Browsing by Subject "Hippocampus"

Kainate receptors (KARs) act as prominent regulators of neuronal excitability, network activity as well as neurotransmitter release in the developing brain. In the neonatal hippocampus the GluK1 subunit containing KARs take part in regulating the activity of the CA3 interneurons and hence the maintenance of early synchronous network oscillations, which are thought to be vital for developing connections. In the interneurons of the CA3 subfield this regulatory activity is likely performed through a noncanonical, G-protein mediated inhibition of a Ca2+ sensitive medium-duration afterhyperpolarizing current (ImAHP). As in various central neurons the ImAHP has been shown to be regulated by voltage-gated calcium channels (VGCCs) and as the activity of the voltage-gated calcium channels has been in turn shown to be modulated by G-protein coupled signaling of GluK1 KARs, we went on to investigate whether a direct link between GluK1 KARs and VGCCs could be detected in the CA3 stratum radiatum interneurons of neonatal hippocampus. Here we show that the pharmacological inhibition of GluK1 KARs does not affect the amplitude of Ca2+ influx through VGCCs in the CA3 stratum radiatum interneurons of acute hippocampal slices from neonatal mice. As G-protein mediated signaling has been shown to induce alterations in the voltage-dependence of the VGCC-mediated currents, we similarly investigated the effects of GluK1 inhibition on the current-voltage relationship of Ca2+ currents in CA3 interneurons during the first postnatal week as well as during the second postnatal week, since GluK1 subunit is known to undergo developmental changes in its expression during this time. No significant effect was however detected in either of the age groups. Although in our experiments the GluK1-KAR inhibition seemed to induce no statistically significant changes in the Ca2+ current amplitudes or in the voltage-dependence of VGCC-mediated currents in the CA3 interneurons, further, more specific studies should be encouraged to investigate the phenomenon in specific interneuron subtypes and in distinct calcium channel families.