Effects of zaprinast and rolipram on olfactory and visual memory in the social transmission of food preference and novel object recognition tests in mice

Abstract

The role of phosphodiesterase (PDE) inhibitors in central nervous system has been investigated and shown to stimulate neuronal functions and increase neurogenesis in Alzheimer patients. The aim of this study is to investigate effect of PDE5 inhibitor zaprinast and PDE4 inhibitor rolipram on visual memory in novel object recognition (NOR) test, on olfactory memory in social transmission of food preference (STFP) test, and also on locomotion and anxiety in open field test in naive mice. Male Balb-c mice were treated intraperitoneally (i.p.) with zaprinast (3 and 10 mg/kg), rolipram (0.05 and 0.1 mg/kg), or physiological saline. Zaprinast (10 mg/kg) significantly increased cued/non-cued food eaten compared to control group, while rolipram had a partial effect on retention trial of STFP test. Zaprinast (10 mg/kg) and rolipram (0.05 and 0.1 mg/kg) significantly increased ratio index (RI) compared to control group in retention trial of NOR test. There was no significant effect of zaprinast and rolipram on total distance moved, speed, and center zone duration in open field test. Results of this study revealed that both zaprinast and rolipram enhanced visual memory in NOR test, however zaprinast exerted a significant memory-enhancing effect compared to rolipram in STFP test in mice.

Keywords: memory; mice; open field test; rolipram; zaprinast.

Figure 1

Effect of zaprinast (3 and 10 mg/kg) and rolipram (0.05 and 0.1 mg/kg) (n = 6) on (A) percentage of cued per non-cued food eaten and (B) total food consumption (in which zaprinast and rolipram were administered 60 and 30 minutes, respectively, before the retention trial) in the STFP test in mice. The data are expressed as the mean ± SEM values of animals. Note: *P < 0.05 compared to control group.

Figure 2

Effect of zaprinast (3 and 10 mg/kg) and rolipram (0.05 and 0.1 mg/kg) on RI (n = 6) (in which zaprinast and rolipram were administered 60 and 30 minutes, respectively, before the retention trial) in the NOR test in mice. The data are expressed as the mean ± SEM values of animals. Notes: *P < 0.05, **P < 0.001 compared to control group.

Figure 3

Effect of zaprinast (3 and 10 mg/kg) and rolipram (0.05 and 0.1 mg/kg) (n = 6) administration on locomotion and anxiety in the open field test. Drugs were injected 60 and 30 minutes, respectively, before testing. The data are expressed as the mean ± SEM values. (A) Total distance moved, (B) speed, and (C) center zone duration in the open field test.