Evoked release of tissue-bound exogenous [1--14C]acetylcholine from rat brain cortex slices

Area of Science:

• Neuroscience
• Neurochemistry

Background:

• Acetylcholine (ACh) is a key neurotransmitter in the central nervous system.
• Understanding the binding and release mechanisms of ACh is crucial for comprehending neuronal function.

Purpose of the Study:

• To investigate the release of exogenous, labeled acetylcholine ([14C]ACh) from rat brain cortex slices.
• To identify conditions that trigger the release of tissue-bound [14C]ACh.

Main Methods:

• Rat brain cortex slices were incubated with 5 mM [14C]ACh to allow binding.
• Slices were then exposed to various conditions in an ACh-free medium to assess [14C]ACh release.
• Conditions included high potassium ([K+]), absence of sodium (Na+) or calcium (Ca2+), and presence of protoveratrine or ouabain.

Main Results:

• Partially bound exogenous [14C]ACh was released by high [K+], Na+ or Ca2+ deprivation, protoveratrine, and ouabain.
• Protoveratrine-induced release was blocked by tetrodotoxin.
• These releasing stimuli affected approximately half of the bound [14C]ACh.
• Complete release was achieved with acid treatment or cell membrane dissolution.

Conclusions:

• The release of bound exogenous [14C]ACh is triggered by conditions similar to those releasing endogenous ACh.
• These findings provide insights into the complex binding and release dynamics of acetylcholine in the brain.