Reward learning requires activity of matrix metalloproteinase-9 in the central amygdala

• Published in: The Journal of neuroscience 2013-09, Vol.33 (36), p.14591-14600
• Main Authors: Knapska, Ewelina, Lioudyno, Victoria, Kiryk, Anna, Mikosz, Marta, Górkiewicz, Tomasz, Michaluk, Piotr, Gawlak, Maciej, Chaturvedi, Mayank, Mochol, Gabriela, Balcerzyk, Marcin, Wojcik, Daniel K, Wilczynski, Grzegorz M, Kaczmarek, Leszek
• Format: Article
• Language: English
• Subjects: Amygdala - metabolism; Amygdala - physiology; Animals; Appetitive Behavior; Conditioning, Operant; Matrix Metalloproteinase 9 - drug effects; Matrix Metalloproteinase 9 - genetics; Matrix Metalloproteinase 9 - metabolism; Mice; Mice, Inbred C57BL; Mice, Knockout; Neurons - metabolism; Neurons - physiology; Reward; Synapses - metabolism; Synapses - physiology; Tissue Inhibitor of Metalloproteinase-1 - pharmacology
• ISSN: 0270-6474; 1529-2401; 1529-2401
• DOI: 10.1523/jneurosci.5239-12.2013

Learning how to avoid danger and pursue reward depends on negative emotions motivating aversive learning and positive emotions motivating appetitive learning. The amygdala is a key component of the brain emotional system; however, an understanding of how various emotions are differentially processed in the amygdala has yet to be achieved. We report that matrix metalloproteinase-9 (MMP-9, extracellularly operating enzyme) in the central nucleus of the amygdala (CeA) is crucial for appetitive, but not for aversive, learning in mice. The knock-out of MMP-9 impairs appetitively motivated conditioning, but not an aversive one. MMP-9 is present at the excitatory synapses in the CeA with its activity greatly enhanced after the appetitive training. Finally, blocking extracellular MMP-9 activity with its inhibitor TIMP-1 provides evidence that local MMP-9 activity in the CeA is crucial for the appetitive, but not for aversive, learning.