IL6 and catalepsy: The role of pro-inflammatory cytokines in the pathogenesis of PD has been shown in several studies (12, 21, 22), although the effect of chronic administration of 5-HT1A receptor agonists on 6-OHDA-induced catalepsy and the role of cytokines such as TNF-α, IL-1β and IL-6 has not been clearly studied yet.