Resistance exercise attenuates skeletal muscle oxidative stress, systemic pro-inflammatory state, and cachexia in Walker-256 tumor-bearing rats.

The aim of this study was to investigate the effects of resistance exercise training (RET) on oxidative stress, systemic inflammatory markers, and muscle wasting in Walker-256 tumor-bearing rats. Male (Wistar) rats were divided into 4 groups: sedentary controls (n = 9), tumor-bearing (n = 9), exercised (n = 9), and tumor-bearing exercised (n = 10). Exercised and tumor-bearing exercised rats were exposed to resistance exercise of climbing a ladder apparatus with weights tied to their tails for 6 weeks. The physical activity of control and tumor-bearing rats was confined to the space of the cage. After this period, tumor-bearing and tumor-bearing exercised animals were inoculated subcutaneously with Walker-256 tumor cells (11.0 × 107 cells in 0.5 mL of phosphate-buffered saline) while control and exercised rats were injected with vehicle. Following inoculation, rats maintained resistance exercise training (exercised and tumor-bearing exercised) or sedentary behavior (control and tumor-bearing) for 12 more days, after which they were euthanized. Results showed muscle wasting in the tumor-bearing group, with body weight loss, increased systemic leukocytes, and inflammatory interleukins as well as muscular oxidative stress and reduced mTOR signaling. In contrast, RET in the tumor-bearing exercised group was able to mitigate the reduced body weight and muscle wasting with the attenuation of muscle oxidative stress and systemic inflammatory markers. RET also prevented loss of muscle strength associated with tumor development. RET, however, did not prevent the muscle proteolysis signaling via FBXO32 gene messenger RNA expression in the tumor-bearing group. In conclusion, RET performed prior tumor implantation prevents cachexia development by attenuating tumor-induced systemic pro-inflammatory condition with muscle oxidative stress and muscle damage.

Oral Administration of Aloe vera (L.) Burm. f. (Xanthorrhoeaceae) and Honey Improves the Host Body Composition and Modulates Proteolysis Through Reduction of Tumor Progression and Oxidative Stress in Rats.

Oxidative stress has a dual role in cancer; it is linked with tumorigenic events and host wasting, as well as senescence and apoptosis. Researchers have demonstrated the importance of coadjuvant therapies in cancer treatment, and Aloe vera and honey have immunomodulatory, anticancer, and antioxidant properties. The preventive and therapeutic effects of Aloe vera (L.) Burm. f. (Xanthorrhoeaceae) and honey in tumor progression and host wasting were analyzed in Walker 256 carcinoma-bearing rats. The animals were distributed into the following groups: C=control-untreated, W=tumor-untreated, WA=treated after tumor induction, A=control-treated, AW=treated before tumor induction, and AWA=treated before and after tumor induction. Proteolysis and oxidative stress were analyzed in the tumor, liver, muscle, and myocardial tissues. The results suggest that the Aloe vera and honey treatment affect the tumor and host by different mechanisms; the treatment-modulated host wasting and cachexia, whereas it promoted oxidative stress and damage in tumor tissues, particularly in a therapeutic context (WA).

Physical exercise and a leucine-rich diet modulate the muscle protein metabolism in Walker tumor-bearing rats.

Leucine-supplemented diet can recover lean body mass and preserve muscle protein mass. Additionally, physical exercise can be an excellent alternative to improve the rehabilitation of cancer patients. Knowing these facts, we examined the effects of a leucine-rich diet with or without physical aerobic exercise on muscle protein metabolism in Walker tumor-bearing rats. Young rats were divided into 4 groups that did or did not perform light aerobic exercise (swim training) and were on a leucine-rich diet or a control diet for 2 mo. After this time, these animals were implanted or not with tumors (subcutaneously) following groups for either control diet or leucine-rich diet fed rats: control, trained, tumor-bearing, and trained tumor-bearing. Twenty-one days after implantation, the tumor growth induced a decrease in the muscle protein synthesis and increased the catabolic process, which was associated with an increase in the expression of the ubiquitin-proteasome subunits (20S, 19S, and 11S). In contrast, the exercise program minimized the muscle degradation process and increased muscle myosin content. Additionally, leucine supplementation also modulated proteasome subunits, especially the 19S and 11S. In summary, the exercise has beneficial effects by reducing tumor growth, leading to an improvement in protein turnover especially when in conjunction with a leucine-rich diet.

