DHEA (dehydroepiandrosterone) is a steroid hormone mainly secreted from the cortex of adrenal gland. DHEA serves as a precursor in testosterone and estrogen synthesis. The plasma levels of DHEA declines rapidly after birth and remain low level until about the age of 6-8; when they begin to rise on prepubertal, then a rapid rise from puberty and reach their maximum level at around age of twentys. It declines rapidly from fortys then; at age of fiftys, it is only about half the peak level; and by age of seventys, it declines to about 10% the peak level. DHEA has about 10% of androgenic activity compared to that of testosterone, but the role of its physiological activities is not yet conclusively defined. It has been reported that DHEA may revolved in cholesterol and lipid metabolism, insulin sensitivity and secretion and immune function. Abnormal DHEA levels have been reported in schizophrenia and obesity. In addition, DHEA is also produced directly in the nervous system, where it may function as a neuroactive and neuroprotective factors.
In blood, over than 90% of DHEA is bound to a plasma protein called corticosteroid-binding globulin (CBG) and plasma albumin, some parts of unbound free DHEA are secreted to saliva. Majority of DHEA in saliva remains unbound to protein. The levels of saliva DHEA are not affected with saliva secretion flow rate, and have good correlation between DHEA measurements in saliva and serum. Furthermore, saliva DHEA is relatively stable to the degradation by enzymes and freezing-thawing cycles. DHEA exhibits a diurnal rhythm similar to cortisol, with highest levels in the morning after awakening, followed by a decline throughout the afternoon and evening.
The newly developed DHEA (saliva) EIA kit by our laboratory provides a high sensitivity, quantitative tool for direct determination of DHEA in saliva without pre-treatment for sample. Furthermore, assays using this kit can be completed within a short period. The DHEA (saliva) EIA kit newly developed will be a quite useful tool for further development in DHEA research.
This EIA kit is used for quantitative determination of DHEA in saliva. It has various advantages, such as no extraction procedure of samples, short assay time, practically no influences of other physiological active substances coexisting in samples assayed.
< Assay range > 22.2– 5400pg/mL
< Assay Principle >
This EIA kit for determination of DHEA is based on a competitive enzyme immunoassay using combination of specific antibody to DHEA and DHEA-horseradish peroxidase (HRP) conjugate(HRP-labeled DHEA) system. The 96 wells plate is coated with DHEA specific antibody, to which DHEA standard or samples, HRP-labeled DHEA are added for competitive immunoreaction. After incubation and plate washing, HRP enzyme activity is determined by 3,3’,5,5’-tetramethylbenzidine(TMB) and the concentration of DHEA is calculated.