An analysis of excitatory amino acids, nitric oxide, and prostaglandin E2 in the cerebrospinal fluid of pregnant women: the effect on labor pain

A comparison of the effects of ENTONOX inhalation and spinal anesthesia on labor pain reduction and apgar score in vaginal delivery: a clinical trial study

INTRODUCTION

The purpose of the present study was to compare the effect of ENTONOX inhalation and spinal injection on the reduction of labor pain, the Apgar score of the neonates, and their side effects on new-born children and pregnant women.

MATERIAL AND METHODS

The present clinical trial study is conducted among the pregnant women in the maternity ward of a child delivery hospital in Iran. All Participants were divided in two groups ENTONOX Inhalation and Spinal Anesthesia. Visual Analogue Scale (VAS) was implemented to measure the pain level experienced by the participants during the procedure. Moreover, the Apgar scale was used to measure the general physical health of the neonates in both groups. In addition, the participants receiving ENTONOX were asked to report the side effects they underwent during gas inhalation. However, the participants in the spinal anesthesia were checked three times. Statistical analysis was performed using SPSS version 22.

RESULTS

The findings showed that the spinal anesthesia technique was significantly more effective than gas inhalation in that it reduced as much as 3 points more than did the inhalation (P-value: 0.001). Moreover, the comparison of the mean Apgar scores showed that the mean Apgar score of the neonates of spinal anesthesia mothers was 0.36 point lower than that of the neonates in the gas inhalation group. However, this difference was not statistically significant at P- value = 0.06.

CONCLUSIONS

the result of the present study indicated that spinal anesthesia was more effective than ENTONOX inhalation in reducing the labor pain.

Regional dysregulation of taurine and related amino acids in the fetal rat brain following gestational alcohol exposure

The fetal brain exhibits exquisite alcohol-induced regional neuronal vulnerability. A candidate mechanism for alcohol-mediated brain deficits is disruption of amino acid (AA) bioavailability. AAs are vitally important for proper neurodevelopment, as they comprise the most abundant neurotransmitters in the brain and act as neurotransmitter precursors, nitric oxide donors, antioxidants, and neurotrophic factors, which induce synaptogenesis, neuronal proliferation, and migration. We hypothesized that gestational alcohol alters brain AA concentrations, disrupts AAs associated with neuropathogenesis, and that alterations are region-specific. We assigned pregnant Sprague-Dawley rats to either a pair-fed control or a binge alcohol treatment group on gestational day (GD) 4. Alcohol animals were acclimatized via a once-daily orogastric gavage of a 4.5 g/kg alcohol dose from GD 5-10, and progressed to a 6 g/kg alcohol dose from GD 11-20. Pair-fed animals received isocaloric maltose dextrin (once daily; GD 5-20). Fetal cerebral cortex, cerebellum, and hippocampus were collected on GD 21. Following collection, Fluorometric High Performance Liquid Chromatography (HPLC) involving pre-column derivatization with o-phthaldialdehyde quantified regional content of 22 AAs. Chronic binge alcohol administration to pregnant dams regionally altered AA concentrations in all three structures, with the cerebral cortex exhibiting the least vulnerability and the hippocampus exhibiting maximal vulnerability. We conjecture that the AA imbalances observed in this study are critically implicated in pathological and compensatory processes occurring in the brain in response to gestational alcohol exposure.

Changes in Purines Concentration in the Cerebrospinal Fluid of Pregnant Women Experiencing Pain During Active Labor

Labor pain has been reported as a severe pain and can be considered as a model of acute visceral pain. It is well known that extracellular purines have an important role in pain signaling in the central nervous system. This study analyzes the relationship between extracellular purines and pain perception during active labor. A prospective observational study was performed. Cerebrospinal fluid (CSF) levels of the purines and their metabolites were compared between women at term pregnancy with labor pain (n = 49) and without labor pain (Caesarian section; n = 47). Control groups (healthy men and women without chronic or acute pain-n = 40 and 32, respectively) were also investigated. The CSF levels of adenosine were significantly lower in the labor pain group (P = 0.026) and negatively correlated with pain intensity measured by a visual analogue scale (r = -0.48, P = 0.0005). Interestingly, CSF levels of uric acid were significantly higher in healthy men as compared to women. Additionally, pregnant women showed increased CSF levels of ADP, GDP, adenosine and guanosine and reduced CSF levels of AMP, GTP, and uric acid as compared to non-pregnant women (P < 0.05). These findings suggest that purines, in special the nucleoside adenosine, are associated with pregnancy and labor pain.

