title: Aquaporin 4 knockout resists negative regulation of neural cell proliferation by cocaine in mouse hippocampus.
abstract: Our previous study revealed that aquaporin 4 (AQP4) knockout attenuated locomotor activity in cocaine exposure mice and reduced the extracellular dopamine levels in the nucleus accumbens, suggesting that AQP4 might participate in cocaine addiction. The aim of the present study was to investigate the impact of AQP4 on cell proliferation of dentate gyrus in the mouse hippocampus after repeated cocaine treatment and withdrawal. The immunohistochemistry results showed that repeated cocaine administration significantly decreased cellular proliferation in the subgranular zone, which was followed by a rebound increase after 2-wk withdrawal and a return to normal level after 3-wk withdrawal. AQP4 knockout resisted cocaine-induced reductions of neural cell proliferation. Further studies through immunohistochemistry and immunoblot analysis showed that AQP4 knockout sustained the levels of glial fibrillary acidic protein in the hippocampus, and suppressed the enhancement of extracellular signal-regulated kinase phosphorylation induced by repeated cocaine administration. Notably, AQP4 knockout increased protein kinase C activity examined by substrate protein phosphorylation method, which was not affected by cocaine administration or withdrawal. We also found that repeated cocaine administration could elevate the expression of AQP4 in wild-type mice. In conclusion, it is reported for the first time that AQP4 knockout resisted cocaine-mediated inhibition of neural cell proliferation via up-regulating PKC-mediated signal transduction, suggesting that AQP4 might regulate neurogenesis during drug addiction. Our findings may have helpful implications in the cell biology of neurogenesis.
authors.affiliation: Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu, P.R. China.
authors.forename: Lu-Lu
authors.initials: LL
authors.lastname: Xie
authors.forename: Xiu-Lan
authors.initials: XL
authors.lastname: Sun
authors.forename: Yi
authors.initials: Y
authors.lastname: Fan
authors.forename: Hui
authors.initials: H
authors.lastname: Kong
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Ding
authors.forename: Gang
authors.initials: G
authors.lastname: Hu
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D051401:Aquaporin 4 / Q000172:deficiency*; D001253:Astrocytes / Q000187:drug effects; D001973:Bromodeoxyuridine / Q000378:metabolism; D002452:Cell Count / Q000379:methods; D049109:Cell Proliferation / Q000187:drug effects; D003042:Cocaine / Q000494:pharmacology*; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology*; D004334:Drug Administration Schedule; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology* / Q000187:drug effects; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009474:Neurons / Q000187:drug effects*; D011493:Protein Kinase C / Q000378:metabolism; D011897:Random Allocation
chemical_list: C496031:Aqp4 protein, mouse; D051401:Aquaporin 4; D018765:Dopamine Uptake Inhibitors; D005904:Glial Fibrillary Acidic Protein; D011493:Protein Kinase C; D048049:Extracellular Signal-Regulated MAP Kinases; D001973:Bromodeoxyuridine; D003042:Cocaine