Effects Of D-aspartate And ZMA Supplementation On Serum Hormones In Rats

Abstract

PURPOSE: Both D-aspartate (DAA) and a commercial supplement containing zinc magnesium aspartate (ZMA) have been proposed to enhance anabolic hormonal profiles and reduce catabolism in human by two distinct mechanisms. However, whether the combination of DAA and ZMA has an additive effect on the release of the anabolic hormones is not known. METHODS:Four groups of 10 rats each drank a solution containing 104 mg DAA (DASP), 77 mg ZMA, 104 mg DAA and 77 mg ZMA (MIX) or a placebo (PLA) for 28 days. Blood samples were collected from carotid arteries and analyzed for serum DAA, total testosterone (TT), free testosterone (FT), luteinizing hormone (LH), estradiol (ES), GnRH, D-aspartate oxidase (DDO), IGF-1, growth hormone (GH) and cortisol. DAA accumulation was determined in the pituitary, the pineal, the adrenal, the thyroid, and the testis. Data were analyzed using independent-samples t tests. RESULTS:DASP significantly increased the serum concentrations of TT (20.34±4.10 vs. 10.41±1.85 ng/ml, p=0.042) and GH (19.83±1.69 vs. 15.05±1.20 ng/ml, p=0.039) compared with PLA. Serum FT was increased in DASP but not significant (788.56±43.88 vs. 673.93±125.99 pg/ml, p=0.070). Compared with DASP, MIX significantly decreased serum FT (613.80±31.10 vs. 788.56±43.88 pg/ml, p=0.005), GH (13.68±1.10 vs. 19.83±1.69 ng/ml, p=0.007) and IGF-1 (180.94±16.50 vs. 246.01±19.96 ng/ml, p=0.023), with a trend to decrease serum TT (11.79±1.24 vs. 20.34±4.10 ng/ml, p=0.076), although ZMA alone did not have any apparent effects on them. DAA accumulation was not changed in all groups except that testicular DAA was increased in DASP (0.036±0.002 vs. 0.027±0.001 nmol/g tissue, p=0.001), and MIX further increased it (0.053±0.004 vs. 0.027±0.001 nmol/g tissue, p<0.001), compared with PLA. ZMA significantly decreased serum LH (8.64±0.56 vs. 11.18±1.10 ng/ml, p=0.047) and MIX further suppressed it (7.97±0.93 vs. 11.18±1.10 ng/ml, p=0.039), compared with PLA. Serum ES, GnRH, DDO and cortisol were unchanged with DAA and/or ZMA treatments. CONCLUSIONS: The present data suggest that DASP increased the accumulation of DAA in testis and has potential to stimulate the release of TT, FT and GH in rats. ZMA did not appear to affect serum anabolic hormone levels. On the contrary, the combination of ZMA and DASP suppressed the anabolic effects of DASP in rats.