Zusammenfassung der Ressource
Neuropeptides
- What are neuropeptides
- Small protein like molecules
- 3-30 aa
- Synthesised from larger precursors
- At least 90 aa
- Removal of signal sequence,
cleavage events and disulphide
bond formation
- In some cases a single precursor molecular
can give rise to multiple bioactive peptides
- Used by neurones to communicate with each other
- More than 100 different neuropeptides
identified in the mammalian brain
- Expressed and released by neurones
- Mediate or modulate neuronal communication by
acting on cell surface receptors e.g. GPCRs
- Act as neuronal signalling molecules, influencing
particular brain functions e.g. learning and memory
- Properties
- Synthesised as a large precursor
molecule at the cell soma
- Transported to release sites in
dense core vesicles
- Slow postsynaptic effects
- Actions terminated by extracellular
proteases or by diffusion
- Can trigger complex
coordinated behaviours
- Actions do not require point to
point synaptic connections
- Differences between NT and neuropeptides
- Much lower concentrations in vesicles
- About 10mM compared with 100 mM
- Much higher affinity for receptors
- Synthesised from precursors and only used once
- Released by lower concentraton of
Ca2+ away from point of entry
- Neuropeptides and NT can be released
form different parts of the nerve terminal
- Major neuropeptides of
the mammalian brain
- Substance P
- Sensory and pain
- Released from the terminals
of specific sensory nerves
- Found in the brain and spinal cord and is
associated with inflammatory processes and pain
- Coexists with the excitatory NT glutamate in primary
afferents that respond to painful stimulation
- Also associated with anxiety, stress, neurogenesis and nausea
- Signalling mediated through Neurokinin 1 (NK1) receptors
- Neurotensin
- Regulation of release of other peptides
- Oxytocin
- Vasopressin
- Neuropeptide Y
- alpha-endorphin
- Met-enkephalin
- Opoid peptides
- Two functional pentapeptides identified
- Enkephalins
- Three additional longer peptides later identified
- Endorphins
- Enkephalins and endorphins found
throughout the brain but are not co-localised in
the same neurones
- Degredation
- Enzymatic
- Aminopeptidase
- Neprilysin
- Insulin degrading enzyme
- Angiotensin converting enzyme