Scientists Mapped the Enzymes That Break Down a Key Brain Cannabinoid in Mice | Research

The takeaway

One enzyme, MAGL, handles about 85% of the brain's 2-AG breakdown, with two lesser-known enzymes handling the rest in distinct brain locations.

Read this if you want to understand the molecular machinery behind your brain's built-in cannabinoid system.

85% of brain 2-AG breakdown handled by a single enzyme (MAGL)

What the researchers found

Using proteomic techniques on mouse brain tissue, researchers identified three enzymes primarily responsible for breaking down 2-arachidonoylglycerol (2-AG), one of the brain's main endocannabinoids.

Monoacylglycerol lipase (MAGL) accounted for approximately 85% of total 2-AG hydrolysis in the brain. The remaining 15% was split between two previously uncharacterized enzymes called ABHD6 and ABHD12.

Notably, each of these three enzymes showed different subcellular distributions within neurons. This spatial separation suggests they may regulate distinct pools of 2-AG rather than serving redundant roles, potentially offering more precise targets for future drug development.

Why it matters

Understanding which enzymes control 2-AG levels in the brain is essential for developing drugs that target the endocannabinoid system. Since 2-AG activates the same receptors that THC does, manipulating its breakdown could theoretically produce therapeutic effects without requiring external cannabinoids.

The numbers in context

MAGL accounted for approximately 85% of brain 2-AG hydrolase activity. ABHD6 and ABHD12 together accounted for most of the remaining 15%.

How the study worked

The researchers used activity-based protein profiling (ABPP), a functional proteomics approach, to identify and quantify all enzymes capable of hydrolyzing 2-AG in mouse brain homogenates. They used selective inhibitors to confirm the relative contributions of each enzyme and mapped their subcellular locations.

What this study cannot tell us

This was conducted entirely in mouse brain tissue, and enzyme distribution or relative activity could differ in human brains. The study examined brain tissue homogenates, which may not fully capture the dynamics of 2-AG metabolism in living, functioning neural circuits.

How to read the evidence

This is an animal study using advanced proteomic methods that provided quantitative data on enzyme contributions, but findings need human validation.

When this study was published

Published in 2007. Subsequent research has confirmed MAGL's dominant role and led to the development of selective MAGL inhibitors now in clinical testing.

The bigger picture

This study laid important groundwork for understanding how the brain regulates its own cannabinoid signaling. The discovery that different enzymes control 2-AG in different cellular compartments opened new possibilities for developing more targeted medications that could modulate endocannabinoid tone with greater precision than broadly acting drugs.

Questions still open

Do ABHD6 and ABHD12 play clinically significant roles in human endocannabinoid regulation? Could selectively inhibiting one of these enzymes produce therapeutic effects with fewer side effects than inhibiting MAGL?

Common questions

What is 2-AG?

2-arachidonoylglycerol (2-AG) is one of two primary endocannabinoids produced naturally in the brain. It activates the same cannabinoid receptors (CB1 and CB2) that THC targets.

Why does it matter that different enzymes are in different locations?

If each enzyme controls 2-AG in a specific part of the cell, scientists could potentially target one enzyme to affect specific aspects of cannabinoid signaling without disrupting the entire system.

Read the original research

A comprehensive profile of brain enzymes that hydrolyze the endocannabinoid 2-arachidonoylglycerol.

Chemistry & biology, 14(12), 1347-56

View on PubMed ↗

Citation

Blankman, Jacqueline L; Simon, Gabriel M; Cravatt, Benjamin F. (2007). A comprehensive profile of brain enzymes that hydrolyze the endocannabinoid 2-arachidonoylglycerol.. Chemistry & biology, 14(12), 1347-56.