Table 3.

Tertiary mediators produced by microglia to affect spinal dorsal horn neurons.

Tertiary mediator	Generated and/or released by microglia	Mimicking neuropathic pain in vivo	Alleviation of neuropathic pain in knockouts or by antagonists etc. in vivo	Demonstrated effect on spinal dorsal horn neurons
BDNF	(150, 151)	(152–154)	(150, 151, 153, 155)	(4, 143, 150, 154, 156–165)
IL-1β	(166–168)	(166, 169) (55)*	(2, 54, 57–60, 166, 170–174)	(175–179)
TNF-α	(54, 180)	(40, 181)	(84, 203, 277, 386).	(175, 182–184)

Microglia to spinal dorsal horn neurons.

^*These experiments involved injection of IL-1β into peripheral nerve, thus its ability to produce allodynia most likely reflected its peripheral role as a primary mediator.