Therapeutic targeting of neuroinflammation in methamphetamine use disorder

Methamphetamine (METH) is a potent psychostimulant that profoundly affects the central nervous system (CNS). Beyond its direct impact on neurotransmitter systems—such as dopamine, norepinephrine, and serotonin—METH triggers a complex cascade of events including oxidative stress, mitochondrial dysfunction, and significant neuroinflammation. This review explores how activation of immune cells in the brain, specifically microglia and astrocytes, contributes to the cognitive deficits and neurodegenerative damage characteristic of methamphetamine use disorder (MUD).

The authors highlight several molecular pathways that serve as promising therapeutic targets for suppressing METH-induced neuroinflammation:

• Toll-like receptor 4 (TLR4): As a pattern recognition receptor, TLR4 plays a key role in the innate immune response. METH exposure has been shown to activate TLR4 and its associated signaling pathways (e.g., MyD88/NF-κB), leading to the production of pro-inflammatory cytokines that exacerbate neuronal injury.
• NLRP3 Inflammasome: This multiprotein complex is essential for processing pro-inflammatory cytokines like IL-1β. METH promotes the assembly and activation of the NLRP3 inflammasome, which contributes to an inflammatory form of cell death known as pyroptosis.
• Sigma-1 Receptor (σ1 R) and Other Regulators: Chaperone proteins like σ1 R, as well as proteins like HMGB1 and mGluR5, are also implicated in METH-induced inflammatory responses. Targeting these proteins can modulate glial activity and potentially protect dopaminergic neurons from further damage.

While the theoretical rationale for targeting neuroinflammation is strong, translating these insights into clinical practice remains difficult. Many current pharmacological interventions for MUD have failed to show consistent efficacy. This failure is often attributed to study limitations—such as small sample sizes and poor medication adherence—as well as the blood-brain barrier (BBB), which restricts the CNS penetration of many candidate drugs. The authors suggest that future research must prioritize the development of more robust trial designs, innovative drug delivery systems (e.g., nanoparticles), and combination therapies that integrate anti-inflammatory pharmacotherapy with established behavioral interventions like cognitive-behavioral therapy.