Altshuler RD, Carpenter CA, Franke TJ, Gnegy ME, Jutkiewicz EM. The protein kinase Cβ-selective inhibitor, enzastaurin, attenuates amphetamine-stimulated locomotor activity and self-administration behaviors in rats.
Psychopharmacology (Berl) 2019;
236:3231-3242. [PMID:
31134292 PMCID:
PMC6832797 DOI:
10.1007/s00213-019-05278-0]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 05/14/2019] [Indexed: 12/31/2022]
Abstract
RATIONALE
Pathological amphetamine (AMPH) use is a serious public health concern with no pharmacological treatment options. Protein kinase Cβ (PKCβ) has been implicated in the mechanism of action of AMPH, such that inhibition of PKCβ attenuates AMPH-stimulated dopamine efflux in vivo. With this in mind, inhibition of PKCβ may be a viable therapeutic target for AMPH use disorder.
OBJECTIVE
The purpose of this study is to demonstrate that selective pharmacological inhibition of PKCβ alters AMPH-stimulated behaviors in rats.
METHODS
Rats were administered intracerebroventricular (i.c.v.) injections of the PKCβ-selective inhibitor enzastaurin 0.5, 3, 6, or 18 h before evaluating AMPH-stimulated locomotion (0.32-3.2 mg/kg). Rats were trained to make responses for different doses of AMPH infusions or sucrose under a fixed ratio 5 schedule of reinforcement, and the effects of enzastaurin pretreatment 3 or 18 h prior to a self-administration session were determined. Also, the effect of enzastaurin on AMPH-stimulated PKC activity in the ventral striatum was evaluated.
RESULTS
A large dose of enzastaurin (1 nmol) decreased AMPH-stimulated locomotor activity 0.5 h following enzastaurin administration. Small doses of enzastaurin (10-30 pmol) attenuated AMPH-stimulated locomotor activity and shifted the AMPH dose-effect curve to the right following an 18-h pretreatment. Rats pretreated with enzastaurin 18 h, but not 3, prior to a self-administration session showed a decrease in the number of responses for AMPH, shifted the ascending limb of the amphetamine dose effect curve, and produced no change in responses for sucrose. AMPH-stimulated PKC activity was decreased following a 0.5- or 18-h pretreatment, but not a 3-h pretreatment of enzastaurin.
CONCLUSIONS
These results demonstrate that inhibition of PKCβ will decrease AMPH-stimulated behaviors and neurobiological changes and suggest that PKCβ is potentially a viable target for AMPH use disorder.
Collapse