A dipsogen is an agent that causes thirst. (From Greek dypsa, "thirst" and the suffix -gen, "to create".)
Physiology
Angiotensin II is thought to be a powerful dipsogen, and is one of the products of the renin-angiotensin pathway, a biological homeostatic mechanism for the regulation of electrolytes and water.
References
Dipsogen Wikipedia(Text) CC BY-SA