Role Of β1- And β2-adrenoceptors In Long-term Potentiation In Hippocampal CA1 Region Of Rats

The hippocampus plays a critical role in learning and memory.Long-term potentiation(LTP)of synaptic transmission in the hippocampus is regarded as the synaptic mechanism for learning and memory.β-Adrenoceptors(β-ARs)are widely distributed in the hippocampus.Previous study in our laboratory showed that,in the CA1 and CA3 regions,β1-ARs are predominately distributed in the cell membrane and cytoplasm of neurons,whereasβ2-ARs not only in the membrane and cytoplasm, but in the nucleus as well.The unique distribution ofβ2-ARs may have functional significance.In the present work,we investigated the regulations byβ1-andβ2-ARs of long term potentiation(LTP)in the CA1 region,using in vivo field potential recording.We found that,intra-CA1 infusion of theβ1-AR agonist dobutamine(10μg/μl,1μl)significantly enhanced LTP,while similar treatment with theβ2-AR agonist clenbuterol(10 ng/μl and 100ng/μl,1μl)significantly inhibited the late phase LTP(L-LTP),with the early phase LTP intact.This inhibitory effect was blocked in the presence of theβ2-AR antagonist ICI118551.The present results suggest thatβ1-andβ2-ARs in the CA1 region might play differential roles in LTP.