Introduction: Leptin, hormon secreted by the fat tissue cells, participates in the energy balance regulation by sending satiety signals. This signaling is activated by the leptine receptors (ObR) placed in the part of the cell membrane called lipid rafts which are mainly composed of gangliosides. In addition to regulating body weight, leptin creates and protects new neurons in the hippocampus and in that way plays an important role in maintaining the function of memory and emotions. Goal: To determine how the exclusion of gene for the synthesis of complex gangliosides in the genetically modified B4Galnt1 affects the expression of the leptin receptor in CA1, CA3 and DG hippocampus regions. Materials and methods: For this study the brains from the genetically modified B4Galnt1 (KO) and the wild type mice (WT) were used. To determine the B4Galnt1 and WT type of the mouse we performed the genotyping using specific primers. Euthanasia and transcardial perfusion were then to follow. The brains were fixed, crioprotected and stored frozen before cutting. To determine the distribution of ObR the immunohistochemical analysis was performed using a specific primary antibody. The results obtained were processed in Fiji and Statistics 12 computer programs. Results: A statistically significant decrease in expression of the leptin receptor in the B4Galnt1 mouse was found in all three investigated hippocampal regions. The most notable decrease was observed in the CA1 region. Conclusion: A proper biosynthesis of ganglioside contributes to the adequate formation of the lipid rafts and the function of the receptors placed in them. The exclusion of the gene for the synthesis of the complex gangliosides in the B4Galnt1 mouse results in decreased expression of the leptin receptor in the hippocampus.