Effect of fish oil supplementation for two generations on changes of lymphocyte function induced by Walker 256 cancer cachexia in rats.

Fish oil supplementation has been shown to improve the cachectic state of tumor-bearing animals and humans. Our previous study showed that fish oil supplementation (1 g per kg body weight per day) for 2 generations had anticancer and anticachetic effects in Walker 256 tumor-bearing rats as demonstrated by reduced tumor growth and body weight loss and increased food intake and survival. In this study, the effect of fish oil supplementation for 2 generations on membrane integrity, proliferation capacity, and CD4/CD8 ratio of lymphocytes isolated from mesenteric lymph nodes, spleen, and thymus of Walker 256 tumor-bearing animals was investigated. We also determined fish oil effect on plasma concentration and ex vivo production of cytokines [tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin-4 (IL-4), IL-6, and IL-10]. Lymphocytes from thymus of tumor-bearing rats presented lower viability, but this change was abolished by fish oil supplementation. Tumor growth increased proliferation of lymphocytes from all lymphoid organs, and fish oil supplementation abolished this effect. Ex vivo production of TNF-alpha and IL-6 was reduced in supplemented animals, but IL-4 and IL-10 secretion was stimulated in both nontumor and tumor-bearing rats. IL-10 and IFN-gamma plasma levels was also decreased in supplemented animals. These results suggest that the anticachetic effects of fish oil supplementation for a long period of time (2 generations) in Walker 256 tumor-bearing rats may be associated to a decrease in lymphocyte function as demonstrated by reduced viability, proliferation capacity, and cytokine production.

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 x 10(7) 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.

The action of extracellular NAD+ in the liver of healthy and tumor-bearing rats: model analysis of the tumor-induced modified response.

The chronic inflammatory state induced by cancer is expected to affect the actions of extracellular NAD(+) in the liver because these are largely mediated by eicosanoids. Under this assumption the present work was planned to investigate the influence of the Walker-256 tumor on the action of extracellular NAD(+) on metabolism and hemodynamics in the perfused rat liver. The experiments were done with livers from healthy and tumor-bearing rats with measurements of gluconeogenesis from lactate, pyruvate production, oxygen consumption and portal pressure. A model describing the biphasic effects of NAD(+) was proposed as an auxiliary worktool for interpretation. The Walker-256 tumor modified the responses of metabolism to extracellular NAD(+) by delaying the peak of maximal responses and by prolonging the inhibitory effects. The transient increase in portal perfusion pressure caused by NAD(+) was enhanced and delayed. The model was constructed assuming the mediation of a down-regulator (inhibition), an up-regulator (stimulation) and receptor dessensitization. Analysis suggested that the productions of both the down- and up-regulators were substantially increased and delayed in time in the tumor-bearing condition. Since the regulators are probably eicosanoids, this analysis is consistent with the increased capacity of producing these agents in the chronic inflammatory state induced by cancer.

Metabolic and morphological alterations induced by proteolysis-inducing factor from Walker tumour-bearing rats in C2C12 myotubes.

