Membrane conductance oscillations in astrocytes induced by phorbol ester

Area of Science:

• Neuroscience
• Cellular Biology
• Neurophysiology

Background:

• Glial cells, particularly astrocytes, play crucial roles in the central nervous system (CNS).
• The complex interplay between glial cells and neurons hinders the study of astrocyte functions.
• A neuron-free preparation is needed to isolate and study astrocyte behavior.

Purpose of the Study:

• To investigate the effects of activating protein kinase C in CNS astrocytes.
• To characterize the biophysical properties of astrocytes in a neuron-free preparation.
• To explore how astrocyte activity influences neuronal excitability.

Main Methods:

• Development of a neuron-free preparation using kainic acid-lesioned hippocampal slices.
• Activation of protein kinase C in astrocytes using the phorbol ester TPA (12-O-tetradecanoyl-phorbol-13-acetate).
• Electrophysiological recordings to measure membrane potential and input resistance.

Main Results:

• TPA induced rhythmic oscillations (0.1-3.0 Hz) in astrocyte membrane potential.
• These oscillations were associated with significant increases (up to eightfold) in input resistance during depolarization.
• Demonstrated endogenous, activity-dependent changes in astrocyte membrane conductance.

Conclusions:

• Astrocytes possess the intrinsic ability to generate significant conductance changes.
• These astrocyte-generated conductance changes can modulate the excitability of surrounding neurons.
• Altered extracellular ion concentrations due to astrocyte activity may influence neuronal function.