Galactogogue
Appearance
A galactogogue is a substance which is used to increase the production of milk in humans and other animals. It may be synthetic, plant-derived, or endogenous.
Most of those discovered have been found to interact with the dopamine system in such a way to increase the production of prolactin endogenously.
Examples include Domperidone & Metoclopramide (synthetic), sweet potato, silymarin, and fenugreek (plant-derived), and prolactin (endogenous).

References
- PubMed Peer-Reviewed Article on synthetics