Two-weeks starvation caused 45% decrease in the metabolism of the Antarctic amphipod Abyssorchomene plebs. Glutamic acid (Glu) in the concentration of 10 mM increased reactions of starved animals three times, but did not change reactions of the fed ones. Two-hours exposure of both starved and fed amphipods in the kynurenic acid (Kyn) solution in the concentration of 0.1 mM blocked the reactions of the latter group for glutamic acid (Glu). The reactions of invertebrates for glutamic acid (Glu) and kynurenic acid (Kyn) are similar to the well-known antagonistic reactions in the brains of vertebrates.