[Hokkaido igaku zasshi] The Hokkaido journal of medical science
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Hokkaido Igaku Zasshi · May 1993
[Effects of conditioned fear stress on monoaminergic systems in the rat brain].
The effects of conditioned fear stress (CFS), an animal model of anxiety, on brain dopamine (DA) and serotonin (5-HT) metabolism and behavior were investigated in rats. CFS (exposure to an environment paired previously with footshock) after single footshock stress increased plasma corticosterone levels and defecation, and induced freezing behavior. It also increased 3,4-dihydroxyphenylacetic acid (DOPAC) levels in the medial prefrontal cortex (mPFC), paraventricular nucleus of the hypothalamus (PVH) and lateral hypothalamus, increased homovanillic acid (HVA) levels in the mPFC and amygdala, and increased 5-hydroxyindoleacetic acid (5-HIAA) level in the mPFC. ⋯ The 5-HT synthesis inhibitor PCPA failed to change freezing. In conclusion, these results suggest that the anxiolytic effect of ipsapirone results from the activation of postsynaptic 5-HT1A receptors and the facilitation of 5-HT neurotransmission decreases anxiety. This model may be useful for detecting the anxiolytic potential for drugs and examining the relationship of 5-HT to anxiety.