TLR4 and Parkinson disease: Moreover, a study on various PD mice models using the intra-striatal injection of neurotoxins or inflammogens, including 6-OHDA, rotenone, LPS, and poly I:C reported a significant upregulation in striatal TLR4 expression at day 28 after 6-OHDA, day four after LPS, and day 14 after poly I:C injections.