Amphetamine injections into the nucleus accumbens affect neither acquisition/expression of conditioned fear nor baseline startle response.
The acoustic startle response is enhanced during states of fear and attenuated during pleasant ones. Our question was whether pharmacological stimulation of the reward system disrupts the learning and retrieval of conditioned fear as measured by fear-potentiated startle. We therefore injected the dopamine agonist amphetamine into the nucleus accumbens (NAC) immediately before either acquisition or expression of conditioned fear and measured the effect of these injections on fear-potentiated startle and baseline startle response. This study clearly showed that amphetamine injections into the NAC had no effect on baseline startle amplitude and acquisition/expression of conditioned fear. In contrast, amphetamine injections into the nucleus accumbens clearly enhanced spontaneous motor activity. These results suggest that dopamine within the NAC is not involved in modulation of fear-potentiated startle and baseline startle.
Schwienbacher
Isabel
I
Tierphysiologie, Zoologisches Institut, Fakultät für Biologie, Universität Tübingen, Auf der Morgenstelle 28, 72076 , Tübingen, Germany. isabel_schwienbacher@gmx.de
Fendt
Markus
M
Schnitzler
Hans-Ulrich
HU
D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D003213:Conditioning, Psychological / Q000187:drug effects* / Q000502:physiology; D004298:Dopamine / Q000378:metabolism; D015259:Dopamine Agents / Q000494:pharmacology; D005239:Fear / Q000187:drug effects* / Q000502:physiology; D007858:Learning / Q000187:drug effects / Q000502:physiology; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D009714:Nucleus Accumbens / Q000033:anatomy & histology / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013216:Reflex, Startle / Q000187:drug effects* / Q000502:physiology; D012201:Reward
D015259:Dopamine Agents; D000661:Amphetamine; D004298:Dopamine