| Light deprivation improves melatonin related suppression of hippocampal plasticity. | |
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MedLine Citation:
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PMID: 19475653 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In early postnatal life, sensory inputs deeply influence development as well as function of the brain. Plasticity of synaptic transmission including its experimentally induced form, long-term potentiation (LTP), is affected by sensory deprivation in neocortex. This study is devoted to assess if dark rearing and a dark phase synthesized hormone melatonin influence LTP in the hippocampus, an area of brain involved in learning and memory. In vivo experiments were carried out on two groups of 45-days-old male Wistar rats kept in standard 12-h light/dark condition [light reared (LR) tested during the light phase] or in complete darkness [dark reared (DR)] since birth to testing. Each group, in turn, was divided to two, vehicle- and melatonin-treated, groups. Stimulating the Schaffer collaterals of CA3 area of hippocampus extracellular postsynaptic potentials (EPSPs) were recorded in the CA1 area. Having the stable baseline responses to the test pulses, the hippocampus was perfused by either vehicle or 2 microg melatonin and EPSPs were recorded for 30 min. Then, for induction of LTP, the tetanus was applied to the Schaffer collaterals and the field potentials were pooled for 120-min post-tetanus. The light deprivation resulted in a significant augmentation in the amplitude of baseline responses. Also, we observed a melatonin-induced increase in amplitude of the baseline recordings in either LR or DR animals. Tetanic stimulation elicited LTP of EPSPs in both LR and DR groups, robustly in the former where it lasted for about 90 min. Generally, melatonin inhibited the production of LTP in the two groups especially in the LR animals leading to a noticeable depression. We concluded that higher level of neuronal activity in the DR rats gives rise to a lower level of LTP. Weaker effect of melatonin on blocking the potentiation of post-tetanus EPSPs in the DR rats may be the result of a desensitization of melatonin receptors due to chronically increased levels of this hormone in the visually deprived rats. |
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Authors:
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Sayyed Alireza Talaei; Vahid Sheibani; Mahmoud Salami |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Hippocampus Volume: 20 ISSN: 1098-1063 ISO Abbreviation: Hippocampus Publication Date: 2010 Mar |
Date Detail:
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Created Date: 2010-03-02 Completed Date: 2010-06-14 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9108167 Medline TA: Hippocampus Country: United States |
Other Details:
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Languages: eng Pagination: 447-55 Citation Subset: IM |
Affiliation:
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Physiology Research Center, Kashan University of Medical Sciences, Kashan, I. R. Iran. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Action Potentials
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drug effects,
physiology Animals Axons / drug effects, physiology CA1 Region, Hippocampal / drug effects, physiology CA3 Region, Hippocampal / drug effects, physiology Circadian Rhythm / physiology* Darkness* Electric Stimulation Excitatory Postsynaptic Potentials / drug effects, physiology Hippocampus / drug effects, physiology* Light Long-Term Potentiation / drug effects, physiology Male Melatonin / pharmacology, physiology*, secretion Neural Inhibition / drug effects, physiology Neural Pathways / drug effects, physiology Neuronal Plasticity / drug effects, physiology* Photic Stimulation* Rats Rats, Wistar |
| Chemical | |
Reg. No./Substance:
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73-31-4/Melatonin |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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