Leptin is a key hormone in the control of appetite and body weight. Predominantly produced by white adipose tissue, it acts on the brain to inhibit homeostatic feeding and food reward. Leptin has free access to circumventricular organs, such as the median eminence, but entry into other brain centers is restricted by the blood–brain and blood–CSF barriers. So far, it is unknown for which of its central effects leptin has to penetrate brain barriers. In addition, the mechanisms mediating the transport across barriers are unclear although high expression in brain barriers suggests an important role of the leptin receptor (LepR).
We selectively deleted LepR in brain endothelial and epithelial cells of mice ( LepR beKO ). The expression of LepR in fenestrated vessels of the periphery and the median eminence as well as in tanycytes was not affected.
Perfusion studies showed that leptin uptake by the brain depended on LepR in brain barriers. When being fed with a rewarding high-fat diet LepR beKO mice gained more body weight than controls. The aggravated obesity of LepR beKO mice was due to hyperphagia and a higher sensitivity to food reward.