The effect of intrahippocampal injections of ritanserin (5HT2A/2C antagonist) and granisetron (5HT3 antagonist) on learning as assessed in the spatial version of the water maze.
5HT(2A/2C) and 5HT(3) receptors have an important role in cognitive behavior specially in spatial learning and memory but the literature concerning the role of these receptors in hippocampus in cognition remains controversial. In the present study a 5HT(2A/2C) antagonist ritanserin (0, 2, 4, 8 microg/0.5 microl) and a 5HT(3) antagonist granisetron (0.0, 0.05, 0.25, 0.5 microg/0.5 microl) were injected bilaterally into the CA1 region of rat hippocampus, 20 min before each training session in Morris Water Maze (MWM) task. Compare with control group, ritanserin (4 microg/0.5 microl) significantly reduced the escape latency and traveled distance of swimming to platform, but granisetron (0.25 microg/0.5 microl) significantly increased those parameters. Both drugs had no effect on escape latency and traveled distance of a non-spatial visual discrimination task. These results suggest a differential role of 5HT(2A/2C) and 5HT(3) receptors during spatial learning that ritanserin improves rat performance in spatial discrimination task whereas granisetron impairs it.
Naghdi
Nasser
N
Department of Physiology and Pharmacology, Pasteur Institute of Iran, Pasteur Ave., Tehran 13164, Iran. naghdi@institute.pasteur.ac.ir
Harooni
Hooman E
HE
D000704:Analysis of Variance; D000818:Animals; D004924:Escape Reaction / Q000187:drug effects; D017829:Granisetron / Q000008:administration & dosage*; D006624:Hippocampus / Q000187:drug effects*; D008297:Male; D018782:Maze Learning / Q000187:drug effects*; D008845:Microinjections; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects; D016713:Ritanserin / Q000008:administration & dosage*; D058830:Serotonin 5-HT2 Receptor Antagonists; D058831:Serotonin 5-HT3 Receptor Antagonists; D012702:Serotonin Antagonists / Q000008:administration & dosage*; D013037:Spatial Behavior / Q000187:drug effects; D013550:Swimming
D017829:Granisetron; D016713:Ritanserin; D058830:Serotonin 5-HT2 Receptor Antagonists; D058831:Serotonin 5-HT3 Receptor Antagonists; D012702:Serotonin Antagonists