Testosterone Regulation

Mechanisms of testosterone regulation. The mechanisms by which neonatal testosterone imprints the expression of liver P450 enzymes during adulthood are only partially understood. Testosterone s primary effects on liver P450 profiles are mediated by the hypothalamic-pituitary axis and its control of the sex-dependent pattern of pituitary GH secretion -Consistent with this conclusion, testosterone has only minor effects on liver enzyme profiles in hypophysectomized rats in most but not all instances. As discussed in Section 4.2, pituitary GH secretory patterns play a key role in regulating the expression of the sex-dependent P450 forms. 

Whereas testosterone has a major positive regulatory influence on the male-specific P450 forms, estrogen plays a somewhat lesser role in the expression of the female-specific and the female-predominant liver P450 enzjmes. Ovariectomy at birth reduces, but does not abolish, expression of hepatic CYP2C7, CYP2C12, and steroid 5a-reductase in adult female rats 56 

---

Mobus E, M Jahn, R Schmid, D Jahn, E Maser (1997) Testosterone-regulated expression of enzymes involved in steroid and aromatic hydrocarbon catabolism in Comamonas testosteroni. J Bacteriol 179 5951-5955. 

Vitvitsky V, Prudova A, Stabler S, Dayal S, Lentz SR, Baneijee R. (2007) Testosterone regulation of renal cystathionine beta-synthase implications for sex-dependent differences in plasma homocysteine levels. Am J Physiol Renal Physiol 293 F594-600. 

In males, testosterone regulates the hypothalamic-pituitary-gonadal axis at both the hypothalamic and pituitary levels, and its negative feedback effect is mediated to a substantial degree by estrogen formed via aromatization. 

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... 

K. Eto and H. Kimura, The production of hydrogen sulfide is regulated by testosterone and S ndcnosyl L-methionine in mouse brain. J. Neurochem. 83, 80-86 (2002). 

In birds, both neural aromatase and 5a-reductase are induced by testosterone, and this regulation provides a way by which androgens can regulate CNS hormone sensitivity without regulating receptor number [ 1 ]. 

Lipids such as cholesterol and testosterone act as hormones to regulate body functions. (Not all hormones are lipids. Some hormones are proteins. Other hormones are neither lipids nor proteins.)... 

---