The Chinese Medicine Wu-Tou Decoction Relieves Neuropathic Pain by Inhibiting Hippocampal Microglia Activation
Authors: Zhiyun Mao
Chunyan Zhu
Na Lin
Qionghong Xu
Journal: Scientific reports (2018)
Discipline: Multidisciplinary
Keywords: nociceptive; mental syndromes; neuropathic pain; Wu-Tou decoction; chronic pain
Affiliations: Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, 100700, China., Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, 100700, China. .

Abstract:  The comorbidity between the nociceptive and mental syndromes adds to the refractoriness of neuropathic pain (NP). Wu-Tou decoction (WTD) has been prescribed for chronic pain for thousands of years in China. Recently, we reported that WTD was helpful for hippocampus and co-curative for the nociceptive, depressive and anxiety behaviors in the spinal cord ligation (SNL) mice. However, the mechanism underlying the rescue of hippocampus, as well as the roles hippocampus assumed in co-curation remain unexplored. In this study, we validated that in SNL mice, the long-lasting damages to limbic system were mainly limited to hippocampus. In addition, hippocampal neurons were proven sensitive to harms induced by microglia and rescued by WTD, which in sum indicated hippocampal microglia as the critical modulator of co-curation. To validate this hypothesis the hippocampal microglia were mal-activated in shamed mice, in which the atrophy of hippocampus and the development of NP syndromes were consolidated and proven rescued by WTD. On the contrary, in the SNL mice, the failure to control hippocampal microglia was sufficient to void all the rescues mediated by WTD. In sum, our study points out that the effective modulation of microglia in hippocampus is of pivotal importance for the co-curation by WTD. 

Retracted: No

PubPeer comments:
  To clarify the brain nuclei, especially nuclei of the limbic system, responsible for the comorbidity and co-curation in NP, the morphological atrophy and remission in ACC, BLA, CA1 and CA3 were analyzed by Golgi staining (detailed data were shown in supplementary sheet 1.1u20131.5). I am not certain how many animals were involved in this study, but the Figure captions mention  n=4 mice group , which I take to be the number of animals in each group sacrificed and dissected at D=3, 7, 10, 14, 18, 21 after real or sham surgery. One would have expected the same number of neurons to be examined in each sample for quantifying dendrite length and connectiveness, but this does not appear to be the case: values of N are all over the place. Supplementary Data table 1.1:  Also, the cohorts of sham-surgery mice appear to have yielded the same distribution for all post-surgery days. This does not match the time-course plotted in Fig 1D,  the analyzations of the total length of dendrites on both the apical and basal sides of CA3.  , 
 Fig 3B compares dendrite interceptions for control mice, mice subjected to a week of daily TNFu03b1 injections into the hippocampus via implanted trocars, and mice injected and gavaged with a herbal decoction.  B) The morphological alternations of neurons in CA1 and CA3 were analyzed by Golgi staining (nu2009=u20094 mice per group, right side). The figures on the left show the imaging of the entire neurons in Sham Injection WTD groups, scale bar 100u2009u03bcm; the scatter diagrams on the right show the statistical data of the intersections ...of dendrites on both the apical and basal sides. Fig 4B compares dendrite intersections for control mice, mice subjected to spinal nerve ligation, mice with SNL and herbal decoction, and mice with SNL, decoction, and a week of daily TNFu03b1 injections into the hippocampus.  (B) The morphological alternations of neurons in CA1 and CA3 were analyzed by Golgi staining (nu2009=u20094 mice per group, right side). The figures on the left show the imaging of the entire neurons in Sham SNL WTD WTD-TNFu03b1 groups, scale bar 100u2009u03bcm; the scatter diagrams on the right show the statistical data of the intersections ... of dendrites on both the apical and basal sides.  The date after initial sham real surgery when mice were sacrificed for brain-dicing is not stated explicitly, but it appears to be D18, judging from the similarity of neuron images and dendrite-intersection profiles with the D18 panels of Fig 1B:  1B compares sham-surgery, real SNL surgery, and surgery+decoction groups of mice. I am not convinced that mice subjected to sham lumbar surgery are comparable controls for mice implanted with transcranial trocars and injections into the brain (or lumbar surgery **and** transcranial trocars) - for these dendrite quantifications, or for the behavioral indices also shown in in Figs 3 and 4. , 
 #1 Thank for your comments. (1) In this part, 4 mice were sacrificed in each group at each time point. Golgi staining is widely used to mark and analyze the morphological alternations of neurons. Actually, glia and neurons were both stained by Golgi kit, the co-localization between neuron and glia adds to the difficulty to clearly trace the whole apical and basal sides of neurons. Therefore, the number of the intact neurons marked in each ICR mouse was limited, the total neurons in each group and time point may not be same. (2) For the sham group, data shown in figures were correct, however data in the supplementary were mistaken. We would in contact with the editorial to make revision. Thanks again and best wishes. ,