title: Mice with genetic deletion of the heparin-binding growth factor midkine exhibit early preclinical features of Parkinson's disease.
abstract: There is considerable evidence showing that the neurodegenerative processes that lead to sporadic Parkinson's disease (PD) begin many years before the appearance of the characteristic motor symptoms and that impairments in olfactory, cognitive and motor functions are associated with time-dependent disruption of dopaminergic neurotransmission in different brain areas. Midkine is a 13-kDa retinoic acid-induced heparin-binding growth factor involved in many biological processes in the central nervous system such as cell migration, neurogenesis and tissue repair. The abnormal midkine expression may be associated with neurochemical dysfunction in the dopaminergic system and cognitive impairments in rodents. Here, we employed adult midkine knockout mice (Mdk(-/-)) to further investigate the relevance of midkine in dopaminergic neurotransmission and in olfactory, cognitive and motor functions. Mdk(/-) mice displayed pronounced impairments in their olfactory discrimination ability and short-term social recognition memory with no gross motor alterations. Moreover, the genetic deletion of midkine decreased the expression of the enzyme tyrosine hydroxylase in the substantia nigra reducing partially the levels of dopamine and its metabolites in the olfactory bulb and striatum of mice. These findings indicate that the genetic deletion of midkine causes a partial loss of dopaminergic neurons and depletion of dopamine, resulting in olfactory and memory deficits with no major motor impairments. Therefore, Mdk(-/-) mice may represent a promising animal model for the study of the early stages of PD and for testing new therapeutic strategies to restore sensorial and cognitive processes in PD.
authors.affiliation: Departamento de Farmacologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, UFSC, Campus Trindade, Florianópolis, SC, 88049-900, Brazil. ruidsp@hotmail.com
authors.forename: Rui D S
authors.initials: RD
authors.lastname: Prediger
authors.forename: Argelia E
authors.initials: AE
authors.lastname: Rojas-Mayorquin
authors.forename: Aderbal S
authors.initials: AS
authors.lastname: Aguiar
authors.forename: Caroline
authors.initials: C
authors.lastname: Chevarin
authors.forename: Raymond
authors.initials: R
authors.lastname: Mongeau
authors.forename: Michel
authors.initials: M
authors.lastname: Hamon
authors.forename: Laurence
authors.initials: L
authors.lastname: Lanfumey
authors.forename: Elaine
authors.initials: E
authors.lastname: Del Bel
authors.forename: Hisako
authors.initials: H
authors.lastname: Muramatsu
authors.forename: José
authors.initials: J
authors.lastname: Courty
authors.forename: Rita
authors.initials: R
authors.lastname: Raisman-Vozari
mesh_terms: D000818:Animals; D001921:Brain / Q000473:pathology / Q000502:physiology; D016207:Cytokines / Q000172:deficiency* / Q000235:genetics; D004195:Disease Models, Animal; D017353:Gene Deletion; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D000078792:Midkine; D020932:Nerve Growth Factor / Q000172:deficiency* / Q000235:genetics; D010300:Parkinson Disease / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D021641:Recognition, Psychology / Q000502:physiology; D012903:Smell / Q000235:genetics
chemical_list: D016207:Cytokines; D000078792:Midkine; D020932:Nerve Growth Factor