Residual effects of chronic cannabis treatment on behavior in mature rats

Psychopharmacology (Berl). 1985;85(4):436-9. doi: 10.1007/BF00429660.


Mature rats (starting weight at least 270 g) were treated daily with cannabis extract (daily THC dose 20 mg/kg) for 3 months. After a 1- to 4-month drug-free period, residual effects on a variety of behaviors were studied. No residual effects were found in learning of an eight-arm radial maze task, nor on a differential reinforcement of low-rate responding (DRL-20) task, nor on open field activity. On the other hand, two-way shuttle box avoidance learning was facilitated by previous cannabis treatment, since cannabis-treated rats exhibited shorter mean latencies to avoid footshock than vehicle controls. The findings indicate greater vulnerability of immature organisms (previous studies) than mature organisms (the present study) to long-term effects of chronic cannabis administration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Avoidance Learning / drug effects
  • Behavior, Animal / drug effects*
  • Cannabis*
  • Conditioning, Operant / drug effects
  • Learning / drug effects
  • Male
  • Motor Activity / drug effects
  • Plant Extracts / pharmacology*
  • Rats
  • Rats, Inbred Strains
  • Reaction Time / drug effects
  • Reinforcement Schedule


  • Plant Extracts