S-Nitrosoglutathione and glutathione act as NMDA receptor agonists in cultured hippocampal neurons.
OBJECTIVE
To characterize the effect of combined pre- and postnatal morphine exposure on N-methyl-D-aspartate receptor (NMDA) receptor signaling in hippocampal neurons of the offspring of morphine-addicted female rats.


METHODS
Cultured hippocampal neurons and synaptosomes were prepared from neonatal and 2-week-old offspring, respectively, of control or morphine-addicted female rats. The increase in the cytosolic Ca2+ concentration ([Ca2+]i) of cultured cells was measured using Fura-2, and glutamate release from synaptosomes was measured enzymatically.


RESULTS
Both glutamate and NMDA caused a dose-dependent increase in the [Ca2+]i. The nitric oxide (NO) donor, S-nitrosoglutathione (GSNO), but not 3-morpholinosydnonimine, sodium nitroprusside, and S-nitroso-N-acetylpenicillamine, also induced a [Ca2+]i increase. GSNO and glutathione caused a dose-dependent increase in the [Ca2+]i with respective EC50 values of 56 and 414 micromol/L. Both effects were inhibited by Mg2+ or an NMDA receptor antagonist and were unaffected by the presence of a glutamate scavenger. The other glutathione derivatives, oxidized glutathione, S-methylglutathione, S-ethylglutathione, S-propylglutathione, and S-butylglutathione, the dipeptides, Glu-Cys and Cys-Gly, and the antioxidants, dithiothreitol and mercaptoethanol, failed to induce a [Ca2+]i increase. In addition, glutathione caused a dose-dependent increase in glutamate release from synaptosomes. The maximal responses and the EC50 values for the glutamate-, NMDA-, GSNO-, and glutathione-induced [Ca2+]i increases and the glutathione-induced glutamate release were indistinguishable in the neurons of the offspring from control and morphine-addicted female rats.


CONCLUSIONS
GSNO and glutathione act as NMDA receptor agonists and, in contrast to hippocampal brain slice, combined pre- and postnatal morphine exposure does not modulate NMDA receptor signaling in the cultured hippocampal neurons.
Chin
Ting-yu
TY
Department of Bioscience Technology, Chung-Yuan Christian University, Chung-Li, Taiwan, China.
Chueh
Sheau-huei
SH
Tao
Pao-luh
PL
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D018698:Glutamic Acid / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology; D005978:Glutathione / Q000008:administration & dosage / Q000494:pharmacology*; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D009020:Morphine / Q000494:pharmacology; D016202:N-Methylaspartate / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists*; D026422:S-Nitrosoglutathione / Q000008:administration & dosage / Q000494:pharmacology*; D015398:Signal Transduction; D013574:Synaptosomes / Q000378:metabolism
D020030:Nitric Oxide Donors; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; D026422:S-Nitrosoglutathione; D016202:N-Methylaspartate; D009020:Morphine; D005978:Glutathione; D008274:Magnesium; D002118:Calcium