What did an experiment involving rats self-injecting drugs demonstrate?

The experiment involving rats self-injecting drugs is significant for its insights into drug preference and addiction. In particular, the finding that rats were more likely to die from cocaine than heroin reflects the higher toxicity and potential lethality associated with cocaine use. This observation underscores the dangers posed by different substances, especially those that can lead to acute health crises such as overdose.

Various studies have shown that cocaine can increase cardiovascular risk, leading to heart attacks and other severe health complications, which contributes to higher mortality rates. In contrast, while heroin is also dangerous and can lead to overdose, the immediate life-threatening effects of cocaine are particularly pronounced in these experiments. This has important implications for understanding addiction, the risks associated with different substances, and the need for targeted interventions in substance abuse treatment.

The other options presented do not capture the core findings of these studies effectively. For instance, the preference for one drug over another, as mentioned in other choices, does not directly pertain to the mortality aspect that is crucial in understanding the implications of drug use. Understanding drug toxicity and its impact on health is essential in the field of addiction treatment and public health.