Resistance training and androgenic anabolic steroids on aged skeletal muscles: a review about methodological approaches

One of the most frequent effects of aging is the involuntary loss of muscle mass, strength and function, termed sarcopenia. Longitudinal data suggest that muscle strength is a robust predictor of functional decline that occur during aging. Since strength capacity appears to also be indicative of disability, resistance training may serve as an effective mode of physical activity to directly improve functional capacity. There is also a growing evidence to indicate that age-related decline in production and activity of hormones plays an important role in aging muscle. Testosterone deficiency has been associated with a marked decrease in measures of whole body protein anabolism and decrease strength. The purpose of the present study was to explore the characteristics of the methodological approaches used in the studies related to the role of resistance training and androgenic anabolic steroids in the aged skeletal muscle that have been published in the last ten years. A literature review was conducted in April 2011 using the following databases: PubMed; Medline; Lilacs; and Scielo. We found sixty two articles analyzing the influence of resistance training on skeletal muscle of aged samples, seven articles which proposed to verify the chronic influence of androgenic anabolic steroids and only one article mixing both interventions. The great variety of analysis methods is notable. Morphological analysis was done in only few articles.

Effects of protein deprivation and refeeding on the subepicardial neurons of rat: subepicardial neurons and low-protein diet

Heart autonomic ganglia play an important role in cardiac rhythm control, protecting against certainarrhythmias due to their parasympathetic activity. Starvation during pregnancy may cause cardiac disorders andhinder optimal cardiac performance. Also, morphology of subepicardial neuron is subjected to the influenceof extrinsic factors. We studied the influence of protein deprivation on subepicardic neurons in rats at earlydevelopment stages and the effect of restoration of a normal diet.: Three groups of pregnant Wistar rats weresubmitted to different diets according to its protein content: normal (NN group) and 5% casein (DD group),until 42 days after delivery and low protein for 21 days with refeeding for a further 21 days (RN group).All animal were weighed. The number and area of neuronal profiles were measured. The neurons werestained by histochemical methods â-nicotinamide adenine dinucleotide (NADH) and â-nicotinamide adeninedinucleotide phosphate diaphorase (NADPH-d) and their ultra structure were observed.Group DD and RNanimals weighed less than those from group NN. The number of neurons and the cellular profile area didnot show significant differences among groups for both techniques. Endoplasmatic reticulum ribosomes inneurons of undernourished animals showed decreased electron density. Protein deprivation in early stages ofdevelopment produces ultra structural changes but does not alter the number and profile area of nerve cellbodies in rats.

Effects of physical exercises on the ventricular myocardium

It is known that people who exercise regularly are less likely to develop heart diseases such as hypertension, obesity, diabetes mellitus, and dyslipidemia decreasing the occurrence of atherosclerosis and its complications: heart failure, stroke, and peripheral vascular disease. In the presence of physical exercises, the myocardium adjusts to the work loads metabolically and mechanically. There are two kinds of physical exercises: aerobic exercise and strength exercise or resistance training. Nowadays, strength exercises have become very popular due to several different reasons. Strength exercises are those performed against a specific opposing gradual resistance to muscular contraction such as weights. According to the literature, both types of exercises have effects on different body tissues. In the present work, a literature review, including scientific articles since 1980, on the effects of aerobic and strength exercises on the ventricular myocardium was conducted. The low and high-intensity strength exercises have different effects, but none of them causes major effects on the cardiovascular function chronically. The most evident alteration of the myocardium subjected to strength exercises is the increase in the cross-sectional area of the cardiac myocytes leading to myocardial hypertrophy.

Dietary sodium intake induced myenteric neuron hypertrophy in Wistar rats

In the present study we investigated the effect of salt intake on myenteric neuron size of the colon of adult male Wistar rats. The animals were placed on either a high-salt (HS; 8 percent; 12 animals) or a low-salt diet (LS; 0.15 percent; 12 animals) for 15 or 52 weeks and blood pressure was measured. The sizes of myenteric neurons of the distal colon from both groups were measured. No difference in neuron size was observed between the HS and LS groups after 15 weeks. After 52 weeks on HS, neuron size was increased (P<0.005) when compared with the LS group. The rats also presented hypertension, which was significantly different at 52 weeks (142 +/- 11 vs 119 +/- 7 mmHg). These results suggest that a long time on an HS diet can significantly increase myenteric nerve cell size.

Dietary sodium intake and cardiac nerve cell hypertrophy in Wistar rats

We determined the effect of dietary sodium intake (0.15 and 8 per cent NACl) on the cardiac neuron size of normotensive 3-week old Wistar rats. An increase in dietary sodium for 48 weeks induced an increase in neuronal size. The number of large neurons (larger than 500 muM2) increased significantly (chi-square test) in rats ingesting 8 per cent NaCl in their food. The rats presented hypertension (128 ñ 9 vs 134 ñ 16 mmHg; difference not significant, Student t-test) and a statistically significant increase in cardiac muscle mass (1.6 ñ 0.1 vs 2.0 ñ 0.2 mg/g of rat). We conclude that food sodium can significantly increase cardiac nerve cell size and this trophic response occurs concomitantly with an increase of cardiac muscle mass.