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Cited by 125Hypothalamic control of reproductive hormonesHormonal and reproductive studiesSperm and Testicular Function

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The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and rats

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Topo, Enza, Soricelli, Andrea, D'Aniello, Antimo, Ronsini, Salvatore, D'Aniello, Gemma·2009·Reproductive Biology and Endocrinology
DOI 10.1186/1477-7827-7-120PMC PMC2774316
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Abstract

Background: D-aspartic acid is an amino acid present in neuroendocrine tissues of invertebrates and vertebrates, including rats and humans. Here we investigated the effect of this amino acid on the release of LH and testosterone in the serum of humans and rats. Furthermore, we investigated the role of D-aspartate in the synthesis of LH and testosterone in the pituitary and testes of rats, and the molecular mechanisms by which this amino acid triggers its action. Methods: For humans: A group of 23 men were given a daily dose of D-aspartate (DADAVIT®) for 12 days, whereas another group of 20 men were given a placebo. For rats: A group of 10 rats drank a solution of either 20 mM D-aspartate or a placebo for 12 days. Then LH and testosterone accumulation was determined in the serum and D-aspartate accumulation in tissues. The effects of D-aspartate on the synthesis of LH and testosterone were gauged on isolated rat pituitary and Leydig cells. Tissues were incubated with D-aspartate, and then the concentration (synthesis) of LH and cGMP in the pituitary and of testosterone and cAMP in the Leydig cells was determined. Results: In humans and rats, sodium D-aspartate induces an enhancement of LH and testosterone release. In the rat pituitary, sodium D-aspartate increases the release and synthesis of LH through the involvement of cGMP as a second messenger, whereas in rat testis Leydig cells, it increases the synthesis and release of testosterone and cAMP is implicated as second messenger. In the pituitary and in testes D-Asp is synthesized by a D-aspartate racemase which convert L-Asp into D-Asp. The pituitary and testes possesses a high capacity to trapping circulating D-Asp from hexogen or endogen sources. Conclusion: D-aspartic acid is a physiological amino acid occurring principally in the pituitary gland and testes and has a role in the regulation of the release and synthesis of LH and testosterone in humans and rats.

