Serotonin receptor binding and mRNA expression in the hippocampus of fearful amygdala-kindled rats

Department of Psychology, University of Saskatchewan, 9 Campus Drive, Saskatoon, Sask., Canada S7N 5A5.
Neuroscience Letters (Impact Factor: 2.03). 04/2006; 396(1):38-43. DOI: 10.1016/j.neulet.2005.11.005
Source: PubMed


Amygdala kindling in rats increases fear behavior. The neural correlates of this fear are not well understood. In this experiment, we investigated the relation between serotonin receptor binding and mRNA expression and fearful behavior in amygdala-kindled rats. Rats received either 100 kindling stimulations or sham stimulations, and their fear behavior was subsequently assessed in an unfamiliar open field. Then, the rats were sacrificed and 5-HT transporter binding, 5-HT1A and 5-HT2A receptor binding, and 5-HT1A mRNA expression in several brain regions was assessed. The kindled rats were significantly more fearful in the open field than the sham-stimulated rats. They also had significantly more 5-HT1A receptor binding and mRNA expression in the dentate gyrus than the sham-simulated rats, and these increases in 5-HT1A receptor binding and mRNA expression were significantly correlated to the increases in fear. There were no significant differences between the kindled and sham-stimulated rats in 5-HT transporter binding or 5-HT2A receptor binding. These results suggest that alterations in 5-HT1A receptors in the dentate gyrus may play a role in the expression of kindled fear.

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Available from: Lisa E Kalynchuk,
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    • "Serotonin receptors are distributed throughout the CNS and several receptors have been implicated in anxiety-like behavior, especially the 5HT1A receptor has received more attention [31,32]. NMDA receptors are known to play an important role in synaptic development and plasticity and are thought to be involved in anxiety-like behavior [33]. "
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    Behavioral and Brain Functions 09/2014; 10(1):30. DOI:10.1186/1744-9081-10-30 · 1.97 Impact Factor
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    • "On the contrary, in our citalopram study, we found that both kindling and citalopram increased 5-HT 1A receptors, although these effects were not apparent in the fluoxetine experiment. While this finding is not consistent with human studies of reduced hippocampal 5-HT 1A receptors in epilepsy (Hasler et al., 2007; Theodore et al., 2007), it does somewhat agree with studies using amygdala kindling (Kalynchuk et al., 2006), which showed upregulation of hippocampal 5-HT 1A receptors in the dentate gyrus. "
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    • "A further reason to consider serotonergic neurotransmission generally and the 5-HT 1A receptor in particular is that this receptor is itself strongly downregulated by corticosterone elevation (Joels and Van Riel, 2004; Lanfumey et al., 2008, p1179); and, when downregulated, disinhibits glutamatergic neurons, potentially aggravating excitotoxicity and epileptogenesis (Yuen et al., 2008). However, at this stage, the data are complex and diffi cult to reconcile; for example, in one study of electrical amygdala kindling of adult rats, raised levels of 5-HT1 A receptor binding and mRNA expression were observed in dentate gyrus (Kalynchuk et al., 2006). "
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