Using extracellular recording techniques in the CA1 region of the rat hippocampus, we have evaluated the effects of the redox reagents 5,5O-dithiobis-2-nitrobenzoic acid (DTNB) and tris (carboxyethyl) phosphine (TCEP) on long-term potentiation (LTP) expressed by alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptors. In physiological conditions a high-frequency stimulation (HFS) of Schaffer collateral-commissural fibers induced a LTP expressed by a persistent increase (73 +/- 13%, mean +/- SE, n = 8/10) of AMPA field potentials (LTPA). In the presence of 10 microM of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and reduced concentration of Mg2+ (0.1 mM) to boost NMDA receptors, the HFS induced LTP of NMDA field potentials (LTPN; 62 +/- 11%, n = 8/10). 2. The thiol-oxidizing reagent DTNB (200 microM) reduced, by 46 +/- 5% (n = 24), NMDA-receptor field potentials (NMDA-FP), and this effect could not be reversed by extensive washing. The disulfide-reducing agent TCEP (200 microM) slightly increased AMPA-FP and reversed the DTNB-induced inhibition of NMDA-FP. 3. DTNB (200 microM, 10 min), and TCEP (200 microM, 20 min), had no effect on AMPA-FP (98 +/- 3% and 101 +/- 5%, respectively, n = 12). 4. DTNB (200 microM, 15 min) did not prevent the induction or expression of LTPA (-12 and -5%, respectively, n = 8/8). Similar results were observed with TCEP (200 microM, 20 min).(ABSTRACT TRUNCATED AT 250 WORDS)
