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Release of spermidine from the rat cortex following permanent middle cerebral artery occlusion
C Carter1, H Poignet, S Carboni
1Synthelabo recherche (LERS), Department of Preclinical Research, Rueil-Malmaison, France.
Abstract:
We have studied the effects of middle cerebral artery (MCA) occlusion in rats on polyamine efflux in the parietal cortex using the microdialysis technique. Dialysis probe implantation itself provoked a delayed, prolonged and vigorous release of spermidine and putrescine. Spermidine release returned to stable baseline levels within 48 hours. Putrescine release also returned to lower levels within this time period but putrescine levels in the dialysate fluctuated dramatically in individual animals. Because of the underlying effects of the dialysis probe (likely a reflection of traumatic cerebral damage and stimulation of polyamine metabolism and release within the immediate vicinity of the dialysis probe), MCA occlusion was performed 48 hours after probe implantation. MCA occlusion persistently (5/5 animals) resulted in a significant increase in cortical spermidine efflux, although the onset, magnitude and duration of this increased release was variable. Putrescine efflux was significantly increased in 2/5 animals with MCA occlusion but the increase in release was similar to the spontaneous fluctuations observed in control animals. Spermine was not detectable in cortical dialysates of control or MCA occluded groups. Spermidine, but not spermine or putrescine is consistently released from the parietal cortex following permanent focal ischaemia and may contribute to ischaemic neuropathology either through its effects at the N-methyl-D-aspartate (NMDA) receptor or via direct, and as yet uncharacterised, neurotoxic effects.
Insights
Middle cerebral artery (MCA) occlusion in rats significantly increased spermidine efflux in the parietal cortex. This polyamine may contribute to ischemic neuropathology via NMDA receptor effects or direct neurotoxicity.
Area of Science:
- Neuroscience
- Biochemistry
- Pathology
Background:
- Polyamines, such as spermidine and putrescine, play crucial roles in cellular functions.
- Ischemic stroke, caused by middle cerebral artery (MCA) occlusion, leads to significant brain damage.
- Understanding polyamine dynamics during ischemia is vital for developing therapeutic strategies.
Purpose of the Study:
- To investigate the effects of MCA occlusion on polyamine efflux in the rat parietal cortex.
- To determine the specific polyamines involved and their release patterns post-occlusion.
Main Methods:
- Utilized the microdialysis technique in rats to measure polyamine efflux.
- Performed MCA occlusion 48 hours after dialysis probe implantation to mitigate probe-induced effects.
- Analyzed spermidine, putrescine, and spermine levels in cortical dialysates.
Main Results:
- Dialysis probe implantation alone induced spermidine and putrescine release.
- MCA occlusion consistently elevated cortical spermidine efflux in all tested animals.
- Putrescine efflux increased in some animals but was comparable to spontaneous fluctuations.
- Spermine was not detected in any experimental group.
Conclusions:
- Spermidine is consistently released from the parietal cortex following permanent focal ischemia.
- Elevated spermidine may contribute to ischemic neuropathology through NMDA receptor interactions or direct neurotoxic mechanisms.
- These findings highlight spermidine as a potential target for therapeutic intervention in ischemic stroke.