Neurons with intensely negatively charged extracellular matrix in the human visual cortex

Area of Science:

• Neuroscience
• Cell Biology
• Biochemistry

Background:

• Neurons possess unique surface coats with distinct biochemical properties.
• Understanding the composition of the neuronal extracellular matrix is crucial for comprehending neural function.

Purpose of the Study:

• To characterize the biochemical composition of the negatively charged surface coats on human visual cortex neurons.
• To investigate the relationship between these surface coats and specific cell surface glycoproteins.

Main Methods:

• Staining with cationic iron colloid and aldehyde fuchsin.
• Enzymatic digestion using hyaluronidase, chondroitinase ABC, heparitinase, and keratanase.
• Electron microscopy and lectin labeling with Vicia villosa agglutinin.

Main Results:

• The neuronal surface coats stained intensely with cationic iron colloid and aldehyde fuchsin.
• Hyaluronidase digestion removed both stains, while chondroitinase ABC, heparitinase, and keratanase only removed iron colloid staining.
• Electron microscopy showed cationic iron deposition in perineuronal spaces, indicating sulfated proteoglycans.
• Neurons with these coats were labeled by Vicia villosa agglutinin, but this labeling was unaffected by hyaluronidase digestion.

Conclusions:

• The surface coats of human visual cortex neurons are composed of sulfated proteoglycans within the perineuronal extracellular matrix.
• These sulfated proteoglycans are distinct from the cell surface glycoproteins recognized by Vicia villosa agglutinin.