A Basic Study For The Role Of Nitric Oxide On The Nociceptive Transmission Of Migraine Attacks

Objection:1. To build a reliable animal model that can mimic the acute migraine attacks and can be used in the basic research on the mechanism, therapeutical drugs and other approaches of vascular headaches such as migraine.2. To observe the role of nitric oxide on the nociceptive transmission of migraine attacks.Methods:1. The preparation and evaluation of animal model: 20 short-hair cats weighted 2.5~3.5Kg were randomly divided into three blocks: the 4h, 8h and 20h blocks, then each block was divided into two-paired groups: the sham-operation group and the stimulation group. The cats were anesthetized with Ketamine (0.01 ml/kg, i.m.) for animals, and then were drilled on their cranium to expose the SSS. The dura mater along with SSS of cats in the stimulation groups was electrically stimulated with square wave current (250us, 1.5mA, 3Hz) for 2 hours at 4, 8 or 20 hours after the operation. No cat was stimulated in the sham-operation groups. 1 hour later, cats were paralyzed and perfused to fix, which the brainstem and the superior cervical spinal cord were removed and post-fixed. The expression of c-fos immuno-reactivity was detected with immunohistochemical method.2. The role of NO in the central nociceptive transmission of trigeminovascular system: 40 short-hair cats weighted 2.5~3.5Kg were randomly divided into the sham-operation group, the stimulationgroup, the saline group, L-NAME ( 100mg/kg ) group and 7-NI (10mg/kg ) group. The expression of c-fos and nNOS immunoreactivities was observed in the successive frozed slices of the brainstem and the super cervical spinal cord of cats after different treatment. Result:1. The preparation and evaluation of animal model: The c-fos immunoreactive positive neurons were observed in laminae I and II of the trigeminal nucleus caudalis, the dorsal horn of the Ci segment of the cervical cord, the commissural and medial nuclei of the solitary tract and the laminae X of the upper cervical cord. The number of c-fos immunoreactive positive neurons in the sham-operation groups was timely decreased. The number of c-fos immunoreactive positive neurons increased markedly in the stimulation groups of the 8h and the 20h block, comparing with the corresponding sham-operation groups.2. The effects of NOS inhibitor on the expression of c-fos: The number of c-fos immunoreactive positive neurons was markedly decreased in the L-NAME group and the 7-NI group comparing with the stimultion group and the saline group, although there was no significant difference between the L-NAME group and the 7-NI group. The number of c-fos immunoreactive positive neurons was significantly increased in the stimultion group and the saline group comparing with the sham-operation group, but there was no significant difference between the stimulation group and the saline group.3. The effect of NOS inhibitor on the expression of nNOS: The neuronswith expression of nNOS immunoreactivity were mainly stained at cytoplasm and were concentrated in the superficial layers (laminae I and II) of the trigeminal nucleus caudalis and the dorsal horn of theCi segment of the cervical cord, similar to the location of c-fos immunoreactive positive neurons. A few of larger, axon-elongated nNOS positive cells were observed in the deep layers, in the commissural and medial nuclei of the solitary tract and the bilateral area of the central canal. Moreover, the nNOS-labelled fibers spreaded over the dorsal horn and the bilateral gray mater of central canal, seemed to project to the ventral, and the superificial layers of dorsal horn where the staining is darker than in any other areas. The longer stained-axon became beaded-like after stimulation. The number of neurons with expression of nNOS immunoreactivity was significantly increased in the stimultion group comparing with the sham-operation group, but there was no significant difference comparing with the saline group. There were significantl...