Rat Hippocampus, Amygdala And Prefrontal Cortex ¦Â Receptor Distribution And Memory

PartⅠ;β1-andβ2-adrenoceptors in the CA1 and CA3 subregions of the rat hippocampus and their roles in memory consolidationThe existence ofβ-adrenoceptors(ARs)in the hippocampus and the importance ofβ-ARs in regulating synaptic plasticity and learning/memory function are well documented.However,little is known about the distributions and functional roles of theβ-AR subtypes,β1-andβ2- ARs,in the hippocampus.Here,we report thatβ1-andβ2- ARs in the CA1 and CA3 regions have differential subcellular distributions and both two subtypes in the CA3 region play an important role in memory consolidation.Using double immunofluorescence labeling and confocal laser scanning microscopy,we found that almost all of the NeuN positive cells expressedβ1- andβ2-ARs,while few GFAP positive cells expressed them.Interestingly,β1-AR is predominantly distributed in cell membrane and cytoplasm,whereasβ2-AR not only in membrane and cytoplasm,but also in the nucleus.We also found that, following the contextual fear conditioning,the expression ofβ1-AR in the CA3 region significantly increased.We then locally infused theβ1- andβ2-AR antagonists into the CA3 region and observed that blockage of eitherβ1-AR orβ2-AR impaired long-term contextual fear memory and water-maze spatial memory.Taken together, the results suggest that theβ1- andβ2-ARs in the CA3 region are involved in memory consolidation. PartⅡ;β1- andβ2-adrenoceptors in the basolateral nucleus of amygdala and their roles in fear memory consolidation in ratsβ-Adrenoceptors(ARs)in the basolateral nucleus of amygdala(BLA)play an essential role in regulating synaptic plasticity and fear memory formation;as they do in the hippocampus.However,the roles ofβ1- andβ2- ARs in the BLA in memory consolidation have not been well addressed.We report thatβ1- andβ2-ARs are predominantly expressed in neurons but not in astrocytes in the BLA.β1-AR is predominantly distributed in the cell membrane and cytoplasm of neurons,whereasβ2-AR not only in the membrane and cytoplasm but also in the nucleus.We locally infused theβ1- andβ2-AR antagonists,metoprolol and ICI118551,into the BLA and observed that blockage of eitherβ1-AR orβ2-AR impaired long-term but not short-term auditory fear memory.These results suggest thatβ1- andβ2-ARs in the BLA are both required for auditory fear memory. PartⅢ;β1- andβ2-adrenoceptors in the medial prefrontal cortex and their roles in working memory in ratsNoradrenergic inputs from the locus coeruleus modulate mediate prefrontal cortical(mPFC)functions.It is well documented that NE produces its beneficial influence on working memory through action atα2-,especiallyα2A-adrenoceptors (ARs)in the PFC.However,the role of prefrontal corticalβ-AR,especially theβ1-andβ2-ARs,in working memory are poorly understood.Here,we report thatβ1- andβ2-ARs are predominantly expressed in neurons but not in astrocytes in the mPFC.β1-AR is predominantly distributed in the cell membrane and cytoplasm of neurons,whereasβ2-AR not only in the membrane and cytoplasm but also in the nucleus.We also found that intra- mPFC infusion of theβ1-AR antagonist metoprolol impaired working memory,whereas intra- mPFC infusion of theβ2- AR antagonist ICI118551 improved working memory.Thus,these results suggest thatβ1-andβ2-ARs in the mPFC play a differential role in working memory.