Intracellularly-recorded effects of glutamate and aspartate on neurones in the guinea-pig olfactory cortex slice.
The effects of bath-applied glutamate, aspartate (and some related amino acids) on neurones of the guinea pig olfactory cortex slice were recorded intracellularly. Neurones were activated either by intracellularly-applied current or orthodromically by stimulating the lateral olfactory tract. In response to orthodromic stimuli several neurones displayed a late hyperpolarizing potential (LHP) after the usual sequence of EPSP, spike and IPSP. Glutamate and aspartate evoked 3 types of response: (a) a depolarization with apparent increase in input conductance; (b) a depolarization with no detectable conductance change; and (c) a hyperpolarization with conductance increase. Some possible mechanisms by which these 3 response-types could be generated are discussed. Depolarizations evoked by the glutamate analogue, kainate, were usually irreversible. Our results emphasize that glutamate and aspartate can evoke a variety of neuronal responses from olfactory cortex neurones. Several of these responses were previously undetected in experiments based on extracellular recordings.
D000818:Animals; D001224:Aspartic Acid / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D005971:Glutamates / Q000494:pharmacology*; D006168:Guinea Pigs; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000187:drug effects; D009830:Olfactory Bulb / Q000187:drug effects*; D009833:Olfactory Pathways / Q000187:drug effects; D013569:Synapses / Q000187:drug effects; D009435:Synaptic Transmission / Q000187:drug effects; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D005971:Glutamates; D001224:Aspartic Acid; D005680:gamma-Aminobutyric Acid; D007608:Kainic Acid