Previous genetic association studies of physical activity, in both animal and human models, have been limited in number of subjects and genetically homozygous strains used as well as number of genomic markers available for analysis. Expansion of the available mouse physical activity strain screens and the recently published dense single-nucleotide polymorphism (SNP) map of the mouse genome (approximately 8.3 million SNPs) and associated statistical methods allowed us to construct a more generalizable map of the quantitative trait loci (QTL) associated with physical activity. Specifically, we measured wheel running activity in male and female mice (average age 9 wk) in 41 inbred strains and used activity data from 38 of these strains in a haplotype association mapping analysis to determine QTL associated with activity. As seen previously, there was a large range of activity patterns among the strains, with the highest and lowest strains differing significantly in daily distance run (27.4-fold), duration of activity (23.6-fold), and speed (2.9-fold). On a daily basis, female mice ran further (24%), longer (13%), and faster (11%). Twelve QTL were identified, with three (on Chr. 12, 18, and 19) in both male and female mice, five specific to males, and four specific to females. Eight of the 12 QTL, including the 3 general QTL found for both sexes, fell into intergenic areas. The results of this study further support the findings of a moderate to high heritability of physical activity and add general genomic areas applicable to a large number of mouse strains that can be further mined for candidate genes associated with regulation of physical activity. Additionally, results suggest that potential genetic mechanisms arising from traditional noncoding regions of the genome may be involved in regulation of physical activity.

The biological regulating factors of physical activity in animals are not well understood. This study investigated differences in central mRNA expression of seven dopamine genes (Drd1, Drd2, Drd3, Drd4, Drd5, TH, and DAT) between high active C57/LJ (n=17) male mice and low active C3H/HeJ (n=20) male mice, and between mice with access to a running wheel and without running wheel access within strain. Mice were housed with running wheels interfaced with a computer for 21 days with distance and duration recorded every 24 hours. On day 21, the striatum and nucleus accumbens were removed during the active period (∼9pm) for dopaminergic analysis. On average, the C57L/J mice with wheels ran significantly farther (10.25±1.37 km/day vs. 0.01±0.09 km/day, p<0.001), longer (329.73±30.52 mins/day vs. 7.81±6.32 mins/day, p<0.001), and faster (31.27±3.13 m/min vs. 11.81±1.08 m/min, p<0.001) than the C3H/HeJ mice with wheels over the 21 day period. No differences in gene expression were found between mice in either strain with wheels and those without wheels suggesting that access to running wheels did not alter dopaminergic expression. In contrast, relative expression for two dopamine genes was significantly lower in the C57L/J mice compared to the C3H/HeJ mice. These results indicate that decreased dopaminergic functioning is correlated with increased activity levels in C57L/J mice and suggests that D1-like receptors as well as Tyrosine Hydroxylase (an indicator of dopamine production), but not D2-like receptors may be associated with the regulation of physical activity in inbred mice.

There is a high risk of voriconazole failure in those with subtherapeutic drug concentrations, which is more common in CYP2C19 (cytochrome P450 2C19) rapid/ultrarapid metabolizers (RMs/UMs). We evaluated CYP2C19 genotype‐guided voriconazole dosing on drug concentrations and clinical outcomes in adult allogeneic hematopoietic cell transplant recipients. Poor (PMs), intermediate (IMs), and normal metabolizers (NMs) received voriconazole 200 mg twice daily; RMs/UMs received 300 mg twice daily. Steady‐state trough concentrations were obtained after 5 days, targeting 1.0–5.5 mg/L. Of 89 evaluable patients, 29% had subtherapeutic concentrations compared with 50% in historical controls (P < 0.001). Zero, 26%, 50%, and 16% of PMs, IMs, NMs, and RMs/UMs were subtherapeutic. Voriconazole success rate was 78% compared with 54% in historical controls (P < 0.001). No patients experienced an invasive fungal infection (IFI). Genotype‐guided dosing resulted in $4,700 estimated per patient savings as compared with simulated controls. CYP2C19 genotype‐guided voriconazole dosing reduced subtherapeutic drug concentrations and effectively prevented IFIs.

Purpose-Measurements of exercise behaviors in rodents such as maximal treadmill endurance and physical activity are often used in the literature; however, minimal data are available regarding the repeatability of measurements used for these exercise behaviors. This study assessed the repeatability of a commonly used maximal exercise endurance treadmill test as well as voluntary physical activity measured by wheel running in mice.Methods-Repeatability of treadmill tests were analyzed for both inbred and outbred mice in addition to a 10 week repeatability analysis using Balb/cJ mice (n=20). Voluntary daily physical activity was assessed by distance, duration, and speed of wheel running (WR). Physical activity measurements on days 5 and 6 of WR in a large cohort (n=739) of both inbred and outbred mice were compared.Results-No significant differences (p>0.05) in exercise endurance were found between different cohorts of Balb/cJ and DBA/2J mice indicating strains overall generally test the same; however, significant differences between tests were seen within BaD2F 2 animals (p<0.001). Bland-Altman analysis revealed lack of agreement between weekly endurance tests within mouse, and correlation analysis showed lack of consistent correlations between weekly endurance tests within mouse. No significant differences were found for WR measurements within mouse between days (p=0.99). High correlations between days within mouse for WR were found (r=0.74-0.85).Conclusions-High intra-mouse variability between repeated endurance tests suggests that treadmill testing in an enclosed chamber with shock grid for motivation to run in mice is not repeatable. Conversely, high correlation and agreement between days of wheel running measurements suggest that voluntary activity (WR) is repeatable and stable within individual mice.

The regulatory mechanisms of physical activity are postulated to include environmental and biological/genetic factors. In particular, the sex steroids appear to have profound effects on wheel running in rodents. The purpose of this project was to investigate the effects of 17β-estradiol and testosterone on wheel running distance, duration, and speed in male and female C57BL/6J mice. The mice (N=46) were provided free access to running wheels interfaced with computers to track daily running distance, duration, and speed. Activity was assessed at baseline in intact mice, after surgical gonadectomy, and after replacement with either 17β-estradiol or testosterone. Upon removal of the gonads, physical activity levels were significantly reduced in both males and females. Distance (10–30% of baseline) and duration (20–47% of baseline) measures were most affected by the loss of endogenous steroids, while running speed (60–77% of baseline) though significantly reduced-decreased by a much lower magnitude. Testosterone replacement fully recovered running distance, duration, and speed to pre-surgical levels in both sexes (100% of baseline). Distance (30–42% of baseline) and duration (43–47% of baseline) were partially recovered by 17β-estradiol, but not to baseline levels. Speed (100% of baseline) was fully recovered by 17β-estradiol replacement in males and females. This study suggests that physical activity in mice is affected by endogenous steroids and can be altered by exogenous steroid replacement. The differences in the recovery abilities of 17β-estradiol and testosterone suggest that both estrogenic and androgenic pathways may be involved to variable degrees in activity regulation.