High-fat diet during pregnancy promotes fetal skeletal muscle fatty acid oxidation and insulin resistance in an ovine model.

Maternal diet during pregnancy is associated with offspring metabolic risk trajectory in humans and animal models, but the prenatal origins of these effects are less clear. We examined the effects of a high-fat diet (HFD) during pregnancy on fetal skeletal muscle metabolism and metabolic risk parameters using an ovine model. White-faced ewes were fed a standardized diet containing 5% fat wt/wt (CON), or the same diet supplemented with 6% rumen-protected fats (11% total fat wt/wt; HFD) beginning 2 wk before mating until midgestation (GD75). Maternal HFD increased maternal weight gain, fetal body weight, and low-density lipoprotein levels in the uterine and umbilical circulation but had no significant effects on circulating glucose, triglycerides, or placental fatty acid transporters. Fatty acid (palmitoylcarnitine) oxidation capacity of permeabilized hindlimb muscle fibers was >50% higher in fetuses from HFD pregnancies, whereas pyruvate and maximal (mixed substrate) oxidation capacities were similar to CON. This corresponded to greater triacylglycerol content and protein expression of fatty acid transport and oxidation enzymes in fetal muscle but no significant effect on respiratory chain complexes or pyruvate dehydrogenase expression. However, serine-308 phosphorylation of insulin receptor substrate-1 was greater in fetal muscle from HFD pregnancies along with c-jun-NH2 terminal kinase activation, consistent with prenatal inhibition of skeletal muscle insulin signaling. These results indicate that maternal high-fat feeding shifts fetal skeletal muscle metabolism toward a greater capacity for fatty acid over glucose utilization and favors prenatal development of insulin resistance, which may predispose offspring to metabolic syndrome later in life.NEW & NOTEWORTHY Maternal diet during pregnancy is associated with offspring metabolic risk trajectory in humans and animal models, but the prenatal origins of these effects are less clear. This study examined the effects of a high-fat diet during pregnancy on metabolic risk parameters using a new sheep model. Results align with findings previously reported in nonhuman primates, demonstrating changes in fetal skeletal muscle metabolism that may predispose offspring to metabolic syndrome later in life.

Tafazzin deficiency impairs CoA-dependent oxidative metabolism in cardiac mitochondria.

Barth syndrome is a mitochondrial myopathy resulting from mutations in the tafazzin (TAZ) gene encoding a phospholipid transacylase required for cardiolipin remodeling. Cardiolipin is a phospholipid of the inner mitochondrial membrane essential for the function of numerous mitochondrial proteins and processes. However, it is unclear how tafazzin deficiency impacts cardiac mitochondrial metabolism. To address this question while avoiding confounding effects of cardiomyopathy on mitochondrial phenotype, we utilized Taz-shRNA knockdown (TazKD ) mice, which exhibit defective cardiolipin remodeling and respiratory supercomplex instability characteristic of human Barth syndrome but normal cardiac function into adulthood. Consistent with previous reports from other models, mitochondrial H2O2 emission and oxidative damage were greater in TazKD than in wild-type (WT) hearts, but there were no differences in oxidative phosphorylation coupling efficiency or membrane potential. Fatty acid and pyruvate oxidation capacities were 40-60% lower in TazKD mitochondria, but an up-regulation of glutamate oxidation supported respiration rates approximating those with pyruvate and palmitoylcarnitine in WT. Deficiencies in mitochondrial CoA and shifts in the cardiac acyl-CoA profile paralleled changes in fatty acid oxidation enzymes and acyl-CoA thioesterases, suggesting limitations of CoA availability or "trapping" in TazKD mitochondrial metabolism. Incubation of TazKD mitochondria with exogenous CoA partially rescued pyruvate and palmitoylcarnitine oxidation capacities, implicating dysregulation of CoA-dependent intermediary metabolism rather than respiratory chain defects in the bioenergetic impacts of tafazzin deficiency. These findings support links among cardiolipin abnormalities, respiratory supercomplex instability, and mitochondrial oxidant production and shed new light on the distinct metabolic consequences of tafazzin deficiency in the mammalian heart.

Experimental oxygen concentration influences rates of mitochondrial hydrogen peroxide release from cardiac and skeletal muscle preparations.

