ABSTRACT
Dehydroepiandrosterone (DHEA) and DHEA.SO4 (DHEAS) are two major steroid hormones produced and secreted by the adrenal gland of human and non-human primates (Miller, 1998; Kroboth et al., 1999; Parker, 1999; Roberts, 1999). In contrast, the levels of these two steroid hormones in most other mammalian species are very low (Belanger et al., 1989; Jo et al., 1989; Guarneri et al., 1994; Shimada et al, 2000). Although the levels of DHEA and DHEAS are very low in the neuronal tissues, there are data to support that their formation or accumulation (or both) in the rat brain depends on in situ mechanisms unrelated to the peripheral endocrine gland (e.g. adrenal, placenta or ovary) (Corpechot et al., 1981). Also there are data to support the contention that the glial cells of the brain are endowed with enzymatic machinery capable of converting cholesterol into DHEA and DHEAS (Corpechot et al. 1981; Shimada et al., 2000). Both of these steroid hormones are not only endogenous to the brain, the administration of exogenous hormones to animals have been shown to exhibit a variety of central nervous system related biologic activities including appetite, memory, learning, mood, anxiety and depression to name a few (Svec et al., 1998). Therefore, DHEA and DHEAS have been associated with a family of steroid hormones collectively known as “Neurosteroids”.
