Questions and Answers
What are the primary roles of growth and trophic factors?
Proliferation, differentiation, survival, innervation, maintenance, plasticity, learning and memory, regeneration and repair.
Which of the following are examples of growth or trophic factors? (Select all that apply)
Retrograde transport is the process by which substances are transported from the cell body to the target area.
False
What is the function of nerve growth factor (NGF)?
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Which neurotrophins are part of the neurotrophin family?
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____ influences neuronal viability and phenotype.
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What role does neurotrophin-3 (NT3) play in development?
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What are the receptor tyrosine kinases associated with neurotrophins called?
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Proneurotrophins promote neuronal growth and survival.
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Study Notes
Growth and Trophic Factors Overview
- Essential for various neuronal processes: proliferation, differentiation, survival, innervation, maintenance, plasticity (learning and memory), regeneration, and repair.
- Involves soluble/diffusible factors, primarily polypeptides.
Neurotrophic Factors
- Target-derived factors produced in specific areas to regulate neuron survival and differentiation.
- Competition for trophic support observed during development; influences survival determined by quality and quantity.
- Examples include:
- Neurotrophins (NTs)
- Fibroblast growth factors (FGFs)
- Cytokines (CNTF, LIF)
- Transforming growth factors (TGFβ, GDNF)
- Insulin-like growth factors (IGF-1)
Transport Mechanisms
- Retrograde transport: movement from target cells back to neuron cell bodies.
- Anterograde transport: movement from neuron cell bodies to target areas.
Nerve Growth Factor (NGF)
- Key player in both peripheral (PNS) and central nervous system (CNS).
- Exists as pro-NGF, which is cleaved into active NGF; consists of dimer with 118 amino acids.
- Promotes neurite outgrowth and neuronal survival.
- Importance in sensory neuron innervation and support for neuron viability.
Neurotrophin Family
- Includes Nerve Growth Factor (NGF), Brain-Derived Neurotrophic Factor (BDNF), Neurotrophin-3 (NT-3), and Neurotrophin-4/5.
- Acts through Trk receptors (receptor tyrosine kinases), activating multiple intracellular signaling pathways.
Signal Transduction Pathways
- Trk receptors lead to crucial pathways, including MAPK and AKT functions.
- Apoptosis and axonal pruning regulated based on activated receptors.
Receptor Interactions
- Co-expression of different receptors can result in varied cellular responses.
- Nogo and Lingo proteins are involved in inhibiting axon outgrowth.
Clinical Relevance of NGF
- Plays maintenance role in mature nervous systems and its relevance to synaptic plasticity, particularly in conditions like Alzheimer's disease.
- Increases expression following neuronal injury, influencing repair strategies.
Neurotrophin-3 (NT-3)
- Early developmental presence, acts as a mitogen for neural crest cells and supports differentiation in specific DRG neurons.
- Has differentiated effects in CNS, particularly on motoneurons.
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Description
Explore the essential roles of growth and trophic factors in neuronal proliferation, differentiation, survival, and maintenance. This quiz emphasizes the understanding of soluble factors and their impact on innervation and plasticity. Test your knowledge on these critical neurobiological concepts!