Mitochondria utilize the majority of oxygen (O2) consumed by aerobic organisms as the final electron acceptor for oxidative phosphorylation (OXPHOS) but also to generate reactive oxygen species (mtROS) that participate in cell signaling, physiological hormesis, and disease pathogenesis. Simultaneous monitoring of mtROS production and oxygen consumption (Jo2) from tissue mitochondrial preparations is an attractive investigative approach, but it introduces dynamic changes in media O2 concentration ([O2]) that can confound experimental results and interpretation. We utilized high-resolution fluorespirometry to evaluate Jo2 and hydrogen peroxide release (Jh2o2) from isolated mitochondria (Mt), permeabilized fibers (Pf), and tissue homogenates (Hm) prepared from murine heart and skeletal muscle across a range of experimental [O2]s typically encountered during respirometry protocols (400-50 µM). Results demonstrate notable variations in Jh2o2 across tissues and sample preparations during nonphosphorylating (LEAK) and OXPHOS-linked respiration states at 250 µM [O2] but a linear decline in Jh2o2 of 5-15% per 50-µM decrease in chamber [O2] in all samples. Jo2 was generally stable in Mt and Hm across [O2]s above 50 µM but tended to decline below 250 µM in Pf, leading to wide variations in assayed rates of Jh2o2/O2 across chamber [O2]s and sample preparations. Development of chemical background fluorescence from the H2O2 probe (Amplex Red) was also O2 sensitive, emphasizing relevant calibration considerations. This study highlights the importance of monitoring and reporting the chamber [O2] at which Jo2 and Jh2o2 are recorded during fluorespirometry experiments and provides a basis for selecting sample preparations for studies addressing the role of mtROS in physiology and disease.

Gut microbiota regulates cardiac ischemic tolerance and aortic stiffness in obesity.

The gut microbiota has emerged as an important regulator of host physiology, with recent data suggesting a role in modulating cardiovascular health. The present study determined if gut microbial signatures could transfer cardiovascular risk phenotypes between lean and obese mice using cecal microbiota transplantation (CMT). Pooled cecal contents collected from obese leptin-deficient (Ob) mice or C57Bl/6j control (Con) mice were transplanted by oral gavage into cohorts of recipient Ob and Con mice maintained on identical low-fat diets for 8 wk (n = 9-11/group). Cardiovascular pathology was assessed as the degree of arterial stiffness (aortic pulse wave velocity) and myocardial infarct size following a 45/120 min ex vivo global cardiac ischemia-reperfusion protocol. Gut microbiota was characterized by 16S rDNA sequencing, along with measures of intestinal barrier function and cecal short-chain fatty acid (SCFA) composition. Following CMT, the gut microbiota of recipient mice was altered to resemble that of the donors. Ob CMT to Con mice increased arterial stiffness, left ventricular (LV) mass, and myocardial infarct size, which were associated with greater gut permeability and reduced cecal SCFA concentrations. Conversely, Con CMT to Ob mice increased cecal SCFA, reduced LV mass, and attenuated myocardial infarct size, with no effects on gut permeability or arterial stiffness. Collectively, these data demonstrate that obesity-related changes in the gut microbiota, independent of dietary manipulation, regulate hallmark measures of cardiovascular pathology in mice and highlight the potential of microbiota-targeted therapeutics for reducing cardiovascular pathology and risk in obesity.NEW & NOTEWORTHY These data are the first to demonstrate that cecal microbiota transplantation (CMT) can alter cardiovascular pathology in lean and obese mice independent from alterations in dietary intake. Myocardial infarct size was reduced in obese mice receiving lean CMT and worsened in lean mice receiving obese CMT. Lean mice receiving obese CMT also displayed increased aortic stiffness. These changes were accompanied by alterations in short-chain fatty acids and gut permeability.

Iridocorneal angle assessment of companion rabbits using gonioscopy, spectral-domain optical coherence tomography (Optovue iVue® ), high-resolution ultrasound, and Pentacam® HR imaging.

OBJECTIVE: Iridocorneal angle (ICA) narrowing is a known risk factor for primary glaucoma in multiple species, but has not been described in companion rabbits. This study aimed to develop an ICA grading scheme for companion rabbits to enable early glaucoma predisposition diagnosis. ANIMALS STUDIED: Twenty healthy rabbits of varying breeds and ages. PROCEDURES: Rabbits received complete ophthalmic examinations, including gonioscopy, and imaging of the ICA using spectral-domain optical coherence tomography (SD-OCT), Scheimpflug imaging (Pentacam® HR), and high-resolution ultrasound (HRUS). Angle opening distance (AOD) and angle recess area (ARA) of the ICA were measured and assessed for agreement using a Bland-Altman analysis. A five-stage gonioscopy grading scheme was created, and Spearman-rank test assessed for correlation between gonioscopy grades and ICA measurements. Differences among age and sex were analyzed with a nonparametric ANOVA and Wilcoxon rank-sum test, respectively. RESULTS: Analysis revealed AOD medians of 0.28mm for SD-OCT [95% CI: 0.24-0.31], 0.20mm for Pentacam® HR [95% CI: 0.18-0.21], and 0.25mm for HRUS [95% CI: 0.22-0.28]. The median ARA was 0.14mm2 for SD-OCT [95% CI: 0.117-0.163], 0.09mm2 for Pentacam® HR [95% CI: 0.082-0.100], and 0.06mm2 for HRUS [95% CI: 0.046-0.054]. The association between gonioscopy grade and SD-OCT ARA was significant (P < 0.05), and there was a significant difference (P < 0.001) between imaging modalities for both ARA and AOD. CONCLUSIONS: Gonioscopy grade correlated well with SD-OCT ARA. Therefore, SD-OCT is recommended as a noncontact method for evaluating companion rabbit ICA. Each imaging device should not be used interchangeably for ICA evaluation.

