Increased excitability of lateral habenula neurons in adolescent rats following cocaine self-administration.
Bottom Line: However, the mechanisms of this effect are poorly understood.We found two major relevant neuronal subtypes: burst firing neurons and regular spiking neurons.These results may help to explain how cocaine and other drugs negatively impact affect states.
Affiliation: Neuroscience Department (Drs Neumann, Ishikawa, Otaka, and Dong), and Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA (Dr Huang); Molecular Neurobiology, European Neuroscience Institute, Göttingen, Germany (Dr Schlüter). firstname.lastname@example.org email@example.com.Show MeSH
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Mentions: After observing that cocaine self-administration leads to an increase in the membrane excitability of LHb neurons 24 to 48 hours later, we then looked at a more protracted withdrawal time point at 45 days to determine if these changes were persistent. The same cell characteristics measured at 24 to 48 hours of withdrawal were then measured after 45 days of withdrawal. Again, spike numbers at each current step were counted as a measure of the membrane excitability (Figure 5a). Two-way repeated-measures ANOVA using spike number as the dependent variable repeated at each current step for cocaine LT and saline LT treatment groups revealed no significant effect of the treatment on the number of spikes across all current steps (F[1, 23] = 0.17, n = 25, P = .68). Thus, it appears that the initial cocaine-induced increase in membrane excitability returns to baseline levels at some time point after 48 hours of withdrawal (Figure 5b). Additionally, the membrane resistance no longer differed significantly from saline-exposed controls 45 days after the last cocaine exposure (Figure 5d). All other cellular measures including action potential threshold, fAHP, and mAHP also showed no statistical differences between treatment groups after LT withdrawal (Figure 5c, e, f). Taken together, these results indicate that the cocaine-induced increase in LHb cell excitability returns to baseline at some point between 2 and 45 days of withdrawal from cocaine and is correlated with changes in membrane resistance.
Affiliation: Neuroscience Department (Drs Neumann, Ishikawa, Otaka, and Dong), and Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA (Dr Huang); Molecular Neurobiology, European Neuroscience Institute, Göttingen, Germany (Dr Schlüter). firstname.lastname@example.org email@example.com.