Related Experiment Videos
Interleukin-2 increases choline acetyltransferase activity in septal-cell cultures
1Douglas Hospital Research Centre, McGill University, Verdun, Quebec, Canada.
Insights
Interleukin-2 (IL-2) enhances choline acetyltransferase (ChAT) activity in developing septal neurons. This effect is concentration-dependent and mediated through IL-2 receptors, suggesting a direct role in cholinergic differentiation.
Area of Science:
- Neuroscience
- Cell Biology
- Immunology
Background:
- Interleukin-2 (IL-2) modulates acetylcholine release in the hippocampus.
- Embryonic septal-cell cultures (E17) are enriched with cholinergic neurons.
- Understanding IL-2's cellular effects on cholinergic phenotype is crucial.
Purpose of the Study:
- To investigate the cellular mechanisms of IL-2's effect on cholinergic phenotype expression.
- To determine the role of IL-2 in choline acetyltransferase (ChAT) activity.
- To explore the concentration-dependent and receptor-mediated actions of IL-2.
Main Methods:
- Culturing embryonic septal cells at varying densities under serum-free conditions.
- Assessing cholinergic phenotype using choline acetyltransferase (ChAT) activity assays.
- Utilizing acetylcholinesterase (AChE) cytochemistry to evaluate neuronal characteristics.
- Employing an IL-2 receptor antibody to block IL-2 signaling.
Main Results:
- IL-2 significantly increased ChAT activity in 5-day-old cultures.
- The magnitude of ChAT enhancement correlated with cell plating density and IL-2 concentration (pM range).
- IL-2's effect was inhibited by an IL-2 receptor antibody and did not alter AChE-positive cell numbers or morphology.
Conclusions:
- IL-2 stimulates ChAT activity in septal neurons via its own receptors.
- The findings suggest a direct role for IL-2 in promoting cholinergic differentiation.
- IL-2 acts at picomolar concentrations, independent of trophic effects on neuronal morphology.
Abstract:
Interleukin-2 (IL-2) is a potent modulator of in vitro acetylcholine release in hippocampal slices [Hanisch et al. (1993) J. Neurosci., 13:3368]. In order to further investigate the cellular nature of this effect, we used embryonic septal-cell cultures (E17), known to be enriched with the cholinergic phenotype. Septal cells were grown at different plating densities under serum-free conditions. The effect of IL-2 on the expression of the cholinergic phenotype was determined using choline acetyltransferase (ChAT) activity and acetylcholinesterase (AChE) cytochemistry. IL-2 significantly enhanced ChAT activity in 5-day-old cultures (5 days in vitro). The amplitude of increases correlated with plating density. At 5 x 10(5) cells/well, the increase in ChAT activity was 35-55% greater than control values in the presence of 10(-14)-10(-10) M IL-2, whereas at 7.5 x 10(5) cells/well, this increase was substantially lower (20%) and only observed at concentrations between 10(-13)-10(-11) M. At 10(6) cells/well, IL-2 had no effect on ChAT activity. The IL-2-induced increase in ChAT activity was significantly inhibited in the presence of an IL-2 receptor antibody. Moreover, this increase was not dependent upon trophic actions, as the number of AChE-positive cells or their morphological characteristics were not altered by IL-2. Taken together, these results suggest that IL-2 can stimulate, at pM concentrations, ChAT activity by acting via its own receptors expressed by septal neurons.