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Sex Steroids Do Not Modulate TRPM2-Mediated Injury in Females following Middle Cerebral Artery Occlusion(1,2,3).

Quillinan N, Grewal H, Klawitter J, Herson PS - eNeuro (2014)

Bottom Line: Interestingly, treatment of female mice with the potent androgen receptor agonist DHT had no effect on ischemic injury and did not permit CTZ neuroprotection.Similarly, DHT-treated females did not exhibit increased levels of ADPribose, the TRPM2 ligand generated by PARP, following ischemia.In conclusion, our data demonstrate that while circulating androgens are necessary for PARP-mediated TRPM2 injury in males, they are not sufficient to produce TRPM2 activation in females.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anesthesiology, University of Colorado School of Medicine, Aurora, Colorado 80045.

ABSTRACT
Calcium-permeable transient receptor potential M2 (TRPM2) ion channel activation contributes to cerebral ischemic injury specifically in males. In male mice, circulating androgens are required for TRPM2 inhibition with clotrimazole (CTZ) to provide protection following experimental stroke. Sufficient levels of circulating androgens are necessary to support ischemia-induced activation of poly ADP ribose polymerase (PARP) and consequent activation of TRPM2 channels. In this study, we tested whether differences in sex steroids contribute to the lack of CTZ neuroprotection in females. Middle cerebral artery occlusion (MCAO) was performed using adult female mice that were hormonally intact, ovariectomized (OVX) or dihydrotestosterone (DHT) treated. CTZ or vehicle was administered at the time of reperfusion, animals were euthanized 24 h later and brains and serum were collected. Infarct analysis revealed no effect of CTZ in intact females or females lacking endogenous sex steroids (OVX). Interestingly, treatment of female mice with the potent androgen receptor agonist DHT had no effect on ischemic injury and did not permit CTZ neuroprotection. Similarly, DHT-treated females did not exhibit increased levels of ADPribose, the TRPM2 ligand generated by PARP, following ischemia. No differences in TRPM2 or androgen receptor expression were observed between males and females. These data suggest that the lack of TRPM2 activation in females following experimental stroke is not due to the presence of estrogen or the absence of androgens. In conclusion, our data demonstrate that while circulating androgens are necessary for PARP-mediated TRPM2 injury in males, they are not sufficient to produce TRPM2 activation in females.

No MeSH data available.


Related in: MedlinePlus

Serum DHT levels and androgen receptor expression. A, Serum DHT levels were measured in males and DHT−/+ females 24 h after MCAO by LC/MS. Females receiving DHT (25 mg) had significantly higher levels of DHT than all other groups (one-way ANOVA; p < 0.0001). B, Androgen receptor expression was measured by qRT-PCR and revealed that female mRNA levels were higher than those in males (one-way ANOVA; p = 0.0008) * indicates p < 0.05.
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Figure 4: Serum DHT levels and androgen receptor expression. A, Serum DHT levels were measured in males and DHT−/+ females 24 h after MCAO by LC/MS. Females receiving DHT (25 mg) had significantly higher levels of DHT than all other groups (one-way ANOVA; p < 0.0001). B, Androgen receptor expression was measured by qRT-PCR and revealed that female mRNA levels were higher than those in males (one-way ANOVA; p = 0.0008) * indicates p < 0.05.

Mentions: Serum DHT levels 24 h after MCAO were measured from males and sham- and DHT-implanted females. DHT levels in sham-implanted females (0.85 ± 0.05, n = 5) were similar to males (1.0 ± 0.18, n = 6; p = 0.98l). DHT levels in females receiving 5 mg/kg DHT were not significantly different from males or sham-implanted females (1.69 ± 0.22, n = 7; p = 0.29m vs males and p = 0.19n vs sham females). DHT levels in females that received 25 mg/kg DHT were significantly higher than all other groups (3.7 ± 0.46, n = 6; p < 0.01o) (Fig. 4A). To assess androgen receptor expression in males and females, qRT-PCR was performed on RNA isolated from contralateral cortical tissue collected 24 h after MCAO. Expression levels were quantitated relative to 18s RNA and normalized to male expression. Relative androgen receptor mRNA levels in sham females were 7.7 ± 1.2 (n = 5) and 9.7 ± 1.7 (n = 5) in DHT-treated females (25 mg/kg), significantly higher than males (1 ± 0.27; p < 0.0008p) (Fig. 4B).


