MC4R Deficiency Causes Dysregulation of Postsynaptic Excitatory Synaptic Transmission as a Crucial Culprit for...

Area of Science:

• Neuroscience
• Endocrinology
• Molecular Biology

Background:

• The Melanocortin 4 receptor (MC4R) in the paraventricular nucleus of the hypothalamus (PVH) plays a critical role in regulating food intake and energy balance.
• Dysregulation of MC4R signaling is implicated in obesity and metabolic disorders.

Purpose of the Study:

• To investigate the synaptic and molecular mechanisms by which MC4R in the PVH influences body weight regulation.
• To elucidate the role of AMPA receptor (AMPAR) function and protein kinase A (PKA) signaling in MC4R-mediated effects on energy homeostasis.

Main Methods:

• Utilized MC4R knockdown (KD) and PKA KD mouse models in the PVH.
• Performed electrophysiological recordings to assess AMPA receptor-mediated postsynaptic responses.
• Analyzed the phosphorylation status and expression of the AMPAR GluA1 subunit.
• Monitored body weight gain and behavioral phenotypes.

Main Results:

• MC4R KD in the PVH attenuated AMPA receptor (AMPAR)-mediated postsynaptic responses by reducing GluA1 subunit phosphorylation via PKA signaling.
• MC4R KD led to rapid body weight gain.
• PKA KD replicated the electrophysiological and behavioral effects of MC4R KD.
• Reduced AMPAR GluA1 expression also resulted in attenuated synaptic responses and body weight gain.

Conclusions:

• MC4R signaling in the PVH regulates body weight through modulation of synaptic plasticity at AMPA receptors.
• Aberrations in synaptic responses, particularly involving AMPAR GluA1, are implicated in the pathogenesis of obesity.
• This study provides synaptic and molecular insights into MC4R's role in energy homeostasis.