Effects of high-fat mixed-lipid diet and exercise on the antioxidant system in skeletal and cardiac muscles of rats with colon carcinoma

Antioxidant Barrier, Redox Status, and Oxidative Damage to Biomolecules in Patients with Colorectal Cancer. Can Malondialdehyde and Catalase Be Markers of Colorectal Cancer Advancement?

This study is the first to assess the diagnostic utility of redox biomarkers in patients with colorectal cancer (CRC). Antioxidant barrier (Cu,Zn-superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), uric acid (UA), reduced glutathione (GSH)), redox status (total antioxidant (TAC)/oxidant status (TOS), ferric reducing ability (FRAP)), and oxidative damage products (advanced glycation end products (AGE), advanced oxidation protein products (AOPP), malondialdehyde (MDA)) were measured in serum/plasma samples of 50 CRC patients. The activity of SOD was significantly higher whereas the activity of CAT, GPx and GR was considerably lower in CRC patients compared to the control group (p < 0.0001). Levels of UA, TOS, and OSI and concentrations of AGE, AOPP, and MDA were significantly higher, and the levels of GSH, TAC, and FRAP were considerably lower in CRC patients compared to the healthy controls (p < 0.0001). AUC for CAT with respect to presence of lymph node metastasis was 0.7450 (p = 0.0036), whereas AUC for MDA according to the depth of tumour invasion was 0.7457 (p = 0.0118). CRC is associated with enzymatic/non-enzymatic redox imbalance as well as increased oxidative damage to proteins and lipids. Redox biomarkers can be potential diagnostic indicators of CRC advancement.

Effect of high-fat mixed lipid diet and swimming on fibre types in skeletal muscles of rats with colon tumours

Skeletal muscle fibre types, whose characteristics are determined by myosin heavy chain (MyHC) isoforms, can adapt to changed physiological demands with changed MyHC isoform expression resulting in the fibre type transitions. The endurance training is known to induce fastto- slow transitions and has beneficial effect in carcinogenesis, whereas the effect of an excessive fat intake and its interaction with the effect of swimming are less conclusive. Therefore, we studied the effect of high-fat mixed lipid (HFML) diet and long-term (21-week) swimming on fibre type transitions and their average diameters by immunohistochemical demonstration of MyHC isoforms in slow soleus (SOL), fast extensor digitorum longus (EDL), and mixed gastrocnemius medialis and lateralis (GM, GL) muscles, divided to deep and superficial portions (GMd, GMs, GLd, GLs), of sedentary and swimming Wistar rats with experimentally (dimethylhydrazine) induced colon tumours and fed either with HFML or low-fat corn oil (LFCO) diet. HFML diet induced only a trend for fast-to-slow transitions in SOL and in the opposite direction in GMd. Swimming triggered significant transitions in unexpected slow-to-fast direction in SOL, whereas in GMs the transitions had tendency to proceed in the expected fast-toslow direction. The average diameters of fibre types were mostly unaffected. Hence, it can be concluded that if present, the effects of HFML diet and swimming on fibre type transitions were counteractive and muscle-specific implying that each muscle possesses its own adaptive range of response to changed physiological conditions.

Effect of carcinogen 1,2-dimethylhydrazine treatment on fiber types in skeletal muscles of male Wistar rats

The cancerogen 1,2-dimethylhydrazine (DMH), widely used in the experimental animal model of carcinogenesis, affects various organs, but its effect on muscle fibers is unknown. To evaluate the effect of 15-week DMH treatment on the fiber size and myosin heavy chain (MyHC) isoforms, which substantially determine fiber types and their contractile characteristics, pure and hybrid fiber types were immunohistochemically determined according to the MyHC isoform expression in soleus, extensor digitorum longus, gastrocnemius medialis and lateralis muscles of DMH-treated and control male Wistar rats. Whereas the size of fibers was mostly unaffected, the MyHC isoform expression was partially affected in both gastrocnemius samples, but not in the soleus and extensor digitorum longus of DMH-treated rats. The lower proportions of hybrid fiber types and especially that of type 1/2x in most gastrocnemius samples of DMH-treated rats resulted in a shift towards a single MyHC isoform expression, but the extent and pattern of the MyHC isoform shift varied across the different gastrocnemius samples. Such variable response to DMH treatment across muscles indicates that each muscle possesses its own adaptive range. These findings are essential for an accurate evaluation of skeletal muscle characteristics in DMH animal model.

