White matter inflammation and cognitive function in a co-morbid metabolic syndrome and prodromal Alzheimer's disease rat model.

Background: Metabolic syndrome, the development of which is associated with high-caloric Western diet (HCD) intake, represent a risk factor for mild cognitive impairment (MCI) and dementia including Alzheimer's disease (AD) later in life. This study aimed to investigate the effect of diet-induced metabolic disturbances on white matter neuroinflammation and cognitive function in a transgenic (TG) Fischer 344 rat carrying a human β-amyloid precursor protein (APP) gene with Swedish and Indiana mutations (APP21 TG), a model of pre-AD and MCI.

Methods: TG and wildtype (WT) rats received either a HCD with 40% kJ from fat supplemented with 20% corn syrup drink or a standard diet for 12 weeks.

Aerobic exercise training improves insulin-induced vasorelaxation in a vessel-specific manner in rats with insulin-treated experimental diabetes.

Vascular insulin resistance often precedes endothelial dysfunction in type 1 diabetes mellitus. Strategies to limit vascular dysfunction include intensive insulin therapy (4-9 mM) and aerobic training. To avoid the risk of hypoglycaemia, individuals often prescribed conventional insulin therapy (9-15 mM) and participate in resistance training.

Exercise Training Induced Cardioprotection with Moderate Hyperglycemia versus Sedentary Intensive Glycemic Control in Type 1 Diabetic Rats.

Intensive insulin therapy (IIT; 4-7 mmol/L) is the preferred treatment for type 1 diabetes mellitus (T1DM) patients to reduce the risk of cardiovascular disease (CVD). However, this treatment strategy has been questioned as it is accompanied with a sedentary lifestyle leading to weight gain and insulin resistance. T1DM patients who partake in high-intensity aerobic training (AT) to reduce CVD often utilize conventional insulin therapy (CIT; 9-15 mmol/L) to offset the risk of hypoglycemia.

Effects of Ginseng Supplementation and Endurance-Exercise in the Artery-Specific Vascular Responsiveness of Diabetic and Sedentary Rats.

This study examined the effects of 12 weeks North-American ginseng supplementation, exercise training, and sedentary behavior on vascular responses in type I diabetic rats. The following hypotheses were tested: (1) ginseng supplementation would result in improved vascular responsiveness and sensitivity; (2) exercise training would result in further improvement in these vascular responses; (3) control rats with no access to exercise would show a depressed vascular response compared to control rats that were not exposed to a sedentary lifestyle. Groups: non-diabetic sedentary control (C), sedentary diabetic (D), sedentary diabetic with ginseng supplementation (D+GS), diabetic with ginseng supplementation and high-intensity endurance exercise (D+GS+EX), and control not exposed to sedentary behavior (C).

Effect of Combined Exercise Versus Aerobic-Only Training on Skeletal Muscle Lipid Metabolism in a Rodent Model of Type 1 Diabetes.

Objectives: Abnormal skeletal muscle lipid metabolism is associated with insulin resistance in people with type 1 diabetes. Although lipid metabolism is restored with aerobic exercise training, the risk for postexercise hypoglycemia is increased with this modality. Integrating resistance and aerobic exercise is associated with reduced hypoglycemic risk; however, the effects of this exercise modality on lipid metabolism and insulin resistance remain unknown.

Aerobic Endurance Training Does Not Protect Bone Against Poorly Controlled Type 1 Diabetes in Young Adult Rats.

Streptozotocin (STZ)-induced type 1 diabetes mellitus (T1DM) decreases trabecular bone volume and bone strength in rodents. The current study investigated the potential protective effects of aerobic endurance training (AET) on bone in STZ-induced T1DM young adult rats. Sixty-four 8-week-old male Sprague-Dawley rats were randomly divided into 4 groups of 16: control non-T1DM sedentary (CS) and exercised (CX), T1DM sedentary (DS) and exercised (DX).

Metabolomic Response of Skeletal Muscle to Aerobic Exercise Training in Insulin Resistant Type 1 Diabetic Rats.

The etiology of insulin resistance in Type 1 Diabetes (T1D) is unknown, however it affects approximately 20% of T1D patients. Intramyocellular lipids (IMCL) have been identified as a mechanism of insulin resistance. We examined skeletal muscle of T1D rats to determine if alterations in lipid metabolism were evident and whether aerobic exercise training improves IMCL and insulin resistance.

The glucoregulatory response to high-intensity aerobic exercise following training in rats with insulin-treated type 1 diabetes mellitus.

An acute bout of exercise elicits a rapid, potentially deleterious, reduction in blood glucose in patients with type 1 diabetes mellitus (T1DM). In the current study, we examined whether a 10-week aerobic training program could alleviate the rapid exercise-associated reduction in blood glucose through changes in the glucoregulatory hormonal response or increased hepatic glycogen storage in an insulin-treated rat model of T1DM. Thirty-two male Sprague-Dawley rats were divided evenly into 4 groups: non-T1DM sedentary (C) (n = 8), non-T1DM exercised (CX) (n = 8), T1DM sedentary (D) (n = 8), and T1DM exercised (DX) (n = 8).

High Intensity Aerobic Exercise Training Improves Deficits of Cardiovascular Autonomic Function in a Rat Model of Type 1 Diabetes Mellitus with Moderate Hyperglycemia.

Indices of cardiovascular autonomic neuropathy (CAN) in experimental models of Type 1 diabetes mellitus (T1DM) are often contrary to clinical data. Here, we investigated whether a relatable insulin-treated model of T1DM would induce deficits in cardiovascular (CV) autonomic function more reflective of clinical results and if exercise training could prevent those deficits. Sixty-four rats were divided into four groups: sedentary control (C), sedentary T1DM (D), control exercise (CX), or T1DM exercise (DX).

Effects of Two Different Weight Training Programs on Swimming Performance and Muscle Enzyme Activities and Fiber Type.

The effects of 2 different weight training programs incorporating bench press (BP) and pullover (PO) exercises on swimming performance, power, enzyme activity, and fiber type distribution were studied on 16 men (age = 23 ± 4 years). A 30-second group (n = 6) performed up to 20 repetitions of BP and PO in 30 seconds. The 2-minute group (n = 6) performed a maximum of 80 repetitions of BP and PO in 2 minutes.

North American ginseng protects against muscle damage and reduces neutrophil infiltration after an acute bout of downhill running in rats.

Eccentric muscle contractions such as those experienced during downhill running are associated with inflammation, delayed-onset of muscle soreness, myofiber damage, and various functional deficits. North American ginseng (Panax quinquefolius L.) has been reported to possess anti-inflammatory properties and thus may offset some of this exercise-induced damage.

Morphological assessment of pancreatic islet hormone content following aerobic exercise training in rats with poorly controlled Type 1 diabetes mellitus.

Regular exercise has been shown to improve many complications of Type 1 diabetes mellitus (T1DM) including enhanced glucose tolerance and increased cardiac function. While exercise training has been shown to increase insulin content in pancreatic islets of rats with T1DM, experimental models were severely hyperglycemic and not undergoing insulin treatment. Further, research to date has yet to determine how exercise training alters glucagon content in pancreatic islets.

Ischemia-reperfusion injury and hypoglycemia risk in insulin-treated T1DM rats following different modalities of regular exercise.

While regular exercise is known to improve cardiovascular function, individuals with type 1 diabetes mellitus (T1DM) have an increased risk for exercise-induced hypoglycemia. Clinical data suggest that higher intensities of acute exercise may alleviate the onset of hypoglycemia; however, the cardiovascular benefit from these forms of exercise in patients with T1DM has yet to be established. The purpose of this study was to investigate the cardiovascular benefit of different regular exercise regimes, while monitoring blood glucose concentrations during the post-exercise period.

The relationship between blood pressure and sciatic nerve blood flow velocity in rats with insulin-treated experimental diabetes.

Peripheral nerve blood flow (NBF) does not autoregulate but, instead, responds passively to changes in mean arterial pressure (MAP). How this relationship is impacted by insulin-treated experimental diabetes (ITED) is unknown. We tested the hypothesis that ITED will reduce NBF across a range of MAP in Sprague Dawley rats.

Exercise training enhances insulin-stimulated nerve arterial vasodilation in rats with insulin-treated experimental diabetes.

Insulin stimulates nerve arterial vasodilation through a nitric oxide (NO) synthase (NOS) mechanism. Experimental diabetes reduces vasa nervorum NO reactivity. Studies investigating hyperglycemia and nerve arterial vasodilation typically omit insulin treatment and use sedentary rats resulting in severe hyperglycemia.

American ginseng acutely regulates contractile function of rat heart.

