ACTH

ACTH, or adrenocorticotropic hormone, is a hormone produced and released by the anterior pituitary gland. ACTH release is stimulated by the secretion of corticotropin-releasing hormone (CRH) from the hypothalamus in response to physical or mental stress. ACTH in turn acts on the adrenal cortex triggering the release of Cortisol, a Glucocorticoid. Cortisol then acts to regulate metabolism by initiating mechanisms to increase blood glucose levels to prepare for the 'fight or flight' response. The production and release of these hormones are part of the hypothalamic-pituitary-adrenal axis (HPA axis).

References 

Clark, R K., Anatomy and Physiology: Understanding the Human Body

Del Rey, Ariana., Chrousos, George., Besedovsky, Hugo., The Hypothalamus-Pituitary-Adrenal Axis, Volume 7 of NeuroImmune Biology