The suppression of long-term potentiation in rat hippocampus by inhibitors of nitric oxide synthase is temperature and age dependent

Abstract

At room temperature (23°C–25°C), the induction of long-term potentiation (LTP) in area CA1 of slices from young male Sprague-Dawley rats was depressed by preincubation with the nitric oxide synthase inhibitors N G-nitro- l-arginine ( l-NA, 100 μM) and N G-nitro- l-arginine methyl ester ( l-NAME, 100 μM). The d isomers were ineffective under the same conditions. Hemoglobin (20 μM) reduced but did not completely block LTP. Neither l-NA (at concentrations up to 1 mM) nor hemoglobin (20 μM) had any significant effect on LTP in slices from adult rats at room temperature, or in young rats at 29°C–30°C. These results suggest that nitric oxide is unlikely to play a role in the induction of LTP under physiological conditions.