Effects of Strength Training and Anabolic Steroid in the Peripheral Nerve and Skeletal Muscle Morphology of Aged Rats

Abstract

Thirty male 20-month-old Wistar rats were divided into groups: IC—initial control (n = 6), FC—final control (n = 6), AC—anabolic hormone control (n = 6), ST—strength trained (n = 6) and STA—strength trained with anabolic hormone (n = 6). All groups were submitted to adaptation, familiarization and maximum load carrying test (MLCT). Strength training (6–8×/session with loads of 50%–100% MLCT, 3×/week and pause of 120 s) was performed in ladder climbing (LC) for 15 weeks. The administration of testosterone propionate (TP) was performed 2×/week (10 mg/kg) in animals in the AC and STA groups. After the experimental period, animals were euthanized and the tibial nerve and plantaris muscle removed and prepared for electron transmission and histochemistry. To compare the groups we used one-way ANOVA (post hoc Bonferroni), student’s t-tests for pre vs. post (dependent and independent variables) comparisons and significance level set at p ≤ 0.05. The following significant results were found: (a) aging decreased the number of myelinated axon fibers; (b) use of isolated TP increased the diameter of myelinated fibers, along with increased thickness of myelin sheath; (c) ST increased area of myelinated and unmyelinated fibers, together with the myelin sheath. These changes made it possible to increase the area occupied by myelinated fibers keeping their quantity and also reduce the interstitial space; and (d) association of anabolic steroid and ST increased the area of unmyelinated axons and thickness of the myelin sheath. Compared to ST, both strategies have similar results. However, Schwann cells increased significantly only in this strategy.

Repercussions on sarcomeres of the myotendinous junction and the myofibrillar type adaptations in response to different trainings on vertical ladder

“…We also found that the LT in the plantaris muscle had a more significant hypertrophy in Type II fibers, which corroborates the results of Krause Neto et al (2017) in a vertical ladder model that describe muscle hypertrophy with an associated higher contraction force generation capacity due to the increase in contractile proteins. This was also described in a review by Hawley et al (2014) that promoted adaptations in Type II fibers with increased oxidative profile, and both fiber types cause hypertrophy and maximal tension output.…”

Aging Induces Changes in the Somatic Nerve and Postsynaptic Component without Any Alterations in Skeletal Muscles Morphology and Capacity to Carry Load of Wistar Rats

“…After selection of the fields in the semi-thin sections, the ultra-thin sections were obtained with a diamond knife, in ultramicrotome (Sorvall MT-2), and contrasted with uranyl acetate and lead citrate, finally being analyzed by the transmission electron microscope. The techniques employed here, were in agreement with other publications done by our research group (Pianca et al, 2015 ; Carbone et al, 2017 ; Krause Neto et al, 2017b ).…”

“…After an incision, a fragment of ~0.5 cm in length from the tibial nerve was removed from the posterior portion of the right leg. Then, we fixed the nerve fragment in 2.5% glutaraldehyde solution in phosphate buffer (0.2 M, pH 7.3) for 3 h (Pianca et al, 2015 ; Carbone et al, 2017 ; Krause Neto et al, 2017b ). Subsequently, we washed the material three times with the same buffer solution for 5 min at a time.…”

“…Both stereological techniques are used in our laboratory to quantify various outcomes in nerves and other tissues (Pianca et al, 2015 ; Krause Neto and Gama, 2017 , and Krause Neto et al, 2017b ).…”

Testosterone improves muscle function of the extensor digitorum longus in rats with sepsis

“…Testosterone is a major male hormone applied in clinical practice in elderly men and patients with severe burns and other weaknesses to improve muscle function and quality of life [5]. In animal experiments, testosterone improved the muscle function of paraplegia, limb fracture and castration [6,7]. In the clinical, testosterone was associated with metabolic syndrome [8].…”