Experimental and Clinical Psychopharmacology
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Major depressive disorder (MDD) is the most common mood disorder in the United States and European Union; however, the limitations of clinically available antidepressant drugs have led researchers to pursue novel pharmacological treatments. Clinical studies have reported that monotherapy with the atypical antipsychotic drug quetiapine produces a rapid reduction in depressive symptoms that are apparent following one week of quetiapine treatment, and it is possible that the active metabolite N-Desalkylquetiapine, which structurally resembles an antidepressant drug, produces antidepressant effects. Neuropharmacological evaluations of the neurotensin NTS1 receptor agonist PD149163 are suggestive of antidepressant efficacy, but the effects of a NTS1 receptor agonist in an antidepressant animal model have yet to be reported. The present study examined the antidepressant-like effects of the N-Desalkylquetiapine, the neurotensin NTS1 receptor agonist PD14916, quetiapine, the tricylic antidepressant drug imipramine, the atypical antipsychotic drug risperidone, and the typical antipsychotic drug raclopride on responding in male Sprague-Dawley rats trained on a differential-reinforcement-of-low-rate (DRL) 72 s operant schedule, a procedure used for screening antidepressant drugs. Quetiapine, PD149163, risperidone, and imipramine exhibited antidepressant-like effects by increasing the number of reinforcers earned, decreasing the number of responses emitted, and shifting the interresponse time (IRT) distributions to the right. N-Desalkylquetiapine produced a partial antidepressant-like effect by decreasing the number of responses emitted and producing a rightward shift in the IRT distributions, but it did not significantly alter the number of reinforcers earned. The typical antipsychotic drug raclopride decreased both reinforcers and responses. These data suggest that N-Desalklyquetiapine likely contributes to quetiapine’s antidepressant efficacy and identifies NTS1 receptor activation as a potential novel pharmacologic strategy for antidepressant drugs.
Hillhouse, Todd M.; Shankland, Zachary; Matazel, Katelin S.; Keiser, Ashley; and Prus, Adam J., "The quetiapine active metabolite N-Desalkylquetiapine and the neurotensin NTS1 receptor agonist PD149163 exhibit antidepressant-like effects on operant responding in male rats" (2014). Journal Articles. 97.