title: The pharmacology of excitatory transmission in the rat olfactory cortex slice.
abstract: The pharmacology of excitatory transmission in slices of olfactory cortex of the rat, perfused with solution containing picrotoxin, has been studied by assessing the effects of cis-2,3-piperidine dicarboxylate, a nonselective antagonist of excitatory amino acid receptors, 2-amino-5-phosphonopentanoate, a selective antagonist of N-methyl-D-aspartate (NMDA) receptors and 2-amino-4-phosphonobutyrate (APB) and baclofen, which act at APB and GABAB sites, respectively, on evoked surface field potentials. Monosynaptic excitatory transmission was monitored by measuring the amplitude of the N'a'-wave, evoked on stimulation of the lateral olfactory tract, whilst di-/polysynaptic excitatory transmission was evaluated by calculating the areas of the potentials evoked on direct stimulation of the superficial and deep-lying association fibre systems. On the basis of the effects of the drugs in this and earlier studies, it is concluded that: (i) transmission at the lateral olfactory tract-pyramidal cell synapse is mediated by kainate/quisqualate but not NMDA receptors and is regulated by inhibitory APB receptors, located on the tract terminals; (ii) NMDA receptors are involved in mediating excitatory transmission at the synapses of superficial association fibres with the proximal apical dendrites of pyramidal cells with inhibitory APB receptors playing a regulatory role; (iii) transmission at synapses of association fibres with basal dendrites of pyramidal cells, is mediated in part by NMDA receptors with (presynaptic?) GABAB receptors exerting a strong inhibitory influence. These proposed roles of NMDA receptors have been confirmed in experiments in which the effects of magnesium ions on field potentials evoked in slices perfused in magnesium-free solution were monitored.
mesh_terms: D015763:2-Amino-5-phosphonovalerate; D000613:Aminobutyrates / Q000494:pharmacology; D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology; D001418:Baclofen / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects* / Q000502:physiology; D004566:Electrodes; D066298:In Vitro Techniques; D009830:Olfactory Bulb / Q000187:drug effects* / Q000502:physiology; D010875:Pipecolic Acids / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D009435:Synaptic Transmission / Q000187:drug effects*; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D000613:Aminobutyrates; D000927:Anticonvulsants; D010875:Pipecolic Acids; C029262:2,3-piperidinedicarboxylic acid; D015763:2-Amino-5-phosphonovalerate; D001418:Baclofen; C012729:2-amino-4-phosphonobutyric acid; D014633:Valine