The Role of Hippocampal 5HT3 Receptors in Harmaline-Induced Memory Deficit

introduction: the plethora of studies indicated that there is a cross talk relationship betweenharmaline and serotonergic (5-ht) system on cognitive and non-cognitive behaviors. thus,the purpose of this study is to assess the effects of hippocampal 5-ht4 receptor on memoryacquisition deficit induced by harmaline. methods: harmaline was injected peritoneally, while 5-ht4 receptor agonist (rs67333) andantagonist (rs23597-190) were injected intra-hippocampal. a single-trial step-down passiveavoidance, open field and tail flick tasks were used for measurement of memory, locomotoractivity and pain responses, respectively. results: the data revealed that pre-training injection of higher dose of harmaline (1 mg/kg),rs67333 (0.5 ng/mouse) and rs23597-190 (0.5 ng/mouse) decreased memory acquisitionprocess in the adult mice. moreover, concurrent pre-training administration of subthreshold doseof rs67333 (0.005 ng/mouse) or rs23597-190 (0.005 ng/mouse) with subthreshold dose ofharmaline (0.5 mg/kg, i.p.) intensify impairment of memory acquisition. all above interventionsdid not change locomotion and tail flick behaviors. discussion: the results demonstrated that the synergistic effect between both hippocampal5-ht4 receptor agonist and antagonist with impairment of memory acquisition induced byharmaline, indicating a modulatory effect for hippocampal 5ht4 receptor on harmaline inducedamnesia.