THC Temperature Responses Changed From Cooling to Warming During Repeated Dosing in Rats
A 1978 rat study found that repeated THC eliminated an initial cooling response and later produced warming. Behavioral adaptation, body-weight gain and brain monoamine measurements did not all follow the same course.
The regimen used daily intravenous exposure
Rats with indwelling catheters received THC for up to ten days. Temperature was recorded over time on selected days, while separate groups supplied brain tissue for monoamine analysis. Tissue measurements therefore were not repeated within the same individual animals.
Adaptation did not mean every outcome normalized
Tolerance to hypothermia appeared by day three, with hyperthermia on later days. Tolerance was described for excitatory and depressant behaviors, but reduced body-weight gain persisted over the study. Temperature returning past baseline in the opposite direction is different from simply losing a drug effect.
Monoamine content was not a direct release measurement
Noradrenaline and dopamine levels were not markedly changed. Serotonin and its metabolite 5-HIAA showed time-dependent differences. These whole-tissue content measures cannot by themselves identify release, receptor activity or the mechanism producing the temperature change. The authors proposed relationships rather than demonstrating a complete causal chain.
The experiment shows why repeated-exposure effects require a time course and multiple endpoints. It does not establish a human temperature-risk prediction or demonstrate that tolerance eliminates nutritional or physiological effects. Dose route, sampling method and the distinction between reversal and recovery remain important.
Related: interpreting cannabis tolerance claims.
Research cited
Taylor DA; Fennessy MR. Relationship between body temperature and brain monoamines during the development of tolerance to delat9-tetrahydrocannabinol in the rat. Psychopharmacology (1978). doi:10.1007/BF00432850. Findings discussed from the study abstract.
