OBJECTIVETo investigate weather there is a toll-like receptor 4 (TLR4)-mediated myeloid differentiation factor 88 (MyD88)-dependent pathway in hippocampal neurons of rats and the probable role of the pathway in neuroinflammation.

METHODSTo establish the proper model, primarily cultured hippocampal neurons were treated with lipopolysaccharides (LPS), or pretreated with TLR4 antibody then co-treated with LPS. The expression of mRNA of MyD88 and TNF-alpha receptor associated factor 6 (TRAF6) were tested by RT-qPCR. The content of MyD88 and TRAF6 were tested by Western blot. The nuclear translocation of nuclear factor-kappaB/P65 (NF-kappaB/p65) was tested by immunofluorescence. The content of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and nitric oxide (NO) were tested by ELISA.

RESULTSLPS could increase MyD88 and TRAF6 mRNA, upregulate protein level of MyD88 and TRAF6 and increase the level of TNF-alpha, IL-1beta and NO in cell culture supernatant. LPS also could promote NF-kappa B/p65 translation to the nucleus. The pretreatment with TLR4 antibody reduced the translocation to nucleus for NF-kappaB/P65 and the contents of TNF-alpha, IL-1beta and NO in the culture supernatant.

CONCLUSIONThere is a TLR4-mediated MyD88-dependent pathway in hippocampal neurons. The activation of this pathway can increase the level of TNF-alpha, IL-1beta and NO in cell culture supernatant. TLR4-mediated MyD88-dependent pathway in hippocampal neurons participate in neuroinflammation, that means neurons are not passive in inflammation.