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Updated: May 29, 2026

Generation of Local CA1 γ Oscillations by Tetanic Stimulation
Published on: August 14, 2015
Toxic effects of midazolam on differentiating neurons in vitro as a consequence of suppressed neuronal
Barbara Sinner1, Oliver Friedrich, York Zausig
1Department of Anesthesiology, University of Regensburg, Regensburg, Germany. barbara.sinner@klinik.uni-regensburg.de
Background:
In immature neurons anesthetics induce apoptosis and influence neuronal differentiation. Neuronal Ca(2+)-oscillations regulate differentiation and synaptogenesis. We examined the effects of the long-term blockade of hippocampal Ca(2+)-oscillations with midazolam on neuronal synapsin expression.
Material And Methods:
Hippocampal neurons were incubated at day 15 in culture with the specific GABA(A) receptor agonist muscimol (50μM) or with midazolam (100 and 300nM), respectively, for 24h. TUNEL and activated-Caspase-3 staining were used to detect apoptotic neurons. Ca(2+)-oscillations were detected using the Ca(2+)-sensitive dye FURA-2 and dual wavelength excitation fluorescence microscopy. Synapsin was identified with confocal anti-synapsin immunofluorescence microscopy.
Results:
Muscimol, when applied for 24h, decreased the amplitude and frequency Ca(2+)-oscillations significantly. Midazolam concentration-dependently suppressed the amplitude and frequency of the Ca(2+)-oscillations. This was associated by a downregulation of the synapsin expression 24h after washout.
Conclusion:
Neuronal Ca(2+)-oscillations mediate neuronal differentiation and are involved in synaptogenesis. By acting via the GABA(A) receptor, midazolam exerts its toxic effect through the suppression of neuronal Ca(2+)-oscillations, a reduction in synapsin expression and consecutively reduced synaptic integrity.
Insights
Anesthetics like midazolam can harm developing neurons by disrupting calcium (Ca2+) oscillations, leading to reduced synapsin expression and impaired synaptic integrity.
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Neuropharmacology
Background:
- Immature neurons are sensitive to anesthetics, which can induce apoptosis and affect differentiation.
- Neuronal calcium (Ca2+) oscillations are critical regulators of neuronal differentiation and synaptogenesis.
- The impact of long-term blockade of hippocampal Ca2+ oscillations by midazolam on synapsin expression requires investigation.
Purpose of the Study:
- To investigate the effects of midazolam-induced blockade of hippocampal Ca2+ oscillations on neuronal synapsin expression.
- To understand the role of GABA(A) receptors in midazolam's neurotoxic effects.
Main Methods:
- Hippocampal neurons were treated with muscimol or midazolam.
- Apoptosis was assessed using TUNEL and activated-Caspase-3 staining.
- Ca2+ oscillations were measured using FURA-2 dye and fluorescence microscopy.
- Synapsin expression was analyzed via confocal anti-synapsin immunofluorescence microscopy.
Main Results:
- Muscimol and midazolam significantly decreased the amplitude and frequency of Ca2+ oscillations.
- Midazolam suppressed Ca2+ oscillations in a concentration-dependent manner.
- A significant downregulation of synapsin expression was observed 24 hours after midazolam washout.
Conclusions:
- Neuronal Ca2+ oscillations are essential for mediating neuronal differentiation and synaptogenesis.
- Midazolam exerts neurotoxic effects by suppressing neuronal Ca2+ oscillations via the GABA(A) receptor.
- This suppression leads to reduced synapsin expression and compromised synaptic integrity in developing neurons.
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