Betaine attenuates methamphetamine-induced reinstatement through CAMKK2-AMPK signaling in the nucleus Accumbens Core

Methamphetamine (MA) use disorder represents a major global public health concern, yet effective pharmacological treatments remain unavailable. Betaine has previously been shown to ameliorate MA-induced depression, cognitive deficits, and behavioral sensitization, suggesting its potential as a therapeutic candidate for MA use disorder. However, its effects on relapse prevention remain unknown. Given that betaine activates adenosine monophosphate-activated protein kinase (AMPK) in peripheral tissues and that AMPK signaling regulates cocaine reinstatement, we hypothesized that betaine attenuates MA relapse through calcium/calmodulin-dependent protein kinase kinase 2 (CAMKK2)-dependent activation of AMPK in the nucleus accumbens (NAc) core. In SH-SY5Y cells, betaine increased AMPK phosphorylation through a CAMKK2-dependent mechanism. Consistently, betaine increased AMPK phosphorylation in the NAc of rats. Using a conditioned place preference (CPP) paradigm in male Sprague-Dawley rats, we found that betaine attenuated MA-primed reinstatement, without affecting CPP acquisition and locomotor activity. Bilateral intra-NAc core infusion of betaine similarly reduced MA-primed reinstatement. Furthermore, intra-NAc core administration of the AMPK inhibitor dorsomorphin or the CAMKK2 inhibitor STO-609 abolished the anti-reinstatement effect of betaine, indicating the involvement of CAMKK2-AMPK signaling. Collectively, these findings demonstrate that betaine suppresses MA relapse-like behavior possibly via CAMKK2-dependent AMPK activation in the NAc core and support its further evaluation as a potential pharmacotherapy for MA use disorder.