Chen, Huang and Colleagues
Cocaine-Induced Membrane Adaptation in the Central Nucleus of Amygdala
Chen B, Ma Y-Y, Wang Y, Wang X, Schülter OM, Dong Y, and Huang YH
After the initial pleasurable feelings subside, chronic drug users typically experience a withdrawal-related negative emotional state that includes unhappiness, stress, anxiety, and depression. The central nucleus of the amygdala (CeA) is a brain area that is involved in the regulation of the negative emotional state during drug withdrawal, although the underlying cellular mechanism remains largely unknown. To shed light on the cells involved, Drs. Bo Chen, Yanhua Huang and colleagues performed electrophysiological recordings of rat CeA neurons after cocaine self-administration.
The investigators found that the two major types of CeA neurons ? regular spiking and low-threshold bursting cells ? responded differently to the stress hormone corticotrophin-releasing factor. In addition, an acute five-day exposure to cocaine induced a temporary decrease in neuronal membrane excitability in regular spiking neurons, but a transient increase in excitability in low-threshold bursting neurons. In contrast, a longer, 21-day self-administration of cocaine induced a long-lasting increase in membrane excitability only in the low-threshold bursting neurons.
Taken together, these findings suggest that regular spiking and low-threshold bursting cells play different roles in cocaine-induced emotional responses. Both cell types exhibited short-term adaptations in membrane excitability after acute cocaine exposure, while the adaptations of low-threshold bursting neurons persisted following extended exposure. The persistent cellular alterations may result in unbalanced CeA processing, suggest the investigators, thereby contributing to the negative emotional responses present during drug withdrawal.
Bo Chen, Yao-Ying Ma, Yao Wang, Xiusong Wang, Yan Dong, Yanhua H Huang (Department of Psychiatry, Department of Neuroscience, University of Pittsburgh)
Oliver M Schülter (Molecular Neurobiology, European Neuroscience Institute, Göttingen, Germany)