Objective To investigate the effects of free radicals (FRs) and amyloid β protein 1 40 (Aβ 1 40 ) on the functions of expressed neurotransmitter receptors (NRs) 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 maturated Xenopus oocytes (stages Ⅴ Ⅵ) with 50?nl (50?ng) for each oocyte The microinjected oocytes were incubated with modified Bath's solution at 19 0℃±1 0℃ for receptor expression and their currents were recorded with double electrode voltage clamp technique Superoxide anion free radicals (SAFRs) were produced via a reaction system (HPX/XO) with hypoxanthine (HPX, 0 05?mol/L) and xanthine oxidase (XO, 0 1?U/L) In order to observe the effects of Aβ and SAFRs on the expressed glutamate receptor, HPX/XO and Aβ 1 40 were added to incubation solution at 12?h, 24?h and 96?h before recording Results The results showed that the oocytes expressed functional NRs originating from rat brain tissues These NRs included muscarinic acetylcholine (mACh), glutamate (Glu), dopamine (DA), serotonin (5 HT) and γ aminobutyric acid (GABA) The current characteristics of expressed receptors were inward currents carried by chloride ion with their equibrilium potentials close to -22?mV The extent of effect on the current of expressed glutamate receptor from rat brain was different among different Aβ concentrations and incubation times Aβ 1 40 at a concentration of 20?nmol/L had little effect on the currents of expressed rat brain glutamate receptors up to 24?h of incubation period; but the currents of glutamate receptor were significantly decreased (25% off, P <0 01) in the treatment of 60?nmol/L Aβ 1 40 over 24?h Moreover, when 20?nmol/L Aβ 1 40 was co incubated over 12?h with SAFRs produced by the reaction system of HPX/XO, it was found that the currents of expressed rat brain glutamate receptors had been cha