Nandrolone Plus Moderate Exercise Increases the Susceptibility to Lethal Arrhythmias

Background:

Until now, no experimental study has directly assessed the arrhythmogenesis of chronic consumption of anabolic androgenic steroids along with moderate-intensity endurance exercise.

Objectives:

We evaluated the influence of integration of anabolic androgenic steroids along with moderate-intensity endurance exercise on susceptibility to lethal ventricular arrhythmias in rat.

Materials and Methods:

The animal groups were as follows: control group (CTL); exercise group (EX) which were under 6 weeks of treadmill exercise; nandrolone group (Nan) which received 5 mg/kg of nandrolone decanoate twice a week; vehicle group (Arach) which received Arachis oil (solvent of nandrolone); trained vehicle group (Arach + Ex); and trained nandrolone group (Nan + Ex). One day after ending of the intervention period, arrhythmia was inducted by intravenous infusion of aconitine and ventricular arrhythmias were recorded. Then malondialdehyde (MDA) and glutathione peroxidase (GPX) of heart tissue were measured.

Results:

Nandrolone, exercise, and their combination were associated with heart hypertrophy. Exercise could prevent the incremental effect of nandrolone on MDA/GPX ratio. Chronic administration of nandrolone with moderate-intensity endurance exercise had no significant effect on blood pressure, heart rate, and basal electrocardiographic parameters. Combination of nandrolone and exercise significantly increased the incidence of ventricular fibrillation (VF) and reduced the VF latency (P < 0.05).

Conclusions:

The findings suggest that chronic coadministration of nandrolone with moderate-intensity endurance exercise facilitates the VF occurrence in rat. Complementary studies are needed to elucidate the involved mechanisms of this abnormality.

Oxidative stress in the pathogenesis of colorectal cancer: cause or consequence?

There is a growing support for the concept that reactive oxygen species, which are known to be implicated in a range of diseases, may be important progenitors in carcinogenesis, including colorectal cancer (CRC). CRC is one of the most common cancers worldwide, with the highest incidence rates in western countries. Sporadic human CRC may be attributable to various environmental and lifestyle factors, such as dietary habits, obesity, and physical inactivity. In the last decades, association between oxidative stress and CRC has been intensively studied. Recently, numerous genetic and lifestyle factors that can affect an individual's ability to respond to oxidative stress have been identified. The aim of this paper is to review evidence linking oxidative stress to CRC and to provide essential background information for accurate interpretation of future research on oxidative stress and CRC risk. Brief introduction of different endogenous and exogenous factors that may influence oxidative status and modulate the ability of gut epithelial cells to cope with damaging metabolic challenges is also provided.

A 6-week training program increased muscle antioxidant system in elderly diabetic fatty rats

Background

It is widely accepted that oxidative stress is associated with the physiopathology of type 2 diabetes mellitus. In fact, it has been pointed out as a therapeutic target in T2DM. Fortunately, several papers have reported that long-term training programs improved the antioxidant system in young and adult diabetic rats. Accordingly, this study was designed to assess the influence of a shorter training program in elderly diabetic fatty rats.

Material/Methods

Study subjects were 24 male homozygous Zucker diabetic fatty rats (Gmi, fa/fa) aged 18 weeks with an average weight of 370–450 g. After a 2-week period of environmental adaptation, animals were randomly distributed into the Exercised Group (n=12) that performed a 6-week swimming training protocol and the Sedentary Group (n=12). Animals were sacrificed under anesthesia 24 h after the last exercise session. Serum metabolic profile was determined. Total antioxidant status (TAS), MnSOD expression, glutathione status and ROS generation were assayed in gastrocnemius muscle.

Results

When compared with controls, exercised rats significantly improved their metabolic profile. Total antioxidant status (0.19±0.002 vs. 0.13±0.002 μg/mg protein; p<0.001) and MnSOD expression (8471±90 vs. 6258±102 U/μg protein; p=0.003) were also increased in exercised rats.

Conclusions

A 6-week swimming training program improved the antioxidant system in elderly fatty diabetic rats. Fortunately, this improvement was enough to reduce oxidative damage, expressed as protein oxidation. A major finding of this study was that our training protocol lasted just 6 weeks, in contrast to longer protocols previously published.

