Microglia are involved in regulating histamine-dependent and non-dependent itch transmissions with distinguished signal pathways.

Although itch and pain have many similarities, they are completely different in perceptual experience and behavioral response. In recent years, we have a deep understanding of the neural pathways of itch sensation transmission. However, there are few reports on the role of non-neuronal cells in itch. Microglia are known to play a key role in chronic neuropathic pain and acute inflammatory pain. It is still unknown whether microglia are also involved in regulating the transmission of itch sensation. In the present study, we used several kinds of transgenic mice to specifically deplete CX3CR1+ microglia and peripheral macrophages together (whole depletion), or selectively deplete microglia alone (central depletion). We observed that the acute itch responses to histamine, compound 48/80 and chloroquine were all significantly reduced in mice with either whole or central depletion. Spinal c-fos mRNA assay and further studies revealed that histamine and compound 48/80, but not chloroquine elicited primary itch signal transmission from DRG to spinal Npr1- and somatostatin-positive neurons relied on microglial CX3CL1-CX3CR1 pathway. Our results suggested that microglia were involved in multiple types of acute chemical itch transmission, while the underlying mechanisms for histamine-dependent and non-dependent itch transmission were different that the former required the CX3CL1-CX3CR1 signal pathway.

[Studies on relationship of phytoplankton and water environmental factors in Shahu Lake].

Analysis approaches of correlation, multiple stepwise regression and canonical correspondence analysis were employed between phytoplankton and water environmental factors in ShaHu Lake based on the data from Apr. 2009 to Jan. 2010. The results showed that the correlation between phytoplankton density, phytoplankton biomass, chlorophyll-a and water temperature (WT), total nitrogen (TN), total phosphorus (TP), potassium permanganate index,5 days biochemical oxygen demand (BOD5) was positive, and phytoplankton density, phytoplankton biomass, chlorophyll-a and Secchi-depth (SD) was negatively correlated. Followed by the importance of environmental factors which affected phytoplankton density in Shahu Lake ranged as follows: WT, potassium permanganate index, SD, BOD5, TP, TN. Those affected phytoplankton biomass ranged as follows: WT,TP, potassium permanganate index,SD,TN. Those affected on chlorophyll-a ranged as follows: potassium permanganate index, WT, SD, TP, TN, BOD5. CCA result showed that 16 species of phytoplankton were divided into 3 groups which had the obvious seasonal distribution characteristics in Shahu Lake. SD, potassium permanganate index,WT, TN, TP were the main water environmental factors correlated with the distribution of phytoplankton community of Shahu Lake.