C-fos is a marker of neuronal activity and its expression may be related to various types of stimulation of primary sensory neurons. We evaluated the effect of superior cervical ganglionectomy on c-fos expression in rat brain, which was expected to have the same effect as stellate ganglion block in human.

Male Sprague-Dawley rats (140-150 g) were divided into 4 groups; a no treatment (control group, n = 10), a 2 hour enflurane inhalation (anesthesia group, n = 10), a cervical skin incision only group (sham group, n = 10) and a superior cervical ganglionectomy group (sympathectomy group, n = 10). Two hours after each procedure, rats were killed and perfused with formaldehyde solution. c-fos protein expressions in the thalamus, hypothalamus, cortex, amygdala and cingulate gyrus were examined by immunohistochemistry using a specific antibody.

In the thalamus, c-fos expression increased in the sympathectomy group vs. the control and the anesthesia groups, and in the sham group vs. the control group. In amygdala, the sham group showed significantly higher c-fos expression than the control group. In the hypothalamus and cortex no significant differences among the 4 groups were apparent. In the cingulate gyrus higher c-fos expression was observed than the control and anesthesia group but no differences with sham group.

Superior cervical ganglionectomy itself may not affect c-fos expression in rat brain. For best results special effort should be made to avoid surgical or emotional stress.