Calcitonin gene-related peptide
Calcitonin gene-related peptide (CGRP) is a member of the calcitonin family of peptides, which in humans exists in two forms, -CGRP and -CGRP. -CGRP is a 37-amino acid peptide and is formed from the alternative splicing of the calcitonin/CGRP gene located on chromosome 11.  The less-studied -CGRP differs in three amino acids (in humans) and is encoded in a separate gene in the same vicinity.

# Function
CGRP is produced in both peripheral and central neurons. It is a potent peptide vasodilator and can function in the transmission of nociception. In the spinal cord, the function and expression of CGRP may differ depending on the location of synthesis. CGRP is derived mainly from the cell bodies of motor neurons when synthesized in the ventral horn of the spinal cord and may contribute to the regeneration of nervous tissue after injury. Conversely, CGRP is derived from dorsal root ganglion when synthesized in the dorsal horn of the spinal cord and may be linked to the transmission of pain. In the trigeminal vascular system, the cell bodies on the trigeminal ganglion are the main source of CGRP. CGRP is thought to play a role in cardiovascular homeostasis and nociception.

# Receptors
CGRP mediates its effects through a heteromeric receptor composed of a G protein-coupled receptor called calcitonin receptor-like receptor (CALCRL) and a receptor activity-modifying protein (RAMP1). CGRP receptors are found throughout the body, suggesting that the protein may modulate a variety of physiological functions in all major systems (e.g., respiratory, endocrine, gastrointestinal, immune, and cardiovascular). The extracellular loop number 2 is fundamental for ligand induced activation, with key interactions of R274/Y278/D280/W283.

# Regulation
Regulation of the calcitonin gene-related peptide (CGRP) gene is in part controlled by the expression of the mitogen-activated protein kinases (MAPK) signaling pathway, cytokines such as TNF  and iNOS.
5HT1 receptor agonists, such as sumatriptan, increase intracellular calcium, which cause decreases in CGRP promoter activity.

# Research
Increased levels of CGRP have been reported in migraine and temporomandibular joint disorder patients as well as a variety of other diseases such as cardiac failure, hypertension, and sepsis.
There is mounting evidence to suggest that CGRP may be beneficial in preventing the development of hypertension and cardiovascular pathologies associated with hypertension. Prophylactic therapy with calcitonin generelated peptides (CGRPs) may have unknown fertility consequences for women of child bearing age. This is of particular concern, as females (16.6%) are more genetically predisposed than males (7.5%) to endure this debilitative health condition.
Preclinical evidence suggests that, during a migraine, activated primary sensory neurons (meningeal nociceptors) in the trigeminal ganglion release CGRP from their peripherally projecting nerve endings located within the meninges. This CGRP then binds to and activates CGRP receptors located around meningeal vessels, causing vasodilation, mast cell degranulation, and plasma extravasation. Human observations have further implicated the role of CGRP in the pathophysiology of migraine. Activation of primary sensory neurons in the trigeminal vascular system in humans can cause the release of CGRP. During some migraine attacks, increased concentrations of CGRP can be found in both saliva and plasma drawn from the external jugular vein. Furthermore, intravenous administration of alpha-CGRP is able to induce headache in individuals susceptible to migraine.