Effects of 4-weeks of treatment with lithium and olanzapine on long-term potentiation in hippocampal area CA1

• Published in: Neuroscience letters Vol. 524; no. 1; pp. 5 - 9
• Main Authors: Shim, Seong S., Hammonds, Michael D., Tatsuoka, Curtis, Jung Feng, I.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 22.08.2012
• Subjects: Animals; Antipsychotic Agents - pharmacology; Benzodiazepines - pharmacology; Bipolar disorder; Brain slice preparation; CA1 Region, Hippocampal - drug effects; CA1 Region, Hippocampal - physiology; Drugs; Excitatory Postsynaptic Potentials; Hippocampus; In Vitro Techniques; Lithium; Lithium Compounds - pharmacology; Long-term potentiation; Long-Term Potentiation - drug effects; Male; Nervous system; Neuroleptics; Neuroprotection; Neuroprotective Agents - pharmacology; Olanzapine; Plasticity (synaptic); Pyramidal cells; Pyramidal Cells - drug effects; Pyramidal Cells - physiology; Rats; Rats, Sprague-Dawley; Synaptic plasticity; Synaptic Transmission; Time Factors; Lithium; Olanzapine; Long-term potentiation; Hippocampus; Synaptic plasticity
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2012.06.047

► 4 weeks lithium treatment enhanced LTP of hippocampal CA1 pyramides. ► 4 weeks olanzapine treatment did not enhance LTP of hippocampal CA1 pyramides. ► 4 weeks olanzapine treatment, not lithium, enhanced I/O of CA1 hippocampal pyramides. Neuroplastic theories propose that lithium has robust neuroprotective and neurotrophic actions leading to the up-regulation of synaptic plasticity, and this action may be associated with the efficacy of lithium in the treatment of bipolar disorder. Olanzapine, an atypical antipsychotic drug, is efficacious in the treatment of bipolar disorder. It has been suggested that olanzapine may also up-regulate synaptic plasticity by its neuroprotective and neurotrophic actions, and this action may be related to antipsychotic and anti-manic effects of the drug. However, few studies have directly examined whether these drugs alter synaptic plasticity. In the present study, to examine the effects of lithium and olanzapine on synaptic plasticity, we examined the effects of chronic treatment with lithium and olanzapine on long-term potentiation (LTP) and input and output (I/O) responses of field excitatory postsynaptic potentials (fEPSP) of CA1 pyramidal cells in hippocampal slices prepared from rats administered the drugs for 4 weeks. Our results show that 4 weeks of lithium treatment magnified LTP of CA1 pyramidal cells. However, the same treatment with olanzapine did not magnify LTP of CA1 pyramidal cells. Four weeks of treatment with lithium did not alter I/O responses of CA1 pyramidal cells. However, the same treatment with olanzapine increased I/O responses of CA1 pyramidal cells. The results suggest that lithium up-regulates synaptic plasticity in the hippocampus, and olanzapine increases synaptic transmission without apparent changes in LTP in the hippocampus.