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Intracerebroventricular administration of quinolinic acid induces a selective decrease of
L S Haug1, A C Ostvold, I Torgner
1Neurochemical Laboratory, University of Oslo, Norway.
Neurochemistry International
|October 7, 1998
Summary
Quinolinic acid (QUIN) neurotoxicity significantly reduces inositol trisphosphate (IP3) receptor levels in rat brains, particularly in the neostriatum. This suggests IP3 receptors are highly sensitive to excitotoxic damage in neurodegenerative conditions.
Area of Science:
- Neuroscience
- Neurochemistry
- Cellular Biology
Background:
- Decreased inositol(1,4,5)-trisphosphate (IP3) binding is observed in neurodegenerative diseases like Alzheimer's.
- IP3 receptor protein reduction correlates with neuronal loss in Alzheimer's brains.
Purpose of the Study:
- To investigate the neurotoxic effects of the glutamate receptor agonist quinolinic acid (QUIN) on IP3 receptor immunoreactivity in the rat brain.
- To assess the selectivity of QUIN-induced neurotoxicity on IP3 receptors compared to other neuronal and glial markers.
Main Methods:
- Rats were injected with QUIN into the neostriatum or infused intracerebroventricularly to induce excitotoxic lesions.
- Immunoreactivity for IP3 receptors, DARPP-32, synaptophysin, PAG, and GFAP was quantified using antibodies.
Main Results:
- QUIN injection caused massive loss of striatal neurons and comparable reduction in IP3 receptor and PAG immunoreactivity.
- Intracerebroventricular QUIN infusion led to a significant decrease (57%) in neostriatal IP3 receptor immunoreactivity, with minimal loss of DARPP-32.
- IP3 receptor loss was less pronounced in the hippocampus, cerebellum, and entorhinal cortex, indicating selectivity.
Conclusions:
- IP3 receptors are highly sensitive to QUIN-induced excitotoxicity in the neostriatum.
- The observed decrease in IP3 receptor immunoreactivity is selective, suggesting a specific vulnerability of this receptor to excitotoxic damage.
- These findings highlight the potential role of IP3 receptor dysfunction in neurodegenerative processes involving excitotoxicity.