DHEA is a weak estrogen. In addition, it is transformed into potent estrogens such as estradiol in certain tissues such as the vagina, and thereby produces estrogenic effects in such tissues.
In addition to its affinity for the androgen receptor, DHEA has also been found to bind to and activate the ERα and ERβestrogen receptors with Ki values of 1.1 μM and 0.5 μM, respectively, and EC50 values of >1 μM and 200 nM, respectively. Though it was found to be a partial agonist of the ERα with a maximal efficacy of 30–70%, the concentrations required for this degree of activation make it unlikely that the activity of DHEA at this receptor is physiologically meaningful. Remarkably however, DHEA acts as a full agonist of the ERβ with a maximal response similar to or actually slightly greater than that of estradiol, and its levels in circulation and local tissues in the human body are high enough to activate the receptor to the same degree as that seen with circulating estradiol levels at somewhat higher than their maximal, non-ovulatory concentrations; indeed, when combined with estradiol with both at levels equivalent to those of their physiological concentrations, overall activation of the ERβ was doubled. As such, it has been proposed that DHEA may be an important and potentially major endogenous estrogen in the body.
In 2011, the surprising discovery was made that DHEA, as well as DHEA-S, directly bind to and activate the TrkA and p75NTR, receptors of neurotrophins like nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), with high affinity. DHEA was subsequently also found to bind to the TrkB and TrkC with high affinity, though it notably activated the TrkC but not the TrkB. DHEA and DHEA-S bound to these receptors with affinities that were in the low nanomolar range (around 5 nM), although the affinities were nonetheless approximately two orders of magnitude lower relative to highly potent polypeptide neurotrophins like NGF (0.01–0.1 nM). In any case, DHEA and DHEA-S both circulate at requisite concentrations to activate these receptors and were thus identified as important endogenous neurotrophic factors. They have since been labeled "steroidal microneurotrophins", due to their small-molecule and steroidal nature relative to their polypeptide neurotrophin counterparts. Subsequent research has suggested that DHEA and/or DHEA-S may in fact be phylogenetically ancient "ancestral" ligands of the neurotrophin receptors from early on in the evolution of the nervous system. The findings that DHEA binds to and potently activates neurotrophin receptors may explain the positive association between decreased circulating DHEA levels with age and age-related neurodegenerative diseases.
Regular exercise is known to increase DHEA production in the body.Calorie restriction has also been shown to increase DHEA in primates. Some theorize that the increase in endogenous DHEA brought about by calorie restriction is partially responsible for the longer life expectancy known to be associated with calorie restriction.Catalpol and a combination of acetyl-carnitine and propionyl-carnitine on 1:1 ratio also improves endogenous DHEA production and release due to direct cholinergic stimulation of CRH release and an increase of IGF-1 expression respectively.
The terminal half-life of DHEA is short at only 15 to 30 minutes. In contrast, the terminal half-life of DHEA-S is far longer, at 7 to 10 hours. As DHEA-S can be converted back into DHEA, it serves as a circulating reservoir for DHEA, thereby extending the duration of DHEA.
Prior to puberty, DHEA and DHEA-S levels elevate upon differentiation of the zona reticularis of the adrenal cortex. Peak levels of DHEA and DHEA-S are observed around age 20, which is followed by an age-dependent decline throughout life eventually back to prepubertal concentrations. Plasma levels of DHEA in adult men are 10 to 25 nM, in premenopausal women are 5 to 30 nM, and in postmenopausal women are 2 to 20 nM. Conversely, DHEA-S levels are an order of magnitude higher at 1–10 μM. Levels of DHEA and DHEA-S decline to the lower nanomolar and micromolar ranges in men and women aged 60 to 80 years.
As almost all DHEA is derived from the adrenal glands, blood measurements of DHEA-S/DHEA are useful to detect excess adrenal activity as seen in adrenal cancer or hyperplasia, including certain forms of congenital adrenal hyperplasia. Women with polycystic ovary syndrome tend to have elevated levels of DHEA-S.
