An analysis of excitatory amino acids, nitric oxide, and prostaglandin E-2in the cerebrospinal fluid of pregnant women: The effect on labor pain

It is still unclear which neurotransmitters are involved in labor pain. We measured the concentrations of excitatory amino acids, nitric oxide, and pr ostaglandin E, in the cerebrospinal fluid (CSF) of pregnant women, particul arly in those with labor pain. The patients included in the study consisted of women who underwent cesarean delivery either with labor pain (Labor Pai n group, n = 40) or without labor pain (Nonlabor Pain group, n = 58). All p atients received spinal anesthesia (intrathecal injection of 10-12 mg of bu pivacaine) for the operation, and 2 mL of CSF was collected before bupivaca ine injection. Concentrations of aspartate and glutamate (0.50 +/- 0.06 muM and 0.79 +/- 0.10 muM, respectively) were significantly larger in the Labo r Pain group than in the Nonlabor Pain group (0.35 +/- 0.03 muM and 0.54 +/ - 0.04 muM, P < 0.05). There were no significant differences in the concent rations of nitric oxide and prostaglandin E, between the groups. A positive correlation was found between CSF concentrations of excitatory amino acids and labor pain.