Thyroid hormones effect

I realize that this is a side track issue, but relevant all the same. Cycle protocols were an approach intended to facilitate optimal growth of muscle tissue. Remember there are two main muscle fiber types Type I, which is endurance orientated, and Type II which is strength orientated. Type "Ha", "Hb", and Type "He" are responsible for most musculature size and have the greatest potential for growth. Testosterone increases the number of Type II fibers at the expense of the Type I transformation. Growth hormone, Insulin, IGF-1, and thyroid hormones effect growth and hyperplasia of both fiber types. This should be another key relating to protocols that were utilized and why. 

Mauer RA (1982b) Relationship between estradiol, ergocryptine, and thyroid hormone effects on prolactin synthesis and prolactin messenger ribonucleic acid levels. Endocrinology 770 1515-1520. 

Hallgren S, Damerud PO (2002) Polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and chlorinated paraffins (CPs) in rats testing interactions and mechanisms for thyroid hormone effects. Toxicology 177 227-243... 

Thyroid hormone effects on metabolism arc diverse. The rates of protein and carbohydrate synthesis and catabolism are inlluenced. An example of the effect of thyroid hormones on lipid metabolism is the observation of a high serum cholesterol in some hypothyroid patients. This is a consequence of a reduction in cholesterol metabolism due to down regulation of low-density lipoprotein (LDL) receptors on liver cell membranes, with a subsequent failure of sterol excretion via the gut. 

Apletalina, E.V, H.C. Li, and D.J. Waxman (2003). Evaluation of thyroid hormone effects on liver P450 reductase translation. Arch. Biochem. Biophys. 409, 172-179. 

One of the most frequent questions asked has been whether or not pure ID results in hypothyroidism (Morreale de Escobar et ai, 1997). The answer to this is especially difficult, because there are few quantitative indices of thyroid hormone action in different tissues. For this reason, we have focused on concentrations of 3,5,3 -triiodo-L-thyronine (T3), which was taken as an index of possible thyroid hormone effectiveness at the individual tissue level, as discussed elsewhere (Escobar-Morreale et ai, 1995). As will be seen, the thyroid status of rats with ID cannot be defined for the animal as a whole, because it is eminently tissue specific At all grades of ID, elevated. 

Therapy with levothyroxine is very safe, provided that thyroid hormone levels are monitored and maintained within the normal range. Excess doses of T4 are associated with a loss of bone mass. A meta-analysis of 41 controlled studies on the impact of thyroid hormone therapy on bone mineral density (Uzzan et al., 1996) has shown that doses of T4 that suppress thyrotropin (TSH) secretion are associated with a significant loss of bone in the lumbar spine and hip in postmenopausal women. Another review of the evidence of the thyroid hormone effect of on skeletal integrity concluded that hyperthyroidism and the use of thyroid hormone to suppress TSH seem to have an adverse effect on bone, especially in postmenopausal women (Greenspan and Greenspan, 1999) however, thyroid hormone replacement seems to have a minimal effect on bone. 

Thyroid hormone effects on the heart and peripheral vasculature... 

Mechanisms for Thyroid Hormone Effects on Motor Units... 

Table 1. Tissue responsiveness to thyroid hormone. Effect of thyroid hormone on oxygen consumption and malic enzyme mRNA levels compared to nuclear T3-binding capacity. Data for selected tissues in adult rats were adapted from the cited references. Oxygen consumption (cu.mm./mg wet weight/h) is the ratio in euthyroid versus thyroidectomized (Tx) rats. The fold of induction of malic enzyme mRNAs was calculated from values obtained from tissues of euthyroid rats and rats treated for 10 days with ISpg T3/IOO g b.w. The binding capacity was measured in normal rats.

Finally, it should be stressed that receptors do not as such control the expression of thyroid hormone effects. In addition to postreceptor events, the interpretation of in vitro findings should also take into account differences in cellular transport of T3 from plasma to cytosol, and from cytosol to nucleus in different tissues [63]. 

J. Legrand, Thyroid hormone effects on growth and development,... 

Bronk, J.R. Thyroid hormone Effects on electron transport. Science 153, 638-639 (1966)... 

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