title: Data supporting a new physiological role for brain apelin in the regulation of hypothalamic oxytocin neurons in lactating rats.
abstract: Apelin is a bioactive peptide identified as the endogenous ligand of the human orphan G protein-coupled receptor APJ in 1998. The present data show that apelin modulates the activity of magnocellular and parvocellular oxytocin (OXY) neurons in the lactating rat. A combination of in situ hybridization and immunohistochemistry demonstrated the presence of apelin receptor mRNA in hypothalamic OXY neurons. Double immunofluorescence labeling then revealed the colocalization of apelin with OXY in about 20% of the hypothalamic OXY-positive neurons. Intracerebroventricular apelin administration inhibited the activity of magnocellular and parvocellular OXY neurons, as shown by measuring the c-fos expression in OXY neurons or by direct electrophysiological measurements of the electrical activity of these neurons. This effect was correlated with a decrease in the amount of milk ejected. Thus, apelin inhibits the activity of OXY neurons through a direct action on apelin receptors expressed by these neurons in an autocrine and paracrine manner. In conclusion, these findings highlight the inhibitory role of apelin as an autocrine/paracrine peptide acting on OXY neurons during breastfeeding.
authors: Institut National de la Santé et de la Recherche Médicale, Paris F-75231, France.
authors: Laurence
authors: L
authors: Bodineau
authors: Christopher
authors: C
authors: Taveau
authors: Hong-Hanh
authors: HH
authors: Lê Quan Sang
authors: Guillaume
authors: G
authors: Osterstock
authors: Isabelle
authors: I
authors: Queguiner
authors: Françoise
authors: F
authors: Moos
authors: Alain
authors: A
authors: Frugière
authors: Catherine
authors: C
authors: Llorens-Cortes
mesh_terms: D000818:Animals; D000073861:Apelin; D005260:Female; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D007774:Lactation / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010121:Oxytocin / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000073861:Apelin; C498579:Apln protein, rat; D036341:Intercellular Signaling Peptides and Proteins; D010121:Oxytocin