4 - Neuropeptides Flashcards
What is a neuropeptide
A small protein or polypeptide that acts as a neurotransmitter in the nervous system
Which neuropeptides also acts as hormones
Oxytocin or vasopressin
What behaviours do endogenous opioids control? (8)
Mood Fear response Pain perception Stress response Drug addiction Attachment formation Decision making Gastrointestinal function
How do we determine the effects of neuropeptides (3)
1) Selective agonists or antagonists to define cellular and behavioural effects
2) Knock-out animals
3) Peptidase inhibitors
What did enkephalin knockouts have
Anxiety
Fear
Altered sexual activity
Changes in food palatability
What are the steps of neuropeptide synthesis
1) Transcription of mRNA
2) Mature mRNA translated on the ribosome to na inactive prepropeptide
3) N-terminal cleavage by a peptidase results in a propeptide
4) Propeptide is packaged into dense core vesicles in trans-golgi network
5) DCV peptide undergoes posttranslational processing
What is the response to endogenous opioids
Coordinated response
One region activated and multiple peptides released
Where do we know the most about the cellular actions of neuropeptides
Hypothalamus
What happens when neuropeptides are released
Target GPCR
May spread large distances (um vs nm for neurotransmitters)
High affinity
Can act at multiple receptors, some receptors have multiple agonists
Receptors may be internalised
Which receptors do opioid receptors work at
mu, delta, kappa
Gi/Go receptors
Are neuropeptides reuptaken
No
Need to resynthesise
What are neuropeptides broken down by
Extracellular peptidase
Are opioids or enkephalins more susceptible to peptidases
Enkephalins