Pulmonary arterial pressure in fattened Angus steers at moderate altitude influences early postmortem mitochondria functionality and meat color during retail display.

Pulmonary hypertension is a noninfectious disease of cattle at altitudes > 1524 m (5,000 ft). Mean pulmonary arterial pressures (PAP) are used as an indicator for pulmonary hypertension in cattle. High PAP cattle (≥50 mmHg) entering the feedlot at moderate elevations have lower feed efficiency as compared to low PAP cattle (< 50 mmHg). The impact of pulmonary arterial pressure on mitochondrial function, oxidative phosphorylation (OXPHOS) protein abundance, and meat color was examined using longissimus lumborum (LL) from high (98 ± 13 mmHg; n = 5) and low (41 ± 3 mmHg; n = 6) PAP fattened Angus steers (live weight of 588 ± 38 kg) during early postmortem period (2 and 48 h) and retail display (days 1 to 9), respectively. High PAP muscle had greater (P = 0.013) OXPHOS-linked respiration and proton leak-associated respiration than low PAP muscles at 2 h postmortem but rapidly declined to be similar (P = 0.145) to low PAP muscle by 48 h postmortem. OXPHOS protein expression was higher (P = 0.045) in low PAP than high PAP muscle. During retail display, redness, chroma, hue, ratio of reflectance at 630 and 580 nm, and metmyoglobin reducing activity decreased faster (P < 0.05) in high PAP steaks than low PAP. Lipid oxidation significantly increased (P < 0.05) in high PAP steaks but not (P > 0.05) in low PAP. The results indicated that high PAP caused a lower OXPHOS efficiency and greater fuel oxidation rates under conditions of low ATP demand in premortem beef LL muscle; this could explain the lower feed efficiency in high PAP feedlot cattle compared to low PAP counterparts. Mitochondrial integral function (membrane integrity or/and protein function) declined faster in high PAP than low PAP muscle at early postmortem. LL steaks from high PAP animals had lower color stability than those from the low PAP animals during simulated retail display, which could be partially attributed to the loss of muscle mitochondrial function at early postmortem by ROS damage in high PAP muscle.

The impact of pulmonary arterial pressure (PAP) on mitochondrial function, oxidative phosphorylation protein abundance, and meat color was examined using longissimus lumborum (LL) from high (98 ± 13 mmHg) and low (41 ± 3 mmHg) PAP fattened Angus steers (live weight of 588 ± 38 kg) during early postmortem period (2 and 48 h) and retail display (days 1 to 9), respectively. The results indicated that high PAP caused a lower oxidative phosphorylation efficiency and greater fuel oxidation rates under conditions of positive energy balance in beef LL muscle. This could explain the lower feed efficiency in high PAP feedlot cattle compared to low PAP counterparts. Mitochondrial integral function declined faster in high PAP than low PAP muscle at early postmortem. LL steaks from high PAP animals had lower color stability than those from the low PAP animals during simulated retail display, which could be partially attributed to the loss of muscle mitochondrial function at early postmortem in high PAP muscle.

Effects of chronic low-dose radiation on cataract prevalence and characterization in wild boar (Sus scrofa) from Fukushima, Japan.

This study evaluated cataracts in wild boar exposed to chronic low-dose radiation. We examined wild boar from within and outside the Fukushima Exclusion Zone for nuclear, cortical, and posterior subcapsular (PSC) cataracts in vivo and photographically. Plausible upper-bound, lifetime radiation dose for each boar was estimated from radioactivity levels in each animal's home range combined with tissue concentrations of 134+137Cesium. Fifteen exposed and twenty control boar were evaluated. There were no significant differences in overall prevalence or score for cortical or PSC cataracts between exposed and control animals. Nuclear (centrally located) cataracts were significantly more prevalent in exposed boar (p < 0.05) and had statistically higher median scores. Plausible upper-bound, lifetime radiation dose ranged from 1 to 1,600 mGy in exposed animals, with no correlation between dose and cortical or PSC score. While radiation dose and nuclear score were positively associated, the impact of age could not be completely separated from the relationship. Additionally, the clinical significance of even the highest scoring nuclear cataract was negligible. Based on the population sampled, wild boar in the Fukushima Exclusion Zone do not have a significantly higher prevalence or risk of cortical or PSC cataracts compared to control animals.