title: [Effects of free radicals and amyloid beta protein on the currents of expressed rat receptors in Xenopus oocytes].
abstract: OBJECTIVE
  To investigate the effects of free radicals (FRs) and amyloid beta protein (A beta 1-40) on the functions of expressed neurotransmitter receptors (NRs) from rat brains in Xenopus oocytes.
  
  
  METHODS
  Total RNA and Messenger RNA (mRNA) was prepared from 3-month-old Wistar rat brain tissues with Promega kits and microinjected into mature Xenopus oocytes (stage V - VI) with 50 nl (50 ng) for each oocyte for receptor expression and their currents were recorded with double electrode voltage clamp technique. Superoxide anion free radicals (SAFRs) and A beta 1-40 was added 12 h, 24 h, 96 h to incubation solution before recording.
  
  
  RESULTS
  The results showed that oocytes expressed mACh, glutamate, dopamine, serotonin and gamma-aminobutyric acid receptors. The current characteristics of these receptors were inward currents carried by chloride ion with their equilibrium potentials close to - 22 mV. A beta 1-40 and free radicals had a kind of inhibitory effect on the expressed GluR. When treated with 60 nmol/L A beta 1-40 over 24 h, the currents of GluR significantly decreased (25% off, P < :0.01). When oocytes were co-treated with 60 nmol/L A beta 1-40 and SAFRs over a period of 12 h, the currents of glutamate receptor significantly decreased (21% of P < 0.05), and the decreased percentage reached 52% over 24h co-treated with 60 nmol/L A beta 1-40 and SAFRs. Vitamin E had partial antagonistic effect against these effects.
  
  
  CONCLUSIONS
  The result suggests that A beta has a kind of inhibitory effects upon glutamate receptor, which is similar to those of free radicals. Their effects can be antagonized by vitamin E. This implies that A beta may play roles via inhibiting receptor function in pathophysiology of Alzheimer's disease.
authors.affiliation: Department of Neurobiology, Institute of Gerontology and Geriatrics, Chinese PLA General Hospital and Postgraduate Medical School, Beijing 100853, China.
authors.forename: F N
authors.initials: FN
authors.lastname: Huang
authors.forename: B L
authors.initials: BL
authors.lastname: Zhang
authors.forename: W B
authors.initials: WB
authors.lastname: Li
authors.forename: X
authors.initials: X
authors.lastname: Cui
authors.forename: Z T
authors.initials: ZT
authors.lastname: Han
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Fang
mesh_terms: D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D005260:Female; D005609:Free Radicals / Q000494:pharmacology*; D008297:Male; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D017470:Receptors, Glutamate / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D014981:Xenopus
chemical_list: D016229:Amyloid beta-Peptides; D005609:Free Radicals; D010446:Peptide Fragments; D017470:Receptors, Glutamate; D017981:Receptors, Neurotransmitter; C078592:amyloid beta-protein (1-40)