Differential neurochemical properties of central serotonergic transmission in Roman high- and low-avoidance rats.
The selective breeding of Roman high- (RHA/Verh) and low-avoidance (RLA/Verh) rats for rapid versus poor acquisition of active avoidant behaviour has produced two behavioural phenotypes with different performances in a variety of animal models of anxiety, in which RLA/Verh rats are consistently more fearful than RHA/Verh rats. In addition, these two lines display different functional properties of brain neurotransmitters like serotonin (5-HT), known to be involved in the expression of anxiety- and depression-related behaviours. Therefore, we used brain microdialysis and [3H]-citalopram binding autoradiography to characterize further the neurochemical properties of 5-HTergic transmission in the two lines. No significant line-related differences were detected in the basal 5-HT output in the frontoparietal cortex (FPCx). In contrast, the increase in the cortical 5-HT output elicited by the systemic administration or the local application, via reverse dialysis, of chlorimipramine and fluoxetine was more robust in RHA/Verh than in RLA/Verh rats. Moreover, the binding signal of [3H]-citalopram to 5-HT re-uptake sites was more intense in the FPCx of RHA/Verh rats than in their RLA/Verh counterparts. These findings suggest that the functional tone of the 5-HTergic projection to the FPCx is stronger in the RHA/Verh line relative to the RLA/Verh line. It is proposed that RLA/Verh rats may be used as a model with heuristic value for studying the role of 5-HTergic transmission in anxiety and in the anxiolytic effects of monoamine re-uptake inhibitors.
Giorgi
O
O
Department of Toxicology, University of Cagliari, Italy. giorgi@unica.it
Piras
G
G
Lecca
D
D
Hansson
S
S
Driscoll
P
P
Corda
M G
MG
D000818:Animals; D001007:Anxiety / Q000235:genetics; D001345:Autoradiography; D001362:Avoidance Learning / Q000502:physiology*; D001522:Behavior, Animal / Q000502:physiology; D001667:Binding, Competitive / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D002490:Central Nervous System / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D015283:Citalopram / Q000493:pharmacokinetics; D002997:Clomipramine / Q000494:pharmacology; D003863:Depression / Q000235:genetics; D005473:Fluoxetine / Q000494:pharmacology; D008297:Male; D017551:Microdialysis; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism*; D017367:Selective Serotonin Reuptake Inhibitors / Q000493:pharmacokinetics; D013045:Species Specificity; D009435:Synaptic Transmission / Q000235:genetics / Q000502:physiology*; D014316:Tritium
D015283:Citalopram; D002997:Clomipramine; D005473:Fluoxetine; D012701:Serotonin; D017367:Selective Serotonin Reuptake Inhibitors; D014316:Tritium