RESUMO
BACKGROUND: Newborn neurons have bean shown to induce long-term potentiation (LTP). Activation of N-methyl-D-aspartic acid (NMDA) receptor subunit NR2B plays an important role in mature neurons-induced LTP. But there have been no reports addressing on the effects of NR2B activation on newborn neuron-induced LTP.OBJECTIVE: To investigate the effects of NR2B receptor antagonist Ro25-6981 on LTP induced by newborn neurons in adult rat dentate gyrus.DESIGN, TIME AND SETTING: An electrophysiological recording trial was performed at the Department of Neuroblology,Shanxi Medical University from February to June 2007.MATERIALS: Twenty-six male Wistar rats, aged 3 months, were provided by Laboratory Animal Center, Shanxi Medical University.METHODS: Following sacrifice for brain harvesting under anesthesia, the hippocempus was taken to preparation of 400 μ mol/L brain slices. Using extracellular field potential recordings, low-frequency stimulation was performed in the medial molecular layer of dentate gyrus with insulated bipolar tungsten electrodes. After having stable recordings, LTP was induced under high-frequency tetanic stimulation. LTP was induced with a protocol developed previously (4 trains, 500 ms each, 100 Hz within the train, repeated every 20 s). Only those slices which produced the field excitatory postsynaptic potential of 1 mV or cerebrospinal fluid (ACSF)-induced LTP (ACSF-LTP): brain slices were divided into 2 groups: ACSF group, in which, slices were continuously perfused using ACSF bubbled with 95% O2 and 5% CO2; ACSF+ Ro25-6981 group: a 10-minute treatment with 3μ mol/L Ro25-6981 was performed prior to tetanic stimulation, and the remaining procedures were the same as ACSF divided into 2 groups: BIC group: a 10-minute treatment with 10 μmol/L BIC was performed prior to titanic stimulation; BIC+Ro25-6981 group: 3μ mol/L Ro25-6981 and 10μ mol/L BIC were simultaneously perfused 10 minutes prior to tetanic stimulation.MAIN OUTCOME MEASURES: LTP recording results.minutes of titanic stimulation, LTP was (164.67±2.40)% and (147.56±6.63)% in the BIC and BIC+ Ro25-6981 groups,respectively, and a significant difference existed between the two groups (P ＜ 0.05).