Rat brain mast cells: contribution to brain histamine levels

Area of Science:

• Neuroscience
• Immunology
• Biochemistry

Background:

• Mast cells (MCs) are found in the rat brain, primarily in the thalamus, and contain histamine (HA).
• The precise contribution of these MCs to overall brain HA levels remains under investigation.

Purpose of the Study:

• To quantify the relationship between mast cell numbers and histamine content in the rat brain.
• To determine the extent to which thalamic mast cells contribute to regional and whole-brain histamine levels.

Main Methods:

• Developed a method to simultaneously assess mast cell counts and histamine content from the same brain tissue.
• Performed correlational analyses between mast cell numbers and histamine levels (amount and concentration) in the thalamus and whole brain.

Main Results:

• Thalamic mast cell numbers showed a strong correlation with both the amount and concentration of histamine within the thalamus (p < 0.005).
• Histamine content per thalamic mast cell was estimated at 2.5 pg/cell in males and 1.3 pg/cell in females.
• Thalamic mast cell numbers correlated significantly with whole-brain histamine amounts and levels (p < 0.005), but not with histamine outside the thalamus.

Conclusions:

• Provides direct biochemical evidence that mast cells contribute significantly to brain histamine levels.
• Thalamic mast cells are a major source of histamine, accounting for up to 90% of thalamic HA and up to 50% of whole-brain HA.