Functional diversity and developmental changes in rat neuronal kainate receptors

• Published in: The Journal of physiology Vol. 532; no. 2; pp. 411 - 421
• Main Authors: Wilding, Timothy J., Huettner, James E.
• Format: Journal Article
• Language: English
• Published: Oxford, UK The Physiological Society 15.04.2001; Blackwell Science Ltd; Blackwell Science Inc
• Subjects: Aging - metabolism; Animals; Animals, Newborn - growth & development; Animals, Newborn - metabolism; Cells, Cultured; Electric Conductivity; Embryo, Mammalian - metabolism; Excitatory Amino Acid Agonists - pharmacology; Ganglia, Spinal - cytology; Ganglia, Spinal - metabolism; Hippocampus - cytology; Hippocampus - metabolism; Isoxazoles - pharmacology; Kainic Acid - pharmacology; Neurons - drug effects; Neurons - metabolism; Neurons - physiology; Original; Propionates - pharmacology; Rats; Rats, Long-Evans; Receptors, Kainic Acid - metabolism; Spinal Cord - cytology; Spinal Cord - metabolism
• ISSN: 0022-3751; 1469-7793
• DOI: 10.1111/j.1469-7793.2001.0411f.x

Whole-cell currents evoked by kainate and the GluR5-selective agonist ( RS )-2-amino-3-(3-hydroxy-5-tertbutylisoxazol-4-yl)propanoic acid (ATPA) were used to compare the physiological properties of kainate receptors expressed by neurons from rat hippocampus, spinal cord and dorsal root ganglia. In contrast to kainate, which evoked desensitizing currents with similar decay rates and steady-state components in all three cell types, responses to ATPA were distinctly different in the three cell populations. Currents evoked by ATPA displayed a significant steady-state component in hippocampal neurons, but decayed rapidly to baseline in dorsal root ganglion (DRG) cells. ATPA failed to evoke current in many of the spinal neurons. ATPA caused steady-state desensitization in DRG cells with an IC 50 of 41 n m . Recovery from desensitization of DRG cell receptors by ATPA was significantly slower than for any previously described agonist. In contrast, hippocampal kainate receptors recovered from desensitization by ATPA within a few seconds. Half-maximal activation of kainate receptors in hippocampal neurons required 938 n m ATPA. In DRG cells treated with concanavalin A the EC 50 for ATPA was 341 n m . ATPA evoked current in embryonic hippocampal neurons but with lower amplitude relative to kainate than in cultured postnatal neurons. Collectively, these results highlight functional differences between neuronal kainate receptors that may reflect their distinct subunit composition and their diverse roles in synaptic transmission.