Muscle growth

Testosterone promotes muscle growth deepening of the voice the growth of body hair and other male secondary sex characteristics Testosterone is formed from cholesterol and IS the biosynthetic precursor of estradiol the principal female sex hormone or estrogen Estradiol is a key substance m the regulation of the menstrual cycle and the reproductive process It is the hormone most responsible for the development of female secondary sex characteristics... 

Somatotropin, the P-adrenergic agonists, and the anaboHc steroids are considered metaboHsm modifiers because these compounds alter protein, Hpid, carbohydrate, mineral metaboHsm, or combinations of these and they partition nutrient use toward greater rates of protein deposition, ie, muscle growth, and lesser rates of Hpid accretion. Historical data leading to understanding of the mechanism (s) of action are found in reviews on anaboHc steroids (1), somatotropin (2—4), and the phenethano1 amines (5—7). 

Mechanism of Action. P-Agonists stimulate skeletal muscle growth by accelerating rates of fiber hypertrophy and protein synthesis, but generally do not alter muscle DNA content in parallel with the increases in protein accretion (133—135). This is in contrast to the effects of anaboHc steroids and ST on skeletal muscle growth. Both of the latter stimulate fiber hypertrophy and muscle protein synthesis, but also increase muscle DNA content coincident with increased protein accretion. Whether the P-agonists decrease muscle protein degradation is equivocal. 

Anabolic steroid (Section 26.15) A steroid that promotes muscle growth. 

Sex Hormones Testosterone and androsterone are the two most important male sex hormones, or androgens. Androgens are responsible for the development of male secondary sex characteristics during puberty and for promoting tissue and muscle growth. Both are synthesized in the testes from cholesterol. Androstenedione is another minor hormone that has received particular attention because of its use by prominent athletes. 

Adrenergic receptor agonists, in particular clen-buterol, have been used for their hypertrophic effects on skeletal and also cardiac muscle. They can increase muscle growth in cattle (illegal in many countries) but have also been used by body-builders and athletes as anabolic dtugs. 

Androgens, represented by testosterone, are male sex hormones involved in reproduction, behavior, and bone and muscle growth. 

NFAT proteins are expressed in skeletal, cardiac, and smooth muscle and play important roles in the regulation of the development and differentiation of these tissues. In skeletal muscle, NFAT isoforms are expressed at different stages of development and regulate progression from early muscle cell precursors to mature myocytes. NFAT proteins have also been shown to control the expression of the myosin heavy chain and positively regulate muscle growth [1, 2]. 

Valine A branched-chain essential amino add that has stimulant activity. It promotes muscle growth and tissue repair. It is a precursor in the penicillin biosynthetic pathway. [NIH]... 

Clowes AW, Clowes MM, Reidy MA. Kinetics of cellular proliferation after arterial injury. 3. Endothelial and smooth-muscle growth in chronically denuded vessels. Lab Invest 1986 54 295-303. 

Berk BC. (2001) Vascular smooth muscle growth Autocrine growth mechanisms. Physiol Rev 81 999-1030. 

Differentiation and growth of the male reproductive tract, stimulation of male secondary sex characteristics, sceletal muscle growth... 

Sex hormones control tissue growth and reproduction. Male sex hormones are testosterone and Sa-dibydrotestosterone, also known as androgens, which are secreted by the testes. The primary male hormone, testosterone, is responsible for the development of secondary sex characteristics during puberty. They also promote muscle growth. The two most important female sex hormones are oestradiol and oestrone, also known as oestrogem estrogens). They are responsible for the development of female secondary sex characteristics. 

Steroid hormones have a variety of important functions, including regulation of carbohydrate and mineral metabolism and development of secondary sexual characteristics (Table 20.4). Steroids are often used in the treatment of diseases such as arthritis. Some athletes use steroids to promote muscle growth. 

Most pro s who were using the stuff said that they had inject 2-3 cc s, 2-4 times per week directly into each target muscle for 2-4 weeks. They then followed this build-up with 3cc once a week for 15-25 weeks, which they had claimed made the gain in size permanent. On the noted plus side, this would stretch muscle fascia so that there is more room for muscle growth naturally. It had often been said that the results are a somewhat encapsulated oil pockets. But the size effects were admittedly dramatic. There were competing bodybuilders who admitted to over 100 weekly injection sites. Sad. 

Banned substances must meet several criteria for anabolic steroids set up in the 1991 Controlled Substances Act. These dietary supplements have met all the criteria but one whether or not they build muscle. A variety of current studies are underway, particularly to determine if these supplements convert to sufficient testosterone to stimulate muscle growth. If research shows this to be true, the DEA is expected to add them to the list of banned substances, since substantial quantities would likely produce the same side effects as AASs. 

Vitamin A has essential roles in vision, bone and muscle growth, reproduction and maintenance of healthy epithelial tissue. Naturally occurring precursors of vitamin A are found in some seeds, leafy green vegetables and forages such as lucerne. The common form of the precursor is p-carotene, which can be converted into vitamin A in the intestinal wall. Carotene is present in considerable quantities in pasture, lucerne hay or meal, and yellow maize. Carotene and vitamin A are rapidly destroyed by exposure to air, light and rancidity, especially at high temperature. Since it is difficult to assess the amount of vitamin A present in the feed, diets should be supplemented with this vitamin. 

Dransfield, E. and Sosnicki, E.A. (1999) Relationship between muscle growth and poultry meat quality. Poultry Science 78, 743-746. 

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