Analgesic, Heart Rate, and Temperature Effects of Δ8-THC during Acute and Chronic Administration to Conscious Rats

Abstract

Acute and chronic effects of △⁸-THC on tail-flick, heart rate, and rectal temperature responses in conscious, unrestrained male rats were studied. In the acute experiment unidirectional, dose-dependent analgesic, hypothermic, and negative chronotropic cardiac effects were observed within the dose range employed. Of the three variables, heart-rate decreases were most sensitive to the effects of THC, reaching significance at 2 mg/kg. Rapid development of tolerance occurred for all three measures, with complete tolerance developing within 13 days only to the heart-rate decreases. The results are discussed in the context of previous data.