c-FOS expression after hippocampal deep brain stimulation in normal rats

Area of Science:

• Neuroscience
• Electrophysiology
• Molecular Biology

Background:

• Deep brain stimulation (DBS) is a therapeutic intervention used for various neurological disorders.
• Understanding the precise neural circuits affected by DBS is crucial for optimizing treatment efficacy and minimizing side effects.
• The inducible transcription factor c-FOS is a widely used marker for neuronal activity.

Purpose of the Study:

• To investigate the effects of unilateral hippocampal DBS on c-FOS expression in the normal rat brain.
• To determine the extent and duration of neural activation following hippocampal DBS.
• To explore potential differences in activation patterns between stimulated and non-stimulated brain regions.

Main Methods:

• Wistar rats underwent electrode implantation in the hippocampus for DBS.
• Animals were subjected to either one-hour or six-hour unilateral hippocampal stimulation sessions.
• Immunohistochemistry was used to visualize c-FOS expression, and electrocorticography monitored brain activity and seizures.

Main Results:

• Unilateral hippocampal DBS led to significant bilateral overexpression of c-FOS in the hippocampus, dentate gyrus, and hilus.
• Activation in CA1 and CA3 regions was predominantly ipsilateral, while the dentate gyrus and hilus showed more symmetric activation.
• Transient ipsilateral amygdala activation was observed after one hour of stimulation, but not after six hours.

Conclusions:

• Unilateral hippocampal DBS induces widespread and persistent bilateral activation within the rat limbic system.
• The observed activation patterns suggest a complex interplay between stimulated and non-stimulated neural pathways.
• These findings offer a foundational understanding of the mechanistic paradigm underlying hippocampal DBS.