FABP4 and obesity due to melanocortin 4 receptor deficiency: Moreover, the Fabp4-Cre phenotypic features of hyperphagia and obesity could be at least partly explained by deletion of Bdnf from macrophages, because BDNF-producing hematopoietic cells have been reported to regulate appetite and energy balance by migrating from bone marrow to the hypothalamus.27 Pre-adipocytes are another possible source of BDNF because Bdnf expression was reported to decrease during adipocyte differentiation29 and Adipoq-mediated recombination may be less efficient in pre-adipocytes than in adipocytes.