No abstract

Exogenous eCG for stimulation of a single dominant follicle or for superovulation are common strategies to improve reproductive efficiency by increasing pregnancy rates and embryo production, respectively. Morphofunctional changes in the CL of eCG-treated cattle include increases in CL volume and plasma progesterone concentrations. Therefore, we tested the hypothesis that eCG alters the content of luteal cells and mitochondria related to hormone production. Twelve crossbred beef cows were synchronized and then allocated into three groups (four cows per group) and received no further treatment (control) or were given eCG either before or after follicular deviation (superovulation and stimulation of the dominant follicle, respectively). Six days after ovulation, cows were slaughtered and CL collected for morphohistologic and ultrastructural analysis. Mitochondrial volume per CL was highest in superovulated followed by stimulated and then control cows (18,500 ± 2630, 12,300 ± 2640, and 7670 ± 3400 μm(3); P < 0.001), and the density of spherical mitochondria and the total number of large luteal cells were increased (P < 0.05) in stimulated cows compared with the other two groups (110.32 ± 14.22, 72.26 ± 8.77, and 70.46 ± 9.58 mitochondria per μm(3) and 678 ± 147, 245 ± 199, and 346 ± 38 × 10(6) cells, respectively. However, the largest diameters of the large luteal cells were increased in superovulated and control cows versus stimulated ones (32.32 ± 0.06, 31.59 ± 0.81, and 29.44 ± 0.77 μm; P < 0.0001). In contrast, the total number of small luteal cells was increased in superovulated cows (1456 ± 268, 492 ± 181, and 822 ± 461 × 10(6), P < 0.05). In conclusion, there were indications of cellular changes related to increased hormonal production (stimulatory treatment) and increased CL volume (superovulatory treatment).

Exercise therapy on skeletal muscle of muscular dystrophies has no defined parameters. The effect of low-intensity treadmill training on the oxidative stress markers and fibrosis on hindlimb muscles was investigated. Sixteen dystrophic male mdx animals were separated in trained ( mdx T/n=8) and untrained ( mdx NT/n=8) groups. Wild type animals (WT/n=8) were used as healthy control. The mdx T group runned at a horizontal treadmill (9 m/min, 30 min/day, 3 times/wk, 8 weeks). Gastrocnemius and tibial anterior muscles were collected for analysis of enzymatic/non-enzymatic oxidant activity, oxidative damage concentration, collagen fibers area morphometry. The mdx T group presented a lower collagen fiber area compared to mdx NT for gastrocnemius ( P =0.025) and tibial anterior ( P =0.000). Oxidative damage activity was higher in the mdx T group for both muscles compared to mdx NT. Catalase presented similar activity for tibial anterior ( P =0.527) or gastrocnemius ( P =0.323). Superoxide dismutase ( P =0.003) and total antioxidant capacity ( P =0.024) showed increased activity in the mdx T group at tibial anterior with no difference for gastrocnemius. Low-intensity training is considered therapeutic as it reduces collagen deposition while improving tissue redox status.

SUMMARY:Duchenne muscular dystrophy (DMD) is a genetic neuromuscular disorder with progressive clinical signs until death, around the second decade of life. Mdx is the most used animal model to pre-clinical studies of DMD. Parameters of exercise on this muscular disease are still unknown. This research aimed to investigate if the low intensity treadmill training would exacerbate the markers of muscle injury, fibrosis, and the composition of the extracellular matrix by type I and III collagens of the mdx model. Dystrophic 11-week-old male mice were separated in exercised (mdxE, n=8) and sedentary (mdxC, n=8) groups. Wild-type mice were used as control (WT, n=8). Exercised group underwent a LIT protocol (9 m/min, 30min, 3days/week, 60 days) on a horizontal treadmill. Gastrocnemius muscle was collected at day 60 and processed to morphological and morphometric analyzes. Sedentary mdx animals presented inflammatory infiltrate and necrotic fibers. Histochemical analysis revealed that the perimysium of the mdxC group is organized into thick and clustered collagen fibers, which generates a larger area of intramuscular collagen fibers for these animals. Histomorphometry attested that fraction area of collagen fibers of mdxC group was higher than mdxE group (p=0.04) and mdxE group values similar to WT group (p=1.00). Centrally located nuclei fibers and the variance coefficient (VC) of minimal Feret's diameter was similar in mdxE and mdxC groups (p=1.00) and both groups presented higher mean values than WT group (p<0.00). Immunohistochemistry revealed the presence of type I collagen mainly in the mdxC group. LIT protocol had not exacerbated muscle injuries resulting from the dystrophindeficiency membrane fragility at the same time that had reduced the intramuscular collagen deposition. LIT had positively influenced these markers of dystrophic muscle injury on gastrocnemius muscle of mdx model.

Recommendations of therapeutic exercise in Duchenne muscular dystrophy are still controversial. The hypothesis that a low-intensity training (LIT) protocol leads to muscle adaptations on mdx mice model was tested. Dystrophic male mice with 8 weeks old were separated in exercised (mdxE, n= 8) and sedentary (mdxC, n= 8) groups. Wild-type mice were used as control (WT, n= 8) group. Exercised group underwent a LIT protocol (9 m/min, 30 min, 3 days/wk, 60 days) on a horizontal treadmill. At day 60 all animals were analyzed regarding parameters of markers of muscle lesion and extracellular matrix turnover of muscle tissue by collagens fibers on tibial anterior muscle. Histomorphometry attested that centrally located nuclei fibers and the coefficient of variance of minimal Feret’s diameter was similar in mdxE and mdxC groups (P= 1.000) and both groups presented higher mean values than WT group (P< 0.001). Fraction area of collagen fibers of mdxE group was lower than mdxC group (P= 0,027) and similar to WT group (P= 0,751). Intramuscular area of Col3 of the mdxE group was higher than mdxC and WT groups (P<0.001). Intramuscular area of Col1 on the mdxE group was similar to the mdxC group (P= 1.000) and both groups were higher than WT group (P< 0.001). LIT protocol had not influenced muscle injuries resulting from the dystrophin-deficiency membrane fragility. Although, LIT had provoked adaptations on extracellular matrix bringing higher elastic feature to dystrophic muscle tissue.