The results obtained from this investigation have demonstrated that this enzyme is present in many rat tissues, and that of the investigated tissues, the pituitary gland is the HTS tissue which contains the highest enzymatic activity, with 20 3. 0 EU mg protein, followed by testis. brain, liver, kidney and serum. In addition, it is also interesting to observe that the Inhibitors,Modulators,Libraries D aspartate racemase activ ity is greater in those tissues in which D Asp also occurs at the higher levels. Discussion In this study using a specific HPLC method combined with the use of D AspO and specific immunoen zymatic methods for the determination of LH and testo sterone as well Inhibitors,Modulators,Libraries as of the second messengers, cAMP and cGMP, we have demonstrated that D aspartic acid plays a role in the release and synthesis of LH and testosterone in humans and rats.

Inhibitors,Modulators,Libraries In humans we found that with the con sumption of a daily dose of 10 ml of 2 M sodium D aspar tate solution for 12 consecutive days, the levels of LH and testosterone in the serum were significantly increased, by 33% and 42% respectively. In 87% of the subjects who have been treated with sodium D aspartate increased the concentration of LH and testosterone in the serum. After 6 days of treatment LH was already found to have increased, but this increase was not statistically significant. Three days after sodium D aspartate suspension, LH still was found higher than that of basal levels, but this increase was not statistically significant, indicat Inhibitors,Modulators,Libraries ing that the increase of LH was dose dependent. The con sumption of sodium D aspartate in humans also induced significant testosterone release in the serum.

In fact, in the same subjects who took D Asp for 12 days, the levels of testosterone increased significantly. ANOVA with repeated measurements indicated a significant value. As with LH, so also with testosterone, 6 days of treatment induced increased serum testosterone in the blood, but this increase was not significant. Interestingly, contrary to what occurred Inhibitors,Modulators,Libraries for LH, three days after suspen sion of the treatment, testosterone still remained increased in the serum 1. 28 fold increase compared with the basal levels, and this increase was significant. A possible explanation of this event is that the ingested D Asp probably also remained accumu lated in the testes 3 days after treatment was stopped, and it continued to stimulate the testosterone production in the testes.

This hypothesis is supported no by results obtained in rats. In fact, after rats had drunk a solution of 20 mM D Asp for 12 days, this amino acid had accumu lated in various tissues, especially the pituitary and the tes tes. However, when D Asp treatment was suspended, D Asp that had accumulated in tissues dimin ished until it reached basal levels, except in the testes, where D Asp still remained significantly increased 1. 88 fold.