Evaluating chronic administration of melanin concentrating hormone (MCH) effects in lactating Long-Evans rats

Abstract

The melanin-concentrating hormone (MCH) is a peptide known to act, among other functions, in regulating the energy balance. Only during lactation, this neuropeptide is synthesized in the ventromedial preoptic area (MPOAvm), a region directly linked to the expression of maternal behavior. However, the role that MCH exerts during lactation, a period of high energy demand, is not elucidated. It is believed that it may be related to signaling termination of lactation for the mother. For this, Long-Evans rats will receive, through osmotic minipumps, chronic administrations of MCH, NEI, the combination of both (MCH+NEI) and the MCH antagonist, by intracerebroventricular injections. The animals will have their behavior recorded to evaluate the appetitive and consummatory aspects of maternal care. The dietary intake of females will be monitored throughout the period. On specific days, milk will be collected for volumetric and nutritional analyzes. It is believed that MCH may also be involved in the mechanism of milk ejection. The females 'brains will be collected for in situ hybridization, immunohistochemistry (MCH-ir), western blotting and qRT-PCR techniques to identify the peptide synthesis and its precursor in specific areas of the females' brains. Combined with behavioral assessments, this study will allow us to have a more detailed and temporal view of the action of MCH during the physiological process of lactation.