High fat mixed lipid diet modifies protective effects of exercise on 1,2 dimethylhydrazine induced colon cancer in rats

The aim of the present study was to evaluate the effect of long-term swimming exercise in conjunction with a high fat mixed lipid (HFML) diet on colon cancer (CC) development and lipid peroxidation in the large bowel. We used forty male Wistar rats, which were randomly divided into one control group and four cancer groups: sedentary and swimming groups fed a standard diet (LFCO) and sedentary and swimming groups fed an HFML diet. Corticosterone was determined during the experiment. After 6 months of swimming, the rats were sacrificed and blood, heart, liver, muscle and large bowel were taken for determining the activity of serum enzymes, antioxidant capacity and CC development. The results demonstrate that exercise has a protective role in CC development. Attenuated development of CC and increased levels of malondialdehyde (MDA) in the large bowel of exercised rats show that one of the protective effects of exercise on developing CC is induction of oxidative stress. However, in terms of the combined effects of dietary fat and exercise, our results indicate that the protective role of exercise on CC development is significantly depressed by an HFML diet. An HFML diet significantly reduced the protective influence of exercise on colon carcinogenesis in rats and affected the degree of peroxidation in the large bowel during exercise, as well as concentrations of serum enzymes (LDH, α-HBDH, CK, ALT and AST). Our results indicate that an HFML diet, which reflects the composition of a Western style diet, is a significant modifier of the protective effects of exercise on CC development in rats.

Exercise training attenuates acute hyperalgesia in streptozotocin-induced diabetic female rats

OBJECTIVES

We investigated the effects of chronic (eight weeks) low-to moderate-intensity swimming training on thermal pain sensitivity in streptozotocin-induced diabetic female rats.

METHODS

Female Wistar rats (n = 51) were divided into the following groups: trained streptozotocin-induced diabetic rats [hyperglycemic trained (HT)], sedentary streptozotocin-induced diabetic rats [hyperglycemic sedentary (HS)], normoglycemic trained rats (NT) and normoglycemic sedentary rats (NS). Diabetes was induced by a single injection of streptozotocin (50 mg/kg, i.p.). One day after the last exercise protocol (60 min/day, five days/week for eight weeks) in the trained groups or after water stress exposure (ten min/twice a week) in the sedentary groups, the rats were subjected to a hot plate test.

RESULTS

After eight weeks of swimming training, streptozotocin-induced diabetic rats presented a significantly lower body mass (trained: 219.5 ± 29 g, sedentary: 217.8 ± 23 g) compared with the normoglycemic groups (trained: 271 ± 24 g, sedentary: 275.7 ± 32 g). Interestingly, we did not find differences in blood glucose levels (mg/dl) between the trained and sedentary groups of the hyperglycemic or normoglycemic rats (HT: 360.2 ± 66.6, HS: 391.7 ± 66.7, NT: 83.8 ± 14.0, NS: 77.5 ± 10.1). In the hot plate test, the rats from the HT group presented a significantly lower latency than the other rats (HT: 11.7 ± 7.38 s, HS: 7.02 ± 7.38 s, NT: 21.21 ± 7.64 s, NS: 22.82 ± 7.82 s).

CONCLUSION

Low-to-moderate swimming training for a long duration reduces thermal hyperalgesia during a hot plate test in streptozotocin-induced diabetic female rats.

Morphological and molecular alterations in 1,2 dimethylhydrazine and azoxymethane induced colon carcinogenesis in rats

The dimethyhydrazine (DMH) or azoxymethane (AOM) model is a well-established, well-appreciated, and widely used model of experimental colon carcinogenesis. It has many morphological as well as molecular similarities to human sporadic colorectal cancer (CC), which are summarized and discussed in this paper. In addition, the paper combines present knowledge of morphological and molecular features in the multistep development of CC recognized in the DMH/AOM rat model. This understanding is necessary in order to accurately identify and interpret alterations that occur in the colonic mucosa when evaluating natural or pharmacological compounds in DMH/AOM rat colon carcinogenesis. The DMH/AOM model provides a wide range of options for investigating various initiating and environmental factors, the role of specific dietary and genetic factors, and therapeutic options in CC. The limitations of this model and suggested areas in which more research is required are also discussed.