Neuroscience letters
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Neuroscience letters · Mar 2014
Sevoflurane induced amnesia inhibits hippocampal Arc expression partially through 5-hydroxytryptamine-7 receptors in the bilateral basolateral amygdala in rats.
This study aimed to investigate whether the regulation of 5-hydroxytryptamine-7 (5-HT7) receptors in the bilateral basolateral amygdala (BLA) could alter the amnesic effects of sevoflurane and change the hippocampal expression of Arc and neural apoptosis. Male Sprague-Dawley rats were randomized into ten groups. First, the animals received bilateral injection of SB269970 (20, 50, or 100 pmol/0.2 μl) or saline (0.2 μl) or AS-19 (2, 10, or 50 pmol/0.2 μl), followed by inhalation of 2% sevoflurane or air for 2h. ⋯ The largest dose of SB269970 (100 pmol) could block sevoflurane-induced amnesia and reverse the inhibitive effect of sevoflurane on Arc expression, while the maximal dose of AS-19 could exacerbate the amnesic effect, and further inhibit Arc expression. Furthermore, pre-training inhalation of 2% sevoflurane for 6h could not induce neural apoptosis in the hippocampus. The amnesic effect of sevoflurane might partly attribute to its impairment of memory formation in the hippocampus via activation of 5-HT7 receptors in the BLA.
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Neuroscience letters · Feb 2014
New therapeutic uses for an alpha2 adrenergic receptor agonist--dexmedetomidine in pain management.
Dexmedetomidine was initially approved for clinical use as a sedative. Its development in pain management has been limited. Dexmedetomidine has analgesic effects and analgesic-sparing properties, especially for patients with obstructed airways. ⋯ Dexmedetomidine has potential adverse effects such as hypotension and bradycardia. Therefore, dexmedetomidine is contraindicated for patients suffering from bradycardia or using β-adrenergic antagonists. Clinical trials of dexmedetomidine in chronic pain or hyperalgesia are lack.
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Neuroscience letters · Feb 2014
Application of intermittent galvanic vestibular stimulation reveals age-related constraints in the multisensory reweighting of posture.
In this study we examined the effects of intermittent short-duration Galvanic Vestibular Stimulation (GVS) during a multisensory perturbation of posture in young and elderly adults. Twelve young (24.91±6.44 years) and eleven elderly (74.8±6.42 years) participants stood upright under two task conditions: (a) quiet standing and (b) standing while receiving pseudo-randomly presented bipolar 2 s GVS pulses. ⋯ Intermittent GVS decreased the excessive postural sway induced by the concurrent visual and proprioceptive perturbation in young but not in elderly participants. It is suggested that GVS increases sensory reliance on the vestibular system while elderly adults are less able to exploit this stimulation in order to reduce the destabilizing effect of the multisensory perturbation on their posture.
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Using functional magnetic resonance imaging in human participants, we show that sedation by propofol to the point of lost overt responsiveness during the performance of an auditory verbal memory task unexpectedly increases functional connectivity of the precuneus with cortical regions, particularly the dorsal prefrontal and visual cortices. After recovery of consciousness, functional connectivity returns to a pattern similar to that observed during the wakeful baseline. In the context of a recent proposal that highlights the uncoupling of consciousness, connectedness, and responsiveness in general anesthesia, the increased precuneus functional connectivity under propofol sedation may reflect disconnected endogenous mentation or dreaming that continues at a reduced level of metabolic activity.