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Interaction between trophic action and electrical activity in spinal cord cultures
Brain Research
|August 1, 1984
Summary
Neurotrophic material (NTM) in conditioned medium (CM) protects neurons from tetrodotoxin (TTX)-induced cell death, particularly during critical developmental periods. NTM availability and neuronal survival depend on ongoing electrical activity.
Area of Science:
- Neuroscience
- Developmental Biology
- Cell Biology
Background:
- Neuronal survival is crucial for nervous system development and function.
- Electrical activity plays a role in neuronal development and survival.
- Tetrodotoxin (TTX) is a neurotoxin that blocks sodium channels, inhibiting electrical activity and potentially causing neuronal cell death.
Purpose of the Study:
- To investigate the effect of conditioned medium (CM) containing neurotrophic material (NTM) on tetrodotoxin (TTX)-mediated neuronal cell death.
- To determine the role of NTM in protecting neurons during critical periods of vulnerability to electrical blockade.
- To explore the relationship between electrical activity and NTM release and neuronal survival.
Main Methods:
- Dissociated spinal cord-dorsal root ganglion (SC-DRG) cultures were used.
- Nutrient medium was collected from developing SC-DRG cultures to create CM.
- TTX was used to block electrical activity in cultures during their critical period of vulnerability (days 7-21).
- Neuronal survival was assessed by cell counts, choline acetyltransferase (ChAT) activity, and [125I]tetanus toxin fixation.
Main Results:
- CM significantly increased neuronal survival, [125I]tetanus toxin fixation, and ChAT activity in TTX-treated cultures in a dose-dependent manner.
- TTX treatment alone resulted in a 20-25% decrease in neuronal number, while CM alone did not affect neuronal counts.
- NTM was detectable in CM collected before day 8 and after day 21, coinciding with periods of high and low neuronal vulnerability, respectively.
- NTM was not detectable in CM from donor cells when electrical activity was blocked by TTX during early development (days 1-5).
Conclusions:
- A critical period for TTX-induced neuron death exists, linked to decreased NTM availability.
- The release of NTM from donor cells and the survival response of target neurons to NTM are dependent on ongoing electrical activity.
- NTM in CM provides a protective effect against TTX-mediated neuronal cell death, highlighting the importance of both trophic support and electrical activity in neuronal survival.