Physiopathological effects of the NO donor 3-morpholinosydnonimine on rat cortical synaptosomes
J Blanco Garcia1, C Aldinucci, S M Maiorca
1Department of Physiology, University of Siena, Siena, Italy.
Abstract:
The NO donor 3-Morpholinosydnonimine (SIN-1) releases NO in the presence of molecular oxygen. In this study, we evaluated the effect of SIN-1 on mitochondria of rat cortical synaptosomes. We demonstrated in vitro that the amount of ONOO(-) generated and H(2)O(2) formation directly correlated with SIN-1 concentration. The mean oxygen consumption by synaptosomal mitochondria was approximately 3.8 nmol of O(2) min(-1) mg(-1) protein, which decreased significantly in the presence of SIN-1 1 mM to 2.5 nmol O(2) min(-1) mg(-1). This decrease was not modified by catalase or Trolox, demonstrating that ONOO(-) was responsible for the effect. The same concentration of SIN-1 caused a significant decrease of ATP production by synaptosomal mitochondria and depolarized the mitochondrial membrane. Moreover, ROS production increased progressively and was completely inhibited by pre-incubation of synaptosomes with Trolox. Finally, phosphatidylserine was externalized and, at the same time, intrasynaptosomal lactate dehydrogenase decreased confirming both, the external membrane breakdown after the addition of SIN-1 and the damage to the synaptosomes.
Insights
The NO donor SIN-1 impairs rat brain mitochondria by increasing peroxynitrite and damaging synaptosomes. This study reveals SIN-1
Area of Science:
- Neuroscience
- Mitochondrial Biology
- Biochemistry
Background:
- 3-Morpholinosydnonimine (SIN-1) is a nitric oxide (NO) donor.
- Mitochondria are crucial for neuronal energy production.
- Synaptosomes are isolated nerve terminals, useful for studying neuronal function.
Purpose of the Study:
- To investigate the effects of SIN-1 on rat cortical synaptosome mitochondria.
- To determine the role of reactive oxygen and nitrogen species in SIN-1-induced mitochondrial dysfunction.
Main Methods:
- In vitro assessment of SIN-1 effects on isolated rat cortical synaptosomes.
- Measurement of oxygen consumption, ATP production, and mitochondrial membrane potential.
- Analysis of reactive oxygen species (ROS), peroxynitrite (ONOO-), phosphatidylserine externalization, and lactate dehydrogenase release.
Main Results:
- SIN-1 exposure increased peroxynitrite and hydrogen peroxide formation in a dose-dependent manner.
- SIN-1 significantly reduced mitochondrial oxygen consumption and ATP production.
- SIN-1 induced mitochondrial depolarization, increased ROS production, and caused synaptosomal membrane damage.
Conclusions:
- Peroxynitrite, generated by SIN-1, is the primary mediator of mitochondrial dysfunction in synaptosomes.
- SIN-1 causes significant damage to rat cortical synaptosomes, impacting mitochondrial function and membrane integrity.
