Different hippocampal activity profiles for PKA and PKC in spatial discrimination learning

Protein kinases are considered essential for the processing and storage of information in the brain. However, the dynamics of protein kinase activatio n in the hippocampus during spatial learning are poorly understood. In this study, rats were trained to learn a holeboard spatial discrimination task and the activity profiles for cyclic adenosine monophosphate (cAMP)-depende nt protein kinase (PKA) and Ca2+/phospholipid-dependent protein kinase C (P KC) in the hippocampus were examined. Hippocampal PKA activity increased ra pidly on Day 1 of spatial learning and remained moderately high at later st ages of acquisition. In contrast, PKC activity increased in particulate fra ctions compared with cytosolic fractions after habituation training and was maximal at Day 3 of spatial acquisition. The results establish a temporal dissociation between PKA and PKC during acquisition of spatial discriminati on learning.