Oligomeric β-Amyloid Suppresses Hippocampal γ-Oscillations through Activation of the mTOR/S6K1 Pathway.

Neuronal synchronization at gamma frequency (30-100 Hz: γ) is impaired in early-stage Alzheimer's disease (AD) patients and AD models. Oligomeric Aβ caused a concentration-dependent reduction of γ-oscillation strength and regularity while increasing its frequency. The mTOR1 inhibitor rapamycin prevented the Aβ-induced suppression of γ-oscillations, whereas the mTOR activator leucine mimicked the Aβ-induced suppression.

Metformin Ameliorates Synaptic Defects in a Mouse Model of AD by Inhibiting Cdk5 Activity.

Cyclin-dependent kinase 5 (Cdk5) is a serine/threonine kinase that is activated by the neuron-specific activators p35/p39 and plays important roles in neuronal development, synaptic plasticity, and cognitive behavior. However, the proteolytic cleavage of p35 to p25 leads to prolonged and aberrant Cdk5 activation and results in synaptic depression, highly mimicking the early pathology of Alzheimer's disease (AD). Therefore, Cdk5 inhibition is a potential promising strategy for AD drug development.

Selective dopamine receptor 4 activation mediates the hippocampal neuronal calcium response via IP and ryanodine receptors.

Intracellular calcium is a key factor in most cellular processes, including cell growth, differentiation, proliferation and neurotransmitter release. Dopamine (DA) mediates synaptic transmission by regulating the intracellular calcium content. It is not clear, however, which specific subunit of the DA receptor contributes to DA modulation of intracellular calcium content changes.

Acute Ethanol Inhibition of γ Oscillations Is Mediated by Akt and GSK3β.

Hippocampal network oscillations at gamma band frequency (γ, 30-80 Hz) are closely associated with higher brain functions such as learning and memory. Acute ethanol exposure at intoxicating concentrations (≥50 mM) impairs cognitive function. This study aimed to determine the effects and the mechanisms of acute ethanol exposure on γ oscillations in an in vitro model.

Atorvastatin enhances kainate-induced gamma oscillations in rat hippocampal slices.

Atorvastatin has been shown to affect cognitive functions in rodents and humans. However, the underlying mechanism is not fully understood. Because hippocampal gamma oscillations (γ, 20-80 Hz) are associated with cognitive functions, we studied the effect of atorvastatin on persistent kainate-induced γ oscillation in the CA3 area of rat hippocampal slices.

Nicotinic modulation of Ca2+ oscillations in rat cortical neurons in vitro.

The roles of nicotine on Ca(2+) oscillations [intracellular Ca(2+) ([Ca(2+)]i) oscillation] in rat primary cultured cortical neurons were studied. The spontaneous [Ca(2+)]i oscillations (SCO) were recorded in a portion of the neurons (65%) cultured for 7-10 days in vitro. Application of nicotine enhanced [Ca(2+)]i oscillation frequency and amplitude, which were reduced by the selective α4β2-nicotinic acetylcholine receptors (nAChRs) antagonist dihydro-β-erythroidine (DHβE) hydrobromide, and the selective α7-nAChRs antagonist methyllycaconitine citrate (MLA, 20 nM).

Early surgery of ruptured anterior circulation aneurysm based on multislice helical computerised tomography angiography.

The purpose of this study is to evaluate the utility of three-dimensional computed tomographic angiography (3D-CTA) as the primary diagnostic investigation in patients with spontaneous subarachnoid haemorrhage (SAH) from anterior circulation aneurysms, and to correlate the results with digital subtraction angiography (DSA) and intraoperative findings. From May 2005 to May 2007 a total of 38 consecutive patients admitted for SAH, suspicious for ruptured anterior circulation cerebral aneurysm, underwent 3D-CTA. Inclusion criteria were a SAH confirmed by a non-contrast head computed tomographic scan or by lumbar puncture.