Reversed effects of RU486 and anisomycin on memory retention of light exposure or corticosterone facilitation in the dark-incubated chicks

Memory formation for a weak passive avoidance task in the dark-incubated chicks is facilitated by lightexposure or corticosterone administration at optimally pre-hatch time points. To explore the potentialmechanisms underlying activation of brain memory function development by light or corticosteroneexposure during late embryo, steroid receptor antagonist RU486, or protein synthetic inhibitor anisomycin,was administered intraembryonically to the embryos of either only 24-h light-exposure or complete dark-hatched on embryonic day 20 (E20). The results showed that RU486 and anisomycin significantly retardedthe facilitated retention both by light and corticosterone exposure in the dark-incubated chicks. They alsosuggest that the act of corticosterone or light exposure on the development of brain memory function ismediated by the effect of steroid receptor, or afterward on related protein syntheses that is involved inmemory formation of post-hatched performance of day-old chicks.