Answer
Enkephalins act as natural opiates.
Work Step by Step
Enkephalins act as natural opiods . The other molecules have interesting chemical properties:
Substance P, like glutamate, transmits pain sensations
Somatostatin is a growth hormone
Cholescystokinin is a digestive hormone
Tachykins are produced at sites of injury. They regulate intestinal
motility and dilate blood vessels.