Postsynaptic long-term enhancement (LTE) by dopamine may be mediated by Ca2+ and calmodulin

Area of Science:

• Neuroscience
• Synaptic Plasticity
• Autonomic Nervous System

Background:

• Long-term enhancement (LTE) is a form of synaptic plasticity.
• The superior cervical ganglion (SCG) is a key component of the sympathetic nervous system.
• Dopamine (DA) is a neurotransmitter with diverse roles in the nervous system.

Purpose of the Study:

• To investigate the mechanism of dopamine-induced long-term enhancement (LTE) in the rabbit superior cervical ganglion.
• To determine the role of calcium ions (Ca2+) and calmodulin in LTE induction.

Main Methods:

• Electrophysiological recordings of postsynaptic responses in the rabbit SCG.
• Application of muscarinic agonist (MCh) to assess responses.
• Manipulation of extracellular Ca2+ concentrations.
• Use of calmidazolium, a calmodulin antagonist.

Main Results:

• Brief exposure to dopamine (DA) induced long-term enhancement (LTE) of postsynaptic slow depolarizing responses to MCh.
• Reduction of external Ca2+ or addition of calmidazolium blocked DA-induced LTE.
• LTE induction was not mediated by depolarization-dependent Ca2+ influx, differentiating it from hippocampal LTP.

Conclusions:

• Dopamine-induced LTE in the rabbit SCG involves Ca2+ and calmodulin.
• The mechanism of LTE induction in the SCG differs from that of long-term potentiation (LTP) in the hippocampus.
• This study elucidates a novel form of synaptic plasticity in the autonomic nervous system.