| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 2001: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2000: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
The effects of inhalation anesthetics, enflurane, isoflurane, and sevoflurane, on the expression of c-Fos protein evoked by formalin injection were studied in the spinal cord in the rat. Male Sprague-Dawley rats were allocated to four treatment groups: 100% oxygen (control, n=6), 3.3% enflurane (1.5MAC, N=6), 2.1% isoflurane (1.5MAC, N=6)4.0%, sevoflurane (1.5 MAC, n=6) for 30 nun. Each rat then received a s.c. inject of 5/o formahn 100μ1 into the left hind paw and anesthesia was maintained. Three hours later the rats were sacrificed and perfused. Section of the Ll〜6 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.
In the sections of L3 and L4 level, the numbers of FLI labeled neurons for groups given enflurane, isoflurane, and sevoflurane were 40 to 50 % less than the control (p<0.05). The decrease occurred predominantly in the deeper layer of the dorsal horn (laminae III〜VI) and ventral gray (laminae VII〜X) but not on the neurons existed in superficial layer (laminae I〜II).
This finding was consistent with the results of the previous studies concerned with halothane. These suggested that most inhalation anesthetics have effects on spinal neurons in the deeper layers, some of which directly receive noxious inputs. Our study failed to confirm previous findings that enflurane and sevoflurane augment the afferent signals evoked by the noxious stimulation.
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