Figure 3.

The migration of microglial cells in response to NRG1 is a true chemotactic response. In a Boyden chamber, microglial cells migrate from an upper to a lower well through a polycarbonate filter in response to a concentration gradient of the putative chemotactic agent. A checkerboard analysis of three independent experiments assessing the chemotactic response to NRG1 performed in triplicate and normalized to the unstimulated control is shown. Microglial cells were suspended in medium alone or with 0.1, 1, or 10 nm NRG1 and then allowed to migrate for 3 h at 37°C toward different concentrations of NRG1 in the lower compartments. Highlighted in gray boxes are the results achieved by using the same concentration of NRG1 in upper and lower wells. Note that in this circumstance NRG1 increases microglial migration, indicating chemokinesis. When there is an increasing concentration gradient from the upper to the lower well (values in gray), migration is clearly enhanced, indicating a true chemotactic response. *p < 0.05 for migration across a gradient vs migration when the NRG1 concentration is the same in both wells. Numbers represent the mean ± SEM.