Intrathecal lidocaine pretreatment attenuates immediate neuropathic pain by modulating Nav1.3 expression and decreasing spinal microglial activation

<p>Abstract</p> <p>Background</p> <p>Intrathecal lidocaine reverses tactile allodynia after nerve injury, but whether neuropathic pain is attenuated by intrathecal lidocaine pretreatment is uncertain.</p> <p>Methods</p> <p>Sixty six adult male Sprague-Dawley rats were divided into three treatment groups: (1) sham (Group S), which underwent removal of the L₆transverse process; (2) ligated (Group L), which underwent left L₅spinal nerve ligation (SNL); and (3) pretreated (Group P), which underwent L₅SNL and was pretreated with intrathecal 2% lidocaine (50 μl). Neuropathic pain was assessed based on behavioral responses to thermal and mechanical stimuli. Expression of sodium channels (Nav_1.3and Nav_1.8) in injured dorsal root ganglia and microglial proliferation/activation in the spinal cord were measured on post-operative days 3 (POD₃) and 7 (POD₇).</p> <p>Results</p> <p>Group L presented abnormal behavioral responses indicative of mechanical allodynia and thermal hyperalgesia, exhibited up-regulation of Nav_1.3and down-regulation of Nav_1.8, and showed increased microglial activation. Compared with ligation only, pretreatment with intrathecal lidocaine before nerve injury (Group P), as measured on POD₃, palliated both mechanical allodynia (<it>p </it>< 0.01) and thermal hyperalgesia (<it>p </it>< 0.001), attenuated Nav_1.3up-regulation (<it>p </it>= 0.003), and mitigated spinal microglial activation (<it>p </it>= 0.026) by inhibiting phosphorylation (activation) of p38 MAP kinase (<it>p </it>= 0.034). p38 activation was also suppressed on POD₇(<it>p </it>= 0.002).</p> <p>Conclusions</p> <p>Intrathecal lidocaine prior to SNL blunts the response to noxious stimuli by attenuating Nav_1.3up-regulation and suppressing activation of spinal microglia. Although its effects are limited to 3 days, intrathecal lidocaine pretreatment can alleviate acute SNL-induced neuropathic pain.</p

Brain type carnosinase in dementia: a pilot study

Research articl

Detection of methylation in promoter sequences by melting curve analysis-based semiquantitative real time PCR

<p>Abstract</p> <p>Background</p> <p>We present two melting curve analysis (MCA)-based semiquantitative real time PCR techniques to detect the promoter methylation status of genes. The first, MCA-MSP, follows the same principle as standard MSP but it is performed in a real time thermalcycler with results being visualized in a melting curve. The second, MCA-Meth, uses a single pair of primers designed with no CpGs in its sequence. These primers amplify both unmethylated and methylated sequences. In clinical applications the MSP technique has revolutionized methylation detection by simplifying the analysis to a PCR-based protocol. MCA-analysis based techniques may be able to further improve and simplify methylation analyses by reducing starting DNA amounts, by introducing an all-in-one tube reaction and by eliminating a final gel stage for visualization of the result. The current study aimed at investigating the feasibility of both MCA-MSP and MCA-Meth in the analysis of promoter methylation, and at defining potential advantages and shortcomings in comparison to currently implemented techniques, <it>i.e. </it>bisulfite sequencing and standard MSP.</p> <p>Methods</p> <p>The promoters of the <it>RASSF1A </it>(3p21.3), <it>BLU </it>(3p21.3) and <it>MGMT </it>(10q26) genes were analyzed by MCA-MSP and MCA-Meth in 13 astrocytoma samples, 6 high grade glioma cell lines and 4 neuroblastoma cell lines. The data were compared with standard MSP and validated by bisulfite sequencing.</p> <p>Results</p> <p>Both, MCA-MSP and MCA-Meth, successfully determined promoter methylation. MCA-MSP provided information similar to standard MSP analyses. However the analysis was possible in a single tube and avoided the gel stage. MCA-Meth proved to be useful in samples with intermediate methylation status, reflected by a melting curve position shift in dependence on methylation extent.</p> <p>Conclusion</p> <p>We propose MCA-MSP and MCA-Meth as alternative or supplementary techniques to MSP or bisulfite sequencing.</p