Chronic ginseng treatments have been purported to improve cardiac performance. However reports of acute administration of ginseng on cardiovascular function remain controversial and potential mechanisms are not clear. In this study, we examined the effects of acute North American ginseng (Panax quinquefolius) administration on rat cardiac contractile function by using electrocardiogram (ECG), non-invasive blood pressure (BP) measurement, and Langendorff isolated, spontaneously beating, perfused heart measurements (LP).

The role of resistance and aerobic exercise training on insulin sensitivity measures in STZ-induced Type 1 diabetic rodents.

Unlabelled: Individuals with Type 1 Diabetes Mellitus (T1DM) can develop insulin resistance. Regular exercise may improve insulin resistance partially through increased expression of skeletal muscle GLUT4 content.

Objective: To examine if different exercise training modalities can alter glucose tolerance through changes in skeletal muscle GLUT4 content in T1DM rats.

Glucose-stimulated insulin secretion causes an insulin-dependent nitric oxide-mediated vasodilation in the blood supply of the rat sciatic nerve.

This study tested the hypothesis that acute hyperglycemia reduces sciatic nerve blood flow in Sprague-Dawley rats. Anesthetized rats underwent cannulation of their right jugular vein (for anesthetic/nutrient/drug infusion) and right carotid artery (for continuous blood pressure measurement via pressure transducer). The left sciatic nerve was exposed and nerve blood velocity (NBV) was assessed from an arterial segment lying superficially along the sciatic nerve (Doppler ultrasound, 40 MHz).

Acute endurance exercise induces changes in vasorelaxation responses that are vessel-specific.

The dynamic adjustment and amplitude of the endothelium-dependent vasorelaxation of the carotid, aorta, iliac, and femoral vessels were measured in response to acute low- (LI) or high-intensity (HI) endurance exercise. Vasorelaxation to 10(-4) M ACh was evaluated in 10 control, 10 LI, and 10 HI rats. Two-millimeter sections of carotid, aorta, iliac, and femoral arteries were mounted onto a myography system.

Impact of exercise and metabolic disorders on heat shock proteins and vascular inflammation.

Heat shock proteins (Hsp) play critical roles in the body's self-defense under a variety of stresses, including heat shock, oxidative stress, radiation, and wounds, through the regulation of folding and functions of relevant cellular proteins. Exercise increases the levels of Hsp through elevated temperature, hormones, calcium fluxes, reactive oxygen species (ROS), or mechanical deformation of tissues. Isotonic contractions and endurance- type activities tend to increase Hsp60 and Hsp70.

Core temperature is a greater influence than endogenous 17β-estradiol on the exercise-induced accumulation of myocardial heat shock protein mRNA.

Female rats typically do not show significant increases in myocardial Hsp70 after exercise unless trained (exercise over days or weeks). 17β-Estradiol (E2) has been linked to this inhibition, but it varies considerably over the rodent estrus cycle. Consequently, we examined whether the inhibitory effects of endogenously produced E2 (measured immediately pre-exercise) were acute in exercised female Sprague-Dawley rats (60 min treadmill running at 30 m·min(-1)).

hsp70 mRNA temporal localization in rat skeletal myofibers and blood vessels post-exercise.

Rapid transcription of the survival transcript, inducible heat shock protein 70 (hsp70), is critical for mounting cytoprotection against severe cellular stress, like elevated temperature. Previous investigations have demonstrated that exercise-induced expression of Hsp70 protein occurs in a fiber-specific pattern; however, the activation pattern of hsp70 mRNA expression remains unclear in skeletal muscle. Consequentially, the temporal localization of hsp70 mRNA was characterized via in situ hybridization (ISH) experiments examining fast-muscle, white vastus: 1, 3, 10, and 24 h after a single bout of intense treadmill running (1 h, 30 m/min, 6% grade) in rats.

Regulation of survival gene hsp70.

Rapid expression of the survival gene, inducible heat shock protein 70 (hsp70), is critical for mounting cytoprotection against severe cellular stress, like elevated temperature. Hsp70 protein chaperones the refolding of heat-denatured peptides to minimize proteolytic degradation as a part of an eukaryotically conserved phenomenon referred to as the heat shock response. The physiologic stress associated with exercise, which can include elevated temperature, mechanical damage, hypoxia, lowered pH, and reactive oxygen species generation, may promote protein unfolding, leading to hsp70 gene expression in skeletal myofibers.