There are obtained data indicating that morphogenesis and, probably, formation of structurally functional interaction of the CART- and dopaminergic neurons occur as early as during embryonic development. Meanwhile development of the AGRergic system and formation of its structural and functional communications are observed in the course of postnatal development of rat. Analysis of literature and re- sults of our own investigation show that differentiation of dopaminergic neurons in hypothalamus and midbrain occurs on the background of development of CARTergic neurons and in the absence of AGRP. Taking into account our data on activating action of the CART-peptide and inhibitory effect of AGRP on dopaminergic brain neurons, we believe that the leading component at formation of functional interactions of these systems is the later maturing AGRPergic system.