A Preliminary Study On Changes In Cortical Hemodynamics During Cortical Spreading Depression In Rats By Optical Imaging

Cortical spreading depression (CSD) is an important disease model for migraine and stroke. Previous studies showed that before the pial artery greatly dilation which were widely observed in CSD, there is also a small constriction occurring in pial arteries. However, the mechanisms contributing to the regulation of this cerebrovascular response remain unknown. As a brain functional imaging technique in vivo, the optical imaging based on intrinsic signals (OISI) offers the highest spatial resolution and proper temporal resolution thus for obtained.In this thesis, a spectroscopic recording of the change in optical intrinsic signal during CSD was performed and an analysis method based on the modified Beer-Lambert law was used to estimate the changes in the concentration of HbO2 and Hb, and changes in light scattering from the spectra data. In all experiments, four-phasic changes in optical reflectance were observed at 450 nm ~570 nm, and triphasic changes in optical reflectance were observed in the range of 570 nm ~750 nm. But at 750 nm ~ 850 nm, only biphasic changes of optical signal were detected. Converting the spectra data to the changes in light scattering and concentration of HbO2 and Hb, we found that the CSD induced an initial increase in concentration of HbO2, which was 26.2±18.6 s earlier than the onset of increase of Hb concentration. Furthermore, the concentration of HbO2 showed a four-phasic change, whereas the concentration of Hb only showed a biphasic change. For the changes in light scattering during CSD, a triphasic change was observed.Then, optical intrinsic signal imaging (OISI) at 550 nm wavelength was used to monitor the responses of the pial arteries during pinprick induced CSD following the application of a ATP-sensitive potassium channels(KATP)antagonist glibenclamide (glyb) and tolazamide (tola), the character of optical signals are used to compare with the control group which applied with artificial cerebrospinal fluid (aCSF) and reflect the pail artery and its dynamic development. By applying the glyb, the initial slight constriction (ISC) is obviously reduced, most of the ISC(10μM :74.5 % ; 100μM :96.2 %)even completely restrained. And the peak large dilation (LD)response of the pial arteries was enhanced to 53.8±19.3 % and 59.8±19.6 % of the control with 10μM and 100μM glyb, respectively. We conclude that KATP in nerve cells of pre and post-synaptically play a lead role in inhibiting CSD-associated hyperemia.