Acta Physiologica 2009; Volume 197, Supplement 672
The 60th National Congress of the Italian Physiological Society
EFFECTS OF SEROTONIN ON AMPA RECEPTOR-MEDIATED SYNAPTIC TRANSMISSION IN RAT AND MOUSE HIPPOCAMPUS: DIFFERENT ROLES OF 5-HT1A AND 5-HT7 RECEPTORS DURING DEVELOPMENT
Abstract number: P47
COSTA1 L, TROVATO2 C, MUSUMECI2 S, CATANIA2,3 MV, CIRANNA1 L
1Department of Physiological Sciences, University of Catania
2Laboratory of Neurobiology, IRCCS Oasi Maria Santissima, Troina
3Institute of Neurological Sciences, National Research Council, Catania (Italy)email@example.com
Several subtypes of serotonin (5-HT) receptors are expressed in the hippocampus and various functions of 5-HT have been hypothesised.
Using whole-cell patch clamp on either rat or mouse brain slices, we tested 5-HT effects on AMPA receptor-mediated excitatory post synaptic currents (EPSCs) evoked in CA1 pyramidal neurons by stimulation of Schaffer collaterals.
At post natal (PN) day 10-20, 5-HT reduced the amplitude of AMPA-mediated EPSCs. This effect was mimicked by the 5-HT1A agonist 8-OH PIPAT and by the mixed 5-HT1A/5-HT7 agonist 8-OH DPAT and was abolished by the 5-HT1A antagonist NAN-190. 5-HT1A agonists increased the paired-pulse facilitation (PPF) ratio, thus probably modified the synaptic release of glutamate. In contrast, at PN 7-9 8-OH DPAT enhanced AMPA-mediated EPSCs; such effect was not antagonised by NAN-190, suggesting the involvement of 5-HT7 receptors. The PPF ratio was unchanged, indicating a post-synaptic effect. Similar results were obtained from rats and mice within the same age group.
We showed that 5-HT1A and 5-HT7 receptors exert opposite effects on CA3-CA1 transmission and suggest their different role during development. The balance between 5-HT1A and 5-HT7 effects might have important consequences on hippocampal-dependent learning, as pointed out by behavioural studies. Further developments of our study may contribute to the understanding of pathologies affecting hippocampal synaptic transmission and provide new suggestions for a pharmacological treatment of developmental cognitive disorders.
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Acta Physiologica 2009; Volume 197, Supplement 672 :P47