticosterone concentrations.     

Effect of treadmill exercise on plasma and urinary cyclic adenosine 3'5'-monophosphate.

The effect of treadmill exercise on plasma and urinary cyclic adenosine 3'5' monophosphate levels (cyclic AMP) was studied in twelve healthy subjects. Plasma cyclic AMP levels were found to be markedly elevated without significant changes in urinary cyclic AMP or cyclic AMP/creatine ratio. Most likely altered plasma glucagon and catecholamine levels were responsible for these changes.     

Effect of bromocriptine on lipid plasma levels in rats

Results show that bromocriptine induced marked alterations in plasma levels of cholesterol and lipids in response to acute and chronic administrations in rats. Two hours after an I.P. dose of 10 mg/kg, bromocriptine mesylate caused significant reductions in plasma levels of total high density lipoprotein (HDL) and high density lipoprotein cholesterol (HDL cholesterol). At a dose of 20 mg/kg, bromocriptine mesylate induced significant elevations in plasma levels of total cholesterol, total HDL, HDL cholesterol, total low density lipoproteins (LDL), and low density lipoprotein cholesterol (LDL cholesterol). Injected at a dose of 4 or 10 mg/kg daily for 14 consecutive days, bromocriptine mesylate caused significant increases in plasma levels of total cholesterol, LDL cholesterol and total LDL whereas the levels of HDL cholesterol, total HDL triglycerides (TG) were reduced. At a dose of 20 mg/kg all parameters were significantly increased. Marked hyperglycaemia was noticed in response to doses of 10, 15 and 20 mg/kg injected daily for 14 consecutive days or 2 hrs after a single administration of 15 mg/kg. Plasma insulin activity was reduced 2 hours after injection of bromocriptine at a dose of 15 mg/kg Likewise, a significant reduction in plasma insulin activity was observed in response to daily I.P. injections of bromocriptine at a dose of 15 mg/kg. Hyperglycaemic and hypoinsulinaemic effects of bromocriptine (acute and chronic) were markedly decreased when sulpiride, a dopaminergic D2 antagonist, was injected at an I.P. dose of 10 mg/kg before bromocriptine. Plasma ACTH activity was significantly increased in response to bromocriptine (15 mg/kg I.P.) in acute and chronic experiments. This effect was markedly diminished when sulpiride was injected prior to bromocriptine. In conclusion, bromocriptine induced marked elevations in plasma levels of total cholesterol and lipids which are likely to be related to hyperglycaemic and hypoinsulinaemic effects.     

Effect of long-term swimming exercise on zinc,magnesium, and copper distribution in aged rats

Trace element content of different tissues might be altered by both age and exercise training. We aimed to determine the effects of a 1-yr swimming protocol (60 min/d, 5 day/wk) on tissue levels and the distribution of zinc (Zn), magnesium (Mg), and copper (Cu) in aging rats. Three groups were formed: sedentary and trained old groups and a young control group. Tissue Zn, Mg, and Cu concentrations were measured in the kidney, heart, liver, lungs, and gastrocnemius and soleus muscles. Kidney zinc concentration significantly decreased in the sedentary old group compared to the young control group (p<0.01) and was significantly higher in the trained old group compared to the sedentary old group (p<0.01), whereas Zn levels in the soleus muscle significantly increased in the sedentary old group in comparison to young controls (p<0.05). Tissue Mg concentrations remained unchanged. The sedentary old group exhibited a significant decrease in kidney Cu concentration compared to the young control group (p<0.01). Although kidney Cu levels also decreased in trained old rats in comparison to young controls (p<0.05), they were significantly higher than in sedentary old rats (p<0.01). The decrease in kidney Zn and Cu content as a result of aging was partly prevented by long-term swimming exercise.