title: Unique Effects of Acute Aripiprazole Treatment on the Dopamine D2 Receptor Downstream cAMP-PKA and Akt-GSK3β Signalling Pathways in Rats.
abstract: Aripiprazole is a wide-used antipsychotic drug with therapeutic effects on both positive and negative symptoms of schizophrenia, and reduced side-effects. Although aripiprazole was developed as a dopamine D2 receptor (D2R) partial agonist, all other D2R partial agonists that aimed to mimic aripiprazole failed to exert therapeutic effects in clinic. The present in vivo study aimed to investigate the effects of aripiprazole on the D2R downstream cAMP-PKA and Akt-GSK3β signalling pathways in comparison with a D2R antagonist--haloperidol and a D2R partial agonist--bifeprunox. Rats were injected once with aripiprazole (0.75 mg/kg, i.p.), bifeprunox (0.8 mg/kg, i.p.), haloperidol (0.1 mg/kg, i.p.) or vehicle. Five brain regions--the prefrontal cortex (PFC), nucleus accumbens (NAc), caudate putamen (CPu), ventral tegmental area (VTA) and substantia nigra (SN) were collected. The protein levels of PKA, Akt and GSK3β were measured by Western Blotting; the cAMP levels were examined by ELISA tests. The results showed that aripiprazole presented similar acute effects on PKA expression to haloperidol, but not bifeprunox, in the CPU and VTA. Additionally, aripiprazole was able to increase the phosphorylation of GSK3β in the PFC, NAc, CPu and SN, respectively, which cannot be achieved by bifeprunox and haloperidol. These results suggested that acute treatment of aripiprazole had differential effects on the cAMP-PKA and Akt-GSK3β signalling pathways from haloperidol and bifeprunox in these brain areas. This study further indicated that, by comparison with bifeprunox, the unique pharmacological profile of aripiprazole may be attributed to the relatively lower intrinsic activity at D2R.
authors.affiliation: Antipsychotic Research Laboratory, Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia; Centre for Translational Neuroscience, School of Medicine, University of Wollongong, Wollongong, NSW, Australia.
authors.forename: Bo
authors.initials: B
authors.lastname: Pan
authors.affiliation: Antipsychotic Research Laboratory, Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.
authors.forename: Jiezhong
authors.initials: J
authors.lastname: Chen
authors.affiliation: Antipsychotic Research Laboratory, Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia; Centre for Translational Neuroscience, School of Medicine, University of Wollongong, Wollongong, NSW, Australia.
authors.forename: Jiamei
authors.initials: J
authors.lastname: Lian
authors.affiliation: Centre for Translational Neuroscience, School of Medicine, University of Wollongong, Wollongong, NSW, Australia.
authors.forename: Xu-Feng
authors.initials: XF
authors.lastname: Huang
authors.affiliation: Antipsychotic Research Laboratory, Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia; Centre for Translational Neuroscience, School of Medicine, University of Wollongong, Wollongong, NSW, Australia.
authors.forename: Chao
authors.initials: C
authors.lastname: Deng
mesh_terms: D000818:Animals; D000068180:Aripiprazole / Q000494:pharmacology*; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D008297:Male; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D017207:Rats, Sprague-Dawley; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D017448:Receptors, Dopamine D2; D000068180:Aripiprazole; D000242:Cyclic AMP; D000071679:Glycogen Synthase Kinase 3 beta; C000605508:Gsk3b protein, rat; D051057:Proto-Oncogene Proteins c-akt; D017868:Cyclic AMP-Dependent Protein Kinases; D038362:Glycogen Synthase Kinase 3