The aim of this study was to determine the effect and mechanism of low concentration of lidocaine on subthreshold membrane potential oscillations (SMPO) and burst discharges in chronically compressed dorsal root ganglion (DRG) neurons. DRG neurons were isolated by enzymatic dissociation method. SMPO, burst discharges and single spike were elicited by whole cell patch-clamp technique in current clamp mode. Persistent Na+ current (INaP) and transient Na+ current (INaT) were elicited in voltage clamp mode. The results showed that SMPO was suppressed and burst discharges were eliminated by tetrodotoxin (TTX, 0.2 μ mol/l) in current clamp mode, INaP was blocked by 0.2 μ mol/l TTX in voltage clamp mode. SMPO, burst discharges and INaP were also suppressed by low concentration of lidocaine (10 μ mol/l) respectively. However, single spike and INaT could only be blocked by high concentration of lidocaine (5 mmol/l). From these results, it is suggested that INaP mediates the generation of SMPO in injured DRG neurons. Low concentration of lidocaine (10 μ mol/l) suppresses SMPO by selectively inhibiting INaP, but not INaT, in chronically compressed DRG neurons., H. Dong, Y.-H. Fan, Y.-Y. Wang, W.-T. Wang, S.J. Hu., and Obsahuje bibliografii a bibliografické odkazy
We used a model of tibial lengthening in rabbits to study the postoperative pain pattern during limb-lengthening and morphological changes in the dorsal root ganglia (DRG), including alteration of substance P (SP) expression. Four groups of animals (naïve; OG: osteotomized only group; SDG/FDG: slow/fast distraction groups, with 1 mm/3 mm lengthening a day, respectively) were used. Signs of increasing postoperative pain were detected until the 10th postoperative day in OG/SDG/FDG, then they decreased in OG but remained higher in SDG/FDG until the distraction finished, suggesting that the pain response is based mainly on surgical trauma until the 10th day, while the lengthening extended its duration and increased its intensity. The only morphological change observed in the DRGs was the presence of large vacuoles in some large neurons of OG/SDG/FDG. Cell size analysis of the S1 DRGs showed no cell loss in any of the three groups; a significant increase in the number of SP-positive large DRG cells in the OG; and a significant decrease in the number of SP-immunoreactive small DRG neurons in the SDG/FDG. Faster and larger distraction resulted in more severe signs of pain sensation, and further reduced the number of SP-positive small cells, compared to slow distraction., K. Pap, Á. Berta, G. Szöke, M. Dunay, T. Németh, K. Hornok, L. Marosföi, M. Réthelyi, M. Kozsurek, Z. Puskár., and Obsahuje bibliografii
Animal models are important for the investigation of mechanisms and therapeutic approaches in various human diseases, including schizophrenia. Recently, two neurodevelopmental rat models of this psychosis were developed based upon the use of subunit selective N-methyl-D-aspartate receptor agonists - quinolinic acid (QUIN) and N-acetyl-aspartyl-glutamate (NAAG). The aim of this study was to evaluate pain perception in these models. QUIN or NAAG was infused into lateral cerebral ventricles neonatally. In the adulthood, the pain perception was examined. The rats with neonatal brain lesions did not show any significant differences in acute mechanical nociception and in formalin test compared to controls. However, the neonatally lesioned rats exhibited significantly higher pain thresholds in thermal nociception. Increased levels of mechanical hyperalgesia, accompanying the sciatic nerve constriction (neuropathic pain), were also observed in lesioned rats. Although hyperalgesia was more pronounced in QUIN-treated animals, the number of c-Fos-immunoreactive neurons of the lumbar spinal cord was similar in experimental and control rats. We conclude that neonatal brain lesions attenuated the thermal perception in both nociceptive and neuropathic pain whereas mechanical pain was increased in the model of neuropathic pain only. Thus, nociceptive and neuropathic pain belongs - in addition to behavioral changes - among the parameters which are affected in described animal models of schizophrenia., M. Franěk ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy