Seena Mathew - Published Work
KAINATE RECEPTORS MODULATE INHIBITORY SYNAPTIC TRANSMISSION IN RAT NEOCORTEX
by S.Mathew; J.Hablitz
Previous studies of kainate receptors (KARs) in the hippocampus have described both facilitatory and inhibitory effects on GABAergic synapses. The present experiments examined possible modulatory effects of KARs in neocortical layer II/III pyramidal cells. Using whole-cell voltage-clamp recordings from identified pyramidal cells, the effect of KAR agonists on evoked and spontaneous inhibitory postsynaptic currents (IPSCs) was examined.
Neocortical slices (300 um) were prepared from 21-25 day old rats. After obtaining stable whole cell recordings from layer II/III pyramidal neurons, using a CsCl-based intracellular solution, spontaneous and miniature IPSCs were recorded in the presence of excitatory amino acid receptor blockers. KA (250nM) was applied for 5 min and effects assessed. The ability of the KA antagonist LY382884 to block KA effects was also examined.
At low concentrations (250 nM) KA significantly increased the frequency of spontaneous IPSCs, from 14.6 11 to 29.8 19 Hz (n = 5). Amplitudes were not affected (57 16 versus 71 27 pA). When miniature IPSCs were recorded in the presence of TTX, their frequency was also increased by KA (1.0 1.6 vs 1.99 .3 Hz) with no significant effect on amplitude (25 17 vs 32.9 22 pA, n = 5). KA effects on spontaneous and mIPSCs were blocked by the KAR antagonist LY382884.
These results demonstrate the existence of KARs on GABAergic neurons in the rat neocortex. Activation of these receptors can facilitate inhibitory inputs to pyramidal cells.
Source: S. Mathew, J. Hablitz. KAINATE RECEPTORS MODULATE INHIBITORY SYNAPTIC TRANSMISSION IN RAT NEOCORTEX. Program No. 803.10. 2003 Washington, DC: Society for Neuroscience, 2003.