BACKGROUND: Patients with advanced cancer suffer from cachexia, which is characterised by a marked weight loss, and is invariably associated with the presence of tumoral and humoral factors which are mainly responsible for the depletion of fat stores and muscular tissue. METHODS: In this work, we used cytotoxicity and enzymatic assays and morphological analysis to examine the effects of a proteolysis-inducing factor (PIF)-like molecule purified from ascitic fluid of Walker tumour-bearing rats (WF), which has been suggested to be responsible for muscle atrophy, on cultured C2C12 muscle cells. RESULTS: WF decreased the viability of C2C12 myotubes, especially at concentrations of 20-25 mug.mL-1. There was an increase in the content of the pro-oxidant malondialdehyde, and a decrease in antioxidant enzyme activity. Myotubes protein synthesis decreased and protein degradation increased together with an enhanced in the chymotrypsin-like enzyme activity, a measure of functional proteasome activity, after treatment with WF. Morphological alterations such as cell retraction and the presence of numerous cells in suspension were observed, particularly at high WF concentrations. CONCLUSION: These results indicate that WF has similar effects to those of proteolysis-inducing factor, but is less potent than the latter. Further studies are required to determine the precise role of WF in this experimental model.

Effect of a high-intensity exercise training on the metabolism and function of macrophages and lymphocytes of walker 256 tumor bearing rats.

Epidemiologic studies suggest that moderately intense training promotes augmented immune function, whereas strenuous exercise can cause immunosupression. Because the combat of cancer requires high immune function, high-intensity exercise could negatively affect the host organism; however, despite the epidemiologic data, there is a lack of experimental evidence to show that high-intensity training is harmful to the immune system. Therefore, we tested the influence of high-intensity treadmill training (10 weeks, 5 days/week, 30 mins/day, 85% VO(2)max) on immune system function and tumor development in Walker 256 tumor-bearing Wistar rats. The metabolism of glucose and glutamine in lymphocytes and macrophages was assessed, in addition to some functional parameters such as hydrogen peroxide production, phagocytosis, and lymphocyte proliferative responses. The metabolism of Walker 256 cells was also investigated. Results demonstrated that high-intensity training increased the life span of tumor-bearing rats, promoted a reduction in tumor mass, and prevented indicators of cachexia. Several changes, such as a reduction in body weight and food intake and activation of glutamine metabolism in macrophages and lymphocytes induced by the presence of Walker 256 tumor, were prevented by high intensity training. The reduction in tumor growth was associated with an impairment of tumor cell glucose and glutamine metabolism. These data suggest that high-intensity exercise training may be a viable strategy against tumors.

Cancer cachexia modifies the zonal distribution of lipid metabolism-related proteins in rat liver.

Cancer cachexia is a syndrome that causes profound metabolic disruption. Lipid metabolism in the liver is markedly affected. We investigated the effect of cachexia upon liver-acinus lipid-metabolism zonation in Walker 245 carcinosarcoma-bearing rats (TB). The expression of protein (by Western blotting) and mRNA (by semi-quantitative polymerase chain reaction) of the enzymes of the carnitine palmitoyltransferase system (CPT I and CPT II) and of liver fatty-acid-binding protein (L-FABP) was studied. Although no changes were found for these parameters, the maximal activities (by radioassay) of CPT I and II were reduced (P<0.05) in TB compared with controls. CPT II activity in the perivenous (PV) region was higher in TB compared with controls. The distribution of CPT II and L-FABP (by immunohistochemistry) within the acinus was modified by cachexia: whereas CPT II positivity was restricted to the PV zone, L-FABP labelling shifted from periportal (control) to perivenous (TB) zone. These changes in metabolic zonation, together with decreased CPT II activity, may contribute to the aggravation of cachexia.

Effect of chronic fish oil supplementation on renal function of normal and cachectic rats.

In the present study we determined the effect of chronic diet supplementation with n-3 PUFA on renal function of healthy and cachectic subjects by providing fish oil (1 g/kg body weight) to female rats throughout pregnancy and lactation and then to their offspring post-weaning and examined its effect on renal function parameters during their adulthood. The animals were divided into four groups of 5-10 rats in each group: control, control supplemented with fish oil (P), cachectic Walker 256 tumor-bearing (W), and W supplemented with fish oil (WP). Food intake was significantly lower in the W group compared to control (12.66 +/- 4.24 vs 25.30 +/- 1.07 g/day). Treatment with fish oil significantly reversed this reduction (22.70 +/- 2.94 g/day). Tumor growth rate was markedly reduced in the P group (16.41 +/- 2.09 for WP vs 24.06 +/- 2.64 g for W). WP group showed a significant increase in mean glomerular filtration rate compared to P and control (1.520 +/- 0.214 ml min-1 kg body weight-1; P < 0.05). Tumor-bearing groups had low urine osmolality compared to control rats. The fractional sodium excretion decreased in the W group compared to control (0.43 +/- 0.16 vs 2.99 +/- 0.87%; P < 0.05), and partially recovered in the WP group (0.90 +/- 0.20%). In summary, the chronic supplementation with fish oil used in this study increased the amount of fat in the diet by only 0.1%, but caused remarkable changes in tumor growth rate and cachexia, also showing a renoprotective function.

