Exercise In Rats Research Articles

Effects of Chronic Exercise on Blood Pressure in Dahl Salt-Sensitive Rats

We tested the hypothesis that daily exercise would reduce directly measured arterial blood pressure (BP) and sympathetic nervous system support of BP in conscious, unrestrained, female Dahl salt-sensitive rats consuming 4.0% NaCl. Dahl S/Jr inbred rats were assigned to daily exercise (EX) or sedentary (SED) treatment conditions (n = 12/group) at 4 weeks of age. Rats in the EX group were housed in cages with attached running wheels. After 5 weeks of exercise, rats were running 10.3 ± 1.7 km/day. After at least 5 wks of treatment, all rats in both groups were placed on a 4.0% NaCl diet for 2 weeks to produce sodium-induced hypertension. Rats continued to either exercise daily or remain sedentary for an additional 2 weeks while consuming the high sodium diet. Carotid and jugular catheters were then implanted for measurements in conscious, resting, unrestrained rats on two separate days. Daily wheel running exercise for 7 to 9 weeks did not alter BP or HR in Dahl S/Jr rats consuming a 4.0% NaCl diet. However, acute arterial depressor responses to ganglionic blockade were less in EX rats. Furthermore, greater α-adrenergic (phenylephrine-induced) pressor responses were observed in the EX group while under ganglionic blockade. The findings suggest that overall resting sympathetic neural activity or cardiac β-adrenergic responsiveness to sympathetic activity is reduced in this model of hypertension by daily wheel running exercise.

Effects of Repeated Sensory Stimulation (Electro‐acupuncture) and Physical Exercise (Running) on Open‐field Behaviour and Concentrations of Neuropeptides in the Hippocampus in WKY and SHR rats

The effects of repeated sensory stimulation (electro-acupuncture) and physical exercise (running) on open-field behaviour and on hippocampal concentrations of neuropeptide Y, neurokinin A, substance P, galanin and vasoactive intestinal peptide (VIP)-like immunoreactivities were studied in WKY (wistar-Kyoto) and SHR (spontaneously hypertensive) rats. Significantly higher concentrations of substance P-like immunoreactivity, neurokinin A-like immunoreactivity and neuropeptide Y-like immunoreactivity were found in the hippocampus immediately after 3 weeks of treatment (electro-acupuncture and running), but not 1 week after the last (tenth) changes in neuropeptide concentrations were similar in the two rat strains. Open-field behaviour was significantly reduced during the treatment period in both strains. There were significant negative correlations between behaviour and neuropeptide concentrations in SHR rats, suggesting interdependency with sympathetic activity. It is proposed that the effects of electro-acupuncture and physical exercise in rats are related to increases in neuropeptide Y, neurokinin A and substance P in the hippocampus.

Intense exercise and food restriction cause similar hypothalamic neuropeptide Y increases in rats

Neuropeptide Y (NPY) is a potent central appetite stimulant whose concentrations rise markedly in hypothalamic appetite-regulating regions in food-deprived rats. To determine whether increased energy expenditure also affects hypothalamic NPY, we studied the effects of intense physical exercise in rats (n = 10) running voluntarily on a large-diameter exercise wheel. Running was initiated by restricting food intake but stabilized at an average of 8 km/day when food intake was matched to that in 11 nonexercised, freely fed controls [23.9 +/- 1.9 (SE) g/day vs. 24.7 +/- 1.3 g/day; P > 0.5]. Running expended approximately 40% of daily energy intake, and weight gain was significantly inhibited. A separate group (n = 10) of nonexercised rats was food restricted (approximately 15 g/day) to match the weights of the exercised rats. The rats were killed after 40 days, when both experimental groups weighed 30% less than controls (P < 0.01). Hypothalamic NPY concentrations showed significant (P < 0.01) increases of 30-70% in specific regions (arcuate and dorsomedial nuclei and medial preoptic and lateral hypothalamic areas) in both the running and food-restricted groups, compared with controls. There were no significant differences between the two experimental groups in NPY concentrations in any hypothalamic region. These findings suggest that negative energy balance, whether caused by reduced energy intake or increased expenditure, increases hypothalamic NPYergic activity. As NPY acts on the hypothalamus to increase body weight, these data support the postulated homeostatic role of NPY in maintaining nutritional state.

Exhaustive physical exercise causes oxidation of glutathione status in blood: prevention by antioxidant administration.

We have studied the effect of exhaustive concentric physical exercise on glutathione redox status and the possible relationship between blood glutathione oxidation and blood lactate and pyruvate levels. Levels of oxidized glutathione (GSSG) in blood increase after exhaustive concentric physical exercise in trained humans. GSSG levels were 72% higher immediately after exercise than at rest. They returned to normal values 1 h after exercise. Blood reduced glutathione (GSH) levels did not change significantly after the exercise. We have found a linear relationship between GSSG-to-GSH and lactate-to-pyruvate ratios in human blood before, during, and after exhaustive exercise. In rats, physical exercise also caused an increase in blood GSSG levels that were 200% higher after physical exercise than at rest. GSH levels did not change significantly. Thus, both in rats and humans, exhaustive physical exercise causes a change in glutathione redox status in blood. We have also found that antioxidant administration, i.e., oral vitamin C, N-acetyl-L-cysteine, or glutathione, is effective in preventing oxidation of the blood glutathione pool after physical exercise in rats.

Catecholamines and exercise-induced glucagon and fatty acid mobilization in the rat.

Physical exercise in rats provokes an increase in plasma glucagon and free fatty acid concentrations. The persistence of exercise-induced glucagon stimulation in adrenodemedullated animals and conversely, its inhibition by immunosympathectomy, (-)-ropranolol, and pindolol substantiate the conclusion that stimulation of the alpha2 cells in exercise involves sympathetic stimulation of the beta-adrenergic receptors. The reduction of free fatty acid mobilization by immunosympathectomy and (-)-propranolol and its persistence after adrenodemedullation suggest that it is similarly mediated, at least in part, by adipose cell beta-sympathetic receptors.

An instrument for measuring rat's exercise amounts

An instrument for measuring rat's exercise amounts