Pharmacology, biochemistry, and behavior
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Pharmacol. Biochem. Behav. · Oct 2004
Dopaminergic mechanisms in the conditioned and unconditioned fear as assessed by the two-way avoidance and light switch-off tests.
The involvement of dopaminergic mechanisms in fear and anxiety is still unclear. Behavioral studies aimed to disclose the involvement of dopamine in anxiety have reported anxiolytic-like, anxiogenic-like and lack of effects with the use of dopaminergic agonists and antagonists in animal models of anxiety. This work was an attempt to contribute to this field by providing evidence that these discrepancies may be due to the kind of aversive situation the animals experience in these models. ⋯ Thus, blockade of D(1) and D(2) receptors may be necessary for attenuating the aversiveness triggered by these conditioned fear stimuli. In contrast, mechanisms mediated by D(2) receptors seem to be involved in the setting up of adaptive responses to innate fear reactions. Therefore, the signal of the modulatory dopaminergic mechanisms on defensive behavior will depend on the type of emotional stimuli triggering the coping reaction.