Melanocortin-3 receptors expressed in Nkx2.1(+ve) neurons are sufficient for controlling appetitive responses to hypocaloric conditioning

Sci Rep. 2017 Mar 15:7:44444. doi: 10.1038/srep44444.

Abstract

Melanocortin-3 receptors (MC3R) have a contextual role in appetite control that is amplified with hypocaloric conditioning. C57BL/6J (B6) mice subjected to hypocaloric feeding schedules (HFS) exhibit compulsive behavioral responses involving food anticipatory activity (FAA) and caloric loading following food access. These homeostatic responses to calorie-poor environs are attenuated in B6 mice in which Mc3r transcription is suppressed by a lox-stop-lox sequence in the 5'UTR (Mc3rTB/TB). Here, we report that optimization of caloric loading in B6 mice subject to HFS, characterized by increased meal size and duration, is not observed in Mc3rTB/TB mice. Analysis of hypothalamic and neuroendocrine responses to HFS throughout the light-dark cycle suggests uncoupling of hypothalamic responses involving appetite-stimulating fasting-responsive hypothalamic neurons expressing agouti-related peptide (AgRP) and neuropeptide Y (Npy). Rescuing Mc3rs expression in Nkx2.1(+ve) neurons is sufficient to restore normal hypothalamic responses to negative energy balance. In addition, Mc3rs expressed in Nkx2.1(+ve) neurons are also sufficient to restore FAA and caloric loading of B6 mice subjected to HFS. In summary, MC3Rs expressed in Nkx2.1(+ve) neurons are sufficient to coordinate hypothalamic response and expression of compulsive behavioral responses involving meal anticipation and consumption of large meals during situations of prolonged negative energy balance.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Agouti-Related Protein / genetics*
  • Animals
  • Appetite / genetics
  • Energy Intake / genetics
  • Energy Metabolism / genetics*
  • Homeostasis
  • Hypothalamus / metabolism
  • Mice
  • Neurons / metabolism
  • Neuropeptide Y / genetics*
  • Photoperiod
  • Receptor, Melanocortin, Type 3 / genetics*
  • Thyroid Nuclear Factor 1 / genetics

Substances

  • Agouti-Related Protein
  • Neuropeptide Y
  • Nkx2-1 protein, mouse
  • Receptor, Melanocortin, Type 3
  • Thyroid Nuclear Factor 1