Examination of the Gateway Hypothesis in a rat model

The Gateway Hypothesis is based on epidemiological data and states there is a progression of drug use from use of a softer drug (e.g., nicotine) to use of a harder drug (e.g., morphine). It has been suggested that this sequence is causal and is relevant to drug prevention policies and programs. The present experiment used an animal model to investigate whether the Gateway Hypothesis involves a causal progression. Subjects were 16 female and 16...