The neurotoxicity of tunicamycin
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D D Leaver1, K M Schneider, M J Rand
1Department of Pharmacology, University of Melbourne, Victoria, Australia.
Abstract:
The neurotoxicity of tunicamycin, an inhibitor of glycosylation of glycoproteins and a potential anti-tumour agent, was investigated by injection of the chemical directly into the lateral ventricle of the brain of rats. A delayed neurological syndrome developed due to anoxic necrosis of brain cells and spongy degeneration of the white matter. In many brains the lesion had the characteristic features of an infarct. Since the predominant lesion was vascular, the action of tunicamycin on blood vessels was investigated in vitro using rabbit aortic rings. In this system the normal relaxation response to acetylcholine in aortic rings pre-contracted with noradrenaline was progressively inhibited as exposure of the ring to tunicamycin increased from 2 h to 5 h. This relaxation response depends on the release of endothelium-derived relaxing factor from endothelial cells. Hence it is proposed that the important primary target in tunicamycin neurotoxicity is endothelial cells of the brain microvessels.
Insights
Tunicamycin, a glycosylation inhibitor, causes neurotoxicity in rats by damaging brain cells and blood vessels. This study suggests its primary target is the endothelial cells within brain microvessels.
Area of Science:
- Neuroscience
- Toxicology
- Vascular Biology
Background:
- Tunicamycin inhibits glycoprotein glycosylation and is explored as an anti-tumour agent.
- Neurotoxicity is a potential side effect requiring investigation.
- Understanding tunicamycin's mechanism of action is crucial for its therapeutic development.
Purpose of the Study:
- To investigate the neurotoxic effects of tunicamycin.
- To elucidate the mechanism underlying tunicamycin-induced neurotoxicity.
- To identify the primary cellular targets of tunicamycin in the brain.
Main Methods:
- Direct injection of tunicamycin into the lateral ventricle of rat brains.
- Histopathological examination of brain tissue to identify lesions.
- In vitro study using rabbit aortic rings to assess vascular effects.
Main Results:
- Tunicamycin induced a delayed neurological syndrome characterized by anoxic necrosis and white matter degeneration.
- Brain lesions exhibited features consistent with infarcts, indicating vascular damage.
- In vitro, tunicamycin progressively inhibited the acetylcholine-induced relaxation response in aortic rings, dependent on endothelium-derived relaxing factor.
Conclusions:
- Tunicamycin causes significant neurotoxicity in rats, leading to brain cell death and vascular damage.
- The vascular effects observed in vivo and in vitro suggest a primary impact on endothelial cells.
- Endothelial cells of brain microvessels are proposed as the critical target in tunicamycin neurotoxicity.