Corazonin is a highly conserved

neuropeptide Neuropeptides are chemical messengers made up of small chains of amino acids that are synthesized and released by neurons. Neuropeptides typically bind to G protein-coupled receptors (GPCRs) to modulate neural activity and other tissues like the ...

found in many

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...

s, in particular locusts and

cockroach Cockroaches (or roaches) are a paraphyletic group of insects belonging to Blattodea, containing all members of the group except termites. About 30 cockroach species out of 4,600 are associated with human habitats. Some species are well-known as ...

es.

Structure

Corazonin is an undecapeptide (11 amino-acid

peptide Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. A ...

) with the amino acid sequence carboxyl-Glu-Thr-Phe-Gln-Tyr-Ser-Arg-Gly-Trp-Thr-Asn-amine. It is blocked by at its N-terminal side and amidated at its C-terminus. This form is called rg(7)corazonin. Other forms include is(7)corazonin, hr(4), His(7)corazonin and yr(3), Gln(7), Gln(10)corazonin.

History

Corazonin was first identified as a cardiostimulatory

in the

American cockroach The american cockroach (''Periplaneta americana'') is the largest species of common cockroach, and often considered a pest. In certain regions of the U.S. it is colloquially known as the waterbug, though it is not a true waterbug since it is not ...

''(Periplaneta americana)''. Due to its ability to accelerate the heart beat in ''P. americana'' it was named corazonin, from 'corazón', the Spanish word for 'heart'. It was then shown to be present also in the moth ''Manduca sexta'', another cockroach species, '' Nauphoeta cinerea'' as well as the locust ''Schistocerca gregaria''. In the latter species the Arg residue was replaced by a His residue. Several years later the peptide was independently identified from locusts, where it was initially named 'dark-color-inducing neurohormone' or 'dark pigmentotropin' due to its ability to induce dark pigmentation in some

Where corazonin is found

rg(7)corazonin was originally identified in

es such as the

''(Periplaneta americana)'' and has also been identified in the genus of flies ''

Drosophila ''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species ...

'', the cricket '' Gryllus bimaculatus'' and the silkworm '' Bombyx mori'' and is now known to be the most common form of this peptide. is(7)corazonin is found in certain locusts, including the migratory locust ''(Locusta migratoria)'' and the

desert locust The desert locust (''Schistocerca gregaria'') is a species of locust, a periodically swarming, short-horned grasshopper in the family Acrididae. They are found primarily in the deserts and dry areas of northern and eastern Africa, Arabia, and sou ...

''(Schistocerca gregaria)'', the stick insect ''

Carausius morosus ''Carausius morosus'' (the 'common', 'Indian' or 'laboratory' stick insect) is a species of Phasmatodea (phasmid) often kept as pets by schools and individuals. Culture stocks originate from a collection from Tamil Nadu, India. Like the majorit ...

'', and in

wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. Th ...

s ('' Vespidae''). hr(4), His(7)corazonin appears only to be found in

bee Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyly, monophyletic lineage within the ...

s, such as the honey bee ''(Apis mellifera)''. yr(3), Gln(7), Gln(10)corazonin is present in wasps. Corazonin appears to be lacking in all beetle species as well as aphids. rg(7)corazonin has also been identified from the tick Ixodes scapularis, but is absent from the spider mite. It may thus well be generally present in Arhropods.

Function

The peptide is typically produced by large neuroendocrine cells in the pars lateralis of the protocerebrum that have axons into the corpora cardiaca where it is released into the hemolymph. In this respect the neuropeptide resembles its vertebrate homolog, GnRH (Gonadotropin Releasing Hormone) which is released into the pituitary gland to stimulate the release of Luteinizing hormone and Follicle Stimulating Hormone in vertebrates, like humans. Corazonin and GnRH are clear homologs, as are their receptors. In the common fruit fly ''

Drosophila melanogaster ''Drosophila melanogaster'' is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly" or "pomace fly". Starting with Ch ...

'', corazonin is expressed in the salivary glands and fat body of both males and females, and is also expressed sexually dimorphically in the abdominal ganglia of males. It acts in part as a stress peptide through regulation of food intake and metabolism and in males specifically, it both enables sperm transfer and sets copulation duration. In the American cockroach ''

Periplaneta americana The american cockroach (''Periplaneta americana'') is the largest species of common cockroach, and often considered a pest. In certain regions of the U.S. it is colloquially known as the waterbug, though it is not a true waterbug since it is not ...

'', rg(7)corazonin acts as a cardiostimulatory neuropeptide and accelerates the heart beat. It also causes contractions of the hyperneural muscle, however this has not been seen in other cockroach species. is(7)corazonin acts as a hormonal factor in locusts and can cause dark pigmentation in albino migratory locusts (''

Locusta migratoria The migratory locust (''Locusta migratoria'') is the most widespread locust species, and the only species in the genus ''Locusta''. It occurs throughout Africa, Asia, Australia and New Zealand. It used to be common in Europe but has now become ...

'') and in green nymphs of the desert locust '' Schistocerca gregaria''. While corazonins found in crickets and moths have no effect on body colour of the crickets or moths themselves, they can cause dark pigmentation in albino nymphs of the migratory locust (''

''). In silkworms ('' Bombyx mori''), corazonin reduces the spinning rate of silk.

References

* {{cite journal , last1 = Nässel , first1 = DR , year = 2002 , title = Neuropeptides in the nervous system of Drosophila and other insects: multiple roles as neuromodulators and neurohormones , journal = Progress in Neurobiology , volume = 68 , issue = 1, pages = 1–84 , doi = 10.1016/S0301-0082(02)00057-6 , pmid = 12427481 , s2cid = 24447517 Neuropeptides