Testosterone thyroid effects

Thyroid Effects. Limited information is available on thyroid effects in PBDE-exposed humans. There are suggestive occupational data as shown by effects that included increased serum FSH, low or borderline low serum T4, and increased thyroid antimicrosomal antibody titers in workers exposed to decaBDE and/or unspecified PBBs. There was no clear association between plasma levels of 2,2, 4,4-tetraBDE and thyroid hormone levels (free and total T3 and T4, TSH, free testosterone, follicle-stimulating hormone, lutenizing hormone, and prolactin) in men who consumed varying amounts of fatty fish from the Baltic Sea. Based on consistent evidence in animals, as summarized below, the thyroid is particularly sensitive to PBDEs and is a likely target of toxicity in exposed humans. 

Developmentally, thyroid hormones interact with sex hormones such that hypothyroidism prolongs the critical period for testosterone-induced defeminization (see below) [3] in contrast, the hyperthyroid state prematurely terminates the sensitivity to testosterone [3]. Undoubtedly, an important link in these and other effects is synapse formation. Hypothyroidism increases synaptic density, at least transiently [3]. Interesting parallels with synapse formation are reported for learning behavior in rats neonatal hypothyroidism impairs learning ability, whereas hyperthyroidism accelerates learning initially, followed by a decline later in life [3]. 

Lithium has several effects on the endocrine system. For example, it can interfere with the synthesis and the release of testosterone, leading to an increase in luteinizing hormone levels. The thyroid system has been most implicated in neuroendocrine theories of lithium s antimanic effects. In particular, thyroid hormones can potentiate b-NE activity, and lithium s ability to block their release may subserve its mood-stabilizing properties (i.e., the thyroid-catecholamine receptor hypothesis)... 

Effects on growth and calorigenesis are accompanied by a pervasive influence on metabolism of drugs as well as carbohydrates, fats, proteins, and vitamins. Many of these changes are dependent upon or modified by activity of other hormones. Conversely, the secretion and degradation rates of virtually all other hormones, including catecholamines, cortisol, estrogens, testosterone, and insulin, are affected by thyroid status. 

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. 

Administration of testosterone (C14, J4), thyroid hormones (M19), and ACTH (E5) has been shown to result in elevation of serum copper levels. The latter effect could have been due to contamination of the ACTH preparation with melanotropin (A2). Antithyroid drugs produce a fall in serum copper levels (F7). 

E4. Engbring, N. H., and Engstrom, W. W., Effects of estrogen and testosterone on circulating thyroid hormone. J. Clin. Endocrinol. Metab. 16, 783-796 (1959). 

In a study on the effects of hormones, testosterone-treated males and estrogen-treated females had a lower incidence of amorphous pigment stones than gonadectomized animals but may have had a higher incidence of cholesterol stones the total incidence was similar (66). Progesterone, on the other hand, lowered the incidence of cholesterol stones in females. Deoxycorticosterone had no clear effect on stone formation. Desiccated thyroid lowered and methyl thiouracil raised the ratio of cholesterol/amorphous pigment stones. 

Leatherland, J.F., and R.A. Sonstegard. 1980. Effect of dietary Mirex and PCBs in combination with food deprivation and testosterone administration on thyroid activity and bioaccumulation of organochlorines in rainbow trout Salmo gairdneri Richardson. Journal of Fish Diseases 3 115-124. 

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