Differential effects of protein kinase inhibitors and activators on memory formation in the 2-day-old chick

Thirteen protein kinase inhibitors (PKIs) were investigated in chicks for their in vitro effects on PKC activity and for their in vivo effects on memory formation for a peck-avoidance task. Amnesia occurred by 15–30 min post-training when agents that inhibit primarily Ca²⁺/calmodulin were injected into brain. Amnesia occurred by 60 min post-training when agents that inhibit PKC-,PKA-, and/or PKG-dependent protein kinases, but not Ca²⁺/calmodulin, were injected. Enhancement of memory formation was accomplished by injecting bradykinin, but not forskolin. Both of these agents, however, attenuated the amnesia produced by H-7. These results are discussed as relevant neural processes involved in memory and synaptic plasticity.