Locus coeruleus input affects glucose metabolism in activated rat barrel cortex

Area of Science:

• Neuroscience
• Neurobiology
• Sensory Systems

Background:

• Neocortical norepinephrine (NE) plays a role in modulating brain activity.
• The locus coeruleus is the primary source of NE in the forebrain.
• Understanding NE's role in sensory processing is crucial for comprehending cortical function.

Purpose of the Study:

• To investigate the role of neocortical norepinephrine (NE) in modulating oxidative metabolism within the rat somatosensory cortex (SmI).
• To determine the functional impact of NE depletion on the metabolic representation of vibrissae in the SmI cortex.

Main Methods:

• Unilateral 6-hydroxydopamine lesions were used to deplete NE in the neocortex of rats.
• 14C-2-deoxyglucose uptake was measured in the SmI cortex.
• Metabolic activity was assessed during stimulation of contralateral C3 facial vibrissae.

Main Results:

• NE depletion (greater than 50%) led to a small ipsilateral decrease (8%) in C3 vibrissa column 14C-2-deoxyglucose uptake.
• A larger increase (24-32%) in the areal extent of uptake was observed, expanding into adjacent metabolic representations.
• These changes occurred during stimulation of contralateral C3 facial vibrissae.

Conclusions:

• Norepinephrine (NE) appears to exert a predominantly inhibitory influence on oxidative metabolism in the rat SmI cortex.
• NE modulates the spatial extent of metabolic representation within the somatosensory cortex during physiological stimulation.
• These findings contribute to understanding NE's role in sensory processing and cortical plasticity.