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Biomedical subjects

A L Dunn

Publications and source records attributed to A L Dunn.

29 records · Page 2Linked to original sources
PubMed1996

Increased open field locomotion and decreased striatal GABAA binding after activity wheel running.

Open-field behavior has been used to model reductions in anxiety-related behaviors in the rat after chronic physical activity. Plausible mechanisms for the increased open field locomotion observed after physical activity have not been studied. Open field locomotion is decreased by gamma-aminobutyric acid (GABA) and its agonists, and increased by GABA antagonists, in the ventral striatum. Hence, we tested the hypothesis that increased open field locomotion following chronic physical activity would be accompanied by a decrease in the number of GABAA receptors in the corpus striatum. Young (approximately 55 days) male Sprague-Dawley rats (N = 24) were randomly assigned to three conditions: 24-h access to an activity wheel (AW), running for 1 h without shock 6 days/week on a motorized treadmill (TM), or sedentary control (C). Open field locomotion (total and center squares traversed), defecation, and urination were assessed on each of 3 consecutive days prior to and again after 8 weeks of physical activity. Open field locomotion (total and center squares) increased after activity wheel running, decreased after treadmill training, and did not change for control animals. GABAA receptor density indicated by [3H] bicuculline binding (fmol/mg) was lower for activity wheel animals compared with treadmill animals and controls. GABA concentration (mumol/g) was not different between activity wheel and treadmill groups but was higher for both groups contrasted with controls. Our findings of decreased GABAA density in the corpus striatum concomitant with an increase in open field locomotion are consistent with an anxiolytic effect of chronic activity wheel running.

Animals↗
PubMed1996

Brain norepinephrine and metabolites after treadmill training and wheel running in rats.

Regional changes in concentrations of brain norepinephrine [NE] and its metabolites after chronic exercise have not been described for exercise protocols not confounded by other stressors. We examined levels of [NE], 3-methoxy-4-hydroxyphenylglycol [MHPG], and 3,4-dihydroxyphenylglycol [DHPG] in the frontal cortex, hippocampus, pons-medulla, and spinal cord after 8 wk of exercise. Male Sprague-Dawley rats (N = 36) were randomly assigned to three conditions: 1) 24-h access to activity wheel running (WR), 2) treadmill running (TR) at 0 degrees incline for 1 h.d-1 at 25-30 m.min-1, or 3) a sedentary control group (C). Levels (nmol.g-1) of [NE], [MHPG], and [DHPG] were assayed by high performance liquid chromatography with electrochemical detection. Planned contrasts (P < 0.05) indicated that exercise training increased succinate dehydrogenase activity (mmol cytochrome C reduced.min-1.g-1 wet weight) in soleus muscle for TR compared with WR or C. [NE] was higher in the pons-medulla and spinal cord for both TR and WR compared with C. [DHPG] was higher in the pons-medulla for TR compared with C, and [MHPG] was higher in the frontal cortex and in the hippocampus for TR compared with C. Our results suggest that treadmill exercise training is accompanied by brain noradrenergic adaptations consistent with increased metabolism of NE in areas containing NE cell bodies and ascending terminals, whereas treadmill running and wheel running are accompanied by increases in levels of NE in the areas of NE cell bodies and the spinal cord, independently of an exercise training effect.

Animals↗
PubMed1996

Getting started--a review of physical activity adoption studies.

The aim of this paper has been to review methods that have been found to be effective in getting sedentary adults to adopt physical activity, to examine these methods within the multilevel framework conceptualised by Winett et al, and to provide recommendations for future research to test new methods and their effectiveness in leading to the adoption of physical activity in sedentary populations. Searches for relevant studies were conducted on the Medline computerised database. Additional studies were located in reference sections of these studies and other review papers. Surveys that specifically identified determinants of adoption of physical activity in adults were included. Reviewed articles were selected on the basis of quasi-experimental and experimental designs that specifically examined the question of how to get sedentary adults to adopt a programme of physical activity or exercise, had completely described methods, and evaluated the effectiveness of methods of increasing physical activity and/or exercise. While numerous reviews have been written on determinants on physical activity adoption and maintenance, only two prospective surveys have identified specifics of adoption of physical activity. Most of the evidence for techniques that help inactive people to adopt physical activity comes from quasi-experimental and experimental intervention studies examining various cognitive and behavioural strategies at the individual level. Fewer studies have examined techniques at the interpersonal, organisational, community, environmental, and policy level. More prospective observational studies aimed at homogeneous subgroups are needed to identify correlates of physical activity adoption to help tailor interventions. Continued clinical studies are needed to differentiate the necessary and sufficient strategies at the personal and interpersonal levels. Interventions aimed at environmental, institutional, and social levels remain largely unexplored and there is a need for more research that specifically targets inactive subgroups at these levels.

Adult↗
PubMed1993

Repeated injections of interferon-alpha A/D in Balb/c mice: behavioral effects.

