The effect of D-aspartate on luteinizing hormone-releasing hormone, alpha-melanocyte-stimulating hormone, GABA and dopamine release.
ABSTRACT Since D-aspartate stimulates prolactin and LH release, our objective was to determine whether D-aspartate modifies the release of hypothalamic and posterior pituitary factors involved in the control of their secretion and whether its effects on these tissues are exerted through NMDA receptors and mediated by nitric oxide. In the hypothalamus, D-aspartate stimulated luteinizing hormone-releasing hormone (LHRH), alpha-melanocyte-stimulating hormone (alpha-MSH) and GABA release and inhibited dopamine release through interaction with NMDA receptors. It increased nitric oxide synthase (NOS) activity, and its effects on LHRH and hypothalamic GABA release were blunted when NOS was inhibited. In the posterior pituitary gland, D-aspartate inhibited GABA release but had no effect on dopamine or alpha-MSH release. We report that D-aspartate differentially affects the release of hypothalamic and posterior pituitary factors involved in the regulation of pituitary hormone secretion.
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ABSTRACT: D-Aspartate (D-Asp) is an endogenous substance in mammals. Degradation of D-Asp is carried out only by D-aspartate oxidase (DDO). We measured DDO activity in porcine tissues, and produced an anti-porcine DDO antibody to examine the cellular localization of DDO. All the tissues examined showed DDO activities, whereas the substrate D-Asp was not detected in kidney cortex, liver, heart, and gastric mucosa. In the kidney, intensive immunohistochemical staining for DDO was found in the epithelial cells of the proximal tubules. In the liver, the epithelial cells of interlobular bile ducts, liver sinusoid-lining cells with cytoplasmic processes, and the smooth muscle cells of arterioles were strongly stained for DDO. In the heart, cardiomyocytes and the smooth muscle cells of arterioles showed DDO-immunoreactivity. In the gastric mucosa, only the chief cells were DDO-positive. These newly identified DDO-positive cells seem to actively degrade D-Asp to prevent an excess of D-Asp from exerting harmful effects on the respective functions of porcine tissues.Amino Acids 10/2010; 41(2):529-36. · 3.91 Impact Factor
- International Journal of Pharmacy and Biological Sciences. 01/2013;
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ABSTRACT: D-Aspartate (D-Asp) is an endogenous amino acid in the central nervous and reproductive systems of vertebrates and invertebrates. High concentrations of D-Asp are found in distinct anatomical locations, suggesting that it has specific physiological roles in animals. Many of the characteristics of D-Asp have been documented, including its tissue and cellular distribution, formation and degradation, as well as the responses elicited by D-Asp application. D-Asp performs important roles related to nervous system development and hormone regulation; in addition, it appears to act as a cell-to-cell signaling molecule. Recent studies have shown that D-Asp fulfills many, if not all, of the definitions of a classical neurotransmitter-that the molecule's biosynthesis, degradation, uptake, and release take place within the presynaptic neuron, and that it triggers a response in the postsynaptic neuron after its release. Accumulating evidence suggests that these criteria are met by a heterogeneous distribution of enzymes for D-Asp's biosynthesis and degradation, an appropriate uptake mechanism, localization within synaptic vesicles, and a postsynaptic response via an ionotropic receptor. Although D-Asp receptors remain to be characterized, the postsynaptic response of D-Asp has been studied and several L-glutamate receptors are known to respond to D-Asp. In this review, we discuss the current status of research on D-Asp in neuronal and neuroendocrine systems, and highlight results that support D-Asp's role as a signaling molecule.Amino Acids 08/2012; 43(5):1873-86. · 3.91 Impact Factor