title: Hypocretinergic system in the medial preoptic area promotes maternal behavior in lactating rats.
abstract: Hypocretin-1 and 2 (HCRT-1 and HCRT-2, respectively) are neuropeptides synthesized by neurons located in the postero-lateral hypothalamus, whose projections are widely distributed throughout the brain. The hypocretinergic (HCRTergic) system has been associated with the generation and maintenance of wakefulness, as well as with the promotion of motivated behaviors. In lactating rats, intra-cerebroventricular HCRT-1 administration stimulates maternal behavior, whilst lactation per se increases the expression of HCRT type 1 receptor (HCRT-R1). Due to the fact that HCRTergic receptors are expressed in the medial preoptic area (mPOA), a region critically involved in maternal behavior, we hypothesize that HCRT-1 promotes maternal behavior acting on this region. In order to evaluate this hypothesis, we assessed the maternal behavior of lactating rats following microinjections of HCRT-1 (10 or 100μM) and the selective HCRT-R1 antagonist SB-334867 (250μM) into the mPOA, during the first and second postpartum weeks. While intra-mPOA microinjections of HCRT-1 (100μM) increased corporal pup licking during the second postpartum week, the blockade of HCRT-R1 significantly decreased active components of maternal behavior, such as retrievals, corporal and ano-genital lickings, and increased the time spent in nursing postures in both postpartum periods. We conclude that HCRTergic system in the mPOA may stimulate maternal behavior, suggesting that endogenous HCRT-1 is necessary for the natural display of this behavior.
authors.affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
authors.forename: Mayda
authors.initials: M
authors.lastname: Rivas
authors.affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
authors.forename: Pablo
authors.initials: P
authors.lastname: Torterolo
authors.affiliation: Sección de Fisiología y Nutrición, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
authors.forename: Annabel
authors.initials: A
authors.lastname: Ferreira
authors.affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay. Electronic address: benedettoluciana@gmail.com.
authors.forename: Luciana
authors.initials: L
authors.lastname: Benedetto
mesh_terms: D000818:Animals; D000067290:Behavior Rating Scale; D001583:Benzoxazoles / Q000494:pharmacology; D005260:Female; D007026:Hypothalamic Area, Lateral / Q000166:cytology / Q000378:metabolism; D007034:Hypothalamus, Posterior / Q000166:cytology / Q000378:metabolism; D057967:Infusions, Intraventricular; D007774:Lactation / Q000378:metabolism*; D008425:Maternal Behavior / Q000187:drug effects / Q000502:physiology*; D008845:Microinjections; D009287:Naphthyridines; D009474:Neurons / Q000378:metabolism; D064446:Orexin Receptors / Q000378:metabolism / Q000502:physiology*; D000068797:Orexins / Q000008:administration & dosage / Q000494:pharmacology / Q000502:physiology*; D011301:Preoptic Area / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D018709:Statistics, Nonparametric; D014508:Urea / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: C420062:1-(2-methylbenzoxazol-6-yl)-3-(1,5)naphthyridin-4-yl urea; D001583:Benzoxazoles; C578627:Hcrtr1 protein, rat; D009287:Naphthyridines; D064446:Orexin Receptors; D000068797:Orexins; D014508:Urea
keywords: Hypocretin; Hypothalamus; Lactation; Neuropeptide; Orexin