Abstract: Encoding of episodic memory requires long-term potentiation (LTP) of neurotransmission at excitatory synapses of the hippocampal circuitry. Previous data obtained with the application of exogenous 5-hydroxytryptamine (5-HT) in hippocampal slices indicate that 5-HT blocks LTP, which contrasts with the facilitatory effect of selective serotonin reuptake inhibitors (SSRIs) on learning and memory observed in vivo. Here, we investigated the effects of endogenous 5-HT, released from terminals by the monoamine releaser 3,4-methylenedioxymethamphetamine (MDMA), on LTP of field EPSPs induced by theta-burst stimulation and recorded at CA3/CA1 synapses of rat hippocampal slices. LTP was greater in the presence of MDMA (10 lM; 45.76 ± 15.75 %; n = 28) than in controls (31.26 ± 11.03; n = 21; p\0.01). This facilitatory effect on LTP persisted when the entry ofMDMAin noradrenergic terminals was prevented by the selective noradrenaline reuptake inhibitor nisoxetine (44.90 ± 14.07 %; n = 27 vs. 34.49 ± 12.94 %; n = 20 in controls; p\0.05). In both conditions, the facilitation of LTP was abolished by the SSRI citalopram that prevented the entry of MDMA in 5-HT terminals and the subsequent 5-HT release. These data show that, unlike exogenous 5-HT application, release of endogenous 5-HT does not impair cellular mechanisms responsible for induction of LTP, indicating that 5-HT is not detrimental to learning and memory. Moreover, facilitation of LTP by endogenous 5-HT may underlie the in vivo positive effects of augmented 5-HT tone on cognitive performance.
Endogenous serotonin facilitates hippocampal long-term potentiation at CA3/CA1 synapses / Boris Mlinar;Gabriella Stocca;Renato Corradetti. - In: JOURNAL OF NEURAL TRANSMISSION. - ISSN 0300-9564. - STAMPA. - 122:(2015), pp. 177-185. [10.1007/s00702-014-1246-7]
Endogenous serotonin facilitates hippocampal long-term potentiation at CA3/CA1 synapses
MLINAR, BORIS;STOCCA, GABRIELLA;CORRADETTI, RENATO
2015
Abstract
Abstract: Encoding of episodic memory requires long-term potentiation (LTP) of neurotransmission at excitatory synapses of the hippocampal circuitry. Previous data obtained with the application of exogenous 5-hydroxytryptamine (5-HT) in hippocampal slices indicate that 5-HT blocks LTP, which contrasts with the facilitatory effect of selective serotonin reuptake inhibitors (SSRIs) on learning and memory observed in vivo. Here, we investigated the effects of endogenous 5-HT, released from terminals by the monoamine releaser 3,4-methylenedioxymethamphetamine (MDMA), on LTP of field EPSPs induced by theta-burst stimulation and recorded at CA3/CA1 synapses of rat hippocampal slices. LTP was greater in the presence of MDMA (10 lM; 45.76 ± 15.75 %; n = 28) than in controls (31.26 ± 11.03; n = 21; p\0.01). This facilitatory effect on LTP persisted when the entry ofMDMAin noradrenergic terminals was prevented by the selective noradrenaline reuptake inhibitor nisoxetine (44.90 ± 14.07 %; n = 27 vs. 34.49 ± 12.94 %; n = 20 in controls; p\0.05). In both conditions, the facilitation of LTP was abolished by the SSRI citalopram that prevented the entry of MDMA in 5-HT terminals and the subsequent 5-HT release. These data show that, unlike exogenous 5-HT application, release of endogenous 5-HT does not impair cellular mechanisms responsible for induction of LTP, indicating that 5-HT is not detrimental to learning and memory. Moreover, facilitation of LTP by endogenous 5-HT may underlie the in vivo positive effects of augmented 5-HT tone on cognitive performance.File | Dimensione | Formato | |
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