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Evaluating Cell Death Signaling by Immunofluorescence in a Rat Model of Ischemic Stroke
Published on: January 3, 2025
Taurine reduces caspase-8 and caspase-9 expression induced by ischemia in the mouse hypothalamic nuclei
A G Taranukhin1, E Y Taranukhina, P Saransaari
1Brain Research Center, University of Tampere Medical School, Tampere, Finland. Andrey.Taranukhin@uta.fi
Abstract:
Taurine is a sulphur-containing amino acid abundant in the nervous system. It protects cells from ischemia-induced apoptosis, but the mechanism underlying this is not well established. The aim of our study was to explore the effects of taurine on two main pathways of apoptosis induced by ischemia: receptor-mediated and mitochondrial cell death. Brain slices containing the supraoptic (SON) and paraventricular (PVN) nuclei of the hypothalamus were incubated in vitro under control and simulated ischemic (oxygen-glucose deprivation for 30 min) conditions in the absence and presence of 20 mM taurine. Brain slices were harvested after the 180-min "postischemic" period and fixed in 4% paraformaldehyde. To estimate apoptosis, immunostaining was done for caspase-8 and caspase-9 in paraffin-embedded sections. Immunoreactive caspase-8 and caspase-9 cells were observed in SON and PVN in all experimental groups, but in the "ischemic" group the expression of caspase-8 and caspase-9 and the number of immunoreactive cells was significantly increased in both hypothalamic nuclei. Addition of taurine (20 mM) to the incubation medium induced a marked decrease in caspase-8 and caspase-9 immunoreactivity after ischemia in SON and PVN when compared with the taurine-untreated "ischemic" group. Taurine reduces ischemia-induced caspase-8 and caspase-9 expression, the key inductors of apoptosis in SON and PVN.
Insights
Taurine protects brain cells from apoptosis caused by ischemia. This study shows taurine significantly reduces the expression of key apoptosis-inducing enzymes, caspase-8 and caspase-9, in hypothalamic nuclei.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Taurine is a sulfur-containing amino acid prevalent in the nervous system.
- Taurine is known to protect cells from ischemia-induced apoptosis, but the exact mechanisms are unclear.
- Apoptosis can be triggered by receptor-mediated or mitochondrial pathways.
Purpose of the Study:
- To investigate taurine's effects on receptor-mediated and mitochondrial apoptosis pathways.
- To examine taurine's impact on caspase-8 and caspase-9 expression in hypothalamic nuclei under ischemic conditions.
Main Methods:
- Brain slices from rat supraoptic (SON) and paraventricular (PVN) nuclei were subjected to simulated ischemia (oxygen-glucose deprivation).
- Slices were treated with or without 20 mM taurine during and after ischemia.
- Apoptosis was assessed by immunostaining for caspase-8 and caspase-9 in post-ischemic brain slices.
Main Results:
- Ischemia significantly increased caspase-8 and caspase-9 expression and immunoreactive cell counts in SON and PVN.
- Taurine treatment markedly reduced ischemia-induced caspase-8 and caspase-9 immunoreactivity in both nuclei.
- Taurine demonstrated a protective effect against apoptosis in the studied hypothalamic regions.
Conclusions:
- Taurine effectively reduces the expression of caspase-8 and caspase-9, critical mediators of apoptosis.
- These findings elucidate a key mechanism by which taurine confers neuroprotection against ischemic injury.
- Taurine shows promise as a therapeutic agent for conditions involving hypothalamic damage due to ischemia.
