Introduction to neuropeptides as regulators of physiological processes
and whole animal-behaviour
Learning objectives
1. Knowledge and understanding of mechanisms of neuropeptide biosynthesis in neurons
2. Knowledge and understanding of physiological roles of neuropeptides as mediators of neuromodulation and
neurohormonal signalling.
3. Knowledge and understanding of mechanisms of neuropeptide action via activation of G-protein coupled receptors
4. Knowledge of neuropeptide diversity
What are neuropeptides?
Signalling molecules that are secreted by neurons
They are peptides
There are different peptides found in the nervous system but not all peptides in the nervous system are neuropeptides
Neuropeptides are specifically the peptides secreted by neurons
Synthesised and released by neurons as intracellular signalling molecules
Range in size from 3 to > 40 residues but are derived from larger precursor proteins
Released from dense-core vesicle, triggered by long-lasting but low frequency bursts of action potentials
Can act locally (as transmitters / modulators) or at a distance (as hormones); typically act at low Nano molar
concentrations, which contrast with ‘’classical’’ transmitters that act in micro molar range.
Typically exert effects by binding to G-proteins coupled receptors, some of which are targets for drugs (e.g.
morphine/heroin)
Evolutionarily ancient; occur in all animals with nervous system, with origins that predate nervous system.
The evolutionary origin of most neuropeptides in human can be tracked back to the common ancestor of the bilateria.
Neuropeptide function
Neuropeptide function can be thought about in 3 levels and so regulate whole animal behaviour
Most proteins function at 2 levels, the molecular level and cellular level.
1. Molecular level
- Neuropeptides bind to and activate membrane associated receptors
- Neuropeptide doesn’t have a function but by binding to receptor it has done its job
2. Cellular level
- Neuropeptide receptor activation causes G-protein mediated effects on cell activity
3. Systems/organismal level
, - Systemic effects of neuropeptides cause changes in physiological processes and/or whole-animal behaviours
- Image not showing 2 crabs but 1 crab shedding its exoskeleton and neuropeptides are involved in that
This is an example of behaviour
Introduction to neuropeptides: enkephalins as an example
Enkenphalins are the most famous neuropeptides due to their links to drugs (morphine and heroin)
Ebkenphalins were discovered in the 1970s, which is the period where most neuropeptides were discovered.
Enkenphalins were discovered on the basis of the observation that they were present in the brain. Specific receptor
proteins that heroin, morphine and analog of these drugs are binding to. The existence in the brain the proteins that
the drugs are binding to indicating that there are endogenous molecules to morphine and heroin in the body
Morphine
Discovery of opiate receptor in the brain
Enkephalins: the body’s morphine-like molecules are neuropeptides
Try-gly-gly-phe-met
Try-gly-gly-phe-leu
Neuropeptide receptors as drug target
Neuropeptides are derived from larger precursor proteins.
The protein that gives rise to these 2 peptides was identified in 1982
and this is its amino acid sequence
and whole animal-behaviour
Learning objectives
1. Knowledge and understanding of mechanisms of neuropeptide biosynthesis in neurons
2. Knowledge and understanding of physiological roles of neuropeptides as mediators of neuromodulation and
neurohormonal signalling.
3. Knowledge and understanding of mechanisms of neuropeptide action via activation of G-protein coupled receptors
4. Knowledge of neuropeptide diversity
What are neuropeptides?
Signalling molecules that are secreted by neurons
They are peptides
There are different peptides found in the nervous system but not all peptides in the nervous system are neuropeptides
Neuropeptides are specifically the peptides secreted by neurons
Synthesised and released by neurons as intracellular signalling molecules
Range in size from 3 to > 40 residues but are derived from larger precursor proteins
Released from dense-core vesicle, triggered by long-lasting but low frequency bursts of action potentials
Can act locally (as transmitters / modulators) or at a distance (as hormones); typically act at low Nano molar
concentrations, which contrast with ‘’classical’’ transmitters that act in micro molar range.
Typically exert effects by binding to G-proteins coupled receptors, some of which are targets for drugs (e.g.
morphine/heroin)
Evolutionarily ancient; occur in all animals with nervous system, with origins that predate nervous system.
The evolutionary origin of most neuropeptides in human can be tracked back to the common ancestor of the bilateria.
Neuropeptide function
Neuropeptide function can be thought about in 3 levels and so regulate whole animal behaviour
Most proteins function at 2 levels, the molecular level and cellular level.
1. Molecular level
- Neuropeptides bind to and activate membrane associated receptors
- Neuropeptide doesn’t have a function but by binding to receptor it has done its job
2. Cellular level
- Neuropeptide receptor activation causes G-protein mediated effects on cell activity
3. Systems/organismal level
, - Systemic effects of neuropeptides cause changes in physiological processes and/or whole-animal behaviours
- Image not showing 2 crabs but 1 crab shedding its exoskeleton and neuropeptides are involved in that
This is an example of behaviour
Introduction to neuropeptides: enkephalins as an example
Enkenphalins are the most famous neuropeptides due to their links to drugs (morphine and heroin)
Ebkenphalins were discovered in the 1970s, which is the period where most neuropeptides were discovered.
Enkenphalins were discovered on the basis of the observation that they were present in the brain. Specific receptor
proteins that heroin, morphine and analog of these drugs are binding to. The existence in the brain the proteins that
the drugs are binding to indicating that there are endogenous molecules to morphine and heroin in the body
Morphine
Discovery of opiate receptor in the brain
Enkephalins: the body’s morphine-like molecules are neuropeptides
Try-gly-gly-phe-met
Try-gly-gly-phe-leu
Neuropeptide receptors as drug target
Neuropeptides are derived from larger precursor proteins.
The protein that gives rise to these 2 peptides was identified in 1982
and this is its amino acid sequence
