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Dopamine release in the nucleus accumbens by hypothalamic stimulation-escape behavior
P V Rada1, G P Mark, B G Hoebel
1Department of Psychology, Princeton University, NJ 08544-1010, USA.
Brain Research
|March 31, 1998
Summary
Dopamine release in the nucleus accumbens (NAc) occurs during escape from hypothalamic stimulation, indicating its role in negative reinforcement. This dopamine (DA) release is linked to escape behavior, not just the unpleasantness of the stimulation itself.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Neurochemistry
Background:
- Lateral hypothalamic stimulation is known to increase dopamine in the nucleus accumbens (NAc).
- The role of dopamine in aversive or escape behaviors is less understood.
Purpose of the Study:
- To investigate whether aversively motivated behavior, specifically escape from hypothalamic stimulation, can also lead to dopamine release in the NAc.
- To determine if dopamine release is correlated with the aversiveness of stimulation or the escape behavior itself.
Main Methods:
- Rats were implanted with microdialysis probes in the NAc and electrodes in the lateral hypothalamus (LH) or medial hypothalamus (MH).
- Extracellular dopamine levels in the NAc were measured during automatic hypothalamic stimulation and during self-stimulation (rewarding) or stimulation-escape (aversive) behaviors.
Main Results:
- Automatic LH stimulation increased NAc dopamine by 30%.
- Escape responding from LH stimulation increased NAc dopamine by 100%, despite less total stimulation.
- Automatic MH stimulation decreased NAc dopamine by 20%, but escape from MH stimulation still increased NAc dopamine by 100%.
Conclusions:
- Dopamine (DA) is released in the NAc during negative reinforcement, specifically when an animal escapes from either lateral or medial hypothalamic stimulation.
- The data suggest that DA release is correlated with stimulation-escape behavior, rather than solely with the aversiveness of the automatic stimulation.