Structural reorganization of medullary dorsal horn astrocytes in a rat model of neuropathic pain.

Multiple studies have shown that astrocytes in the medullary dorsal horn (MDH) play an important role in the development of pathologic pain. However, little is known about the structural reorganization of the peripheral astrocytic processes (PAP), the main functional part of the astrocyte, in MDH in neuropathic state. For this, we investigated the structural relationship between PAP and their adjacent presynaptic axon terminals and postsynaptic dendrites in the superficial laminae of the MDH using electron microscopical immunohistochemistry for ezrin, a marker for PAP, and quantitative analysis in a rat model of neuropathic pain following chronic constriction injury of the infraorbital nerve (CCI-ION). We found that, compared to controls, in rats with CCI-ION, (1) the number, % area, surface density, and volume fraction of ezrin-positive (+) PAP, as well as the fraction of synaptic edge apposed by ezrin + PAP and the degree of its coverage of presynaptic axon terminals and postsynaptic dendrites increased significantly, (2) these effects were abolished by administration of the mGluR5 antagonist 2-methyl-6-(phenylethynyl) pyridine (MPEP). These findings indicate that PAP undergoes structural reorganization around the central synapses of sensory afferents following nerve injury, suggest that it may be mediated by mGluR5, and may represent the structural basis for enhancing astrocyte-neuron interaction in neuropathic pain.

Congenital Anomalies in Multiple Pregnancy: A Literature Review.

Importance: Multiple pregnancy is relatively common in many countries and is associated with various pregnancy complications, including preterm birth, low birth weight, and congenital anomalies. In particular, a poorer prognosis has been reported when congenital anomalies overlap with other pregnancy complications in multiple pregnancy compared with singleton pregnancy. Objective: This study reviews the characteristics of congenital anomalies that occur in multiple gestations as compared with singleton pregnancies. Evidence Acquisition: An extensive manual search of major electronic databases was conducted in June 2023. This literature review provides a comprehensive coverage of the congenital anomalies in multiple pregnancy. Results: Most studies have shown that multiple gestations are associated with an increased risk of congenital anomalies compared with singleton pregnancies. In addition, higher rates of congenital anomalies and concordance have been observed in monozygotic versus dizygotic twins. The effect of assisted reproductive therapies on the risk of congenital anomalies appears to be smaller in multiple gestations than in singleton pregnancies. Conclusions: Multiple pregnancy is significantly associated with an increased risk of congenital anomalies. Relevance: This review provides obstetrical providers with the requisite knowledge to offer appropriate antenatal care and prenatal anomaly screening to patients with multiple pregnancies.

Effect of Pethidine Injection on the Duration of Labor and Pregnancy Outcomes: A Retrospective Cohort Study.

Background and Objectives: Long and ineffective labor causes hardships for mothers and doctors and increases the rate of cesarean sections and medical comorbidities. Several factors contribute to effective and less painful labor, including maternal age, parity, fetal characteristics, and the medications or procedures that obstetricians use for labor. We aimed to study the factors that affect labor duration and identify those that make labor more effective. Materials and Methods: This retrospective study included 141 patients who underwent normal vaginal deliveries at the Daegu Catholic University Medical Center between April 2013 and April 2022. Among the 141 patients, 44 received pethidine intravenously, 88 received oxytocin intravenously, and 64 received epidural anesthesia. The duration of the active phase and second stage of labor were recorded according to the findings of a manual examination of the cervix and continuous external electronic monitoring. We analyzed maternal and neonatal medical records and performed binomial logistic regression to identify the factors associated with a shorter active phase of labor. The clinical outcomes in mothers and neonates were also evaluated. Results: Among the various clinical factors, multiparity (odds ratio of parity 0.325) and the use of pethidine (odds ratio 2.906) were significantly associated with shortening the active phase of labor to less than 60 min. The use of epidural anesthesia or oxytocin was not significantly associated with reducing the active phase of labor. When patients were divided into two groups based on whether a pethidine injection had been used during labor, the duration of the active phase was shorter in the pethidine injection group than in the control group for both nulliparas and multiparas. No significant differences in the duration of the second stage of labor were observed between the pethidine injection and control groups. There were no significant differences in pregnancy outcomes, including the need for mechanical ventilation of neonates, Apgar scores, neonatal intensive care unit admissions, number of precipitous deliveries, maternal adverse side effects of drugs, or duration of maternal hospitalization between the two groups. Conclusions: Pethidine can be safely administered to women during labor to help reduce the duration of the active phase by promoting dilatation of the cervix and preventing complications that may result from prolonged labor. Pethidine may be helpful, especially for those who cannot receive epidural anesthesia or who cannot afford it. However, large-scale randomized controlled studies are required to evaluate the efficacy and safety of this drug during labor. Furthermore, it would be helpful if various studies were conducted depending on the timing of administration and indications for delivery.

Increase of glutamate in satellite glial cells of the trigeminal ganglion in a rat model of craniofacial neuropathic pain.

Introduction: Satellite glial cells (SGCs) that envelop the cell bodies of neurons in sensory ganglia have been shown to both release glutamate, and be activated by glutamate in the context of nociceptive signaling. However, little is known about the subpopulations of SGCs that are activated following nerve injury and whether glutamate mechanisms in the SGCs are involved in the pathologic pain. Methods: To address this issue, we used light and electron microscopic immunohistochemistry to examine the change in the glutamate levels in the SGCs and the structural relationship between neighboring neurons in the trigeminal ganglion (TG) in a rat model of craniofacial neuropathic pain, CCI-ION. Results: Administration of ionomycin, ATP and Bz-ATP induced an increase of extracellular glutamate concentration in cultured trigeminal SGCs, indicating a release of glutamate from SGCs. The level of glutamate immunostaining in the SGCs that envelop neurons of all sizes in the TG was significantly higher in rats with CCI-ION than in control rats, suggesting that SGCs enveloping nociceptive as well as non-nociceptive mechanosensitive neurons are activated following nerve injury, and that the glutamate release from SGCs increases in pathologic pain state. Close appositions between substance-P (SP)-immunopositive (+) or calcitonin gene-related peptide (CGRP)+, likely nociceptive neurons, between Piezo1+, likely non-nociceptive, mechanosensitive neurons and SP+ or CGRP+ neurons, and between SGCs of neighboring neurons were frequently observed. Discussion: These findings suggest that glutamate in the trigeminal SGCs that envelop all types of neurons may play a role in the mechanisms of neuropathic pain, possibly via paracrine signaling.