Figure 5.

Effects of NO-donor and cyclic GMP (cGMP) analog on long-term memory (LTM) in aged adult crickets. One group of 1-week-old crickets and five groups of 3-week-old crickets were subjected to two sets of differential conditioning. In (A), the 1-week-old cricket group was injected with 3-μl saline into the hemolymph (a) and three groups of 3-week-old crickets were each injected with 3-μl saline alone (b), saline containing 200 μM of an NO donor, S-nitroso-n-acetyl-penicillamine (SNAP) (c), or 200 μM of a cyclic GMP (cGMP) analog, 8-bromoguanosine 3′:5′-cyclic monophosphate (8br-cGMP) (d), into the hemolymph at 20 min prior to conditioning. In (B), two groups of 3-week-old crickets were each injected with 3-μl saline containing 200-μM SNAP (a) or 200-μM 8br-cGMP (b) into the hemolymph at 20 min after conditioning. The time schedule of the experiment is shown above the figure. PIs for rewarded odor before conditioning (white bars) and 1 day after conditioning (hatched bar in 1-week-old crickets; shaded graphs in 3-week-old crickets) are shown as means ± SE. The results of statistical comparisons within each group (WCX test) or between groups (M–W test), adjusted by Holm’s method, are shown as asterisks (***p < 0.001). The number of animals tested is shown at each data point.