Catálogo de Investigaciones | 2013-2014

151 CATÁLOGO DE INVESTIGACIONES | AÑO ACADÉMICO 2013 -2014 Developmental Decline in Modulation of Glutamatergic Synapses in Layer IV Of The Barrel Cortex by Group II Metabotropic Glutamate Receptors Previously, we demonstrated that group II mGluRs reduce glutamate release from thalamocortical synapses during early postnatal development (P7-11). To further examine the role of group II mGluRs in the modulation of somatosensory circuit, we determined whether group II mGluRs continue to modulate thalamocortical synapses until adulthood and whether these receptors also modulate intra-cortical synapses in the barrel cortex. To address these issues, we examined the effect of the group II mGluRs agonists on thalamocortial EPSCs and intra-barrel EPSCs in slices from animals of different ages (P7-53). We found that the depression of thalamocortial EPSCs by stimulation group II mGluRs rapidly declined after the second postnatal week. In contrast, adenosine continued to depress thalamocortial EPSCs via a presynaptic mechanism in young adult mice (P30- 50). Activation group II mGluRs also reduced intra-barrel EPSCs through a postsynaptic mechanism in young mice (P7-11). Similar to the thalamocortial synapses, the group II mGluRs modulation of intra-barrel excitatory synapses declined with development. In young adult animals (P30-50), group II mGluRs stimulation had little effect on intra-barrel EPSCs but did hyperpolarize the neurons. Together our results demonstrated that group II mGluRs modulate barrel cortex circuit by presynaptic and postsynaptic mechanisms depending on the source of the circuit by presynaptic and postsynaptic mechanisms depending on the source of the synapse and that this modulation declines with development. This work was supported by National Institutes of Health Grant S06 GM08239 TO J.T.P. AND Z.M was supported by National Institutes of Health Grant F34 GM070406. dra. zaira mateo mayol colegio de ciencias dr. james porter ponce school of medicine and health sciences barrel cortex metabotropic glutamate receptors development