Hormones/Cytokines W6 Flashcards
What way do hormones/cytokines regulate anabolic processes?
Upstream
What hormones promote anabolism?
Hepato growth factor
IL-5/ IL-6
Fibroblast Growth factor
Leukaemia Inhibitory factory
Insulin
What happens to insulin levels during exercise?
They are suppressed
What does insulin induce?
Mitosis
Differentiation of satellite cells
What does insulin greater affect?
Attenuating proteolysis rather than protein synthesis
What does IGF-1 do?
Main anabolic response for the body
Enhances effects in mechanical loading
Where are IGF-1 receptors found?
Satellite cells
Adults myofibres
Schwann cells
What are the 3 isoforms of IGF-1?
Systemic form: IGF-1Ea
Systemic form: IGF-1Eb
Splice variant: IGF-1Ec
What does IGF-1Ea do?
Enhance fusion of satellite cells with muscle fibres
Facilitates donation of myonuclei
Maintains optimal DNA: protein in muscle
What does IGF-1Eb and IGF-1Ec do?
Activates satellite cells
Mediates proliferation and differentiation
How does IGF-1 induce hypertrophy?
Autocrine and Paracrine manner
How does IGF-1 promote anabolism?
Increasing rate of protein synthesis in differentiated myofibres
What does IGF-1 activate?
L-type Ca channel gene expression
What happens when the L-type Ca channel gene expression is activated?
Increased intracellular Ca2+ concentrations
Activation of multiple anabolic Ca2+ dependent pathways
What is testosterone?
Cholesterol derived
Anabolic effect on tissue
How does testosterone interact with receptors on neurons?
Increase cell body size/ amount of neurotransmitters released
Regenerate nerves
How is testosterone synthesised and secreted?
Leydig cells (testes)
How can weakly bound testosterone become active?
By rapidly disassociating from albumin
What happens when unbound testosterone binds to androgen receptors?
Causes conformational change
Transport testosterone to the cell nucleus to interact with DNA
How does testosterone promote anabolsim?
Increasing protein synthetic rate
Inhibiting protein breakdown
How does does testosterone contribute to protein accretion?
Indirectly
Stimulates the release of anabolic hormones
What does GH do?
Induces fat metabolism toward mobilisation of triglycerides
Stimulating cellular uptake/ incorporation of amino acids into various proteins
What does GH do when there is absence of mechanical loading?
Upregulates mRNA of systemic IGF-1
Mediates nonhaptic IGF-1 gene expression in an autocrine/paracrine manner
What is the GH secreted by?
Anterior pituitary gland
In muscle fibres, how does GH effect it?
Increases hypertrophy in type I and type II
What does a hypertrophic facilitate?
Fibre recovery
What is GH releasement associated with?
Marked upregulation of iGF-1gene in muscle so that more is spliced toward the MGF isoform
What does GH regulate?
Immune function
Bone modelling
Extracellular fluid volume
How do hypertrophic responses occur?
Enhanced interaction with muscle cell receptors
