For example, disruption of the brain-derived neurotrophic factor(BDNF)-TrkB pathway can lead to hyperphagia and obesity in mice.15 Small-molecule, orally active inhibitors might also be more acceptable and cost effective than monoclonal antibodies,16, 17 but selectivity for TrkA against related tyrosine kinase receptors has proved difficult to achieve. This evidence concerns the gene BDNF and obesity disorder.