Elevated level of the proinflammatory chemokine, RANTES/CCL5, in the periaqueductal grey causes hyperalgesia in rats

The present data provide the first in vivo evidence that the proinflammatory chemokine, Regulated on Activation Normal T cell Expressed and Secreted (RANTES/CCL5) microinjected directly into the periaqueductal grey in rats, a brain region critical to the processing of pain signals, and a primary site of action of many analgesic compounds, induced hyperalgesia. Pretreatment with Antibodies against RANTES/CCL5 prevented the hyperalgesic response, indicating that RANTES/CCL5 is able to interfere with the control of hyperalgesia at the level of the periaqueductal grey and suggesting that chemokine blockers could have analgesic properties.