title: Brain region differences in regulation of Akt and GSK3 by chronic stimulant administration in mice.
abstract: Acute amphetamine administration activates glycogen synthase kinase-3 (GSK3) by reducing its inhibitory serine-phosphorylation in mouse striatum and cerebral cortex. This results from Akt inactivation and is required for certain behavioral effects of amphetamine, such as increased locomotor activity. Here we tested if regulation of Akt and GSK3 was similarly affected by longer-term administration of amphetamine, as well as of methylphenidate, since each of these is administered chronically in patients with attention deficit hyperactivity disorder (ADHD). Akt is activated by post-translational phosphorylation on Thr308, and modulated by Ser473 phosphorylation, whereas phosphorylation on Ser21/9 inhibits the two GSK3 isoforms, GSK3α and GSK3β. After eight days of amphetamine or methylphenidate treatment, striatal Akt and GSK3 were dephosphorylated similar to reported changes after acute amphetamine treatment. Oppositely, in the cerebral cortex and hippocampus Akt and GSK3 phosphorylation increased after eight days of amphetamine or methylphenidate treatment. These opposite brain region changes in Akt and GSK3 phosphorylation matched opposite changes in the association of Akt with β-arrestin and GSK3, which after eight days of amphetamine treatment were increased in the striatum and decreased in the cerebral cortex. Thus, whereas the acute dephosphorylating effect of stimulants on Akt and GSK3 in the striatum was maintained, the response switched in the cerebral cortex after eight days of amphetamine or methylphenidate treatment to cause increased phosphorylation of Akt and GSK3. These results demonstrate that prolonged administration of stimulants causes brain region-selective differences in the regulation of Akt and GSK3.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Miller School of Medicine, University of Miami, Miami, FL 33136, United States.
authors.forename: Marjelo A
authors.initials: MA
authors.lastname: Mines
authors.forename: Richard S
authors.initials: RS
authors.lastname: Jope
mesh_terms: D000661:Amphetamine / Q000008:administration & dosage*; D000818:Animals; D019390:Arrestins / Q000378:metabolism; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy; D001931:Brain Mapping; D000697:Central Nervous System Stimulants / Q000008:administration & dosage; D002540:Cerebral Cortex / Q000187:drug effects; D003342:Corpus Striatum / Q000187:drug effects; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006624:Hippocampus / Q000187:drug effects; D008774:Methylphenidate / Q000008:administration & dosage; D051379:Mice; D008810:Mice, Inbred C57BL; D051058:Oncogene Protein v-akt / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects*; D015398:Signal Transduction; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; D000697:Central Nervous System Stimulants; D000071557:beta-Arrestins; D008774:Methylphenidate; D000661:Amphetamine; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D051058:Oncogene Protein v-akt; D038362:Glycogen Synthase Kinase 3