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Moderate Voluntary Exercise Attenuates the Metabolic Syndrome in Melanocortin-4 Receptor-deficient Rats Showing Central Dopaminergic Dysregulation

Abstract

Objective: Melanocortin-4 receptors (MC4Rs) are highly expressed by dopamine-secreting neurons of the mesolimbic tract, but their functional role has not been fully resolved. Voluntary wheel running (VWR) induces adaptations in the mesolimbic dopamine system and has a myriad of long-term beneficial effects on health. In the present experiments we asked whether MC4R function regulates the effects of VWR, and whether VWR ameliorates MC4R-associated symptoms of the metabolic syndrome.

Methods: Electrically evoked dopamine release was measured in slice preparations from sedentary wild-type and MC4R-deficient Mc4r (K314X) (HOM) rats. VWR was assessed in wild-type and HOM rats, and in MC4R-deficient loxTB (Mc4r) mice, wild-type mice body weight-matched to loxTB (Mc4r) mice, and wild-type mice with intracerebroventricular administration of the MC4R antagonist SHU9119. Mesolimbic dopamine system function (gene/protein expression) and metabolic parameters were examined in wheel-running and sedentary wild-type and HOM rats.

Results: Sedentary obese HOM rats had increased electrically evoked dopamine release in several ventral tegmental area (VTA) projection sites compared to wild-type controls. MC4R loss-of-function decreased VWR, and this was partially independent of body weight. HOM wheel-runners had attenuated markers of intracellular D1-type dopamine receptor signaling despite increased dopamine flux in the VTA. VWR increased and decreased ΔFosB levels in the nucleus accumbens (NAc) of wild-type and HOM runners, respectively. VWR improved metabolic parameters in wild-type wheel-runners. Finally, moderate voluntary exercise corrected many aspects of the metabolic syndrome in HOM runners.

Conclusions: Central dopamine dysregulation during VWR reinforces the link between MC4R function and molecular and behavioral responding to rewards. The data also suggest that exercise can be a successful lifestyle intervention in MC4R-haploinsufficient individuals despite reduced positive reinforcement during exercise training.

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References
1.
Bi S, Scott K, Hyun J, Ladenheim E, Moran T . Running wheel activity prevents hyperphagia and obesity in Otsuka long-evans Tokushima Fatty rats: role of hypothalamic signaling. Endocrinology. 2004; 146(4):1676-85. DOI: 10.1210/en.2004-1441. View

2.
Richard C, Tolle V, Low M . Meal pattern analysis in neural-specific proopiomelanocortin-deficient mice. Eur J Pharmacol. 2011; 660(1):131-8. PMC: 3096011. DOI: 10.1016/j.ejphar.2010.12.022. View

3.
Lewis E, Harrington C, Chikaraishi D . Transcriptional regulation of the tyrosine hydroxylase gene by glucocorticoid and cyclic AMP. Proc Natl Acad Sci U S A. 1987; 84(11):3550-4. PMC: 304912. DOI: 10.1073/pnas.84.11.3550. View

4.
Kravitz A, Freeze B, Parker P, Kay K, Thwin M, Deisseroth K . Regulation of parkinsonian motor behaviours by optogenetic control of basal ganglia circuitry. Nature. 2010; 466(7306):622-6. PMC: 3552484. DOI: 10.1038/nature09159. View

5.
Patterson C, Levin B . Role of exercise in the central regulation of energy homeostasis and in the prevention of obesity. Neuroendocrinology. 2007; 87(2):65-70. DOI: 10.1159/000100982. View