Different signal transduction cascades are activated simultaneously in the rat insular cortex and hippocampus following novel taste learning.
Novel taste learning is a robust one-trial incidental learning process, dependent on functional activity of the insular (taste) cortex. In contrast to that of the cortex, the role of the hippocampus in taste learning is controversial. We set out to identify the time courses of the activation of mitogen-associated protein kinase (MAPK), transcription factor cAMP-response element-binding protein (CREB) and Akt/PKB (protein kinase B) in the insular cortex and hippocampus of rats subsequent to novel taste learning. Following taste learning, an early response (20 min) occurred at the same time in the insular cortex and the hippocampus. However, whereas MAPK was activated specifically in the insular cortex, CREB and Akt were phosphorylated in the hippocampus but not in the cortex. In addition, the immediate early gene, CCAAT/enhancer binding protein (C/EBPbeta) was induced in both the hippocampus and the insular cortex 18 h following taste learning. The results demonstrate, for the first time, correlative activation and gene expression in the hippocampus following novel taste learning. Moreover, the results suggest that different signal transduction cascades necessary for taste learning are activated in concert in different brain structures, to enable taste learning and consolidation.
Yefet
Keren
K
Department for Neurobiology and Ethology, Center for Brain and Behaviour, University of Haifa, Haifa 31905, Israel.
Merhav
Maayan
M
Kuulmann-Vander
Shelly
S
Elkobi
Alina
A
Belelovsky
Katya
K
Jacobson-Pick
Shlomit
S
Meiri
Noam
N
Rosenblum
Kobi
K
D000818:Animals; D001522:Behavior, Animal; D050882:CREB-Binding Protein / Q000235:genetics / Q000378:metabolism; D002540:Cerebral Cortex / Q000502:physiology*; D004789:Enzyme Activation / Q000502:physiology; D006624:Hippocampus / Q000502:physiology*; D007858:Learning / Q000502:physiology*; D008297:Male; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism; D051058:Oncogene Protein v-akt / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012439:Saccharin / Q000008:administration & dosage; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013549:Sweetening Agents / Q000008:administration & dosage; D013649:Taste / Q000502:physiology*
D012333:RNA, Messenger; D013549:Sweetening Agents; D012694:Serine; D050882:CREB-Binding Protein; C494365:Crebbp protein, rat; D051058:Oncogene Protein v-akt; D020929:Mitogen-Activated Protein Kinase Kinases; D012439:Saccharin