Ketamine and MAG Lipase Inhibitor-Dependent Reversal of Evolving Depressive-Like Behavior During Forced Abstinence From Alcohol Drinking

Abstract

Although alcoholism and depression are highly comorbid, treatment options that take this into account are lacking, and mouse models of alcohol (ethanol (EtOH)) intake-induced depressive-like behavior have not been well established. Recent studies utilizing contingent EtOH administration through prolonged two-bottle choice access have demonstrated depression-like behavior following EtOH abstinence in singly housed female C57BL/6J mice. In the present study, we found that depression-like behavior in the forced swim test (FST) is revealed only after a protracted (2 weeks), but not acute (24 h), abstinence period. No effect on anxiety-like behavior in the EPM was observed. Further, we found that, once established, the affective disturbance is long-lasting, as we observed significantly enhanced latencies to approach food even 35 days after ethanol withdrawal in the novelty-suppressed feeding test (NSFT). We were able to reverse affective disturbances measured in the NSFT following EtOH abstinence utilizing the N-methyl D-aspartate receptor (NMDAR) antagonist and antidepressant ketamine but not memantine, another NMDAR antagonist. Pretreatment with the monoacylglycerol (MAG) lipase inhibitor JZL-184 also reduced affective disturbances in the NSFT in ethanol withdrawn mice, and this effect was prevented by co-administration of the CB1 inverse agonist rimonabant. Endocannabinoid levels were decreased within the BLA during abstinence compared with during drinking. Finally, we demonstrate that the depressive behaviors observed do not require a sucrose fade and that this drinking paradigm may favor the development of habit-like EtOH consumption. These data could set the stage for developing novel treatment approaches for alcohol-withdrawal-induced mood and anxiety disorders.

Figure 1

EtOH two-bottle choice with sucrose fade reliably induces significant EtOH preference. (a) Timeline of EtOH two-bottle choice with sucrose fade. 10% EtOH given from day 1 to day 42 with sucrose fade as indicated. (b) Preference for EtOH-containing sipper during 6-week access to EtOH (N=85). (c) Daily preference for EtOH-containing sipper during the last week of access in the first cohort (N=12). (d) Daily EtOH consumption (g/kg/day) during the last week of access in the first cohort (N=12). (e) Individual BECs for mice after 42 days of drinking. Data are represented as mean±SEM. Dashed line indicates 50% preference in panels (b) and (c); dashed line indicates 80 mg/dl in panel (e). EPM, elevated plus maze; FST, forced swim test; NSFT, novelty-Suppressed feeding test.

Figure 2

Removal of EtOH induces long-lasting depression-like behavior that requires an abstinence period. (a, b) Abstinence from EtOH significantly increases immobility time in the FST (a) 18 days, but not (b) 1 day, after EtOH removal. (c) Anxiety-like behavior in the EPM is unaffected 14 days after EtOH abstinence as measured by time spent in the open or closed arms of the apparatus. (c') Locomotion, measured by distance traveled in the EPM apparatus, is unaltered after 14 days of EtOH abstinence. (d) Depression-like behavior induced by EtOH abstinence is long-lasting. EtOH-exposed mice demonstrate depression-like behavior—increased latency to consume chow in the NSFT—at both 15 and 35 days following removal of EtOH. Data are represented as mean±SEM. **P<0.01; ***P<0.001.

Figure 3

Ketamine (3 mg/kg; 30 min prior to testing) was able to reduce NSFT latency to control levels in EtOH mice 15 days after EtOH removal. Groups were compared with Control-Vehicle for statistics. Data represented as mean±SEM. **P<0.01.

Figure 4

Endocannabinoid modulation of depression-like behavior and eCB levels during two-bottle choice paradigm and EtOH abstinence. (a) JZL-184 (8 mg/kg; 2 h prior to testing) completely reduced NSFT latency to baseline levels in EtOH abstinent mice after 15 days of abstinence, but memantine (20 mg/kg; 30 min prior to testing) had no effect on depression-like behavior. (b) Rimonabant (1 mg/kg; 2 h prior to testing) blocked the effect of JZL-184 in EtOH mice 15 days after EtOH removal. All drugs were administered i.p. In panel (a), groups were compared with Control-Vehicle for statistics. Groups were compared with every other group in panel (b). (c) Levels of 2-AG, AA, and AEA in the BLA after 42 days of drinking (On) or after 15 days of EtOH abstinence (Abst.) Data are represented as mean±SEM. *P<0.05; **P<0.01; ***P<0.001. A full color version of this figure is available at the Neuropsychopharmacology journal online.

Figure 5

Assessment of factors governing EtOH consumption and depressive responses. (a) Timeline of EtOH Ramp drinking paradigm. EtOH is gradually introduced and no sucrose is used. (b) Comparison of sucrose fade EtOH (EtOH (Sucr), N=85) and EtOH Ramp (N=28). (c–e) Preference, consumption, and dosage of a 3% EtOH solution over 2 days in naïve (3% (Naïve); N=9) or EtOH-exposed (3% (Exposed); N=10) mice, compared with mice drinking 10% EtOH at the end of two-bottle choice paradigm (10% EtOH; N=10). (c) Preference for 3% EtOH is increased in mice with previous exposure to 6 weeks of 10% EtOH. (d, e) Consumption of 3% EtOH is putatively habit-driven. (d) The same average daily volume of EtOH solution is consumed by 10% EtOH mice and 3% (Exposed) mice. Both groups drink a greater volume than 3% (Naïve) mice. (e) Neither 3% (Naïve) or 3% (Exposed) mice drink sufficient quantities to match dosage (g/kg/day) of 10% EtOH mice. (f, g) The EtOH Ramp procedure induces similar depression-like behavior in the NSFT following (f) 15 and (g) 35 days of abstinence. Data are represented as mean±SEM. *P<0.05; **P<0.01; ***P<0.001; ****P<0.0001.