Abstract

The dissociative anesthetic phencyclidine (PCP) and PCP derivatives, including 4′-F-PCP, are illegally sold and abused worldwide for recreational and non-medical uses. The psychopharmacological properties and abuse potential of 4′-F-PCP have not been fully characterized. In this study, we evaluated the psychomotor, rewarding, and reinforcing properties of 4′-F-PCP using the open-field test, conditioned place preference (CPP), and self-administration paradigms in rodents. Using Western immunoblotting, we also investigated the expression of dopamine (DA)-related proteins and DA-receptor-mediated downstream signaling cascades in the nucleus accumbens (NAc) of 4′-F-PCP-self-administering rats. Intraperitoneal administration of 10 mg/kg 4′-F-PCP significantly increased locomotor and rearing activities and increased CPP in mice. Intravenous administration of 1.0 mg/kg/infusion of 4′-F-PCP significantly enhanced self-administration during a 2 h session under fixed ratio schedules, showed a higher breakpoint during a 6 h session under progressive ratio schedules of reinforcement, and significantly altered the expression of DA transporter and DA D1 receptor in the NAc of rats self-administering 1.0 mg/kg 4′-F-PCP. Additionally, the expression of phosphorylated (p) ERK, pCREB, c-Fos, and FosB/ΔFosB in the NAc was significantly enhanced by 1.0 mg/kg 4′-F-PCP self-administration. Taken together, these findings suggest that 4′-F-PCP has a high potential for abuse, given its robust psychomotor, rewarding, and reinforcing properties via activation of DAergic neurotransmission and the downstream signaling pathways in the NAc.

Highlights

  • Phencyclidine (PCP) and PCP derivatives are dissociative anesthetics of the arylcyclohexylamine class and they are used clinically in animals and humans as general anesthetics [1,2]

  • We demonstrated for the first time the abuse potential of 4 -F-PCP

  • The results showed that 4 -F-PCP significantly (1) increased locomotor and rotational activities in mice; (2) produced a drug-paired place preference in mice; (3) increased number of active lever-pressing responses and drug infusions under the fixed ratio (FR) and progressive ratio (PR) schedules of reinforcement in rats; (4) decreased the expression of dopamine transporter (DAT) in the nucleus accumbens (NAc) of 4 -F-PCP-self-administered rats; (5) enhanced the expression of DA D1 receptor (DAD1R) in the NAc of 4 -F-PCP-self-administered rats; and (6) enhanced the expression of pERK, pCREB, c-Fos, FosB, and ∆FosB in the NAc of 4 -F-PCP-self-administered rats

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Summary

Introduction

Phencyclidine (PCP) and PCP derivatives are dissociative anesthetics of the arylcyclohexylamine class and they are used clinically in animals and humans as general anesthetics [1,2]. The recreational and non-medical uses of PCP and PCP derivatives have emerged as a major problem because they cause severe adverse effects including abuse, trance-like ecstatic states, hallucinations, and violent behavior in humans [2,8]. A study demonstrated that novel fluorinated PCP derivatives have a high binding affinity to NMDAR in vitro and pharmacological efficacy in vivo [12] These findings suggest that fluorinated PCP derivatives may have the potential to induce euphoric effects and they could be illegally abused like other PCP derivatives. PCP and PCP derivatives were significantly self-administered in rodent and primate animal models [18,20,21,22] These findings suggest that PCP and PCP derivatives cause psychotomimetic effects [2], and produce psychological dependence with chronic use, due to their reward potential. We evaluated the expression of DA-related proteins and extracellular signal-regulated kinase (ERK), cyclic AMP response-element binding protein (CREB), and Fos-family proteins in the NAc, a primary brain region mediating reward or reinforcing behavior, of 4 -F-PCP-self-administered rats

Results
Discussion
Animals
Open-Field Test
Conditioned Place Preference Paradigm
Food Training and Catheter Implantation Surgery for Self-Administration
Drug Self-Administration
Western Immunoblotting Procedures
Findings
Statistical Analyses
Full Text
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