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Inhibiting astrocytic activation: a novel analgesic mechanism of ketamine at the spinal level?
Author(s) -
Mei Xiaopeng,
Wang Wei,
Wang Wen,
Li Yunming,
Zhang Hui,
Wu Shengxi,
Li Yunqing,
Xu Lixian
Publication year - 2009
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2009.06087.x
Subject(s) - neuropathic pain , ketamine , analgesic , medicine , intraperitoneal injection , astrocyte , nociception , pharmacology , morphine , anesthesia , central nervous system , receptor
Although ketamine is widely used as an analgesic agent and has an anti‐allodynic effect on neuropathic pain, the underlying analgesic mechanisms are not fully explained by the modern ‘neuronal‐based’ theories. As emerging studies have focused on the critical role of spinal astrocytes in the pathological pain states, we have hypothesized that there exist some ‘astrocytes‐related’ mechanisms in the analgesic function of ketamine. In the present study, using the spinal nerve ligation (SNL) pain model, we investigated the anti‐nociceptive effects of intraperitoneal or intrathecal ketamine on SNL‐induced neuropathic pain response, meanwhile, we investigated the astrocytic activation after ketamine administration on SNL rats. Behavioral data showed that either intraperitoneal or intrathecal ketamine inhibited SNL‐induced allodynia, however, immunohistochemistry showed that SNL induced astrocytic activation was suppressed by intrathecal but not intraperitoneal ketamine. Using quantitative Western blot analysis, our report showed that intrathecal ketamine down‐regulated glial fibrillary acidic protein expression, suggesting inhibition of SNL‐induced astrocytic activation, which wasn’t influenced by intraperitoneal administration. We conclude that intraperitoneal ketamine could alleviate SNL‐induced neuropathic pain via the classical ‘neuronal‐based’ mechanisms, but in addition, ‘astrocytes‐related’ mechanisms were also important underlying the anti‐allodynic effect of intrathecal ketamine.