IL6 and Parkinson disease: Overall, the main findings of the present study are that (1) IL-1β, IL-6, and TNF-α and their receptors in membrane expression are upregulated in the dl-PAG of PD rats; and (2) blocking those individual receptors in this brain region attenuates hypersensitive responses to mechanical and thermal stimuli in PD rats likely by improving impaired GABAergic descending inhibitory system.