A method to quantify glial fibrillary acidic protein immunoreactivity on the suprachiasmatic nucleus

The aim of the present study was to develop a quantitative method to measur e the immunoreactivity of the glial fibrillary acidic protein on the suprac hiasmatic nucleus of hamster. For this purpose, optical microscopy images f rom brain sections processed for glial fibrillary acidic protein immunostai ning were digitised under different light conditions. Image treatment and i mmunoreactivity quantification were performed following five different meth ods using the program Adobe Photoshop(R). The results were analysed in orde r to determine the ability of each method to differentiate immunoreactivity levels, and their susceptibility to the light conditions during image acqu isition. Four of the five methods were found to be susceptible to the teste d light conditions, while the other was not. This last method, which permit s detection of differences in immunoreactivity between the different sectio ns, was considered for further quantification of glial fibrillary acidic pr otein immunoreactivity on the suprachiasmatic nucleus. (C) 1999 Elsevier Sc ience B.V. All rights reserved.