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Nicotine and psychostimulants are often abused in combination and drug abuse often begins during adolescence and can have long-term consequences. Behavioral sensitization has been suggested as an animal model of neuroplasticity implicated in the development of drug addiction. We evaluated whether the pretreatment with nicotine (0.4 mg/kg; s.c.) or amphetamine (5.0 mg/kg; i.p.) in adolescent rats [from postnatal day (P) 28 to P34] could induce cross-sensitization to nicotine and amphetamine when animals were challenged during both adolescence (P37) and adulthood (P70), in separate groups of animals. Adolescent animals pretreated with amphetamine displayed behavioral sensitization to nicotine, which persisted until adulthood. Moreover, adolescent animals pretreated with nicotine showed sensitized locomotor response to amphetamine in the adulthood. These data suggest that adolescents who abuse nicotine may be particularly susceptible to the effects of amphetamine and vice versa. Moreover, this increased vulnerability may persist through their development until adulthood.

This exploratory study investigated the effects of early vs. delayed time-restricted eating (TRE) plus caloric restriction (CR) on body weight, body composition, and cardiometabolic parameters in adults with overweight and obesity. Adults (20 to 40 years) were randomized to 1 of 3 groups for 8 weeks: early TRE (eTRE; 8:00-16:00) plus CR, delayed TRE (dTRE; 12:00-20:00) plus CR, or only CR (CR; 8:00-20:00). All groups were prescribed a 25% energy deficit relative to daily energy requirements. Thirteen participants completed the study in the eTRE and CR groups, and eleven in the dTRE group (n=37). After the interventions, there was no significant difference between the three groups for any of the outcomes. Compared to baseline, significant decreases were observed in body weight (eTRE group: -4.2 kg; 95% CI, -5.6 to -2.7; dTRE group: -4.8 Kg; 95% CI, -5.9 to -3.7; CR: -4.0 kg; 95% CI, -5.9 to -2.1), fat mass (eTRE group: -2.9 kg; 95% CI, -3.9 to -1.9; dTRE group: -3.6 Kg; 95% CI, -4.6 to -2.5; CR: -3.1 kg; 95% CI, -4.3 to -1.8), and fasting glucose levels (eTRE group: -4 mg/dL; 95% CI, -8 to -1; dTRE group: -2 mg/dL; 95% CI, -8 to 3; CR: -3 mg/dL; 95% CI, -8 to 2). In a free-living setting, TRE with a caloric deficit, regardless of the time of day, promotes similar benefits in weight loss, body composition and cardiometabolic parameters. However, given the exploratory nature of our study, further investigation is needed to confirm these findings.

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