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Diazepam enhances intrasynaptosomal free calcium concentrations.
J V Martin1, D R Keir, H Y Lee
1Department of Biology, Rutgers University, Camden, N.J. 08102.
Brain Research
|May 10, 1991
Summary
Diazepam significantly increases intracellular calcium levels in rat brain synaptosomes. This effect was observed in both depolarized and non-depolarized conditions, suggesting a potent role for diazepam in modulating calcium homeostasis.
Area of Science:
- Neuroscience
- Pharmacology
Background:
- Synaptosomes are crucial for understanding neurotransmission.
- Calcium ions (Ca2+) play a vital role in synaptic function.
- Diazepam is a widely used anxiolytic drug with known effects on the central nervous system.
Purpose of the Study:
- To investigate the effect of diazepam on intracellular calcium levels in rat brain synaptosomes.
- To examine the influence of membrane potential and external calcium on diazepam's effect.
- To elucidate the interaction between diazepam and the sodium-calcium exchanger (Na+/Ca2+ exchanger).
Main Methods:
- Preparation of rat brain synaptosomes.
- Incubation of synaptosomes with varying concentrations of diazepam.
- Measurement of intracellular Ca2+ levels using the fluorescent dye fura-2.
- Manipulation of membrane potential and external Ca2+ concentrations.
Main Results:
- Diazepam significantly enhanced Ca2+ levels in depolarized synaptosomes with added Ca2+.
- Even at low concentrations (1 microM), diazepam increased Ca2+ in non-depolarized synaptosomes.
- The combined effects of depolarization and diazepam on intrasynaptosomal Ca2+ were synergistic.
Conclusions:
- Diazepam effectively increases intracellular calcium concentration in synaptosomes.
- The drug's effect on Ca2+ is present under various conditions, including non-depolarized states.
- Diazepam's action on calcium levels may contribute to its overall pharmacological effects.