title: Activity-dependent secretion of neuronal activity regulated pentraxin from vasopressin neurons into the systemic circulation.
abstract: Neuronal activity regulated pentraxin (Narp) is a secreted, synaptic protein that has been implicated in modulating synaptic transmission. However, it is unclear how Narp secretion is regulated. Since we noted prominent Narp immunostaining in vasopressin neurons of the hypothalamus and in the posterior pituitary, we assessed whether it, like vasopressin, is released into the systemic circulation in an activity-dependent fashion. Consistent with this hypothesis, electron microscopic studies of the posterior pituitary demonstrated that Narp is located in secretory vesicles containing vasopressin. Using affinity chromatography, we detected Narp in plasma and found that these levels are markedly decreased by hypophysectomy. In addition, we confirmed that injection of a viral Narp construct into the hypothalamus restores plasma Narp levels in Narp knockout mice. In checking for activity-dependent secretion of Narp from the posterior pituitary, we found that several stimuli known to trigger vasopressin release, i.e. hypovolemia, dehydration and endotoxin, elevate plasma Narp levels. Taken together, these findings provide compelling evidence that Narp is secreted from vasopressin neurons in an activity-dependent fashion.
authors: Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, Baltimore, MD 21205, USA. imreti@jhmi.edu
authors: I M
authors: IM
authors: Reti
authors: M
authors: M
authors: Miskimon
authors: M
authors: M
authors: Dickson
authors: R S
authors: RS
authors: Petralia
authors: K
authors: K
authors: Takamiya
authors: R
authors: R
authors: Bland
authors: J
authors: J
authors: Saini
authors: M J
authors: MJ
authors: During
authors: R L
authors: RL
authors: Huganir
authors: J M
authors: JM
authors: Baraban
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D002097:C-Reactive Protein / Q000378:metabolism*; D002846:Chromatography, Affinity; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D003681:Dehydration / Q000503:physiopathology; D005822:Genetic Vectors; D006801:Humans; D020896:Hypovolemia / Q000503:physiopathology; D007150:Immunohistochemistry; D008070:Lipopolysaccharides / Q000633:toxicity; D051379:Mice; D018345:Mice, Knockout; D008854:Microscopy, Electron; D016253:Microscopy, Immunoelectron; D009043:Motor Activity / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000097:blood / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism* / Q000502:physiology*; D010902:Pituitary Gland / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012149:Restraint, Physical; D013315:Stress, Psychological / Q000378:metabolism / Q000503:physiopathology; D014667:Vasopressins / Q000502:physiology*; D000099153:Pentraxins
chemical_list: D002097:C-Reactive Protein; D018076:DNA, Complementary; D008070:Lipopolysaccharides; D009419:Nerve Tissue Proteins; D014667:Vasopressins; D000099153:Pentraxins