[Dynamics of the level of extracellular dopamine in the rat brain during formation of conditioned fear and acoustic startle habituation].
The content of extracellular dopamine (DA) was estimated in dorsal striatum (DS), nucleus accumbens (Nac), and prefrontal cortex (Pfc) of rat brain during two sessions of acoustic startle habituation consisting of 10 trials each with 24-hour intersession and 20-s intertrial intervals. Startle amplitude and freezing behavior were recorded. A decrease in the content of extracellular DA in the DS and an increase in the DA content in Nac were observed during both sessions of habituation with return to a baseline level immediately after termination of the sessions. During the second session, the startle amplitude and change in the DA content in both structures were much lower than during the first session. During the first session, the DA level in DS remained unchanged but dropped in Nac. In the Pfc the DA level increased during both habituation sessions and in the period between the session. Time of freezing prior to acoustic stimulation in the second sessions (that is known to be an indication of conditioned fear) correlated with the DA level in DS on the day of training and with the DA level in Nac just before the beginning of the second session. The role of the dopaminergic system in formation and retrieval of different components of defensive behavior is discussed.
Storozheva
Z I
ZI
Anohkin Institute of Normal Physiology, Institute of Pharmacology, Russian Academy of Medical Sciences, Moscow.
Afanas'ev
I I
II
Proshin
A T
AT
Kudrin
V S
VS
D000818:Animals; D001921:Brain / Q000378:metabolism*; D003214:Conditioning, Classical; D004298:Dopamine / Q000378:metabolism*; D005239:Fear; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013216:Reflex, Startle
D004298:Dopamine