British journal of anaesthesia
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General anaesthetics affect loss of consciousness by disrupting information-passing and integration within thalamo-cortical (TC) networks. Feedback cortical connections that carry internally generated signals such as expectation and attention appear more sensitive to anaesthesia than feedforward signals. However, direct evidence for this effect in non-primary cortex is lacking. In addition, direct comparisons between TC core and matrix, and between cortico-cortical (CC) feedforward and feedback responses have not been reported. ⋯ Differential sensitivity of CC feedback synaptic responses to isoflurane in a clinically relevant range suggests a role for disruption of these afferents in the hypnotic effects of anaesthetic agents.
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Nerve growth factor (NGF) has been implicated in hyperalgesia by sensitising nociceptors. A role for NGF in modulating myocardial injury through ischaemic nociceptive signalling is plausible. We examined whether inhibition of spinal NGF attenuates myocardial ischaemia-reperfusion injury and explored the underlying mechanisms. ⋯ Spinal NGF contributes to myocardial ischaemia-reperfusion injury by mediating nociceptive signal transmission.
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Orexin can facilitate emergence after general anaesthesia via multiple neural pathways. Dopaminergic neurones in the ventral tegmental area (VTA) participate in behavioural arousal from anaesthesia. We investigated the regulation of dopaminergic VTA neurones by orexinergic neurones during emergence from general anaesthesia. ⋯ Orexin promotes emergence from isoflurane anaesthesia through activation of dopaminergic neurones in the VTA.