title: Acute Morphine, Chronic Morphine, and Morphine Withdrawal Differently Affect Pleiotrophin, Midkine, and Receptor Protein Tyrosine Phosphatase β/ζ Regulation in the Ventral Tegmental Area.
abstract: Pleiotrophin (PTN) and midkine (MK) are secreted growth factors and cytokines, proposed to be significant neuromodulators with multiple neuronal functions. PTN and MK are generally related with cell proliferation, growth, and differentiation by acting through different receptors. PTN or MK, signaling through receptor protein tyrosine phosphatase β/ζ (RPTPβ/ζ), lead to the activation of extracellular signal-regulated kinases (ERKs) and thymoma viral proto-oncogene (Akt), which induce morphological changes and modulate addictive behaviors. Besides, there is increasing evidence that during the development of drug addiction, astrocytes contribute to the synaptic plasticity by synthesizing and releasing substances such as cytokines. In the present work, we studied the effect of acute morphine, chronic morphine, and morphine withdrawal on PTN, MK, and RPTPβ/ζ expression and on their signaling pathways in the ventral tegmental area (VTA). Present results indicated that PTN, MK, and RPTPβ/ζ levels increased after acute morphine injection, returned to basal levels during chronic opioid treatment, and were upregulated again during morphine withdrawal. We also observed an activation of astrocytes after acute morphine injection and during opiate dependence and withdrawal. In addition, immunofluorescence analysis revealed that PTN, but not MK, was overexpressed in astrocytes and that dopaminergic neurons expressed RPTPβ/ζ. Interestingly, p-ERK 1/2 levels during chronic morphine and morphine withdrawal correlated RPTPβ/ζ expression. All these observations suggest that the neuroprotective and behavioral adaptations that occur during opiate addiction could be, at least partly, mediated by these cytokines.
authors.affiliation: Group of Cellular and Molecular Pharmacology, Department of Pharmacology, University of Murcia, Campus de Espinardo, 30100, Murcia, Spain. daniel.garcia9@um.es.|IMIB, Instituto Murciano de Investigación Biosanitaria, Murcia, Spain. daniel.garcia9@um.es.
authors.forename: Daniel
authors.initials: D
authors.lastname: García-Pérez
authors.affiliation: Group of Cellular and Molecular Pharmacology, Department of Pharmacology, University of Murcia, Campus de Espinardo, 30100, Murcia, Spain.|IMIB, Instituto Murciano de Investigación Biosanitaria, Murcia, Spain.
authors.forename: M Luisa
authors.initials: ML
authors.lastname: Laorden
authors.affiliation: Group of Cellular and Molecular Pharmacology, Department of Pharmacology, University of Murcia, Campus de Espinardo, 30100, Murcia, Spain.|IMIB, Instituto Murciano de Investigación Biosanitaria, Murcia, Spain.
authors.forename: M Victoria
authors.initials: MV
authors.lastname: Milanés
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis*; D016207:Cytokines / Q000096:biosynthesis*; D004334:Drug Administration Schedule; D008297:Male; D000078792:Midkine; D009020:Morphine / Q000008:administration & dosage* / Q000009:adverse effects; D051381:Rats; D017208:Rats, Wistar; D054633:Receptor-Like Protein Tyrosine Phosphatases, Class 5 / Q000096:biosynthesis*; D013375:Substance Withdrawal Syndrome / Q000378:metabolism*; D017557:Ventral Tegmental Area / Q000187:drug effects / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D016207:Cytokines; C066845:pleiotrophin; D000078792:Midkine; D009020:Morphine; D054633:Receptor-Like Protein Tyrosine Phosphatases, Class 5
keywords: Glial fibrillary acidic protein; Midkine; Opiate dependence; Pleiotrophin; Reward pathway