The LNQ has been dedicated to studying the anatomical organization, connections, and functionality of the melanin-concentrating hormone (MCH) and its family peptides. For just over a decade, we have been trying to understand the participation of MCH in the control of maternal behavior since its unusual appearance in the ventromedial part of the medial preoptic area (MPOA), only during the period of lactation, that remains not entirely known. The methodology used to achieve the objectives are retrograde and anterograde neuronal tracers, transcription factors and immunohistochemistry, qRT-PCR, microarray, Western-blotting, enzyme immunoassay, ELISA, RNAseq, smallRNA-seq.