Influence Of β1 Integrin In The Inhibition Of Long-term Potentiation Induced By β-amyloid

Object: The present study is to explain the influence of Itgβ1-subunit(Itg-β1) during the inhibition of LTP induced by Aβin the rats'hippocamal CA1 region in vivo. through electrophysiological technology.Materials and methods:All our experiments were carried out on male SD rats weight 250-300g, anaesthetized by 20% urethane solution (1.0-1.5g/kg, i.p.). Body temperature was controlled at about 37.0℃. The rats were fixed on the stereotaxic apparatus. Excitative postsynaptic potential(EPSP) were recorded in right hippocamal hemisphere, stratum radiatum in CA1 area in response to the stimulation of the ipsilateral Schaffer collateral-commissural pathway. Stereo location was according to the position of bregma: stimulating electrode located 4.2mm post-bregma and 3.8mm right of midline, recording electrode located 3.4mm post-bragma and 2.5mm right of midline, the hole for intracerebroventricular injection (i.c.v.) located 1.0mm post-bregma and 0.9mm right of midline. Physiology saline, Aβand specific inhibitor of Itg-β1 are applied separately and EPSPs are recorded persistently from 10min before vehicle applying to 3h after high frequency stimulate(HFS). Results:In the control, LTP was successfully induced(mean 144.0±16.0%, n=5), maximum 172.3%, appeared at about 120-150min after HFS; for the Aβtreated rats, LTP was significantly inhibited(mean 99.5±4.7%,n=5,p<0.001); in the JB1A treated ones, LTP presented obviously recovery, which was close to the control(mean 141.9±7.4%, n=5,p>0.05), maximum 159.2%,appeared at post-HFS 120-160min approximately. β-amyloid(Aβ) is the major component of extracelluar depositional plaques in the nervous systems of patients with Alzheimer disease(AD). There is evidence showing that exogenous Aβinhibits the inductiuon of long-term potentiation(LTP) in hippocampus. Several other studies have demonstrated that integrin (Itg) family plays an important mediate role in this inhibition. Itg includesα-subunit andβ-subunit. The present study aimed to evaluate the influence of Itgβ1-subunit(Itg-β1) during the inhibition of LTP induced by Aβin the rats'hippocamal CA1 region in vivo. We found that specific inhibitor of Itg-β1 prevented the inhibition of LTP, indicating that Itg-β1 mediated the inhibition of LTP, and its mechanism possibly occurred in the dysfunction of synapses before neuro-degeneration.