Interferon-alpha decreases food intake and activity in mice and humans. The present study further explores parallels between effects of this protein in humans and mice, using a hybrid recombinant interferon-alpha A/D (INF-alpha A/D) that has antiviral and hepatic activity in mice. Measures of activity (open field), muscle strength (forelimb grip strength), and motor ability (swim posture and endurance with 0, 3, and 6% added weight) were examined in Balb/c mice injected with 1600 U/g of hybrid rhuIFN-alpha A/D daily for 5 days (n = 9) or with IFN vehicle (n = 11). Open field activity was significantly depressed in the group exposed to IFN. The number of times the nose dipped under the water when swimming with 3% added body weight was higher in the IFN-treated mice, while float time was decreased with 6% added weight. The IFN-treated mice were slower to adopt the new strategies necessary to swim with added weight. Depression of motor activity is a robust, general effect of IFN treatment observed in this as well as previously published studies. Together, these studies demonstrate activity decrements in two different strains of mice, two different activity measures, acute and chronic injections, and recombinant and nonrecombinant IFN preparations.

Animals↗
PubMed1988

Open-field behavior is not related to treadmill performance in exercising rats.

We examined the association between open-field behavior and treadmill performance in 39 adult male Sprague-Dawley rats. Three daily, five-minute trials were conducted in an open field of 49 19 cm squares. The objectivity of the open-field test was established by intraclass correlations (R) for observer agreement on total squares traversed (R = .99) and a subjective behavioral rating scale for anxiety (R = .92). As expected, total squares were inversely correlated (r = -.86) with the subjective anxiety ratings. An independent observer also rated animals on treadmill performance across six daily, five-minute trials of level running at 15 m/min. Performance ratings were objective (rs = .89) and reproducible (R = .91). A volitional endurance run at 30 m/min on level grade was also conducted on a subsequent day. Extreme groups of low anxious (N = 7) and high anxious (N = 7) animals were then identified from convergent responses on total square traversals and the subjective behavioral ratings that were reproducible (R = .72 to .78) of trials two and three of the open-field test. Repeated measures ANOVA showed no group differences (p greater than 0.10) on mean treadmill performance across trials. Endurance was also the same for each group (p greater than 0.05). Our findings indicate that the open-field test is objective and reliable, and it does not reveal a selection bias effect on treadmill performance or endurance. Thus, open-field behavior can be used as a dependent or subject-matching variable in studies of adult male Sprague-Dawley rats when motor-driven treadmill running is a behavioral intervention or outcome measure.

Animals↗
PubMedDate not supplied

Reduction in cardiovascular disease risk factors: 6-month results from Project Active.

BACKGROUND: Project Active is a randomized clinical trial that compares a lifestyle physical activity intervention with a traditional structured exercise intervention. The purpose of this paper is to report 6-month results of these interventions on cardiovascular disease (CVD) risk factors among healthy, sedentary, middle-aged men and women, and to examine the psychological strategies used in each group (Lifestyle and Structured) to reach the level of physical activity recommended by the Centers for Disease Control and Prevention (CDC) and American College of Sports Medicine (ACSM) and to achieve changes in these CVD risk factors. METHODS: A total of 116 initially sedentary men (mean +/- SD self-reported physical activity, 33.2 +/- 1.4 kcal.kg-1.day-1) and 119 women (32.9 +/- 1.0 kcal.kg-1.day-1), ages 35-60 years (46.0 +/- 6.7 years) were randomly assigned to a 6-month lifestyle physical activity counseling intervention or a 6-month gymnasium-based structured program. At baseline and 6 months, changes in lipid and lipoprotein-cholesterol concentrations, blood pressure, and body composition and cognitive and behavioral measures of change were assessed. One-way analyses of variance with covariate adjustment were used to test for between-group differences in CVD risk factors. Associations between achieving the CDC/ACSM criterion and changes in cognitive and behavioral measures were assessed with multiple logistic regression models. RESULTS: After 6 months of intervention, 78% of Lifestyle participants and 85% of Structured participants were meeting or exceeding the CDC/ACSM recommendation of accumulating 30 min or more of moderate-intensity physical activity on most, preferably all, days of the week. This was verified by a significant increase in cardiorespiratory fitness in both groups. The adjusted mean increase in maximal METs (VO2peak divided by 3.5 ml.kg-1.min-1) between treadmill tests was 0.4 kcal.kg-1.hr-1 (P < 0.001) for Lifestyle and 1.1 kcal.kg-1.hr-1 (P < 0.001) for Structured. There was a significant difference between intervention groups for this outcome. Both groups had significant reductions in total cholesterol, total cholesterol/HDL-C ratio, diastolic blood pressure, and percentage of body fat. There were no significant between-group differences in changes in these outcomes. Adjusted mean changes in total cholesterol, systolic blood pressure, and percentage of body fat in Lifestyle [in Structured] participants were -0.2 [-0.3] mmol.L-1, -3.2[-1.8] mm Hg, and -1.4 [-1.7] %, respectively. There were significant associations between achieving the CDC/ACSM physical activity criterion and greater use of the cognitive and behavioral strategies of change. Both groups changed self-efficacy and many of the behavioral measures, but there were no significant differences between intervention groups. CONCLUSIONS: These results demonstrate that lifestyle physical activity counseling is as effective as structured exercise programs in increasing physical activity and improving CVD risk factors after 6 months among initially sedentary men and women. Furthermore, specific cognitive and behavioral counseling strategies were increased significantly as a result of the intervention. These strategies are effective and could be used in a wide variety of settings.

Adult↗