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Role of dopamine receptors in the ventral tegmental area in conditioned fear.
Behav Brain Res 2009; 199(2):271-7BB

Abstract

The increased startle reflex in the presence of a stimulus that has been previously paired with footshock has been termed fear-potentiated startle (FPS) and is considered a reliable index of anxiety. Some studies have suggested an association between stressful situations and alterations in dopaminergic (DA) transmission. Many studies converge on the hypothesis that the mesocorticolimbic pathway, originating from DA neurons in the ventral tegmental area (VTA), is particularly sensitive to fear-arousing stimuli. The present study explored the involvement of VTA DA receptors in the acquisition and expression of conditioned fear to a light conditioned stimulus (CS). We evaluated the effects of intra-VTA administration of SKF 38393 (D(1) agonist), SCH 23390 (D(1) antagonist), quinpirole (D(2) agonist), and sulpiride (D(2) antagonist) on FPS. All drugs were administered bilaterally into the VTA (1.0 microg/0.2 microl/site). Locomotor activity/exploration and motor coordination were evaluated in the open-field and rotarod tests. None of the drugs produced significant effects on FPS when injected before conditioning, indicating that VTA DA receptors are not involved in the acquisition of conditioned fear to a light-CS. In contrast, when injected before the test session, quinpirole significantly reduced FPS, whereas the other drugs had no effect. Quinpirole's ability to decrease FPS may be the result of an action on VTA D(2) presynaptic autoreceptors that decrease dopamine levels in terminal fields of the mesocorticolimbic pathway. Altogether, the present results suggest the importance of VTA DA neurons in the fear-activating effects of Pavlovian conditioning. In addition to demonstrating the importance of dopaminergic mechanisms in the motivational consequences of footshock, the present findings also indicate that these neural circuits are mainly involved in the expression, rather than acquisition, of conditioned fear.

Authors+Show Affiliations

Laboratório de Psicobiologia, FFCLRP-USP, Ribeirão Preto, SP, Brazil.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19111792

Citation

de Oliveira, Amanda Ribeiro, et al. "Role of Dopamine Receptors in the Ventral Tegmental Area in Conditioned Fear." Behavioural Brain Research, vol. 199, no. 2, 2009, pp. 271-7.
de Oliveira AR, Reimer AE, Brandão ML. Role of dopamine receptors in the ventral tegmental area in conditioned fear. Behav Brain Res. 2009;199(2):271-7.
de Oliveira, A. R., Reimer, A. E., & Brandão, M. L. (2009). Role of dopamine receptors in the ventral tegmental area in conditioned fear. Behavioural Brain Research, 199(2), pp. 271-7. doi:10.1016/j.bbr.2008.12.004.
de Oliveira AR, Reimer AE, Brandão ML. Role of Dopamine Receptors in the Ventral Tegmental Area in Conditioned Fear. Behav Brain Res. 2009 May 16;199(2):271-7. PubMed PMID: 19111792.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Role of dopamine receptors in the ventral tegmental area in conditioned fear. AU - de Oliveira,Amanda Ribeiro, AU - Reimer,Adriano Edgar, AU - Brandão,Marcus Lira, Y1 - 2008/12/07/ PY - 2008/11/03/received PY - 2008/11/29/revised PY - 2008/12/02/accepted PY - 2008/12/30/entrez PY - 2008/12/30/pubmed PY - 2009/5/20/medline SP - 271 EP - 7 JF - Behavioural brain research JO - Behav. Brain Res. VL - 199 IS - 2 N2 - The increased startle reflex in the presence of a stimulus that has been previously paired with footshock has been termed fear-potentiated startle (FPS) and is considered a reliable index of anxiety. Some studies have suggested an association between stressful situations and alterations in dopaminergic (DA) transmission. Many studies converge on the hypothesis that the mesocorticolimbic pathway, originating from DA neurons in the ventral tegmental area (VTA), is particularly sensitive to fear-arousing stimuli. The present study explored the involvement of VTA DA receptors in the acquisition and expression of conditioned fear to a light conditioned stimulus (CS). We evaluated the effects of intra-VTA administration of SKF 38393 (D(1) agonist), SCH 23390 (D(1) antagonist), quinpirole (D(2) agonist), and sulpiride (D(2) antagonist) on FPS. All drugs were administered bilaterally into the VTA (1.0 microg/0.2 microl/site). Locomotor activity/exploration and motor coordination were evaluated in the open-field and rotarod tests. None of the drugs produced significant effects on FPS when injected before conditioning, indicating that VTA DA receptors are not involved in the acquisition of conditioned fear to a light-CS. In contrast, when injected before the test session, quinpirole significantly reduced FPS, whereas the other drugs had no effect. Quinpirole's ability to decrease FPS may be the result of an action on VTA D(2) presynaptic autoreceptors that decrease dopamine levels in terminal fields of the mesocorticolimbic pathway. Altogether, the present results suggest the importance of VTA DA neurons in the fear-activating effects of Pavlovian conditioning. In addition to demonstrating the importance of dopaminergic mechanisms in the motivational consequences of footshock, the present findings also indicate that these neural circuits are mainly involved in the expression, rather than acquisition, of conditioned fear. SN - 1872-7549 UR - https://www.unboundmedicine.com/medline/citation/19111792/Role_of_dopamine_receptors_in_the_ventral_tegmental_area_in_conditioned_fear_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0166-4328(08)00672-4 DB - PRIME DP - Unbound Medicine ER -