Leptin (LEP) is a 16 kDa adipokine primarily produced by white adipose tissue. Encoded by the LEP gene, it circulates in the bloodstream and acts as a key regulator of energy homeostasis.Leptin signals through the leptin receptor (LEPR), with the long isoform (LEPRb) being crucial for mediating its effects. The hormone travels to the brain, particularly the hypothalamus, where it inhibits appetite and increases energy expenditure, creating a negative feedback loop between fat stores and the central nervous system.Beyond energy regulation, leptin influences reproduction, immune function, and bone metabolism. Its discovery revolutionized the understanding of obesity, revealing the role of hormonal communication between the body's periphery and the brain.Besides,Suppressors Of Cytokine Signaling 3 (SOCS3) has been identified as an interactor of LEP, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human LEP and recombinant mouse SOCS3. Briefly, LEP was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to SOCS3-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-LEP pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 µL stop solution to the wells and read at 450/630nm immediately. The binding activity of recombinant human LEP and recombinant mouse SOCS3was shown in Figure 1, and this effect was in a dose dependent manner.