Molecule guides
Neuropeptide Reagents: Families, Formats and Choosing Between Them
The short signalling peptides neurons release alongside classical transmitters — what each family is ordered for, and when a kit beats peptide plus antibody.
What neuropeptide research deals with are the short signalling peptides neurons release alongside the classical transmitters — neuropeptide Y, substance P, orexin, galanin and their relatives, modulating feeding, pain, arousal, stress and social behaviour. Assembled on our neuropeptide topic page are the catalogue items laboratories buy for that work: synthetic standards, species-specific fragments, antisera raised in rabbits, labeled tracers and immunoassay kits, arranged by family. Below, the families inside that topic are set out, with what each is studied for and which reagent format suits which experiment.
What we file as a neuropeptide
An item goes under the neuropeptide topic when its parent molecule is expressed in neural or neuroendocrine tissue and signals through G-protein-coupled receptors in the nervous system. Hypothalamic feeding peptides belong here, as do the opioid peptides, the tachykinins and the stress-axis peptides. Overlap with other topics is common — obesity research also claims NPY, cardiovascular work also claims CGRP — so one family page may be reached from several topics. Everything is supplied solely for research in vitro and in animals; nothing in this section is a drug product.
Families most often ordered
Below are the family pages requested most within the neuropeptide topic, together with the research areas each tends to be bought for:
- Neuropeptide Y (NPY) — among the most plentiful peptides in the mammalian brain, and a fixture of work on feeding circuits, anxiety models and sympathetic signalling. Receptor-selective analogues and fragments separate Y1, Y2 and Y5 pharmacology.
- Substance P — the original tachykinin, at the centre of studies on pain transmission and neurogenic inflammation, and also ordered as fragments for mapping the NK1 receptor.
- Orexin (hypocretin) — standards for orexin-A and orexin-B underpin research on arousal and the sleep/wake cycle, narcolepsy models included.
- Galanin — used in models of seizure, mood and feeding; because the rat, human and porcine variants differ in sequence, matching the standard to your organism is not optional.
- Neurotensin — a fixture of dopamine-circuit and gut–brain work, where NT(8–13) is the usual active fragment.
- Somatostatin — for receptor-subtype pharmacology and as a cortical interneuron marker; both SST-14 and SST-28 are held in stock.
- CGRP — calcitonin gene-related peptide, the migraine field's best-known target, available as alpha and beta isoforms plus the antagonist fragment CGRP(8–37).
- Oxytocin and vasopressin — used in research on social behaviour, stress and osmoregulation, with EIA kits and antibodies commonly bought alongside the peptides.
- Dynorphin, enkephalin and endorphin — the three classical opioid-peptide families, applied in studies of receptor selectivity and stress-induced analgesia.
- PACAP — a pleiotropic peptide investigated in circadian biology and neuroprotection, where the PACAP-27 and PACAP-38 forms do not behave alike in assays.
- Kisspeptin — sitting upstream of the GnRH neurons and central to reproductive neuroendocrinology.
- Neuropeptide S and neuropeptide W — more recent families tied to arousal and feeding, with literatures still expanding.
Formats within the topic
Whatever formats exist for a family appear on its page. Across the neuropeptide topic there are four product types:
- Research peptides — lyophilized synthetic standards, typically 98%+ by HPLC, in fills from micrograms to milligrams. These do the everyday work of receptor assays, standard curves and perfusion in electrophysiology.
- Labeled peptides — biotinylated, fluorescent (FAM/TAMRA) and radioiodinated forms for imaging, binding assays and receptor autoradiography. Binding studies on neuropeptides have long leaned on I-125 tracers.
- Polyclonal antibodies and antisera — raised against the parent peptide for immunohistochemistry on brain sections and for detection by RIA or EIA.
- ELISA, EIA and RIA kits — for quantifying endogenous peptide in plasma, CSF or tissue extract; compare the standard range with your expected concentrations before ordering.
Choosing within a family
Four questions recur. The species sequence comes first: NPY differs between rat and human by just one residue, whereas in families such as galanin the gaps are wider and antibody cross-reactivity cannot be assumed — family pages state each item's species. Second, full-length or fragment: things like NPY(13–36) and CGRP(8–37) are tools for dissecting receptor subtypes, not stand-ins for the parent peptide in quantitation. Third, labeled or not: the classic competition-binding pair is unlabeled peptide together with a labeled tracer. Fourth, peptide or kit: where the question is how much endogenous peptide a sample contains, an immunoassay kit usually beats assembling antibody, tracer and standards yourself.
Handling notes for this topic
Neuropeptides are mostly small, between 1 and 4 kDa, and as dry lyophilized powder they keep for years at −20 °C. Solutions are another story: peptides containing methionine, among them some tachykinins, oxidise, and cysteine-bearing families can dimerise. The usual approach is to reconstitute in a small volume, divide it into aliquots immediately, and avoid repeated freeze–thaw — the workflow described in our peptide storage guide and aliquoting guide. Where the work is quantitative, verify content against the certificate of analysis instead of treating label mass as peptide mass; peptide content versus gross weight is explained in our COA guide.
Where to go next
Browse the whole neuropeptide topic, or begin at the research catalogue hub if your target crosses topics. Among adjacent guides in this series, the obesity and appetite section shares many hypothalamic families with this one, and the neurodegeneration section covers amyloid, tau and trophic factor reagents.
Questions
How does a neuropeptide differ from a neurotransmitter?
The classical transmitters — glutamate, GABA, dopamine — are small molecules released quickly at the synapse. Neuropeptides are short amino acid chains, released more slowly, that mostly work through G-protein-coupled receptors to modulate circuits over seconds and minutes. Plenty of neurons release both, which is why peptide standards sit beside transmitter pharmacology in circuit research.
Human or rat sequence?
Wherever a species variant exists, match the sequence to the organism you are studying. Certain families are identical throughout mammals, while others — galanin and the NPY-related peptides among them — diverge enough to alter receptor affinity and antibody recognition. Every catalogue item's species is listed on its family page.
Can fragments substitute for the full-length peptide?
They cannot. Fragments generally serve as receptor-subtype tools — CGRP(8–37), for instance, antagonises where full-length CGRP is the agonist. Reserve the full-length parent for quantitation and standard curves, and bring in fragments only where the design specifically requires them.
When is an ELISA kit the better buy?
Choose a kit whenever the question is how much endogenous peptide is present in plasma, CSF or tissue extract, since the kit packages matched antibody, standards and detection chemistry across a validated range. Buy peptide and antibody separately for immunohistochemistry, binding assays or developing an assay of your own.
How should reconstituted neuropeptides be kept?
Dry stocks last for years at −20 °C or below provided moisture is excluded. Once in solution, split the material into single-use volumes at once and freeze them, avoiding repeated freeze–thaw, which measurably degrades many neuropeptides within only a few cycles.