ABSTRACT
BACKGROUND: Obesity and chronic disease disproportionately affect American Indians (AI). Identifying barriers to physical activity (PA) may promote PA and healthier lifestyles. OBJECTIVE: To identify perceptions of the built environment and examine whether there is an association between environmental perceptions and self-reported PA in AI communities. METHODS: We conducted a survey among 459 AI adults (survey response of 91.4%) residing in Choctaw Nation and Chickasaw Nation, both located in primary rural areas, and we examined perceived PA environment and its association with PA adequacy (≥5 days/week). Participants provided self-report of PA frequency and duration (of ≥30 minutes per day), as well as the opportunity for exercise in indoor and outdoor, town center, and biking and school areas frequency and duration (of ≥30 minutes per day), and their opportunities for exercise in indoor, outdoor, town center, biking, and school areas. RESULTS: Of respondents, 29% met the recommendations of at least 150 minutes of exercise per week, and 56% were obese. The majority had indoor and outdoor exercise areas in their towns, but many did not use them. Higher town center built environment summary scores were associated with adequate PA (estimate = 0.43; p = 0.02). Not feeling like there were streets with marked crosswalks (odds ratio [OR], 0.25; 95% confidence interval [CI], 0.07-0.84) or being neutral/not sure about nice sidewalks (OR, 0.33; 95% CI, 0.13-0.78) were associated with lower odds of getting adequate PA, and not feeling like the town center had working streetlights was associated with higher odds of getting adequate PA (OR, 5.22; 95% CI, 1.34-21.01). CONCLUSIONS: We found that marked crosswalks and nice sidewalks in the town center were associated with getting adequate PA. This research, which identifies specific built environment factors that affect peoples' PA, may be used by tribal and local organizations to more effectively prioritize community interventions to improve PA and potentially the health of the community, specifically in regards to crosswalks and sidewalks.
ABSTRACT
In rodents, livestock and primate species, a single dose of the synthetic glucocorticoid dexamethasone acutely lowers testosterone biosynthesis. To determine the mechanism of decreased testosterone biosynthesis, stallions were treated with 0.1mg/kg dexamethasone 12h prior to castration. Dexamethasone decreased serum concentrations of testosterone by 60% compared to saline-treated control stallions. Transcriptome analyses (microarrays, northern blots and quantitative PCR) of testes discovered that dexamethasone treatment decreased concentrations of glucocorticoid receptor alpha (NR3C1), alpha actinin 4 (ACTN4), luteinizing hormone receptor (LHCGR), squalene epoxidase (SQLE), 24-dehydrocholesterol reductase (DHCR24), glutathione S-transferase A3 (GSTA3) and aromatase (CYP19A1) mRNAs. Dexamethasone increased concentrations of NFkB inhibitor A (NFKBIA) mRNA in testes. SQLE, DHCR24 and GSTA3 mRNAs were predominantly expressed by Leydig cells. In man and livestock, the GSTA3 protein provides a major 3-ketosteroid isomerase activity: conversion of Δ(5)-androstenedione to Δ(4)-androstenedione, the immediate precursor of testosterone. Consistent with the decrease in GSTA3 mRNA, dexamethasone decreased the 3-ketosteroid isomerase activity in testicular extracts. In conclusion, dexamethasone acutely decreased the expression of genes involved in hormone signaling (NR3C1, ACTN4 and LHCGR), cholesterol synthesis (SQLE and DHCR24) and steroidogenesis (GSTA3 and CYP19A1) along with testosterone production. This is the first report of dexamethasone down-regulating expression of the GSTA3 gene and a very late step in testosterone biosynthesis. Elucidation of the molecular mechanisms involved may lead to new approaches to modulate androgen regulation of the physiology of humans and livestock in health and disease.