Melanocortin-4 receptor (MC4R) in paraventricular nucleus in hypothalamus (PVH) shows bidirectional characterization in modulating food intake and energy homeostasis. Here, we demonstrated that MC4R knock down (MC4R KD) in PVH could attenuate AMPA receptor (AMPAR) mediated postsynaptic responses by altering AMPAR GluA1 subunit phosphorylation via protein kinase A (PKA) dependent signaling cascade and simultaneously lead to rapid body weight gain. Further, PKA knock down (PKA KD) in PVH engendered similar electrophysiological and behavioral phenotypes as MC4R KD mice. Importantly, we observed that the reduction of AMPAR GluA1 expression not only led to attenuated synaptic responses but also caused body weight gain, suggesting that the aberration of synaptic responses may be one of the crucial pathogeny for obesity. Our study provided the synaptic and molecular explanations of how body weight is regulated by MC4R in PVH.© 2022 by the American Diabetes Association.