Grim TW, Wiebelhaus JM, Negus SS, Lichtman AH, Lichtman AH. Effects of acute and repeated dosing of the synthetic cannabinoid CP55,940 on intracranial self-stimulation in mice.
Drug Alcohol Depend 2015;
150:31-7. [PMID:
25772438 PMCID:
PMC4601922 DOI:
10.1016/j.drugalcdep.2015.01.022]
[Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 01/19/2015] [Accepted: 01/21/2015] [Indexed: 01/19/2023]
Abstract
BACKGROUND
Synthetic cannabinoids have emerged as a significant public health concern. To increase the knowledge of how these molecules interact on brain reward processes, we investigated the effects of CP55,940, a high efficacy synthetic CB1 receptor agonist, in a frequency-rate intracranial self-stimulation (ICSS) procedure.
METHODS
The impact of acute and repeated administration (seven days) of CP55,940 on operant responding for electrical brain stimulation of the medial forebrain bundle was investigated in C57BL/6J mice.
RESULTS
CP55,940 attenuated ICSS in a dose-related fashion (ED50 (95% C.L.)=0.15 (0.12-0.18)mg/kg). This effect was blocked by the CB1 receptor antagonist rimonabant. Tolerance developed quickly, though not completely, to the rate-decreasing effects of CP55,940 (0.3mg/kg). Abrupt discontinuation of drug did not alter baseline responding for up to seven days. Moreover, rimonabant (10mg/kg) challenge did not alter ICSS responding in mice treated repeatedly with CP55,940.
CONCLUSIONS
The finding that CP55,940 reduced ICSS in mice with no evidence of facilitation at any dose is consistent with synthetic cannabinoid effects on ICSS in rats. CP55,940-induced ICSS depression was mediated through a CB1 receptor mechanism. Additionally, tolerance and dependence following repeated CP55,940 administration were dissociable. Thus, CP55,940 does not produce reward-like effects in ICSS under these conditions.
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