Modulation of Amygdala Synaptic Transmission by Metabotropic Glutamate Receptors

Modulation of Amygdala Synaptic Transmission by Metabotropic Glutamate Receptors

Metabotropic glutamate receptors (mGluRs), classified into three groups (group I, II, III), play a critical role in modulation of synaptic transmission at central and peripheral synapses. In the present study, extracellular field potential recording techniques were used to investigate effects of mGluR agonists on excitatory synaptic transmission at thalamic input synapses onto the lateral amygdala. The non-selective mGluR agonist t-ACPD (100<FONT FACE= 바탕 >μM) produced reversible, short-term depression, but the group III mGluR agonist L-AP4 (50<FONT FACE= 바탕 >μM) did not have any significant effects on amygdala synaptic transmission, suggesting that group I and/or II mGluRs are involved in the modulation by t-ACPD. The group I mGluR agonist DHPG (100<FONT FACE= 바탕 >μM) produced reversible inhibition as did t-ACPD. Unexpectedly, the group II mGluR agonist LCCG-1 (10<FONT FACE= 바탕 >μM) induced long-term as well as short-term depression. Thus, our data suggest that activation of group I or II mGluRs produces short-term, reversible depression of excitatory synaptic transmission at thalamic input synapses onto the lateral amygdala. Considering the long-term effect upon activation of group II mGluRs, lack of long-term effects upon activation of group I and II mGluRs may indicate a possible cross-talk among different groups of mGluRs.