Opioid-Induced Reductions in Amygdala Lateral Paracapsular GABA Neuron Circuit Activity

Area of Science:

• Neuroscience
• Neurobiology
• Molecular Psychiatry

Background:

• Opioid use disorders and associated anxiety involve complex behavioral adaptations.
• The basolateral amygdala (BLA) plays a crucial role in regulating these behaviors.
• Lateral paracapsular (LPC) GABAergic inhibitory neurons within the BLA are implicated due to their expression of µ-opioid receptors (MORs).

Purpose of the Study:

• To investigate the impact of opioid exposure on the activity and excitability of LPC neurons.
• To determine the role of MORs and δ-opioid receptors in LPC neurons.
• To elucidate neurocircuitry changes underlying opioid use disorders and anxiety-like behaviors.

Main Methods:

• Immunohistochemistry to identify opioid receptor expression in BLA neurons.
• Electrophysiological recordings to assess synaptic currents and intrinsic membrane excitability of LPC neurons.
• In vivo morphine administration followed by ex vivo analysis of neuron function.

Main Results:

• LPC neurons, along with other BLA neurons, express both MORs and δ-opioid receptors.
• Activation of MORs by DAMGO reduced inhibitory postsynaptic currents in LPC neurons.
• Repeated morphine exposure in vivo led to decreased intrinsic excitability in LPC neurons, characterized by increased afterhyperpolarization and enhanced adenylyl cyclase activity.

Conclusions:

• MORs in the BLA are highly sensitive targets for opioid-induced inhibition.
• Repeated opioid exposure results in functional impairments of LPC neuron excitability.
• These neurocircuitry alterations in the BLA may contribute to the development of opioid use disorders and anxiety.