Annals of the New York Academy of Sciences
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Ann. N. Y. Acad. Sci. · Jun 2010
Timing versus duration: determinants of anesthesia-induced developmental apoptosis in the young mammalian brain.
Rapidly accumulating evidence indicates that clinically used general anesthesia causes massive, widespread neuroapoptotic degeneration in the developing mammalian brain. Susceptibility to anesthesia-induced neurotoxicity has been documented in rats, mice, guinea pigs, primates, and in this study, piglets; in short, anesthesia-induced developmental neuroapoptosis is not species-dependent. ⋯ However, the highly reproducible findings in different species also indicate that the timing of exposure to anesthesia is critically important; that is, brain regions that are at the peak of synaptogenesis are most vulnerable even when the exposure to anesthesia is relatively brief. Because the peak of synaptogenesis is characterized by intense, highly programmed neuronal communication that is vital for the survival and proper function of immature neurons, we conclude that anesthesia causes severe disturbances in the fine equilibrium between excitatory and inhibitory neurotransmission in the developing mammalian brain, ultimately leading to neuronal redundancy and death.
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Ann. N. Y. Acad. Sci. · Jun 2010
Role of NKCC1 and KCC2 in the development of chronic neuropathic pain following spinal cord injury.
Neuropathic pain is a common problem following spinal cord injury (SCI). Effective analgesic therapy has been hampered by the lack of knowledge about the mechanisms underlying post-SCI neuropathic pain. Current evidence suggests GABAergic spinal nociceptive processing is a critical functional node in this complex phenotype, representing a potential target for therapeutic intervention. ⋯ Inhibition of NKCC1 with its potent antagonist bumetanide reduces pain behavior in rats following SCI. Moreover, the injured spinal cord tissues exhibit a significant transient upregulation of NKCC1 protein and a concurrent downregulation of KCC2 protein. Thus, imbalanced function of NKCC1 and KCC2 may contribute to the induction and maintenance of the chronic neuropathic pain following SCI.
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Ann. N. Y. Acad. Sci. · Jun 2010
Isoflurane modulates neuronal excitability of the nucleus reticularis thalami in vitro.
The thalamus has a key function in processing sensory information, sleep, and cognition. We examined the effects of a common volatile anesthetic, isoflurane, on modulation of neuronal excitability in reticular thalamic nucleus (nRT) in intact brain slices from immature rats. In current-clamp recordings, isoflurane (300-600 micromol/L) consistently depolarized membrane potential, decreased input resistance, and inhibited both rebound burst firing and tonic spike firing modes of nRT neurons. ⋯ Thus, at clinically relevant concentrations, isoflurane inhibits neuronal excitability of nRT neurons in developing brain via multiple ion channels. Inhibition of the neuronal excitability of thalamic cells may contribute to impairment of sensory information transfer in the thalamocortical network by general anesthetics. The findings may be important for understanding cellular mechanisms of anesthesia, such as loss of consciousness and potentially damaging consequences of general anesthetics on developing mammalian brains.
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The pathophysiology of fibromyalgia (FM) is not completely understood. The disease is characterized by a central sensitization with an amplification of pain perception. A combination of interactions among external stressors, behavioral constructs, neurotransmitters, hormones, immune, and sympathetic nervous systems appears to be involved. ⋯ Recent data highlight the putative role of cytokines in the pathogenesis of FM. The autonomic nervous system is implicated in the maintenance of the physiological homeostasis and sympathetic activity appears increased in FM. Neuropeptide Y and its receptors Y1 and Y2 seem to have a complex role in pain modulation.
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Fibromyalgia (FM) is a chronic pain syndrome characterized by widespread pain, fatigue, sleep alterations, and distress. Emerging evidence points toward augmented pain processing within the central nervous system as having a primary role in the pathophysiology of this disorder. Recent studies have identified distinct FM subgroups on the basis of clinical, neurochemical, and neuroendocrinological abnormalities, including increased cerebrospinal fluid levels of substance P and excitatory amino acids and functional abnormalities in the hypothalamic-pituitary-adrenal axis, and sympathoadrenal (autonomic nervous) system. ⋯ Antidepressants, nonsteroidal anti-inflammatory drugs, opioids, sedatives, muscle relaxants, and alpha2-delta agonists have all been used to treat FM with varying results. Physical exercise and multimodal cognitive-behavioral therapy seem to be the most widely accepted and beneficial forms of nonpharmacological therapy. Studies predicting treatment response indicate that it is useful if not essential to tailor the choice of treatment components to the needs of individual patients.