Local 5,7-dihydroxytryptamine lesions of rat amygdala: release of punished drinking, unaffected plus-maze behavior and ethanol consumption.
Several serotonergic drugs are effective for anxiety disorders, but underlying mechanisms are unclear, and findings in experimental animals are difficult to reconcile with human data. It has been proposed that differential effects of serotonin within specific anatomical systems may account for these difficulties, and the amygdala has been suggested as one of the structures involved. To examine this hypothesis, the neurotoxin 5,7-dihydroxytryptamine was administered locally in rat amygdala. Within the amygdala, serotonin was depleted by approximately 80%, with other transmitters unaffected, and serotonin transporter labelling was decreased by approximately 85%. Cortical areas near the lesion site were also affected, although to a lesser degree. Other forebrain areas were unaffected. Lesions resulted in a specific anti-conflict effect in a punished drinking test, but did not influence elevated plus-maze behavior (under baseline conditions and after restraint stress), locomotor activity or ethanol intake. These data suggest that the punished drinking test and the elevated plus-maze may activate different components of fear circuitry, and that the serotonergic input to the amygdala specifically participates in fear-related behavioral suppression mediated by this structure.
Sommer
W
W
Addiction Centre South, Dept of NEUROTEC, Karolinska Institute, Stockholm, Sweden. wolfgang.sommer@neurotec.ki.se
Möller
C
C
Wiklund
L
L
Thorsell
A
A
Rimondini
R
R
Nissbrandt
H
H
Heilig
M
M
D015116:5,7-Dihydroxytryptamine / Q000008:administration & dosage*; D000679:Amygdala / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D000818:Animals; D001345:Autoradiography; D001362:Avoidance Learning / Q000187:drug effects*; D001522:Behavior, Animal / Q000187:drug effects; D001667:Binding, Competitive; D002352:Carrier Proteins / Q000378:metabolism; D002755:Choice Behavior / Q000187:drug effects*; D015283:Citalopram / Q000378:metabolism; D004327:Drinking Behavior / Q000187:drug effects*; D000431:Ethanol / Q000494:pharmacology; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008297:Male; D018782:Maze Learning / Q000187:drug effects*; D008562:Membrane Glycoproteins / Q000378:metabolism; D026901:Membrane Transport Proteins; D008845:Microinjections; D009043:Motor Activity / Q000187:drug effects; D009419:Nerve Tissue Proteins; D018377:Neurotransmitter Agents / Q000378:metabolism; D011678:Punishment; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism; D018490:Serotonin Agents / Q000008:administration & dosage; D050486:Serotonin Plasma Membrane Transport Proteins
D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D018377:Neurotransmitter Agents; D018490:Serotonin Agents; D050486:Serotonin Plasma Membrane Transport Proteins; C493232:Slc6a4 protein, rat; D015283:Citalopram; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D000431:Ethanol; D006897:Hydroxyindoleacetic Acid