Obesity is considered as a global epidemic both in developed and developing countries. One of the most important factors promoting obesity epidemic is the consumption of high fat diets (HFD) rich in saturated fatty acids such as palmitic acid (PA). Chronic intake of HFD is associated with the onset of metabolic diseases, including insulin resistance. Importantly, following chronic HFD exposure, PA accumulates in mice hypothalamus, the brain area responsible for the maintenance of energy homeostasis and for the regulation of body metabolism. One of the key cellular homeostatic processes impaired after HFD consumption is autophagy, a catabolic pathway aimed at recycling cytoplasmic components and damaged organelles by a lysosome-mediated process. During autophagy, the cellular cargo is sequestered within a double membrane vesicle called autophagosome, which fuses with a lysosome, to form the autolysosome, where, thanks to the activity of lysosomal enzymes, the autophagic cargo is degraded. The entire process from the autophagosome synthesis, up to their lysosomal degradation is termed autophagic flux. Importantly, autophagy dysregulation in hypothalamic neurons leads to metabolic disorders suggesting a key role for hypothalamic autophagy in the control of body metabolism. In addition, increased PA levels have been associated with autophagy impairment and with insulin resistance in the hypothalamus. However, the specific mechanism by which PA decreases autophagy in hypothalamic neurons is currently unknown. We propose PA-mediated inhibition of autophagy in hypothalamic neurons as a key mediator of obesity-associated metabolic disorders as insulin resistance. The hypothesis of this thesis is that palmitic acid inhibits the autophagic flux and decreases insulin sensitivity in hypothalamic neuronal cells. We observed, in the N43/5 hypothalamic cell line and in primary hypothalamic neurons, that PA increases the number of autophagic structures and the amount of SQSTM1/p62, a protein degraded by the autophagic pathway, suggesting that PA inhibits the autophagic flux in hypothalamic neuronal cells. Importantly, the levels of several autophagy related genes essential for autophagosome formation were not increased by PA exposure, suggesting that PA induces the accumulation of autophagic structures as consequence of decreased autophagic flux in N43/5 cells. Moreover, by electron microscopy, we observed that PA induces the accumulation of large cellular degradative compartments in N43/5 hypothalamic neuronal cells. However, PA does not affect lysosomal acidity or their activity in our model. Then, we evaluated autophagosome-lysosome fusion by immunofluorescence, using N43/5 cells transfected with mCherry-GFP-LC3 and by assessing the co-localization between autophagosome and lysosome markers. We observed that PA decreased autophagosome-lysosome fusion, and that PA induced the accumulation of big autophagic structures. Furthermore, using a pull down assay, we quantified the activation state of Rab7, a protein involved in autophagosome-lysosome fusion, and we determined that PA increases the amount of Rab7 in the GTP-bound form, suggesting that PA impairs autolysosomes formation through the regulation of Rab7 activity. Additionally, through stable isotope labeling with amino acid in cell culture (SILAC), we found in isolated lysosomes from N43/5 cells treated with PA, increased levels of additional proteins involved with the control of endolysosomal trafficking and with autophagic maturation, which can further explain the mechanism by which PA impairs autophagy in hypothalamic neurons. Finally, we evaluated whether PA exposure contributes to metabolic disorders in our cellular model, and we confirmed that PA decreases insulin sensitivity in hypothalamic N43/5 cells. Furthermore, inhibition of autophagy or autophagic flux also affects insulin sensitivity in these cells. In summary, this study suggests that, in hypothalamic neuronal cells, autophagic flux inhibition induced by PA causes endolysosomal trafficking dysregulation and reduces insulin sensitivity. These data may help to elucidate the cellular mechanisms that underlie the effects of PA on the promotion of obesity-associated metabolic disorders.