Brain activity for chronic knee osteoarthritis: dissociating evoked pain from spontaneous pain

Chronic pain is a hallmark of osteoarthritis (OA), yet little is known about its properties and representation in the brain. Here we use fMRI combined with psychophysics to study knee pain in fourteen OA patients and nine healthy controls. Mechanical painful pressure stimuli were applied to the knee in both groups and ratings of evoked pain and related brain activity examined. We observe that psychophysical properties and brain activation patterns of evoked pain are essentially the same between OA patients and healthy subjects, and between worse and better OA knees. In OA patients, stimulus-related brain activity could be distinguished from brain activity associated with spontaneous pain. The former activated brain regions commonly observed for acute painful stimuli in healthy subjects, while the spontaneous pain of OA engaged prefrontal-limbic regions closely corresponding to areas observed for spontaneous pain in other chronic pain conditions, such as chronic back pain and post-herpetic neuralgia. Arthritis-related clinical characteristics of knee OA also mapped to prefrontal-limbic regions. In a subgroup of patients (n=6) we examined brain activity changes for a 2-week, repeat measure, cyclooxygenase-2 inhibitor (valdecoxib) therapy. Treatment decreased spontaneous pain for the worse knee and clinical characteristics of OA, and increased blood and csf levels of the drug which correlated positively with prefrontal-limbic brain activity. These findings indicate dissociation between mechanically induced and spontaneous OA knee pain, the latter engaging brain regions involved in emotional assessment of the self, and challenge the standard clinical view regarding the nature of OA pain.

Effects of anesthetic propofol on release of amino acids from the spinal cord during visceral pain

As one of general anesthetics, propofol, has been used for surgical procedures of visceral organs. However, the mechanisms underlying the action of propofol on visceral nociception remain controversial. The aim of this study is to test whether the antinociception of systemic administration of propofol against visceral stimuli is related to the changes in release of excitatory and inhibitory amino acids in the spinal cord. The spinal microdialysis catheters were implanted subarachnoidally via the atlanto-occipital membrane in healthy SD rats. The rats received an intraperitoneal injection of acetic acid for visceral pain induction 10min after intraperitoneal pretreatment with vehicle or propofol (100mg/kg). The acetic acid-induced writhing assay was used to determine the degree of antinociception. Cerebrospinal fluid dialysate was collected by microdialysis from the spinal subarachnoid space before pretreatment and after visceral pain induction. Visceral pain-induced release of amino acids into the dialysate, including glutamate, aspartate, and γ-amino butyric acid was evaluated by measuring the changes in the concentrations of these amino acids. Acetic acid increased release of aspartate and glutamate, and decreased release of γ-amino butyric acid in the cerebrospinal fluid as measured by microdialysis. Pretreatment with propofol significantly decreased writhing responses induced by visceral pain, suppressed the visceral pain-induced aspartate and glutamate release, and reversed the decreased release of γ-amino butyric acid in the cerebrospinal fluid. These data provide evidence for a potential mechanism for the antinociceptive effects of propofol on visceral nociception.

Changes in purines concentration in the cerebrospinal fluid of patients experiencing pain: a case-control study

This study analyzes the relationship between extracellular purines and pain perception in humans. Cerebrospinal fluid (CSF) levels of purines and their metabolites were compared between patients displaying acute and/or chronic pain syndromes and control subjects. The CSF levels of IMP, inosine, guanosine and uric acid were significantly increased in the chronic pain group and correlated with pain severity (P<0.05). Patients displaying both chronic and acute pain presented similar changes in the CSF purines concentration (P<0.05). However, in the acute pain group, only CSF inosine and uric acid levels were significantly increased (P<0.05). These findings suggest that purines, in special inosine, guanosine and uric acid, are associated with the spinal mechanisms underlying nociception.

Changes in amino acids and nitric oxide concentration in cerebrospinal fluid during labor pain

This study analyzes the relationship between amino acids and pain perception during active labor. Cerebrospinal fluid (CSF) levels of the excitatory amino acids (EAAs)-glutamate, aspartate and their amide forms, inhibitory amino acids (IAAs)-glycine, gamma-amino butyric acid (GABA) and taurine and nitric oxide (NO) related compounds-arginine and citrulline (by-product of NO synthesis) were compared between pregnant women at term pregnancy with labor pain (n = 38) and without labor pain (Caesarian section; n = 30). The levels of aspartate, glycine, GABA and citrulline were significantly higher; whilst taurine was significantly lower in the labor pain group. These findings suggest that aspartate and NO are associated with labor pain. An inhibitory role for the IAA taurine and a pronociceptive role for glycine in labor pain are proposed.