biogenic amines , including norepinephrine , dopamine , serotonin , acetylcholine , and gamma-aminobutyric acid have excitatory or inhibitory effects at brain sites to modulate hypothalamic control . alpha-adrenergic mechanisms have been shown to be of particular importance in the regulation of physiologic gh secretion , which is characterized by episodic surges of release .
C0005496
biogenic amines
C0001041
acetylcholine