title: The role of melanin-concentrating hormone in conditioned reward learning.
abstract: 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.
authors: Department of Psychological and Brain Sciences, Johns Hopkins University, Ames Hall, 3400 N. Charles Street, Baltimore, MD, USA.
authors: Andrew
authors: A
authors: Sherwood
authors: Marlena
authors: M
authors: Wosiski-Kuhn
authors: Truc
authors: T
authors: Nguyen
authors: Peter C
authors: PC
authors: Holland
authors: Bernard
authors: B
authors: Lakaye
authors: Antoine
authors: A
authors: Adamantidis
authors: Alexander W
authors: AW
authors: Johnson
mesh_terms: D000818:Animals; D003214:Conditioning, Classical; D017353:Gene Deletion; D007858:Learning; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D009842:Oligopeptides / Q000494:pharmacology; D011979:Receptors, Pituitary Hormone / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D012201:Reward
chemical_list: C527780:Ac-Arg-(Cys-Met-Ava-Arg-Val-Tyr-Ava-Cys)-NH2; D009842:Oligopeptides; D011979:Receptors, Pituitary Hormone; C092274:melanin-concentrating hormone receptor