FURTHER SUPPORT FOR NITRIC OXIDE-DEPENDENT MEMORY PROCESSING IN THE DAY-OLD CHICK

There is considerable evidence that nitric oxide activity is essential for memory formation, particularly from studies using inhibitors of n itric oxide synthase. The particular stage of memory formation requiri ng nitric oxide activity has not, however, been systematically investi gated. In the current experiments, day-old black Australorp-white Legh orn chicks were trained on a passive avoidance task. Intracranial inje ctions of the nitric oxide synthase inhibitor, L-N-G-nitroarginine met hylester (0.5 mM), were found to inhibit memory formation shortly afte r training, when injected pre-or posttraining. This effect was replica ted with a second inhibitor, L-N-G-nitroarginine (1 mM), and counterac ted by the NO donor, sodium nitroprusside (150 mu M). These findings p rovide covergent evidence that nitric oxide activity plays a critical role in the consolidation of memory in the day-old chick. (C) 1998 Aca demic Press.