- Email: [email protected]
175 The effect of dopaminergic receptors on spatial learning and rhythmic slow activity of the hippocampus
175
176
THE EFFECT OF DOPAMINERGIC RECEPTORS ON SPATIAL LEARNING AND RHYTHMIC SLOW ACTIVITY OF THE HIPPOCAMPUS
INVOLVEMENT OF MONOSIALOGANGLIOSIDE GM1 ON SPATIAL LEARNING AND LONG-TERM POTENTIATION IN RATS A.A. Moazedi, F. Motamedi, S. Semnanian and A. Hosseine Dept. of Biology, School of Science, Shahid Chamran University and Tarbiat Modarres University, Ahwaz, Iran
M. Khalili’, F. Motamedi and M. Mahdavi Dept. of Physiology, Shahed University of Medical Science, Dept. of Physiology, Shaheed Behesti University of Medical Science, Tehran, Iran
Gangliosides participates in the regulation of neurogenesis, synaptogenesis, registration and neurotransmission. In this work the behavioral and electrophysiological effects of GM1 were studied on learning. Behavioral experiments were carried out in a Y-maze based on an active avoidance task. Our results show that intraperitoneal injections of GM1 (2,5 and 10 mg/kg) into rats significantly @<0.05) increase the learning capability, compared to the control group which received saline. In electrophysiological experiments we recorded excitatory postsynaptic potentials (EPSPs) from hippocampal slices incubated with GM1 and then the level of long-term potent&ion (LTP) was calculated. Our results show that the level of LTP significantly increases with GM1 (0.01, 0.03, 0.05 and 0.08 g/I) administration in a dose-dependent manner, compared to controls incubated with artificial cerebrospinal fluid (p
In the present study the effect of dopaminergic receptor antagonist on the spatial descrimination task in an &arm radial maze as well as on the rhytmic slow activity (RSA) of the hippocampus was investigated. A pair of electrodes were implanted in the dorsal hippocampus of rats and after a week of recovery they were trained in an g-arm radial maze apparatus and RSA was recorded every day before training. The frequency of RSA and also the ratio of RSA to non-RSA were increased by the learning procedure. Injection of Dl antagonist SCH23390 (0.05 mg/kg i.p.), given on days 1,4,7 and 10, impaired acquisition and also decreased the frequency of RSA wawes and the RSA to non-RSA ratio on the injection days. The effect of postsynaptic D2 antagonist sulpiride (50 mg/kg i.p.) was the same as DI antagonist, but presynaptic D2 antagonist sulpinde (25 m&g i.p.) did not have any effect. The concurrent administration of postsynaptic Dl and D2 antagonists produced a synergistic effect in both decreasing acquisition and RSA wawes. Our data suggest that both postsynaptic Dl and D2 receptors have a role in the rhythmic slow activity of the hippocampus and in spatial learning.
177 THE EFFECTS OF CITALOPRAM ADMINISTRATION ON SPATIAL, DISCRIMINATION, REVERSAL LEAR!!NG AND EXTINCTION IN THE RAT. N. Naghhm N MaJkSSl. Phystology D Pharmacolo~ Department Pasteur lnshtute of Lran, Tehran 13163. I R IR4N In the Present study the effects of c&alopr~m a ~elechv~ serotonm reuptake &bltor on spahal learrung. reversal and estmchon were assessed III rats using a T-maze a positively reinforced spatial dtscrnnmahnn task Admimstration of citalopram (at doses of 1. 2, S and 10 mg’kg IP) 30 mmutes before tram@ each day produced dose-dependent decreases III the number of tnais to reach cntenon, errors made by ammals, and latencles to enter the chosen arm throughout spahal &scrnninahon and reversal leammg These data seem to suggest the factitatory effect of citalopram on rat performance m spahal leammg tasks
93
176
THE EFFECT OF DOPAMINERGIC RECEPTORS ON SPATIAL LEARNING AND RHYTHMIC SLOW ACTIVITY OF THE HIPPOCAMPUS
INVOLVEMENT OF MONOSIALOGANGLIOSIDE GM1 ON SPATIAL LEARNING AND LONG-TERM POTENTIATION IN RATS A.A. Moazedi, F. Motamedi, S. Semnanian and A. Hosseine Dept. of Biology, School of Science, Shahid Chamran University and Tarbiat Modarres University, Ahwaz, Iran
M. Khalili’, F. Motamedi and M. Mahdavi Dept. of Physiology, Shahed University of Medical Science, Dept. of Physiology, Shaheed Behesti University of Medical Science, Tehran, Iran
Gangliosides participates in the regulation of neurogenesis, synaptogenesis, registration and neurotransmission. In this work the behavioral and electrophysiological effects of GM1 were studied on learning. Behavioral experiments were carried out in a Y-maze based on an active avoidance task. Our results show that intraperitoneal injections of GM1 (2,5 and 10 mg/kg) into rats significantly @<0.05) increase the learning capability, compared to the control group which received saline. In electrophysiological experiments we recorded excitatory postsynaptic potentials (EPSPs) from hippocampal slices incubated with GM1 and then the level of long-term potent&ion (LTP) was calculated. Our results show that the level of LTP significantly increases with GM1 (0.01, 0.03, 0.05 and 0.08 g/I) administration in a dose-dependent manner, compared to controls incubated with artificial cerebrospinal fluid (p
In the present study the effect of dopaminergic receptor antagonist on the spatial descrimination task in an &arm radial maze as well as on the rhytmic slow activity (RSA) of the hippocampus was investigated. A pair of electrodes were implanted in the dorsal hippocampus of rats and after a week of recovery they were trained in an g-arm radial maze apparatus and RSA was recorded every day before training. The frequency of RSA and also the ratio of RSA to non-RSA were increased by the learning procedure. Injection of Dl antagonist SCH23390 (0.05 mg/kg i.p.), given on days 1,4,7 and 10, impaired acquisition and also decreased the frequency of RSA wawes and the RSA to non-RSA ratio on the injection days. The effect of postsynaptic D2 antagonist sulpiride (50 mg/kg i.p.) was the same as DI antagonist, but presynaptic D2 antagonist sulpinde (25 m&g i.p.) did not have any effect. The concurrent administration of postsynaptic Dl and D2 antagonists produced a synergistic effect in both decreasing acquisition and RSA wawes. Our data suggest that both postsynaptic Dl and D2 receptors have a role in the rhythmic slow activity of the hippocampus and in spatial learning.
177 THE EFFECTS OF CITALOPRAM ADMINISTRATION ON SPATIAL, DISCRIMINATION, REVERSAL LEAR!!NG AND EXTINCTION IN THE RAT. N. Naghhm N MaJkSSl. Phystology D Pharmacolo~ Department Pasteur lnshtute of Lran, Tehran 13163. I R IR4N In the Present study the effects of c&alopr~m a ~elechv~ serotonm reuptake &bltor on spahal learrung. reversal and estmchon were assessed III rats using a T-maze a positively reinforced spatial dtscrnnmahnn task Admimstration of citalopram (at doses of 1. 2, S and 10 mg’kg IP) 30 mmutes before tram@ each day produced dose-dependent decreases III the number of tnais to reach cntenon, errors made by ammals, and latencles to enter the chosen arm throughout spahal &scrnninahon and reversal leammg These data seem to suggest the factitatory effect of citalopram on rat performance m spahal leammg tasks
93