The term "dehydroepiandrosterone" is ambiguous chemically because it does not include the specific positions within epiandrosterone at which hydrogen atoms are missing. DHEA itself is 5,6-didehydroepiandrosterone or 5-dehydroepiandrosterone. A number of naturally occurring isomers also exist and may have similar activities. Some isomers of DHEA are 1-dehydroepiandrosterone (1-androsterone) and 4-dehydroepiandrosterone. These isomers are also technically "DHEA", since they are dehydroepiandrosterones in which hydrogens are removed from the epiandrosterone skeleton.
^Schulman RA, Dean C (2007). Solve It With Supplements. New York City: Rodale, Inc. p. 100. ISBN978-1-57954-942-8. DHEA (Dehydroepiandrosterone) is a common hormone produced in the adrenal glands, the gonads, and the brain.
^ abMo Q, Lu SF, Simon NG (April 2006). "Dehydroepiandrosterone and its metabolites: differential effects on androgen receptor trafficking and transcriptional activity". The Journal of Steroid Biochemistry and Molecular Biology. 99 (1): 50–8. doi:10.1016/j.jsbmb.2005.11.011. PMID16524719.
^Gravanis A, Calogeropoulou T, Panoutsakopoulou V, Thermos K, Neophytou C, Charalampopoulos I (October 2012). "Neurosteroids and microneurotrophins signal through NGF receptors to induce prosurvival signaling in neuronal cells". Science Signaling. 5 (246): pt8. doi:10.1126/scisignal.2003387. PMID23074265.
^ abcCiolino HP, MacDonald CJ, Yeh GC (July 2002). "Inhibition of carcinogen-activating enzymes by 16alpha-fluoro-5-androsten-17-one". Cancer Research. 62 (13): 3685–90. PMID12097275.
^McCormick DL, Johnson WD, Kozub NM, Rao KV, Lubet RA, Steele VE, Bosland MC (February 2007). "Chemoprevention of rat prostate carcinogenesis by dietary 16alpha-fluoro-5-androsten-17-one (fluasterone), a minimally androgenic analog of dehydroepiandrosterone". Carcinogenesis. 28 (2): 398–403. doi:10.1093/carcin/bgl141. PMID16952912.
^Auci D, Kaler L, Subramanian S, Huang Y, Frincke J, Reading C, Offner H (September 2007). "A new orally bioavailable synthetic androstene inhibits collagen-induced arthritis in the mouse: androstene hormones as regulators of regulatory T cells". Annals of the New York Academy of Sciences. 1110: 630–40. doi:10.1196/annals.1423.066. PMID17911478.
^Filaire E, Duché P, Lac G (October 1998). "Effects of amount of training on the saliva concentrations of cortisol, dehydroepiandrosterone and on the dehydroepiandrosterone: cortisol concentration ratio in women over 16 weeks of training". European Journal of Applied Physiology and Occupational Physiology. 78 (5): 466–71. doi:10.1007/s004210050447. PMID9809849.
^Copeland JL, Consitt LA, Tremblay MS (April 2002). "Hormonal responses to endurance and resistance exercise in females aged 19-69 years". The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences. 57 (4): B158–65. doi:10.1093/gerona/57.4.B158. PMID11909881.
^Roberts E (February 1999). "The importance of being dehydroepiandrosterone sulfate (in the blood of primates): a longer and healthier life?". Biochemical Pharmacology. 57 (4): 329–46. doi:10.1016/S0006-2952(98)00246-9. PMID9933021..
^Banaszewska B, Spaczyński RZ, Pelesz M, Pawelczyk L (2003). "Incidence of elevated LH/FSH ratio in polycystic ovary syndrome women with normo- and hyperinsulinemia". Roczniki Akademii Medycznej W Bialymstoku. 48: 131–4. PMID14737959.
Labrie F, Martel C, Bélanger A, Pelletier G (April 2017). "Androgens in women are essentially made from DHEA in each peripheral tissue according to intracrinology". The Journal of Steroid Biochemistry and Molecular Biology. 168: 9–18. doi:10.1016/j.jsbmb.2016.12.007. PMID28153489.