THC’s T-Maze and Acetylcholine Effects Persisted on Different Timelines After Repeated Treatment
A preclinical THC study found no tolerance to either reduced T-maze alternation accuracy or reduced extracellular hippocampal acetylcholine after repeated treatment. The two effects also began at different times, limiting a simple explanation in which one measured change directly tracked the other.
The study tested persistence during repeated exposure
The regimen involved twice-daily injected THC for two weeks. Researchers examined correct alternation in a T-maze and extracellular acetylcholine concentration in the hippocampus. These were separate behavioral and neurochemical endpoints, not a single test of overall cognition.
The behavioral change appeared earlier
Reduced correct alternation began about 20 minutes after treatment, while the acetylcholine decrease appeared only around 80 minutes afterward. That timing difference does not exclude a relationship, but it does undermine a claim that the measured neurochemical decline and task deficit occurred in strict temporal correspondence.
CB1 blockade affected both outcomes
The antagonist SR141716A blocked the cognitive and cholinergic effects described in the abstract, supporting CB1 receptor involvement. However, receptor involvement does not establish that decreased extracellular acetylcholine alone caused the behavioral effect. The authors explicitly suggested that the two effects could be differentiated.
The important result is persistent sensitivity under this particular regimen. Repeated THC exposure does not guarantee tolerance on every endpoint. Conversely, this experiment cannot establish that every memory function remains affected in cannabis users or determine whether an individual person was impaired at a particular time.
Related: interpreting cannabis tolerance claims.
Research cited
Nava F; Carta G; Colombo G; Gessa GL. Effects of chronic Delta(9)-tetrahydrocannabinol treatment on hippocampal extracellular acetylcholine concentration and alternation performance in the T-maze. Neuropharmacology (2001). doi:10.1016/s0028-3908(01)00075-2. Findings discussed from the study abstract.
