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.We also found that lateral habenula regular spiking neurons had higher membrane excitability for at least 7 days following cocaine self-administration, likely due to a greater 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). email@example.com firstname.lastname@example.org.Show MeSH
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Mentions: After observing that the cocaine-induced increases in membrane excitability and membrane resistance returned to saline-control levels by day 45 of withdrawal, we decided to examine a 5- to 7-day moderate term (MT) withdrawal point to better understand the time course of these observed changes. Again, the same cell characteristics were measured at this MT time point as were measured at the ST and LT withdrawal time points. A 2-way repeated-measures ANOVA using spike number as the dependent variable repeated at each current step for saline MT and cocaine MT treatment groups showed that the cocaine MT treatment had a significant increase in cell excitability (F[1, 35] = 5.39, n = 37, P < .05), similar to the cocaine ST treatment group (Figure 6a, b). Bonferroni's multiple comparisons test was used to check for differences at each current step. This result reveals that LHb neurons maintain increased levels of excitability until at least 7 days after cocaine self-administration training (a Bonferroni posttest comparing withdrawal days 5–7 showed no differences between withdrawal days; P = 1.00 for all comparisons). Measurements of other cellular characteristics including the action potential threshold, fAHP, and mAHP again revealed no significant effects of cocaine at the MT withdrawal point (Figure 6c, e, f). However, the membrane resistance of LHb cells after MT withdrawal from cocaine self-administration was again significantly different from saline controls (Figure 6d; p < .01, n sal/coc = 18/19), further supporting a correlation between membrane excitability and 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). email@example.com firstname.lastname@example.org.