They serve as messenger substances and are released either endocrinically as neurosecretory peptide hormones or paracrinely as cotransmitter . As hormones, they reach the target cells via the bloodstream. As cotransmitters, they act as neuromodulators by modulating, i.e. supporting or inhibiting, the action of the neurotransmitters . To date, over 100 different neuropeptides are known. Well-known representatives are z. B. the endorphins as the body's own opioids .
In contrast to low molecular weight messenger substances, the synthesis and the transport are rather slow and sluggish. The neuropeptides are synthesized on the ribosomes in the perikaryon and not - as is the case with low-molecular messenger substances - in the axon . In addition, cotransmitters do not bind directly to ion channels and therefore do not change the tension of the postsynaptic membrane, but act via receptors on cell functions and on the cell structure of the postsynaptic target cell.
Neurosecretory peptide hormones
- ACTH - stimulates the release of glucocorticoids in the adrenal cortex and is involved in the regulation of vegetative functions in the brain via the melanocortin receptors .
- Angiotensin II - involved in the regulation of blood pressure and water balance
- Antidiuretic hormone (ADH, vasopressin) - " thirst hormone ", causes increased reabsorption of water by the kidneys . Centrally it limits the rise in fever .
- Bombesin - stimulates secretion verschiedenster messengers of the gastrointestinal tract to
- Bradykinin - has a histamine-like effect and is involved in the inflammatory process
- Calcitonin Gene-Related Peptide - the most powerful endogenous vasodilator known to date
- Cholecystokinin - hormone of the gastrointestinal tract, stimulates motility and secretion
- Galanin - regulating hormone (release of various neurotransmitters and hormones, motility of the gastrointestinal tract)
- Motilin - has a stimulating effect on the motor skills of the gastrointestinal tract
- Neurotensin - inhibits gastric acid secretion, stimulates intestinal contraction and glucagon release
- Oxytocin - causes uterine muscle contractions and emptying of the mammary gland, and also affects behavior .
- Prolactin - promotes mammary gland growth and milk production
- Secretin - stimulates the sodium bicarbonate production in the pancreas , gall bladder and small intestine to
- Somatostatin - paracrine function in the pancreas, inhibits the release of glucagon and insulin
- Thyrotropin (TSH) - stimulates hormone production in the thyroid gland
- Vasoactive intestinal peptide (VIP) - gastrointestinal peptide hormone, causes vasodilation and inhibits gastric acid production
The following list shows a selection of neurotransmitters and some of the peptide cotransmitters that occur with them.
- Norepinephrine cotransmitter
- Cotransmitter from GABA
- Acetylcholine cotransmitter
- Adrenaline cotransmitter
- More cotransmitters
- Medical Dictionary, keyword 'neuropeptides' . Retrieved October 4, 2013.