Neuropeptides Flashcards
What are Neurotransmitters?
- Fast vesicle recycling, ultra-short distance, and ionotropic receptors
What are neuropeptides?
- Slow vesicle cycling
- Local diffusion
- G-protein coupled receptors
What are examples of neuropeptides?
- Vasopressin
- Sunstance P
- NPY etc
Define a neuropeptide?
A small protein like molecules (peptides) used by neurons to communicate with each other.
What are forms of chemical signalling?
What are Neuropeptides responsible for?
- Neuronal signallling molecules
- Responsible for brain function:
1. Analgesia
2. Food intake
3. Learning & memory
4. Metabolism, reproduction
5. Social behaviours
What are the differences between syhthesis of Neurotransmitter vs neuropeptides?
- NP-Synth in RER and golgi apparatus
- NT-Synth in cytosol of presynaptic neuron terminals
What are the differences between concentrations of Neurotransmitter vs neuropeptides?
- NP - Synth in low concs
- NT - Synth in high conc
What are the differences between the location of Neurotransmitter vs neuropeptides?
- NP - Found all over neuron
- NT - Only found in axon terminals of presyn neurons
What are the differences between where Neurotransmitter and neuropeptides are stored?
- NP - Stored in large dense-core vesicles
- NT - Stored in small secretory vesicles
What are the differences between the molecular weight of Neurotransmitter vs neuropeptides?
- NP - High molecular weight
- NT - Low
What are the differences between the activity of Neurotransmitter vs neuropeptides?
- NP - Slow acting
- NT - Fast acting
What are the differences between the response of Neurotransmitter vs neuropeptides?
- NP - Produce slow response
- NT - Produce acute response
What are the differences between the duration of Neurotransmitter vs neuropeptides?
- NP - Prolonged action
- NT - Trigger short-term response
What are the differences between the release of Neurotransmitter vs neuropeptides?
- NP - Axonal streaming of NT occurs in few cm/day
- NT - Released within few milliseconds upon arrival of AP
What are the differences between what Neurotransmitter vs neuropeptides are released with?
- NP - Released to synaptic cleft/surroundings along woth another NT
- NT - Released individually depending on AP
What are the differences between cytosolic Ca2+ conc of Neurotransmitter vs neuropeptides?
- NP - Released at low cytosolic Ca2+ conc
- NT - Released at high Cytosolic Ca2+ conc
What are the differences between the site of action of Neurotransmitter vs neuropeptides?
- NP - Have different action site thn origin - Diffusion
- NT - Released in direct appostion to target cells
What are the differences between potency of Neurotransmitter vs neuropeptides?
- NP - ~1000 times more potent than NTs
- NT - Less potent comp to NP
What are large dense core vesicles?
- 70-200nm
- Cont NP, growth factors and classical NT and hormones
- Synth in cell body
- Transported to terminals
- No recycling
- Fewer than small electron translucent vesicles
- Located distant from active zone
- Rel with high freq trains of AP
- Provide diffuse, slow neuromodulatory actions
What is Tachykinin (TAC)?
- Largest family of neuropeptides
- Characteristic:
1. Conserved COOH terminal seq but varying N-terminal
What is neuropeptide Y? (NPY)
- 36 AA
- Acts as NT in the brain & ANS
What do NPY receptors do?
- NPY receptors – NPY1R, Y2R, Y4R, Y5R, and Y6R – G-protein coupled receptors which lead to the inhibition of adenylate cyclase and finally the inhibition of cAMP accumulation or PLC activation
- NPY1,5,6 are inhibitor
- NPY2,4 are excitatory
What is substance P?
- Belongs to TAC neruopeptide family
What are the receptors for substance P?
- NKIR -GPCR
- AA residues that are responsible for binding SP and its antagonists are present in extracellular loops and transmem regions of NK1
What are SP antagonists?
- E.g. Capsacin is clinically used as analgesic and anti-inf agent
Why else is substance P interesting?
- SP could promote wound healing of non-healing ulcers in humans
- SP is a potent vasodilator.
What is Somatostatin siganlling?
- 2 active forms of the peptide exists.
- Their activity overlaps
- 14 AA works mainly in the brain
- 28 AA works mainly in the GI tract
- Functions such as motor activity, sleep, sensory, and cognitive processes,
- Involved in Alzheimer’s Parkinson’s disease, depression, and schizophrenia
- Somatostatin neurones in the central amygdala mediate anxiety