Re-assessment of the renal hydrosaline dysfunction in rats bearing the Walker-256 tumor.

Sodium retention is a frequent effect of cancer in humans and animals, but the mechanism involved is not yet understood. In the Walker-256 tumor, sodium retention has been considered to be a late effect, secondary to retention in the tumor mass, and/or to adrenal hypertrophy. Normally, (in rats receiving single tumor implants), the development of different tumor systemic effects (TSE) such as anorexia, sodium and fluid retention, anemia and immune depression in rats is synchronous within each individual but random among individuals of a given group in which they appear 6-47 days, or more, after inoculation. In present study, multifocal simultaneous inoculations of tumor cells resulted in a rapid and synchronous initiation of TSE (in 3-4 days) in all rats when no local effects of metastases could mask the results. Sodium retention is a special tumor effect on Na+ balance and a very sensitive indicator of TSE initiation. The results from multifocally inoculated rats were averaged in each (sub-clinical (SubC), moderate (mCP) and grave (gCP)) clinical phase and compared to food-restricted (FR) rats. There was a significant, early decrease in urinary Na+ excretion during mCP when compared to SubC and FR. The renal sites involved were studied in awake, unrestrained animals by measuring of sodium, creatinine and lithium clearances. There was an initial increase in the absolute proximal (mCP: 21.4 +/- 1.7 vs FR: 16.0 +/- 1.1 mmol/min/100 g b.w., p < 0.05) and post-proximal (mCP: 11.1 +/- 0.4 vs FR: 6.6 +/- 0.4 mmol/min/100 g b.w., p < 0.001) Na+ reabsorption, which were partially compensated for by a rise in glomerular filtration rate (mCP: 213 +/- 11.4 vs FR: 162 +/- 10.2 microL/min/100 g b.w., p < 0.01) and by a fall in fractional proximal Na+ reabsorption (mCP: 62.8 +/- 2.2% vs FR: 70.1 +/- 1.7%, p < 0.05), despite significant Na+ and fluid retention. The terminal phase of illness (gCP) culminated with a marked decrease in creatinine clearance, suggesting a significant fall in renal function. The multifocal model proved useful for studying the initial TSE, since the sites of action would, in principle, be easy to identify. These observations may be of physiological interest since TSE may result from the abnormal production of physiological modulators.

The effect of adrenaline and Walker-256 tumour-induced cachexia upon Kupffer cell metabolism.

Kupffer cells (KC), the liver macrophages, are able to produce PGE(2), which is involved in immune suppression and in the aggravation of cancer cachexia due to interference with lipid metabolism in the liver. Since tumour-bearing (TB) rats present high plasma epinephrine levels, and this hormone is able to affect macrophage metabolism and function, we have assessed the effect of epinephrine (5 nM) upon Kupffer cell PGE(2) production. Epinephrine induced increased production of PGE(2) both by control (3.5-fold) and TB rats (27 per cent) KC, an effect blocked by propranolol. Enhancement of cAMP content in the cells by addition of isoproterenol (0.1 microM) to the incubations, however, failed to induce the same response in the cells. Nevertheless, when phenylephrine (1 microM) was added to the incubation, a similar pattern of PGE(2) production to that observed for epinephrine was found for control and TB rat KC. We propose that the effect of epinephrine upon KC PGE(2) production is mediated by alpha-adrenergic receptors and that Ca(2+) is involved in the response, since increasing concentrations of the ion added to the incubation medium (0.25, 0.5 and 1.0 mM) enhanced the eicosanoid production, while EDTA abolished the response.

