Correlation of the Expression Level of C1q mRNA and the Number of C1q-Positive Plaques in the Alzheimer Disease Temporal Cortex

• Published in: Dementia and geriatric cognitive disorders 2001, Vol.12 (4), p.237-242
• Main Authors: Tooyama, Ikuo, Sato, Haruhisa, Yasuhara, Osamu, Kimura, Hiroshi, Konishi, Yoshinori, Shen, Yong, Walker, Douglas G., Beach, Thomas G., Sue, Lucia I., Rogers, Joseph
• Format: Article
• Language: English
• Subjects: Original Research Article
• ISSN: 1420-8008; 1421-9824
• DOI: 10.1159/000051265

We compared the expression level of C1q mRNA and the number of C1q-positive plaques in adjacent or nearby brain sections from Alzheimer disease (AD) and control cases. Small blocks of temporal cortex were fixed with 4% paraformaldehyde for 2 days at 4°C. After cryoprotection with solutions containing 10–20% glycerol and 2% dimethylsulfoxide, 40-µm sections were cut from the tissue blocks. A section from each case was stained by immunohistochemistry using a C1q antibody, while RNA was purified from adjacent or nearby sections using a combination of proteinase K pretreatment followed by extraction using Trizol reagent. The expression of C1q B chain mRNA was analyzed in these samples by the reverse-transcription polymerase chain reaction (RT-PCR). The intensities of the PCR products were measured by an image analyzer. The expression of C1q B chain mRNA was significantly more abundant in AD than in control cases (p < 0.05). Immunohistochemical analysis showed that C1q protein was localized in senile plaques in the AD brain. The number of C1q-positive plaques correlated with the expression level of C1q gene (p < 0.05). The present results suggest that C1q protein in senile plaques originates is endogenously produced in the AD brain.