Activity-dependent Synaptic Recruitment of Neuroligin 1 in Spinal Dorsal Horn Contributed to Inflammatory Pain.

Neuroligin 1 (NLGN1), a cell adhesion molecule present at excitatory glutamatergic synapses, has been shown to be critical for synaptic specialization and N-methyl-d-aspartate (NMDA)-subtype glutamate receptor-dependent synaptic plasticity. Whether and how NLGN1 is engaged in nociceptive behavioral sensitization remains largely unknown. In this study, we found an activity-dependent regulation of NLGN1 synaptic expression in pain-related spinal cord dorsal horns of mice. The enhancement of neuronal activity by pharmacological activation of NMDA receptor (NMDAR) or removal of GABAergic inhibition in intact mice significantly increased NLGN1 concentration at synaptosomal membrane fraction. Intraplantar injection of complete Freund's adjuvant (CFA) also increased the NLGN1 expression at synapses. NMDAR might act through Ca2+/calmodulin-dependent protein kinase II (CaMKII) and Src-family protein tyrosine kinase member Fyn to induce the synaptic redistribution of NLGN1. We also found that one of the important roles of NLGN1 was to facilitate the clustering of NMDAR at synapses. The NLGN1-targeting siRNA suppressed the synaptic expression of GluN2B-containing NMDAR in CFA-injected mice and meanwhile, attenuated the inflammatory mechanical allodynia and thermal hypersensitivity. These data suggested that tissue injury-induced synaptic redistribution of NLGN1 was involved in the development of pain hypersensitivity through facilitating the synaptic incorporation of NMDARs.

Inhibition of protein tyrosine phosphatase 1B in spinal cord dorsal horn of rats attenuated diabetic neuropathic pain.

Protein tyrosine phosphatase 1B (PTP1B) has been shown to dephosphorylate and inactivate insulin receptors, which contributes to the pathogenesis of diabetes. Neuropathic pain is one of the severe complications that results from diabetic neuropathy. However, whether PTP1B was involved in the development of diabetic neuropathic pain is largely unknown. The current study illustrated that PTP1B was located in spinal cord dorsal horn neurons of Sprague-Dawley rats. Western blot analysis demonstrated that the diabetic neuropathic pain induced by intraperitoneal injection of streptozotocin was associated with an increased protein expression and a dynamic redistribution of spinal PTP1B into excitatory glutamatergic synapses. We found that PTP1B operated to stimulate Src kinase and enhance the tyrosine phosphorylation of N-methyl-D-aspartate (NMDA) subtype of glutamate receptors. The siRNA-mediated knockdown of PTP1B in streptozotocin-injected rats repressed Src activity, decreased NMDA receptor phosphorylation and alleviated the thermal hyperalgesia and mechanical allodynia. A similar analgesia against diabetic neuropathic pain was also achieved when PTP1B activity was manipulated by a chemical PTP Inhibitor or PTP1B(C215S) mutant. These data revealed a regulated expression of PTP1B in spinal cord dorsal horn of rats after diabetic neuropathy, and demonstrated that inhibition of PTP1B was beneficial for the treatment of pain hypersensitivity related to diabetes.

Adenosine A1 receptor potentiated glycinergic transmission in spinal cord dorsal horn of rats after peripheral inflammation.

Adenosine is present at the extracellular space within spinal cord dorsal horn and engaged in the processing of nociceptive sensory signals. Systemic or spinal administration of exogenous adenosine produces a potent analgesia against pathological pain. Here we found that inhibitory glycinergic neurotransmission was an important target for adenosine regulation. In spinal cord slices from intact rats, adenosine increased the inhibitory postsynaptic currents mediated by glycine receptors (GlyRs). In spinal slices from Complete Freund's Adjuvant-injected rats, adenosine potentiated glycinergic transmission to a more degree than in control rats. This synaptic potentiation was dependent on the activation of adenosine A1 receptor (A1R), and attributed to the modification of postsynaptic GlyRs function. The Gi protein-coupled A1R typically signals through Gαi/cAMP-dependent protein kinase (PKA) and Gßγ pathways. We found that blockade of either Gαi/PKA or Gßγ signaling attenuated the ability of adenosine to increase glycinergic synaptic responses in inflamed rats. To identify which GlyRs subunit was subjected to A1R regulation, we recorded glycine-evoked whole-cell currents in HEK293T cells co-transfected with A1R and distinct GlyRs subunit. We found that α1, the most abundant functional GlyRs subunit in adult spinal cord, was insensitive to A1R activation. However, when GlyRs α3 subunit or α1ins subunit, a longer α1 isoform, was co-expressed with A1R, adenosine caused a significant increase of glycinergic currents. Inhibition of PKA and Gßγ abolished the stimulatory effects of A1R on α3 and α1ins, respectively. These data suggested that A1R might potentiate glycinergic transmission through Gαi/PKA/α3 and Gßγ/α1ins pathways in inflamed rat.

[The Value of Early Diastolic Transmitral Velocity to Early Mitral Anulus Diastolic Velocity Ratio for Pulmonary Edema in Severe Sepsis Patients].

OBJECTIVES: To determine the association between the value of early diastolic transmitral velocity to early mitral anulus diastolic velocity ratio (E/E')measured by bedside ultrasound and pulmonary edema in severe sepsis (including septic shock) patients. METHODS: Data were obtained from the critical ultrasound database between November 2014 and August 2015. The severe sepsis (including septic shock) patients were eligible, but those with chronic heart disease or acute heart failure were excluded. Pulmonary edema was quantified by lung ultrasound score. The patients were divided into two groups according to lateral E/E'. E/E'-high group was defined as the lateral E/E'>8, and the others were in E/E'-low group. The severity and distribution of pulmonary edema were compared between the two groups. The correlation analysis and logistic regression analysis were performed to determine whether E/E' was the independent risk factor of pulmonary edma. RESULTS: There were 82 cases included. The lung ultrasound score of E/E'-high group was significantly higher than that of E/E'-low group ( P=0.007). There was no statistic difference of pulmonary edema severity in the bilateral 5 th and 6 th ultrasound exam areas, but E/E'-high group were more severe in the bilateral 1 th to 4 th ultrasound exam areas ( P=0.004). Linear-regression analysis demonstrated that E/E' and inferior vena cava diameter were independent risk factors of pulmonary edema (standardized regression coefficients were 0.425 and 0.249, respectively, P<0.05). CONCLUSIONS: E/E' is the independent risk factor of pulmonary edema in severe sepsis and septic shock patients.