Blockade of α₂-adrenergic Receptors Markedly Potentiates Glutamate-evoked Activity of Locus Coeruleus Neurons

Abstract

The locus coeruleus (LC) is a small pontine nucleus with widely distributed efferents that supply the majority of norepinephrine in brain. Evidence from our laboratory has implicated α₂-adrenergic receptors on LC neurons in regulating the magnitude of the bursting response of LC neurons to both sensory stimulation and systemically administered drugs. Sub-stimulation of α₂-adrenergic receptors in the LC and the resulting hyper-responsiveness of LC neurons is thought to at least partially mediate depression in an animal model. The present study extends previous work in our laboratory by demonstrating that blockade of α₂-adrenergic receptors also markedly augments the bursting response of LC neurons to locally – via microiontophoresis-applied glutamate.

Key Words:

• Locus coeruleus
• α₂
• Norepinephrine
• Glutamate