Table 2.

Overall experimental design of the nicotine self-administration experiment.

Nicotine Dose-Effect Curves	Daily Post-session THC dose groups
	0 mg/kg	3 mg/kg	30 mg/kg
1st nicotine self-administration dose-effect curve (Figure 2)	Single (nicotine only) use	Separate use (low dose daily THC and nicotine at different times)	Separate use (high dose daily THC and nicotine at different times)
Subsequent three nicotine dose-effect curves (pre-injection with 0.3, 3, or 30 mg/kg THC before nicotine session) (Figure 3)	Simultaneous use (THC injection 30 min prior to nicotine self-administration session)	Simultaneous and separate use (THC injection 30 min prior to nicotine self-administration session AND low dose daily THC and nicotine at different times)	Simultaneous and separate use (THC injection 30 min prior to nicotine self-administration session AND high dose daily THC and nicotine at different times)