Biomedical subjects

R K Dishman

Publications and source records attributed to R K Dishman.

58 records · Page 4Linked to original sources

PubMedDate not supplied

Failure of neonatal clomipramine treatment to alter forced swim immobility: chronic treadmill or activity-wheel running and imipramine.

We examined whether chronic running on a treadmill or activity wheel would attenuate the increased swim immobility that has been reported after neonatal clomipramine (CLI) treatment. Male Sprague-Dawley pups (N = 60) were injected with the monoamine reuptake inhibitor clomipramine hydrochloride (40 mg/kg per day i.p.) from 8 to 21 days of age. Another group (N = 12) received saline vehicle. At age 4 weeks, the CLI pups were randomly assigned to experimental conditions: (1) sedentary; (2) 24-h access to an activity wheel; (3) sedentary that received the antidepressant drug imipramine hydrochloride (10 mg/kg twice daily) during the last 10 days of the experiment; (4) activity wheel + imipramine; (5) treadmill running (30 m/min for 1 h at 0 degrees incline, 6 days/week). At age 16 weeks, rats underwent the Porsolt swim test 48 h after the last imipramine injection and/or the last exercise session. The increase in swim immobility among CLI-treated rats was small (one quarter of SD) and not statistically significant (p>0.10). The results are not consistent with our previous finding of antidepressant-like effects of activity-wheel running based on brain noradrenergic adaptations and enhanced male copulatory performance after neonatal CLI treatment. The lack of change in swim performance after clomipramine questions the generalizability of the CLI model of depression and the validity of the forced swim test as a behavioral measure of depression when it is used after neonatal CLI injection or chronic activity-wheel running.

Adrenergic Uptake Inhibitors↗

PubMedDate not supplied

Activity-wheel running blunts suppression of splenic natural killer cell cytotoxicity after sympathectomy and footshock.

We used chemical sympathectomy by 6-hydroxydopamine (6-OHDA) to examine whether adaptation by the sympathetic nervous system (SNS) is a plausible explanation for our prior finding that activity-wheel running blunts the suppression of splenic natural killer cell cytotoxicity after footshock. Male Fischer rats were assigned to treatments using a group (activity wheel vs. sedentary)x treatment (6-OHDA vs. saline)x condition (footshock vs. no shock) design. After 5-6 weeks, rats were injected i.p. with saline or with 40, 80, and 80 mg/kg 6-OHDA on pre experimental days -5, -3, and -1. Half the rats received 6 min of random footshock during a 40-min period. Cytotoxicity was determined by standard 4-h 51Cr release assay. Sympathectomy reduced splenic [NE] by 72%. After 6-OHDA injection and footshock, percent lysis was 33% lower in sedentary rats compared with activity-wheel runners and home-cage controls, p=0.048. The results suggest that activity-wheel running leads to adaptations that offset an altered SNS modulation of splenic NK cell cytotoxicity in response to footshock.

Animals↗

PubMedDate not supplied

Supervised and free-living physical activity: no differences in former athletes and nonathletes.

The association of past participation in school sports with present physical activity was studied in 265 Caucasian men who represented a broad spectrum of cardiovascular health. In cross-sectional and prospective analyses of free-living and supervised settings, no differences in contemporary adult activity were observed between former athletes and nonathletes (p greater than .05). Statistical control for selection bias effects by age, body mass index, sum of skin folds, exercise tolerance, and coronary health status did not alter the results. Recall of free-living physical activity was verified by significant (p less than .05) correlations with a concurrent self-report of activity and with body mass index and exercise tolerance adjusted for coronary health status. Previous reports of an association between school sports participation and adult activity have failed to control for subject selection bias and confounding variables, verify activity recall, and examine both supervised and free-living environments. Although these data do not support the role of youthful sports participation in adult physical activity, future studies could provide objective measures of school and community sports participation and subjective measures of the sports experience in relation to other sex, race, and ethnic factors.

Adult↗

PubMedDate not supplied

The determinants of physical activity and exercise.

Evaluation and delivery of physical activity and exercise programs appear impeded by the substantial numbers of Americans who are unwilling or unable to participate regularly in physical activity. As a step toward identifying effective interventions, we reviewed available research on determinants relating to the adoption and maintenance of physical activity. We categorized determinants as personal, environmental, or characteristic of the exercise. We have considered supervised participation separately from spontaneous activity in the general population. A wide variety of determinants, populations, and settings have been studied within diverse research traditions and disciplines. This diversity and the varied interpretation of the data hinder our clearly summarizing the existing knowledge. Although we provide some directions for future study and program evaluation, there is a need for research that tests hypotheses derived from theoretical models and that has clear implications for intervention programs. We still need to explore whether general theories of health behavior or approaches relating to specific exercises or activities can be used to predict adoption and maintenance of physical activity.

Age Factors↗