Abstract: Objective To investigate the involvement of sympathetic nerve system in the transmission of nociceptive information related to vascular headache. Methods Fos expression in the midbrain periaqueductal grey (PAG) induced by electrical stimulation of dural matter near the superior sagittal sinus (SSS) of the rat was determined before and after the extirpation of the superior cervical ganglion (SCG) using standard avidin-biotin immunohistochemistry. Results Fos immunoreactive positive neurons were detected in the ventrolateral PAG, and were bilateral symmetry. Fos expression was (133.3±12.5) in SCG extirpated group, and higher than that in sham-operated group (76.0±11.3). Conclusion The sympathetic system may be involved in the transmission of nociceptive information through PAG, associated with vascular headache such as migraine.

Key words: sympathetic nerve, superior sagittal sinus(SSS), c-fos, midbrain periaqueductal grey(PAG), vascular headache