The influence of septal lesions on sodium and water retention induced by Walker 256 tumor.

In the course of studies on the effects of septal area lesions on neuroimmunomodulation and Walker 256 tumor development, it was observed that tumor-induced sodium and water retention was less marked in lesioned than in non-lesioned rats. In the present study possible mechanisms involved in this phenomenon were investigated. The experiments were performed in septal-lesioned (LW; N = 15) and sham-operated (SW; N = 7) 8-week-old male Wistar rats, which received multifocal simultaneous subcutaneous (sc) inoculations of Walker 256 tumor cells about 30 days after the stereotaxic surgery. Control groups (no tumor, sham-operated food-restricted (SFR), N = 7) and lesioned food-restricted (LFR, N = 10) were subjected to a feeding pattern similar to that observed in tumor-bearing animals. Multifocal inoculation of Walker 256 tumor rapidly induces anorexia, which is paradoxically accompanied by an increase in body weight, as a result of renal Na+ and fluid retention. These effects of the tumor were also seen in LW rats, although the rise in fractional sodium balance during the early clinical period was significantly smaller than in SW rats (day 4: SW = 47.6 +/- 6.4% and LW = 13.8 +/- 5.2%; day 5: SW = 57.5 +/- 3.5% and LW = 25.7 +/- 4.8%; day 6: SW = 54.4 +/- 3.8% and LW = 32.1 +/- 4.4%; P < 0.05), suggesting a temporary reduction in tumor-induced sodium retention. In contrast, urine output was significantly reduced in SW rats and increased in LW rats (LW up to -0.85 and SW up to 4.5 ml/100 g body weight), with no change in osmolar excretion. These temporary changes in the tumor's effects on LW rats may reflect a "reversal" of the secondary central antidiuretic response induced by the tumor (from antidiuretic to diuretic).

The influence of septal lesions on sodium and water retention induced by Walker 256 tumor

In the course of studies on the effects of septal area lesions on neuroimmunomodulation and Walker 256 tumor development, it was observed that tumor-induced sodium and water retention was less marked in lesioned than in non-lesioned rats. In the present study possible mechanisms involved in this phenomenon were investigated. The experiments were performed in septal-lesioned (LW; N = 15) and sham-operated (SW; N = 7) 8-week-old male Wistar rats, which received multifocal simultaneous subcutaneous (sc) inoculations of Walker 256 tumor cells about 30 days after the stereotaxic surgery. Control groups (no tumor, sham-operated food-restricted (SFR), N = 7) and lesioned food-restricted (LFR, N = 10) were subjected to a feeding pattern similar to that observed in tumor-bearing animals. Multifocal inoculation of Walker 256 tumor rapidly induces anorexia, which is paradoxically accompanied by an increase in body weight, as a result of renal Na+ and fluid retention. These effects of the tumor were also seen in LW rats, although the rise in fractional sodium balance during the early clinical period was significantly smaller than in SW rats (day 4: SW = 47.6 = 6.4 percent and LW = 13.8 = 5.2 percent; day 5: SW = 57.5 = 3.5 percent and LW = 25.7 = 4.8 percent; day 6: SW = 54.4 = 3.8 percent and LW = 32.1 = 4.4 percent; P<0.05), suggesting a temporary reduction in tumor-induced sodium retention. In contrast, urine output was significantly reduced in SW rats and increased in LW rats (LW up to -0.85 and SW up to 4.5 ml/100 g body weight), with no change in osmolar excretion. These temporary changes in the tumor's effects on LW rats may reflect a "reversal" of the secondary central antidiuretic response induced by the tumor (from antidiuretic to diuretic)

In vivo inhibition of Walker 256 tumour carnitine palmitoyltransferase I by soya oil dietary supplementation.

