A quantitative study of the actions of excitatory amino acids and antagonists in rat hippocampal slices

Abstract

4 Similar amino acid-induced depolarizations were observed in slices of just the CA1 region or in whole slices bathed in tetrodotoxin. Isolated alvear fibres, however, were insensitive to the excitatory amino acids. 5 D-2-Amino-5-phosphonovalerate (APV, 50pM) selectively and reversibly antagonized responses induced by NMDA (apparent pA2 = 5.21). 6 Kynurenic acid (1 mM) reversibly depressed responses to the three agonists tested. The doseratios for antagonism of AMPA, kainate and quisqualate were 6.9, 5.6 and 4.6 respectively. 7 This preparation has a different sensitivity profile to agonists from those of previously reported preparations of spinal cord, neocortex and cerebellum. The greater sensitivity to NMDA may be due to the higher density of NMDA receptors in the hippocampus. The effects of the antagonists, APV and kynurenate, are similar to those found in other brain areas.

Intracerebral microdialysis combined with recording of extracellular field potential: a novel method for investigation of depolarizing drugs in vivo

“…Despite a possible difference in the electrogenesis of the recorded signal, and although the present study was performed in the striatum, the time course of NMDA-, AMPA-, kainate-and glutamate-evoked depolarizations were very similar to those recorded with cortical wedges (Harrison & Simmonds, 1985;Home & Simmonds, 1989;Urenjak, unpublished data), and hippocampal (Blake et al, 1988;Martin & Nadler, 1991) and cerebellar slices (Garthwaite et al, 1986). Simmonds, 1989;Davies et al, 1993).…”

“…The threshold concentrations and. estimated EC50 for NMDA, AMPA and glutamate were around 10-20 times higher than those previously reported with cortical (Harrison & Simmonds, 1985;Home & Simmonds, 1989) and hippocampal slices (Blake et al, 1988;Martin & Nadler, 1991). The latter difference was anticipated since the diffusion of the drugs to the tissue is limited by the dialysis membrane (see below).…”

Tyrosine Phosphatases Regulate AMPA Receptor Trafficking during Metabotropic Glutamate Receptor-Mediated Long-Term Depression

“…Grease-gap recordings were obtained from the CA1 region as described previously (Blake et al, 1988;Moult et al, 2002). Briefly, slices were placed on a glass coverslip on the surface of an inclined temperature-controlled unit (maintained at ϳ30°C).…”

Signal transduction pathways involved in the acute potentiation of NMDA responses by 1S,3R‐ACPD in rat hippocampal slices

“…Experiments were performed on 4001 m transverse hippocampal slices, obtained from adult female rats (33 ± 7 days old) by use of a grease-gap method, as described previously (Blake et al, 1988). In brief, following removal of the CA3 region, the alveus was partially dissected from the CAl region and placed under a Ag/AgCl wick electrode.…”