Institute of Neuroscience, Newcastle University, Medical School, Framlington Place, Newcastle-upon-Tyne NE2 4HH, UK; Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, BCMT-T728, Houston, TX 77030, USA.
Neuroscience. 2013 Dec 3;253:142-54. doi: 10.1016/j.neuroscience.2013.08.028. Epub 2013 Aug 28.
Noradrenaline (NA) in the hippocampus plays an important role in memory function and has been shown to modulate different forms of synaptic plasticity. Oscillations in the gamma frequency (20-80 Hz) band in the hippocampus have also been proposed to play an important role in memory functions and, evidence from both in vitro and in vivo studies, has suggested this activity can be modulated by NA. However, the role of different NA receptor subtypes in the modulation of gamma frequency activity has not been fully elucidated. We have found that NA (30 μM) exerts a bidirectional control on the magnitude of kainate-evoked (50-200 nM) gamma frequency oscillations in the cornu Ammonis (CA3) region of the rat hippocampus in vitro via activation of different receptor subtypes. Activation of alpha-adrenergic receptors (α-AR) reduced the power of the gamma frequency oscillation. In contrast, activation of beta-adrenergic receptors (β-AR) caused an increase in the power of the gamma frequency oscillations. Using specific agonists and antagonists of AR receptor subtypes we demonstrated that these effects are mediated specifically via α1A-AR and β1-AR subtypes. NA activated both receptor subtypes, but the α1A-AR-mediated effect predominated, resulting in a reversible suppression of gamma frequency activity. These results suggest that NA is able to differentially modulate on-going gamma frequency oscillatory activity that could result in either increased or decreased information flow through the hippocampus.
去甲肾上腺素（NA）在海马体中发挥着重要的记忆功能作用，并被证明可以调节不同形式的突触可塑性。海马体中γ频带（20-80 Hz）的振荡也被认为在记忆功能中起着重要作用，来自体外和体内研究的证据表明，这种活动可以被 NA 调节。然而，不同 NA 受体亚型在调节γ频带活动中的作用尚未完全阐明。我们发现，NA（30 μM）通过激活不同的受体亚型，对体外大鼠海马体 CA3 区中由海人藻酸（kainate）引发的（50-200 nM）γ频带振荡的幅度产生双向控制。α-肾上腺素能受体（α-AR）的激活减少了γ频带振荡的幅度。相比之下，β-肾上腺素能受体（β-AR）的激活导致γ频带振荡幅度增加。使用 AR 受体亚型的特异性激动剂和拮抗剂，我们证明这些效应是通过α1A-AR 和β1-AR 亚型特异性介导的。NA 激活了这两种受体亚型，但α1A-AR 介导的效应占主导地位，导致γ频带活动的可逆抑制。这些结果表明，NA 能够有差异地调节正在进行的γ频带振荡活动，从而导致海马体中的信息流增加或减少。
