Tyrosine hydroxylase (TH) expressing neurons in the arcuate nucleus of hypothalamus (ARC), has a central role in regulating appetite and metabolism. It has been shown that activity changes in these neurons are necessary and sufficient to acutely regulate feeding behavior. TH neurons send dense intrahypothalamic axonal projections and make synaptic connections to paraventricular nucleus (PVN), which have been shown to be the key downstream target region. Since the ARCTH→PVN synaptic connection plays a crucial role in feeding, possible changes in the strength of this connection are also likely to be critical for the regulation of appetite. In the present study, we aimed to investigate electrical activities of the ARCTH → PVN connection following feeding with chronic high fat diet (HFD).Male TH-Cre mice were used in the study. We used a combination of optogenetic and electrophysiology to study ARCTH → PVN synapses. For this, we used channel-rhodopsin assisted circuit mapping (CRACM) approach to isolate TH axon evoked synaptic currents from PVN neurons and evaluated impact of various neuromodulators.Our results showed that ARCTH→PVN synapses from HFD mice rapidly depressed and were unable to sustain the release of neurotransmitter (p<0.05). In addition, we also revealed that HFD significantly increased average firing rate of PVN neurons (p<0.001).Our findings showed that HFD has dramatically strong effects on the synaptic connection of ARCTH → PVN. At this point, changes in this synaptic connection may cause food intake disorders.Acknowledgement: This study was supported by TÜBİTAK (Project # 122S382).