Melanin-concentrating hormone receptor 1 (MCH1-R) antagonism: reduced appetite for calories and suppression of addictive-like behaviors.
BACKGROUND
The hypothalamic neuropeptide melanin-concentrating hormone and its MCH1 receptor have been implicated in regulation of feeding and energy homeostasis, as well as modulation of reward-related behaviors. Here, we examined whether the MCH system plays a role both in caloric and motivational aspects of sugar intake.


METHODS
The non-peptide MCH1-R antagonist GW803430 (3, 10, 30 mg/kg, i.p.) was first tested on self-administration under a fixed ratio schedule of reinforcement of both a caloric (10% w/v sucrose) and a non-caloric (0.06% w/v saccharin) sweet solution. GW803430 was then tested for its ability to alter motivational properties and seeking of sucrose. Lastly, the drug was tested to concurrently examine its effects on the escalated consumption of both sugar and food in animals following intermittent sugar access.


RESULTS
The MCH1-R antagonist reduced sucrose- but not saccharin-reinforced lever pressing, likely reflecting a decreased appetite for calories in GW803430-treated rats. GW803430 reduced sucrose self-administration under a progressive ratio schedule, and suppressed cue-induced reinstatement of sucrose seeking, suggesting effects on rewarding properties of sucrose. GW803430 attenuated food intake in rats on intermittent access to sucrose at all doses examined (3, 10, 30 mg/kg), while reduction of sugar intake was weaker in magnitude.


CONCLUSIONS
Together, these observations support an involvement of the MCH system in regulation of energy balance as well as mediation of sucrose reward. MCH may be an important regulator of sugar intake by acting on both caloric and rewarding components.
Laboratory of Clinical and Translational Studies, National Institute on Alcohol Abuse and Alcoholism-NIAAA, National Institutes of Health-NIH, Bethesda, MD, USA.
Camilla
C
Karlsson
Michelle
M
Zook
Roberto
R
Ciccocioppo
Donald R
DR
Gehlert
Annika
A
Thorsell
Markus
M
Heilig
Andrea
A
Cippitelli
D000818:Animals; D001066:Appetite / Q000187:drug effects*; D016739:Behavior, Addictive / Q000523:psychology*; D002241:Carbohydrates; D003216:Conditioning, Operant / Q000187:drug effects; D003463:Cues; D002149:Energy Intake / Q000187:drug effects*; D004777:Environment; D008297:Male; D009042:Motivation; D011744:Pyrimidinones / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D017481:Receptors, Somatostatin / Q000037:antagonists & inhibitors*; D012008:Recurrence; D012055:Reinforcement Schedule; D012439:Saccharin; D012646:Self Administration; D013876:Thiophenes / Q000494:pharmacology*
C540748:6-(4-chlorophenyl)-3-(3-methoxy-4-(2-pyrrolidin-1-ylethoxy)phenyl)-3H-thieno(3,2-d)pyrimidin-4-one; D002241:Carbohydrates; C491208:MCHR1 protein, rat; D011744:Pyrimidinones; D017481:Receptors, Somatostatin; D013876:Thiophenes; D012439:Saccharin