Table 4.

Results and details of recent animal studies investigating polysubstance use.

Reference	Species	Sex	Route of Administration, Dose	Age of Exposure (PND)	Age at Test(s) (PND)	Behavior Category	Behavioral Test(s)	Behavioral Results	Brain Region	Results
Hamidullah et al. [231]	Rat	M	Alcohol: Oral s-a, 10% THC: Vapor, 10 mg/pad	28–42	28	Drug Consumption	2 BC	↑ preference for alcohol when THC is absent
Smiley et al. [233]	Rat	M	-THC: Vapor, 200 mg/ml THC + 20 mg/ml CBD - Alcohol: Vapor	-45–49 -50–62	64	Fear	Pavlovian fear conditioning	↑ Freezing, no additive effect of THC and alcohol	PL	↑ calcium activity in response to shock
Lárraga et al. [239]	Rat	M, F	-Alcohol: Intravenous s-a (1–100 mg/kg/infusion) -Nicotine (7.5–30 µg/kg/infusion) solution	32–41	48	Drug Consumption	S-A, 2 BC for alcohol	↑ alcohol consumption in males, no effect in females
Cross & Leslie [240]	Rat	M	Intravenous injection of nicotine (30 µg/kg) + alcohol (4 mg/kg) solution	32	32	Drug reward, anxiety	OF	↑ locomotor activity, ↓ALB	Posterior VTA	↑ cFos expression in adults, no effect in adolescents
Ruffolo et al. [241]	Rat	M, F	Alcohol: oral s-a, 10% Nicotine: Vapor, 5%	30–46	72	-Reward learning -Fear learning	-Sign-tracking -Contextual fear conditioning	-↑ sign-tracking in males -↓ freezing -No additive drug effects
Dukes et al. [243]	Mouse	M, F	WIN: 0.2, 2 mg/kg i.p. Nicotine: 0.36 mg/kg, s.c.	38–49	70	Drug consumption	Nicotine s-a	↑ nicotine s-a in males, ↑ nicotine s-a in females

Note: PND post-natal days, M male, F female, s-a self-administration, i.p intraperitoneal, s.c. subcutaneous, 2 BC 2-bottle choice, OF open field, ALB anxiety-like behavior, DLB depression-like behavior, empty spaces indicate information that was not relevant to study or was not specified.