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Altered expression of P(2) receptor mRNAs in the basilar artery in a rat double hemorrhage model
R C Carpenter1, L Miao, Y Miyagi
1Department of Neurosurgery, University of Mississippi MedicalCenter, 2500 N State St, Jackson, MS 39216, USA.
Background And Purpose:
Extracellular ATP might induce cerebral vasospasm after subarachnoid hemorrhage through P(2) receptor. To investigate the roles of P(2) receptor subtypes in vasospasm, we examined the changes in mRNA expression of P(2) receptor subtypes in basilar arteries from double cisternal blood injection rat models.
Methods:
One hundred male Sprague-Dawley rats, each weighing 350 to 400 g, were divided into 2 groups of 50. In the first group (n=50), the autologous arterial blood (0.2 to 0.3 mL) was injected into the cisterna magna on days 0 and 2. The rats were killed on day 3, 5, or 7 (n=10 in each group). In the sham group (n=10), the rats were injected with saline (0.3 mL) instead of blood. Ten rats were killed without blood or saline injection and served as control. The basilar arteries from rats in each group were used for reverse transcription and polymerase chain reaction. In another group of 50 rats, the same experiment was conducted, and the basilar arteries were collected for transmission electron microscopic study.
Results:
In the subarachnoid hemorrhage groups, transmission electron microscopy showed the reduction in vessel perimeter on days 5 and 7 to be approximately 30% to 40%. The P(2X1) mRNA level was significantly decreased on day 3 and recovered on days 5 and 7. The P(2Y1) mRNA level was transiently increased on day 5, and the P(2Y2) mRNA level was elevated from day 5 to day 7 (P:<0.05).
Conclusions:
The differential expression of the P(2) receptors indicates that P(2X1) subtype might not play an important role in vasospasm. The upregulation of P(2Y1) and P(2Y2) receptors might enable ATP to produce contraction at low levels of concentration.
Insights
P2Y1 and P2Y2 receptor mRNA levels increased after subarachnoid hemorrhage, suggesting their role in cerebral vasospasm. P2X1 receptor expression changes did not correlate with vasospasm development.
Area of Science:
- Neuroscience
- Vascular Biology
- Molecular Biology
Background:
- Cerebral vasospasm is a serious complication after subarachnoid hemorrhage.
- Extracellular adenosine triphosphate (ATP) is implicated in vasospasm via P2 receptors.
Purpose of the Study:
- To investigate the role of specific P2 receptor subtypes in the development of cerebral vasospasm.
- To analyze changes in mRNA expression of P2 receptor subtypes in rat basilar arteries following induced subarachnoid hemorrhage.
Main Methods:
- A rat model of subarachnoid hemorrhage was created using double cisternal blood injection.
- Basilar arteries were analyzed for P2 receptor subtype mRNA expression using reverse transcription and polymerase chain reaction.
- Vessel morphology was assessed using transmission electron microscopy.
Main Results:
- Subarachnoid hemorrhage induced significant basilar artery constriction (30-40% reduction in perimeter) by days 5 and 7.
- P2X1 receptor mRNA levels decreased on day 3 and normalized by days 5-7.
- P2Y1 and P2Y2 receptor mRNA levels were significantly upregulated on days 5 and 7, respectively.
Conclusions:
- The P2X1 receptor subtype is unlikely to be a primary driver of cerebral vasospasm.
- Upregulation of P2Y1 and P2Y2 receptors may contribute to ATP-mediated arterial contraction at lower concentrations.
- These findings highlight potential therapeutic targets for managing post-subarachnoid hemorrhage vasospasm.