TACR1 and central nervous system cancer: However, ketamine, a parenteral anesthetic drug, acts as a competitive antagonist of the excitatory neurotransmitter N-methyl-D-aspartate receptor and antagonizes SP functions by binding to the NK-1R of glioma cells by inhibiting the synthesis of IL-6 and IL-8 in U-373 MG glioma cells through the suppression of the phosphorylation of several signaling molecules such as NF-κB, p38MAPK, and p42/44 MAPK [72].