Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8841667 | Neuroscience Letters | 2018 | 5 Pages |
Abstract
The brainstem locus coeruleus (LC) controling behaviors like arousal, sleep, breathing, pain or opioid withdrawal is an established model for spontaneous action potential synchronization. Such synchronous 'spiking' might produce an extracellular field potential (FP) which is a crucial tool for neural network analyses. We found using â¥10â¯Î¼m tip diameter suction electrodes in newborn rat brainstem slices that the LC generates at â¼1â¯Hz a robust rhythmic FP (rFP). During distinct rFP phases, LC neurons discharge with a jitter of ±33â¯ms single spikes that summate to a â¼200 ms-lasting population burst. The rFP is abolished by blocking voltage-gated Na+ channels with tetrodotoxin (TTX, 50â¯nM) or gap junctions with mefloquine (100â¯Î¼M) and activating μ-opioid receptors with [D-Ala2,N-Me-Phe4,Gly5-ol]-Enkephalin (DAMGO, 1â¯Î¼M). Raising superfusate K+ from 3 to 7â¯mM either increases rFP rate or transforms its pattern to slower and longer multipeak bursts similar to those during early recovery from DAMGO. The results show that electrical coupling of neonatal LC neurons does not synchronize their spiking as previously proposed. They also indicate that both increased excitability (by elevated K+) and recovery from inhibition (by opioids) can enhance spike desynchronization to transform the population burst pattern. Both observations show that this gap junction-coupled neural network has a more complex connectivity than currently assumed. These new findings along with the inhibitory drug effects that are in line with previous reports based on single neuron recording point out that field potential analysis is pivotal to further the understanding of this brain circuit.
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Authors
Vladimir Rancic, Bijal Rawal, Bogdan Panaitescu, Araya Ruangkittisakul, Klaus Ballanyi,