Neuronal activity in the periaqueductal gray associated with chronic cannula implantation and microdialysis

Chronic cannula implantation 및 microdialysis가 periaqueductal gray내 신경세포 활성에 미치는 영향

Immunohistochemical technique of the c-fos primary gene protein, Fos, was used to analyze the effects of external factors on the neuronal activities in the periaqueductal gray(PAG) of the intact rats, sham-operated rats and post-operated stress control rats. In addition, the number of Fos positive neurons has been evaluated to verify the effects of cannula implantation and veratridine treatment on the neuronal activities in PAG area. The results were summerized as follow : 1. There was no significant difference in the number of Fos positive neurons observed in the caudal and middle portion of lateroventral PAG from cannula implanted rats and sham operated rats. 2. The number of Fos positive neurons in the PAG was not changed by the stress induced by connection of collecting tube to rats for 12 hours as compared to that of intact rats. 3. In the saline treated group, the Fos immunoreactivity in the PAG did not changed at 30 minutes and 1 hour after saline treatment as compared to that of intact rats. However, the number of Fos positive neurons was significantly increased at 2 hours after treatment compared to that of saline treated rats at 30 minutes after treatment. 4. The Fos immunoreactivity was dramatically increased at 30 minutes, 1 hour and 2 hours after veratridine treatment as compared to those of saline treated groups. The number of Fos immunoreative neurons showed the maximal level at 2 hours after veratridine treatment. 5. The Fos positive neurons induced by saline and veratridine treatment were mainly distributed in front of the microdialysis window. These results suggest that new microdialysis demonstrated in this study improves efficiency and accuracy to confine the neuronal activity in front of microdialysis window site. Moreover, this directional specificity allows us to locate probe tips adjacent to the brain area of the interest site rather than centering the probes within that brain area. Finally, This microdialysis method can be used to dialyse the neurotransmitters using concious and freely moving rats.