The role of dietary fatty acids in the regulation of carnitine palmitoyltransferase (CPT) activity has been shown in liver but their role in the regulation of tumour CPT activity in vivo is unknown. The present study investigated the effects of several oils, given as dietary supplements, upon the activity of CPT I and II in the Walker 256 rat tumour and the inhibition or stimulation of tumour growth. CPT I activity was markedly inhibited by soya oil, rich in linoleic acid (70% inhibition vs control). CPT I mRNA expression was not inhibited by any of the oils studied, indeed soya oil caused a marked increase (132% vs control) in expression. These results suggest that soya oil can modulate, in vivo, the beta-oxidative pathway of tumour tissue and further supports the hypothesis of tumour CPT I regulation by polyunsaturated fatty acids.

Effect of Walker 256 tumor growth on intestinal absorption of leucine, methionine and glucose in newly weaned and mature rats.

In tumor-bearing rats, most of the serum amino acids are used for synthesis and oxidation processes by the neoplastic tissue. In the present study, the effect of Walker 256 carcinoma growth on the intestinal absorption of leucine, methionine and glucose was investigated in newly weaned and mature rats. Food intake and carcass weight were decreased in newly weaned (NT) and mature (MT) rats bearing Walker 256 tumor in comparison with control animals (NC and MC). The tumor/carcass weight ratio was higher in NT than in MT rats, whereas nitrogen balance was significantly decreased in both as compared to control animals. Glucose absorption was significantly reduced in MT rats (MT = 47.3 +/- 4.9 vs MC = 99.8 +/- 5.3 nmol min-1 cm-1, Kruskal-Wallis test, P < 0.05) but this fact did not hamper the evolution of cancer. There was a significant increase in methionine absorption in both groups (NT = 4.2 +/- 0.3 and MT = 2.0 +/- 0.1 vs NC = 3.7 +/- 0.1 and MC = 1.2 +/- 0.2 nmol min-1 cm-1, Kruskal-Wallis test, P < 0.05), whereas leucine absorption was increased only in young tumor-bearing rats (NT = 8.6 +/- 0.2 vs NC = 7.7 +/- 0.4 nmol min-1 cm-1, Kruskal-Wallis test, P < 0.05), suggesting that these metabolites are being used for synthesis and oxidation processes by the neoplastic cells, which might ensure their rapid proliferation especially in NT rats.

Variability and discontinuity of the pathognomonic systemic effects caused by Walker 256 tumor progression in rats.

Cancer pathognomonic systemic effects (PSE) have high individual variability. For this reason present data were collected daily and synchronized considering four main points: inoculation day, onset of PSE, aggravation and death. The subclinical period free of PSE ranged between 15.7 +/- 2.2 days, the clinical period was less variable, 8.9 +/- 0.5 days, divided in a moderate and a grave phase of nearly the same length. PSE involved disturbances of fundamental homeostatic regulations: appetite, sodium, water, immune, etc. PSE triggering correlated highly with survival (r2 = 0.95, P < 0.01), but poorly with primary tumor growth, and it was anticipated by metastases from 20.5 +/- 2.6 to 10.6 +/- 1.1 days (P < 0.01). After multifocal simultaneous inoculations, PSE triggering was anticipated to 4.2 +/- 0.2 days (marked reduction of individual variability), in the presence of small total-tumor masses, absence of macroscopic metastases, and without changes in the following clinical period features. PSE triggering seems to be a major prognostic indicator probably related to multifocal tumor growth.

Insulin secretion in Walker 256 tumor cachexia.

The effect of cachexia on insulin secretion was examined in adult male rats. Isolated islets of Langerhans from Walker 256 tumor-bearing rats secreted less insulin by glucose stimuli as compared with the control group; this was accompanied by significant change in 45Ca2+ outflow rate. Reduced insulin secretion to glucose stimuli in tumor-bearing rats probably led to low insulinemia (one-third). These findings indicate that reduced insulin secretion is probably an important factor for the development of cachexia in Walker 256 tumor-bearing rats.