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Cytochrome oxidase histochemistry in the rat hippocampus. A quantitative methodological study
1Department of Anatomy, University of Würzburg, Federal Republic of Germany.
Histochemistry
|January 1, 1988
Summary
This study optimized the diaminobenzidine (DAB) method for measuring cytochrome c oxidase (cyt ox) activity in rat hippocampus. Pretreatment enhanced cyt ox detection, revealing its mitochondrial localization.
Area of Science:
- Neuroscience
- Biochemistry
- Histochemistry
Background:
- Cytochrome c oxidase (cyt ox) is crucial for cellular respiration.
- Accurate microphotometric determination of cyt ox activity is vital for studying cellular function.
- Existing methods for cyt ox detection in rat hippocampus require optimization.
Purpose of the Study:
- To adapt and validate the diaminobenzidine (DAB) method for microphotometric determination of cytochrome c oxidase (cyt ox) in rat hippocampus.
- To investigate the effects of pretreatment methods on cyt ox activity detection.
- To determine the optimal conditions for kinetic and endpoint measurements of cyt ox activity.
Main Methods:
- Adaptation of the diaminobenzidine (DAB) method for microphotometric analysis.
- Qualitative and quantitative investigations using light microscopy.
- Ultracytochemical demonstrations for topochemical control.
- Optimization of incubation medium composition (DAB, PVA, DMSO, Hepes buffer).
- Kinetic and endpoint measurements to assess reaction linearity.
Main Results:
- Acetone and cytochrome c pretreatment significantly increased demonstrable cyt ox activities in cryostat sections.
- The optimized incubation medium contained 7.5 mM DAB, 2% PVA, 6% DMSO in 0.1 M Hepes buffer (pH 7.5).
- Linear reaction response was observed only in the initial 5-6 minutes.
- Ultracytochemistry confirmed reaction product localization exclusively in mitochondria (cristae and intermembranous space).
- Cryostat sections of aldehyde-fixed hippocampi showed positive mitochondrial reactions, unlike vibratome sections.
Conclusions:
- The adapted DAB method provides a reliable means for microphotometric determination of cyt ox activity in rat hippocampus.
- Pretreatment strategies, particularly acetone, enhance cyt ox detection sensitivity.
- Diffusion of DAB through mitochondrial membranes is a key factor influencing reaction efficiency, especially in ultracytochemistry.