Final answer:
Heroin and morphine increase the activity of dopamine neurons by inhibiting GABAergic interneurons, leading to enhanced effects but also potential for abuse.
Step-by-step explanation:
Opiates and opioids like heroin and morphine increase the activity of dopamine neurons in the Ventral Tegmental Area (VTA) by inhibiting GABAergic interneurons that normally exert an inhibitory effect on them. These drugs mimic the endogenous opioids that our body produces, which bind to opioid receptors to reduce pain and induce euphoria.
However, the pharmacological effects of opiates can lead to significant public health concerns due to their high potential for abuse and addiction.