Evidence that conditioned stress enhances outflow of dopamine in rat prefrontal cortex: A search for the influence of diazepam and 5-HT1A agonists
✍ Scribed by Krzysztof Wedzony; Marzena Mackowiak; Katarzyna Fijal; Krystyna Golembiowska
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 974 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0887-4476
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✦ Synopsis
We evaluated the impact of conditioned stress on outflow of dopamine in the rat prefrontal cortex. Exposure of rats to a n environment associated with aversive stimuli-foot shock enhanced outflow of dopamine in a similar way as seen during the conditioning session when foot shocks were applied. Diazepam (2.5 and 10 mgkg) dosedependently decreased outflow of dopamine and, when given in a dose of 10 mgkg, but not 2.5 mgkg, decreased enhanced dopamine outflow evoked by conditioned stress. On the other hand, ipsapirone (10 mgkg, but not 2.5 mgkg) and buspirone (2.5 mgkg) enhanced basal outflow of dopamine. When ipsapirone (10 mgkg) and buspirone (2.5 mgkg) were given to rats exposed to conditioned stress, the stress-evoked elevation in dopamine outflow was abolished. Ipsapirone in a dose of 2.5 m g k g was ineffective in the stress paradigm tested. It is concluded that conditioned stress in vivo enhances dopaminergic neurotransmission in the rat prefrontal cortex, this effect being attenuated by diazepam, a classic anxiolytic drug, and by such novel anxiolytics as ipsapirone and buspirone, which operate via serotonergic 5-HTIA receptors. Although ipsapirone and buspirone blocked stress-induced enhancement of dopamine outflow, this effect seems to result from their influence on the basal outflow of dopamine. Differential effects of diazepam and 5-HTIA agonists on basal and stress-induced alterations in dopamine outflow are discussed in terms of their possible effectiveness in various types of general anxiety disorders. o 1996 Wiley-Liss, Inc.