BETAINE ALLEVIATES CUE-INDUCED REINSTATEMENT OF KETAMINE SEEKING VIA AMPK ACTIVATION IN THE NUCLEUS ACCUMBENS CORE
Authors: Hung *Yun Ting , Lee Mei Yi , Chan Ming Huan , Chen Hwei Hsien 
Published: February 2025

Abstract

Background
Betaine is a functional nutrient with a variety of potential health benefits1.2. It has been shown to attenuate the reinstatement of ketamine-seeking behavior in rats3. Moreover, betaine activates AMP-activated protein kinase (AMPK) and functions as a partial agonist of the NMDA receptor glycine binding site, both of which have been associated with reducing cue-induced reinstatement4.5.6.

Aims & Objectives
The study aimed to both identify the brain regions associated with betaine's reduction effect on cue-induced reinstatement of ketamine seeking and to explore the involvement of NMDA receptor and AMPK in the potential underlying mechanisms.

Methods
Male Sprague-Dawley rats were trained to respond for intravenous ketamine (0.5 mg/kg/infusion) self-administration, followed by extinction. Prior to cue-induced reinstatement, rats received bilateral microinjection of betaine (100 μ g/μ l/side) either into the prelimbic cortex (PrL) or the nucleus accumbens (NAc) core. The impact of pretreatment of 7-chlorokynurenate (7-CK) (20 μ g/μ l/side), an antagonist of NMDA receptor glycine binding site, or dorsomorphin (6 μ g/μ l/side), an AMP-activated protein kinase (AMPK) inhibitor, on betaine's effects in the NAc core regarding cue-induced reinstatement were examined.

Results
Our data demonstrated a significant reduction in cue-induced reinstatement of ketamine-seeking behavior when betaine was administered into the NAc core, with no such effect observed in the PrL. In addition, dorsomorphin, but not 7-CK, blocked the effect of betaine on cue-induced reinstatement of ketamine- seeking behavior.

Discussion & Conclusions
These findings suggest the potential benefits of betaine supplementation for individuals with ketamine use disorder. Moreover, it sheds light on betaine's capacity to mitigate cue-induced reinstatement of ketamine-seeking behavior by activating AMPK in the NAc core.

References
1(Arumugam et al., 2021)
2(Bhatt et al., 2023)
3(Carlezon and Wise, 1996)
4(McGlinchey et al., 2016)
5(Gao et al., 2017)
6(Chen et al., 2021)
ARUMUGAM, M. K., PAAL, M. C., DONOHUE, T. M., GANESAN, M., OSNA, N. A. & KHARBANDA, K. K.2021.Beneficial Effects of Betaine: A Comprehensive Review. Biology-Basel,
10. BHATT, M., DI IACOVO, A., ROMANAZZI, T., ROSETI, C. & BOSSI, E. 2023. Betaine-The dark knight of the brain. Basic Clin Pharmacol Toxicol.
CARLEZON, W. A. & WISE, R. A. 1996. Rewarding actions of phencyclidine and related drugs in nucleus accumbens shell and frontal cortex. Journal of Neuroscience, 16, 3112-3122.
CHEN, W., ZHANG, X., XU, M., JIANG, L., ZHOU, M., LIU, W., CHEN, Z., WANG, Y., ZOU, Q. & WANG, L. 2021. Betaine prevented high-fat diet-induced NAFLD by regulating the FGF10/AMPK signaling pathway in ApoE(-/-) mice. Eur J Nutr, 60, 1655-1668.
GAO, X. J., YUAN, K., CAO, L., YAN, W., LUO, Y. X., JIAN, M., LIU, J. F., FANG, Q., WANG, J. S., HAN, Y., SHI, J. & LU, L. 2017. AMPK signaling in the nucleus accumbens core mediates cue-induced reinstatement of cocaine seeking. Sci Rep, 7, 1038.
MCGLINCHEY, E. M., JAMES, M. H., MAHLER, S. V., PANTAZIS, C. & ASTON-JONES, G. 2016. Prelimbic to Accumbens Core Pathway Is Recruited in a Dopamine-Dependent Manner to Drive Cued Reinstatement of Cocaine Seeking. Journal of Neuroscience, 36, 8700-8711.