The sigma receptor ligand N-phenylpropyl-N′-(4-methoxyphenethyl)3piperazine (YZ-067) enhances the cocaine conditioned-rewarding properties while inhibiting the development of sensitization of cocaine in mice

Rationale: The N-phenylpropyl-N′-substituted piperazines SA-4503 (N-phenylpropyl-N′-(3,4-dimethoxyphenethyl)piperazine) and YZ-185 (N-phenylpropyl-N′-(3-methoxyphenethyl)piperazine) bind to sigma (σ) receptors and block the development of cocaine-induced conditioned place preference at concentrations that inhibit cocaine-induced hyperactivity. YZ-067 (N-phenylpropyl-N′-(4-methoxyphenethyl)piperazine) also binds to sigma receptors and attenuates cocaine-induced hyperactivity in mice. Objectives: The present study determined the effect of YZ-067 on the development and expression of cocaine (66 μmol/kg or 33 μmol/kg) conditioned place preference (CPP) and locomotor sensitization in mice. Results: YZ-067 (10 or 31.6 μmol/kg) did not have intrinsic effects on place preference or place aversion. Interestingly, the 31.6 μmol/kg YZ-067 dose enhanced the development of cocaine place preference, while 10 μmol/kg YZ-067 attenuated the development of cocaine-induced locomotor sensitization. However, YZ-067 did not alter the expression of cocaine place preference nor cocaine-induced locomotor sensitization. In follow-up studies, YZ-067 did not affect performance in the zero maze or rotarod, indicating that sigma receptors probed by this ligand do not regulate anxiety-like or coordinated motor skill behaviors, respectively. Conclusion: Overall, these results are consistent with previous studies demonstrating a role for sigma receptors in the behavioral effects of cocaine. However, the present findings also indicate that N-phenylpropyl-N′-substituted piperazines do not strictly block cocaine’s behavioral effects and that sigma receptor may differentially mediate cocaine-induced hyperactivity and place conditioning.