Sex Steroids Do Not Modulate TRPM2-Mediated Injury in Females following Middle Cerebral Artery Occlusion(1,2,3).

Quillinan N, Grewal H, Klawitter J, Herson PS - eNeuro (2014)

Serum DHT levels and androgen receptor expression. A, Serum DHT levels were measured in males and DHT−/+ females 24 h after MCAO by LC/MS. Females receiving DHT (25 mg) had significantly higher levels of DHT than all other groups (one-way ANOVA; p < 0.0001). B, Androgen receptor expression was measured by qRT-PCR and revealed that female mRNA levels were higher than those in males (one-way ANOVA; p = 0.0008) * indicates p < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4596140&req=5

Figure 4: Serum DHT levels and androgen receptor expression. A, Serum DHT levels were measured in males and DHT−/+ females 24 h after MCAO by LC/MS. Females receiving DHT (25 mg) had significantly higher levels of DHT than all other groups (one-way ANOVA; p < 0.0001). B, Androgen receptor expression was measured by qRT-PCR and revealed that female mRNA levels were higher than those in males (one-way ANOVA; p = 0.0008) * indicates p < 0.05.
Mentions: Serum DHT levels 24 h after MCAO were measured from males and sham- and DHT-implanted females. DHT levels in sham-implanted females (0.85 ± 0.05, n = 5) were similar to males (1.0 ± 0.18, n = 6; p = 0.98l). DHT levels in females receiving 5 mg/kg DHT were not significantly different from males or sham-implanted females (1.69 ± 0.22, n = 7; p = 0.29m vs males and p = 0.19n vs sham females). DHT levels in females that received 25 mg/kg DHT were significantly higher than all other groups (3.7 ± 0.46, n = 6; p < 0.01o) (Fig. 4A). To assess androgen receptor expression in males and females, qRT-PCR was performed on RNA isolated from contralateral cortical tissue collected 24 h after MCAO. Expression levels were quantitated relative to 18s RNA and normalized to male expression. Relative androgen receptor mRNA levels in sham females were 7.7 ± 1.2 (n = 5) and 9.7 ± 1.7 (n = 5) in DHT-treated females (25 mg/kg), significantly higher than males (1 ± 0.27; p < 0.0008p) (Fig. 4B).

Bottom Line: Interestingly, treatment of female mice with the potent androgen receptor agonist DHT had no effect on ischemic injury and did not permit CTZ neuroprotection.Similarly, DHT-treated females did not exhibit increased levels of ADPribose, the TRPM2 ligand generated by PARP, following ischemia.In conclusion, our data demonstrate that while circulating androgens are necessary for PARP-mediated TRPM2 injury in males, they are not sufficient to produce TRPM2 activation in females.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anesthesiology, University of Colorado School of Medicine, Aurora, Colorado 80045.

ABSTRACT
Calcium-permeable transient receptor potential M2 (TRPM2) ion channel activation contributes to cerebral ischemic injury specifically in males. In male mice, circulating androgens are required for TRPM2 inhibition with clotrimazole (CTZ) to provide protection following experimental stroke. Sufficient levels of circulating androgens are necessary to support ischemia-induced activation of poly ADP ribose polymerase (PARP) and consequent activation of TRPM2 channels. In this study, we tested whether differences in sex steroids contribute to the lack of CTZ neuroprotection in females. Middle cerebral artery occlusion (MCAO) was performed using adult female mice that were hormonally intact, ovariectomized (OVX) or dihydrotestosterone (DHT) treated. CTZ or vehicle was administered at the time of reperfusion, animals were euthanized 24 h later and brains and serum were collected. Infarct analysis revealed no effect of CTZ in intact females or females lacking endogenous sex steroids (OVX). Interestingly, treatment of female mice with the potent androgen receptor agonist DHT had no effect on ischemic injury and did not permit CTZ neuroprotection. Similarly, DHT-treated females did not exhibit increased levels of ADPribose, the TRPM2 ligand generated by PARP, following ischemia. No differences in TRPM2 or androgen receptor expression were observed between males and females. These data suggest that the lack of TRPM2 activation in females following experimental stroke is not due to the presence of estrogen or the absence of androgens. In conclusion, our data demonstrate that while circulating androgens are necessary for PARP-mediated TRPM2 injury in males, they are not sufficient to produce TRPM2 activation in females.

No MeSH data available.


Related in: MedlinePlus