16-11-2014, 23:48
Sort of, increased SHBG:
Sex hormone-binding globulin (SHBG) is a glycoprotein synthesized by the liver. Circulating androgen and estrogen concentrations influence SHBG synthesis. The regulation of SHBG synthesis, combined with SHBG's higher affinity for testosterone, impacts bioavailable testosterone levels.
SHBG binds up to 98 percent of the steroid hormones in the blood including 5a-dihydrotestosterone (DHT), testosterone and androstenediol with particularly high affinity, and estradiol and estrone with slightly lower affinity
Male and female children have similar SHBG concentrations until the onset of puberty, when SHBG levels begin decreasing more rapidly in males than in females. Levels are higher in women than in men, due to the higher ratio of estrogens to androgens in women. Levels are especially elevated during late pregnancy and in women taking oral contraception.
Excellent info here:
http://www.digitalnaturopath.com/cond/C654345.html
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Estrogen, DHT and testosterone all compete inside the same cell receptor...SHBG a carrier protien but not active, the active carrier protien is albumin.
prostate androgen receptor and prostate-specific antigen secretion through the intermediacy of sex hormone-binding globulin.
Abstract
These experiments were designed to examine the relationship between the effects of steroid hormones mediated by classic intracellular steroid hormone receptors and those mediated by a signaling system subserved at the plasma membrane by a receptor for sex hormone-binding globulin. It is known that unliganded sex hormone-binding globulin (SHBG) binds to a receptor (RSHBG) on prostate membranes. The RSHBG.SHBG complex is rapidly activated by estradiol to stimulate adenylate cyclase, with a resultant increase in intracellular cAMP. In this paper we examine the effect of this system on a prostate gene product known to be activated by androgens, prostate-specific antigen. In serum-free organ culture of human prostates, dihydrotestosterone caused an increase in prostate specific antigen secretion. This event was blocked by the anti-androgens cyproterone acetate and hydroxyflutamide. In the absence of androgens, estradiol added to prostate tissue, whose RSHBG was occupied by SHBG, reproduced the results seen with dihydrotestosterone. Neither estradiol alone nor SHBG alone duplicated these effects. The estradiol.SHBG-induced increase in prostate-specific antigen was not blocked by anti-estrogens, but was blocked both by anti-androgens and a steroid (2-methoxyestradiol) that prevents the binding of estradiol to SHBG. Furthermore, an inhibitor of protein kinase A prevented the estradiol.SHBG-induced increase in prostate-specific antigen but not that which followed dihydrotestosterone. These data indicate that there is a signaling system that amalgamates steroid-initiated intracellular events with steroid-dependent occurrences generated at the cell membrane and that the latter signaling system proceeds by a pathway that involves protein kinase A.
http://www.ncbi.nlm.nih.gov/pubmed/9054366
Sex hormone-binding globulin (SHBG) is a glycoprotein synthesized by the liver. Circulating androgen and estrogen concentrations influence SHBG synthesis. The regulation of SHBG synthesis, combined with SHBG's higher affinity for testosterone, impacts bioavailable testosterone levels.
SHBG binds up to 98 percent of the steroid hormones in the blood including 5a-dihydrotestosterone (DHT), testosterone and androstenediol with particularly high affinity, and estradiol and estrone with slightly lower affinity
Male and female children have similar SHBG concentrations until the onset of puberty, when SHBG levels begin decreasing more rapidly in males than in females. Levels are higher in women than in men, due to the higher ratio of estrogens to androgens in women. Levels are especially elevated during late pregnancy and in women taking oral contraception.
Excellent info here:
http://www.digitalnaturopath.com/cond/C654345.html
----------------------
Estrogen, DHT and testosterone all compete inside the same cell receptor...SHBG a carrier protien but not active, the active carrier protien is albumin.
prostate androgen receptor and prostate-specific antigen secretion through the intermediacy of sex hormone-binding globulin.
Abstract
These experiments were designed to examine the relationship between the effects of steroid hormones mediated by classic intracellular steroid hormone receptors and those mediated by a signaling system subserved at the plasma membrane by a receptor for sex hormone-binding globulin. It is known that unliganded sex hormone-binding globulin (SHBG) binds to a receptor (RSHBG) on prostate membranes. The RSHBG.SHBG complex is rapidly activated by estradiol to stimulate adenylate cyclase, with a resultant increase in intracellular cAMP. In this paper we examine the effect of this system on a prostate gene product known to be activated by androgens, prostate-specific antigen. In serum-free organ culture of human prostates, dihydrotestosterone caused an increase in prostate specific antigen secretion. This event was blocked by the anti-androgens cyproterone acetate and hydroxyflutamide. In the absence of androgens, estradiol added to prostate tissue, whose RSHBG was occupied by SHBG, reproduced the results seen with dihydrotestosterone. Neither estradiol alone nor SHBG alone duplicated these effects. The estradiol.SHBG-induced increase in prostate-specific antigen was not blocked by anti-estrogens, but was blocked both by anti-androgens and a steroid (2-methoxyestradiol) that prevents the binding of estradiol to SHBG. Furthermore, an inhibitor of protein kinase A prevented the estradiol.SHBG-induced increase in prostate-specific antigen but not that which followed dihydrotestosterone. These data indicate that there is a signaling system that amalgamates steroid-initiated intracellular events with steroid-dependent occurrences generated at the cell membrane and that the latter signaling system proceeds by a pathway that involves protein kinase A.
http://www.ncbi.nlm.nih.gov/pubmed/9054366