Human Hormones

Vasoactive intestinal peptide (VIP) is a hormone found in the human body. It is produced in the pancreas. VIP consists of 28 amino acid residues. It is classified as a peptide hormone.
Secretion and Production

VIP is produced in the pancreas. Its role in the intestine is to greatly stimulate secretion of water and electrolytes, as well as dilating intestinal smooth muscle, dilating peripheral blood vessels, stimulating pancreatic bicarbonate secretion, and inhibiting gastrin-stimulated gastric acid secretion.

It is also found in the brain and some autonomic nerves. One region of the brain includes a specific region of the suprachiasmatic nuclei, which is the location of the master circadian pacemaker. Given that the SCN is responsible for detecting ambient light communicated directly from the retina, it is likely that VIP plays a key role in the mammalian time keeping machinery.

VIP is also found in the heart and has significant effects on the cardiovascular system. It causes coronary vasodilatation as well as having a positive inotropic and chronotropic effect. Research is being performed to see if it may have a beneficial role in the treatment of heart failure.

It has a half-life in the blood of about 2 minutes. There is currently no use for synthetic VIP.

Thyrotropin-releasing hormone (TRH) is a hormone found in the human body. It is secreted from the pituitary gland. TRH is classified as a peptide hormone.
Secretion and Production

TRH is produced in the hypothalamus and travels across the median eminence to the pituitary where it is excreted. The effects of TRH secretion are the stimulation and release of both thyroid-stimulating hormone and prolactin.

Pharmacological Uses

Synthetic TRH is commonly used as a drug to test the response of the anterior pituitary gland when a person suffers from thyroid deficiency. By testing the response of the anterior pituitary gland, doctors can determine whether or not the thyroid deficiency is being caused by a lack of thyroid-stimulating hormone production and secretion.