Cognitive recovery by chronic activation of the large-conductance calcium-activated potassium channel in a mouse model of Alzheimer's disease. (May 2015)

• Record Type: Journal Article
• Authors: Wang, Li; Kang, Huicong; Li, Yongzhi; Shui, Yuan; Yamamoto, Ryo; Sugai, Tokio; Kato, Nobuo
• Is Part Of: Neuropharmacology. Volume 92(2015)
• Page Start: 8
• Page End: 15
• Publication Date: 2015-05
• Subjects: Large conductance calcium-activated potassium channels -- Alzheimer's disease -- Excitability -- Synaptic plasticity -- Learning and memory; Neuropsychopharmacology -- Periodicals; Autonomic Agents -- Periodicals; Neuropsychopharmacologie -- Périodiques; Neuropsychopharmacology; Periodicals; Electronic journals; 615.78
• DOI: 10.1016/j.neuropharm.2014.12.033
• Languages: English
• ISSNs: 0028-3908

Abstract

Abstract: We previously showed that activity of the large conductance calcium-activated potassium (Big-K; BK) channels is suppressed in 3xTg Alzheimer disease (AD) model mice. However, its behavioral significance is not known. In the present report, ventricular injection of the BK channel activator isopimaric acid (ISO) was conducted to examine whether BK channel activation ameliorates cognition in 3xTg mice. The novel object recognition (NOR) test revealed that chronic injection of ISO improved non-spatial memory in 3xTg mice. In the Morris water maze, the probe test demonstrated an improved spatial memory after ISO injection. Electrophysiological underpinnings of the ISO effect were then examined in slices obtained from the mice after behavior. At hippocampal CA1 synapses, the basic synaptic transmission was abnormally elevated and long-term potentiation (LTP) was partially suppressed in 3xTg mice. These were both recovered by ISO treatment. We then confirmed suppressed BK channel activity in 3xTg mice by measuring the half-width of evoked action potentials. This was also recovered by ISO treatment. We previously showed that the recovery of BK channel activity accompanies reduction of neuronal excitability in pyramidal cells. Here again, pyramidal cell excitability, as assessed by calculating the frequency of evoked spikes, was elevated in the 3xTg mouse and was normalized by ISO. ELISA experiments demonstrated an ISO-induced reduction of Aβ1–42 content in hippocampal tissue in 3xTg mice. The present study thus suggests a potential therapeutic utility of BK channel activators for AD. Highlights: The BK channel activator isopimarate ameliorated cognition in Alzheimer's model mice. The BK channel activator was chronically injected into the lateral ventricle. Hippocampal synaptic transmission and plasticity was normalized. An Aβ-lowering effect by isopimarate was demonstrated by ELISA. BK channel activation may be potential measures against Alzheimer's disease.