Dorsal raphe serotonin neurotransmission is required for the expression of nursing behavior and for pup survival

Proper maternal care is an essential factor of reproductive success in mammals, involving a repertoire of behaviors oriented toward the feeding and care of the offspring. Among the neurotransmitters involved in the initiation of these behaviors, serotonin (5-HT) seems to play an important role. Here we compared pup-oriented maternal behaviors in mice with constitutive 5-HT depletion, the tryptophan hydroxylase 2-knock-out (Tph2-KO) and the Pet1-KO mice. We report that the only common pup-oriented defect in these 2 hyposerotoninergic models is a defective nursing in parturient mice and altered nursing-like (crouching) behavior in virgin mice, while pup retrieval defects are only present in Tph2-KO. Despite a normal mammary gland development and milk production, the defect in appropriate nursing is responsible for severe growth retardation and early lethality of pups born to hyposerotonergic dams. This nursing defect is due to acute rather constitutive 5-HT depletion, as it is reproduced by adult knockdown of Tph2 in the dorsal raphe nucleus in mothers with a prior normal maternal experience. We conclude that 5-HT innervation from the dorsal raphe is required for both the initiation and maintenance of a normal nursing behavior. Our findings may be related to observations of reduced maternal/infant interactions in human depression.Fil: Muzerelle, Aude. Sorbonne University; Francia. Inserm; FranciaFil: Soiza Reilly, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Hainer, Cornelia. Max-Delbrück Center for Molecular Medecine; AlemaniaFil: Ruet, Pierre Louis. Inserm; Francia. Sorbonne University; FranciaFil: Lesch, Klaus Peter. University Of Würzburg; Alemania. Universiteit Maastricht.; Países BajosFil: Bader, Michael. Max-Delbrück Center for Molecular Medecine; AlemaniaFil: Alenina, Natalia. Max-Delbrück Center for Molecular Medecine; AlemaniaFil: Scotto Lomassese, Sophie. Inserm; Francia. Sorbonne University; FranciaFil: Gaspar, Patricia. Sorbonne University; Francia. Inserm; Franci