Gelatin Zymography Can Be Performed on Fixed Brain Tissue

Area of Science:

• Biochemistry
• Histochemistry
• Neuroscience

Background:

• Gelatin zymography is standard for detecting gelatinase activity, typically on fresh tissue due to concerns about fixation inactivating enzymes.
• Fixed tissues offer advantages like preventing decay and preserving morphology, but their use in zymography is limited by enzyme inactivation fears.

Purpose of the Study:

• To investigate the impact of common fixatives (ethanol, acetone, ZBF, PFA) on gelatinolytic activity in mouse brain tissue.
• To identify effective protein extraction protocols for fixed brain tissues that preserve enzymatic activity for zymography.

Main Methods:

• Mouse brain tissues were fixed using ethanol, acetone, ZBF, and PFA.
• Protein extraction was performed using various solutions (Triton, DMSO, urea, CHAPS, SDS).
• Gelatinase activity and protein presence were assessed using in situ zymography (ISZ) and Western blotting/in-gel zymography (IGZ).

Main Results:

• Ethanol, acetone, ZBF, and short-time PFA fixation did not inhibit gelatinolytic activity detectable by ISZ.
• Urea/CHAPS and SDS solutions effectively extracted gelatinase proteins from certain fixed tissues while retaining activity.
• SDS with heating extracted proteins from all fixatives but abolished gelatinolytic activity.

Conclusions:

• Gelatin zymography (ISZ and IGZ) is feasible on fixed brain tissue, overcoming limitations of fresh tissue use.
• Optimized protein extraction protocols are crucial for successful analysis of gelatinase activity in fixed specimens.
• This approach offers an improvement over conventional zymography by enabling analysis on preserved tissue structures.