• Brain research · Mar 1997

    Inhalation anesthetics suppress the expression of c-Fos protein evoked by noxious somatic stimulation in the deeper layer of the spinal cord in the rat.

    • S Hagihira, N Taenaka, and I Yoshiya.
    • Department of Anesthesiology, Osaka University Medical School, Japan. hagihira@anes.med.osaka-u.ac.jp
    • Brain Res. 1997 Mar 14; 751 (1): 124-30.

    AbstractThe effects of inhalation anesthetics, nitrous oxide (N2O) and halothane, on the expression of c-Fos protein evoked by formalin injection were studied in the spinal cord in the rat. The expression of c-Fos protein was detected by immunocytochemistry following the injection of formalin (5%, 100 microliters) into the plantar surface of the left hindpaw. After 15 min of halothane (F) anesthesia, the anesthetics was switched to 40% or 70% of N2O, 0.5% or 1.5% of F or room air (for control) immediately following the formalin injection. Two hours later the rats were sacrificed and perfused. Sections of the L4 level of spinal cord were immunostained with anti c-Fos antibody. We counted the number of Fos-like immunoreactive (FLI) cells in every specific lamina as follows: superficial layer (laminae I and II), nucleus proprius (laminae III and IV), neck of the dorsal horn (laminae V and VI) and ventral gray (laminae VII-X). Then we compared the results of each category of sample. Both N2O and halothane suppressed the expression of c-Fos in the neck of the dorsal horn and ventral gray in a dose-dependent manner, but no effects were seen at the superficial layer or nucleus proprius. Suppression of c-Fos expression was greater under N2O than halothane anesthesia. This finding suggests that N2O had a stronger analgesic effect than halothane. The current study indicates that inhalation anesthetics do not act equally on every kind of spinal neurons. Both N2O and halothane have effects on spinal neurons in the deeper layers but not on the neurons existed in laminae I-II, some of which directly receive noxious inputs. Pretreatment with 2 mg/kg of naloxone, which completely reversed the effects of morphine, did not alter the effect of 70%N2O, suggesting that the analgesic effect of N2O is not mediated by an intrinsic opioid mechanism at the spinal cord level.

      Pubmed     Full text   Copy Citation     Plaintext  

      Add institutional full text...

    Notes

     
    Knowledge, pearl, summary or comment to share?
    300 characters remaining
    help        
    You can also include formatting, links, images and footnotes in your notes
    • Simple formatting can be added to notes, such as *italics*, _underline_ or **bold**.
    • Superscript can be denoted by <sup>text</sup> and subscript <sub>text</sub>.
    • Numbered or bulleted lists can be created using either numbered lines 1. 2. 3., hyphens - or asterisks *.
    • Links can be included with: [my link to pubmed](http://pubmed.com)
    • Images can be included with: ![alt text](https://bestmedicaljournal.com/study_graph.jpg "Image Title Text")
    • For footnotes use [^1](This is a footnote.) inline.
    • Or use an inline reference [^1] to refer to a longer footnote elseweher in the document [^1]: This is a long footnote..

    hide…