Cholinergic modulation of pavlovian fear conditioning in rats: Differential effects of intrahippocampal infusion of mecamylamine and methyllycaconitine
| Autor: | Raymond P. Kesner, David R. Vago |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Male
Microinjections Aconitine Cognitive Neuroscience Conditioning Classical Hippocampus Experimental and Cognitive Psychology Nicotinic Antagonists Mecamylamine Receptors Nicotinic Article Nicotine Behavioral Neuroscience chemistry.chemical_compound medicine Animals Rats Long-Evans Fear conditioning Nicotinic Antagonist Methyllycaconitine Classical conditioning Fear Rats Nicotinic agonist Cholinergic Fibers chemistry Psychology Neuroscience medicine.drug |
| Zdroj: | Neurobiology of Learning and Memory. 87:441-449 |
| ISSN: | 1074-7427 |
| Popis: | The cholinergic system has consistently been implicated in Pavlovian fear conditioning. Considerable work has been done to localize specific nicotinic receptor subtypes in the hippocampus and determine their functional importance; however, the specific function of many of these subtypes has yet to be determined. An α7 nicotinic antagonist methyllycaconitine (MLA) (35 μg), and a broad spectrum non-α7 nicotinic antagonist mecamylamine (35 μg) was injected directly into the dorsal hippocampus or overlying cortex either 15 minutes pre-, 1 minute post-, or 6 hours post-fear conditioning. One week after conditioning, retention of contextual and cue (tone) conditioning were assessed. A significant impairment in retention of contextual fear was observed when mecamylamine was injected 15 minutes pre- and 1 minute post-conditioning. No significant impairment was observed when mecamylamine was injected 6 hours post-conditioning. Likewise, a significant impairment in retention of contextual fear was observed when MLA was injected 1 minute post-conditioning; however, in contrast, MLA did not show any significant impairments when injected 15 minutes pre-conditioning, but did show a significant impairment when injected 6 hours post-conditioning. There were no significant impairments observed when either drug was injected into overlying cortex. No significant impairments were observed in cue conditioning for either drug. In general, specific temporal dynamics involved in nicotinic receptor function were found relative to time of receptor dysfunction. The results indicate that the greatest deficits in long-term retention (1 week) of contextual fear are produced by central infusion of MLA minutes to hours post-conditioning or mecamylamine within minutes of conditioning. |
| Databáze: | OpenAIRE |
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