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Figure 1 Typical HPLC analysis of D-Asp and other amino acids from rat pituitary gland. Panel A, HPLC profile of amino acids from a standard mixture consisting of 50 pmoles of D-Asp and 100 pmoles of various L-amino acids. Panel B is the HPLC analysis of the same amino a cids, but after treatment with D-AspO. Panel C shows the HPLC analysis of free amino acids from 0.05 mg of rat hippocampus, and panel D is the same sample, but after treatment with D-AspO. The peak of D-Asp disappeared completely after incubation of the sample with D-AspO (panels B and D), indicating that the peak area of D-Asp was completely due to D-Asp.
Figure 1 Typical HPLC analysis of D-Asp and other amino acids from rat pituitary gland. Panel A, HPLC profile of amino acids from a standard mixture consisting of 50 pmoles of D-Asp and 100 pmoles of various L-amino acids. Panel B is the HPLC analysis of the same amino a cids, but after treatment with D-AspO. Panel C shows the HPLC analysis of free amino acids from 0.05 mg of rat hippocampus, and panel D is the same sample, but after treatment with D-AspO. The peak of D-Asp disappeared completely after incubation of the sample with D-AspO (panels B and D), indicating that the peak area of D-Asp was completely due to D-Asp.CC BY · PubMed Central
Figure 2 Effects of D-Asp on LH and cGMP synthesis in isolated rat pituitary glands. Pituitary glands were incubated at 37°C for 60 min in a medium with Na-D-aspartate 0.1 or 1.0 mM and then LH and cGMP levels were determined in the total gland homogenate plus medium. The left panel shows that the increase of LH (LH synthesis) due to the action of the two concentrations of D-Asp versus the control (pituitary incubated without D-Asp): A, B (p < 0.001); a, b (p < 0.02). The right panel shows the total concentration of cGMP determined in the same samples as above obtained (cGMP synthesis): A, B and C, D(p < 0.001). Results are the mean ± SEM obtained from 5 individual experiments. Asterisks indicate that the difference in value between treated rats and control rats was significant at p < 0.0001, evaluated by one-way ANOVA.
Figure 2 Effects of D-Asp on LH and cGMP synthesis in isolated rat pituitary glands. Pituitary glands were incubated at 37°C for 60 min in a medium with Na-D-aspartate 0.1 or 1.0 mM and then LH and cGMP levels were determined in the total gland homogenate plus medium. The left panel shows that the increase of LH (LH synthesis) due to the action of the two concentrations of D-Asp versus the control (pituitary incubated without D-Asp): A, B (p < 0.001); a, b (p < 0.02). The right panel shows the total concentration of cGMP determined in the same samples as above obtained (cGMP synthesis): A, B and C, D(p < 0.001). Results are the mean ± SEM obtained from 5 individual experiments. Asterisks indicate that the difference in value between treated rats and control rats was significant at p < 0.0001, evaluated by one-way ANOVA.CC BY · PubMed Central
Figure 3 Effects of D-Asp on the synthesis of testosterone and cAMP in isolated rat Leydig cells. 1 ml of purified Leydig cells (1.0 × 106 cells) was incubated at 37°C for 60 min with Na-D-Asp 0.1 or 1.0 mM and control and then the testosterone and cAMP synthesis was determined. The left panel shows the total production of testosterone in the medium plus the Leydig cell homogenate, in the control sample and in the samples incubated with 0.1 mM or with 1.0 mM D-Asp: A, B and C, D (p < 0.001). The right panel shows the concentration of cAMP in the same above samples: A, B and C, D (p < 0.001). Values are the mean ± SEM obtained from 5 individual experiments. Asterisks indicate that the increased levels were significant compared with the controls at p < 0.001 as evaluated by one-way ANOVA.
Figure 3 Effects of D-Asp on the synthesis of testosterone and cAMP in isolated rat Leydig cells. 1 ml of purified Leydig cells (1.0 × 106 cells) was incubated at 37°C for 60 min with Na-D-Asp 0.1 or 1.0 mM and control and then the testosterone and cAMP synthesis was determined. The left panel shows the total production of testosterone in the medium plus the Leydig cell homogenate, in the control sample and in the samples incubated with 0.1 mM or with 1.0 mM D-Asp: A, B and C, D (p < 0.001). The right panel shows the concentration of cAMP in the same above samples: A, B and C, D (p < 0.001). Values are the mean ± SEM obtained from 5 individual experiments. Asterisks indicate that the increased levels were significant compared with the controls at p < 0.001 as evaluated by one-way ANOVA.CC BY · PubMed Central
Figure 4 D-Aspartate racemase activity in rat tissues: Synthesis of D-Asp. Homogenized tissue were incubated with L-Asp for 60 min at 37°C and then the amount of D-Asp synthesized was detected. The D-Asp that developed was determined by a colorimetric method based on the use of D-AspO. One enzyme unity (EU) was defined as the amount of the enzyme capable of generating 1 nmol of D-Asp in 60 min of incubation at 37°C and in the above assay conditions. The specific activity was defined as the EU/mg protein. The values are the mean ± SEM as obtained from five determinations, each carried out on a different rat.
Figure 4 D-Aspartate racemase activity in rat tissues: Synthesis of D-Asp. Homogenized tissue were incubated with L-Asp for 60 min at 37°C and then the amount of D-Asp synthesized was detected. The D-Asp that developed was determined by a colorimetric method based on the use of D-AspO. One enzyme unity (EU) was defined as the amount of the enzyme capable of generating 1 nmol of D-Asp in 60 min of incubation at 37°C and in the above assay conditions. The specific activity was defined as the EU/mg protein. The values are the mean ± SEM as obtained from five determinations, each carried out on a different rat.CC BY · PubMed Central

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Metadata

Authors
Topo, E., Soricelli, A., D'Aniello, A., Ronsini, S., & D'Aniello, G.
Affiliations
  • Stazione Zoologica Anton Dohrn (IT)
  • Parthenope University of Naples (IT)
ORCID
Soricelli, Andrea
Venue
Reproductive Biology and Endocrinology
Publisher
Springer Science and Business Media LLC
Published
2009-10-27
Volume
7
Issue
1
Pages
120-120
ISSN
1477-7827 (ISSN-L)
DOI
10.1186/1477-7827-7-120
PMC
PMC2774316
OpenAlex
W2135320785
Cited by
125
References
30
Citations by year
2026: 2 · 2025: 8 · 2024: 7 · 2023: 11 · 2022: 10 · 2021: 5 · 2020: 11 · 2019: 10 · 2018: 6 · 2017: 12 · 2016: 10 · 2015: 8 · 2014: 11 · 2013: 3 · 2012: 3
FWCI
3.94
Type
journal article
Language
en
Open access
Licence
cc-by
Locations
  • Reproductive Biology and Endocrinology (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • CINECA IRIS Institutial research information system (Parthenope University of Naples) (submittedVersion)
Topics
  • Health Sciences › Medicine › Reproductive Medicine › Hypothalamic control of reproductive hormones
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Hormonal and reproductive studies
  • Health Sciences › Medicine › Reproductive Medicine › Sperm and Testicular Function
Keywords
D-aspartic acid, luteinizing hormone, testosterone, pituitary gland, Leydig cells, cyclic GMP, cyclic AMP, second messengers, male fertility
MeSH terms
Adult, Animals, Blood Chemical Analysis, Chromatography, High Pressure Liquid, Humans, Luteinizing Hormone, Male, Pituitary Gland, Placebos, Testis, Testosterone, Signal Transduction, Rats, Wistar, D-Aspartic Acid, Rats

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