A.S., M.W.K. and T.N. contributed equally to this work.
The role of melanin-concentrating hormone in conditioned reward learning
Article first published online: 8 JUL 2012
© 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd
European Journal of Neuroscience
Volume 36, Issue 8, pages 3126–3133, October 2012
How to Cite
Sherwood, A., Wosiski-Kuhn, M., Nguyen, T., Holland, P. C., Lakaye, B., Adamantidis, A. and Johnson, A. W. (2012), The role of melanin-concentrating hormone in conditioned reward learning. European Journal of Neuroscience, 36: 3126–3133. doi: 10.1111/j.1460-9568.2012.08207.x
- Issue published online: 14 OCT 2012
- Article first published online: 8 JUL 2012
- Received 11 March 2012, revised 18 May 2012, accepted 30 May 2012
- conditioned reinforcement;
- Pavlovian-instrumental transfer
The orexigenic neuropeptide melanin-concentrating hormone (MCH) is well positioned to play a key role in connecting brain reward and homeostatic systems due to its synthesis in hypothalamic circuitry and receptor expression throughout the cortico-striatal reward circuit. Here we examined whether targeted-deletion of the MCH receptor (MCH-1R) in gene-targeted heterozygote and knockout mice (KO), or systemic treatment with pharmacological agents designed to antagonise MCH-1R in C57BL/6J mice would disrupt two putative consequences of reward learning that rely on different neural circuitries: conditioned reinforcement (CRf) and Pavlovian-instrumental transfer (PIT). Mice were trained to discriminate between presentations of a reward-paired cue (CS+) and an unpaired CS−. Following normal acquisition of the Pavlovian discrimination in all mice, we assessed the capacity for the CS+ to act as a reinforcer for new nose-poke learning (CRf). Pharmacological disruption in control mice and genetic deletion in KO mice impaired CRf test performance, suggesting MCH-1R is necessary for initiating and maintaining behaviors that are under the control of conditioned reinforcers. To examine a dissociable form of reward learning (PIT), a naïve group of mice were trained in separate Pavlovian and instrumental lever training sessions followed by the PIT test. For all mice the CS+ was capable of augmenting ongoing lever responding relative to CS− periods. These results suggest a role for MCH in guiding behavior based on the conditioned reinforcing value of a cue, but not on its incentive motivational value.