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Glycine receptor in rat hippocampal and spinal cord neurons as a molecular target for rapid actions of 17-beta-estradiol.

Jiang P, Kong Y, Zhang XB, Wang W, Liu CF, Xu TL - Mol Pain (2009)

Bottom Line: Here we show that, in cultured rat hippocampal (HIP) and spinal dorsal horn (SDH) neurons, 17-beta-estradiol (E2) rapidly and reversibly reduced the peak amplitude of whole-cell glycine-activated currents (IGly).Moreover, the E2 effect on IGly persisted in the presence of the calcium chelator BAPTA, the protein kinase inhibitor staurosporine, the classical ER (i.e. ERalpha and ERbeta) antagonist tamoxifen, or the G-protein modulators, favoring a direct action of E2 on GlyRs.In HEK293 cells expressing various combinations of GlyR subunits, E2 only affected the IGly in cells expressing alpha2, alpha2beta or alpha3beta subunits, suggesting that either alpha2-containing or alpha3beta-GlyRs mediate the E2 effect observed in neurons.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Neuroscience and State Key Laboratory of Neuroscience, Chinese Academy of Sciences, Shanghai 200031, PR China.

ABSTRACT
Glycine receptors (GlyRs) play important roles in regulating hippocampal neural network activity and spinal nociception. Here we show that, in cultured rat hippocampal (HIP) and spinal dorsal horn (SDH) neurons, 17-beta-estradiol (E2) rapidly and reversibly reduced the peak amplitude of whole-cell glycine-activated currents (IGly). In outside-out membrane patches from HIP neurons devoid of nuclei, E2 similarly inhibited IGly, suggesting a non-genomic characteristic. Moreover, the E2 effect on IGly persisted in the presence of the calcium chelator BAPTA, the protein kinase inhibitor staurosporine, the classical ER (i.e. ERalpha and ERbeta) antagonist tamoxifen, or the G-protein modulators, favoring a direct action of E2 on GlyRs. In HEK293 cells expressing various combinations of GlyR subunits, E2 only affected the IGly in cells expressing alpha2, alpha2beta or alpha3beta subunits, suggesting that either alpha2-containing or alpha3beta-GlyRs mediate the E2 effect observed in neurons. Furthermore, E2 inhibited the GlyR-mediated tonic current in pyramidal neurons of HIP CA1 region, where abundant GlyR alpha2 subunit is expressed. We suggest that the neuronal GlyR is a novel molecular target of E2 which directly inhibits the function of GlyRs in the HIP and SDH regions. This finding may shed new light on premenstrual dysphoric disorder and the gender differences in pain sensation at the CNS level.

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Inhibitory effect of E2 on recombinant GlyRs. (A) Sample traces demonstrating the effects of 10 μM E2 on various homomeric and heteromeric GlyRs. (B) Summary of results from all experiments similar to those shown in A. E2 selectively inhibited the peak amplitude of IGly mediated by α2-containing GlyRs and α3β heteromeric GlyR. Each column represents the average value of 6–11 neurons. ***P < 0.001, Paired Student's t-test, compared with the control without E2 treatment (dashed line).
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Figure 4: Inhibitory effect of E2 on recombinant GlyRs. (A) Sample traces demonstrating the effects of 10 μM E2 on various homomeric and heteromeric GlyRs. (B) Summary of results from all experiments similar to those shown in A. E2 selectively inhibited the peak amplitude of IGly mediated by α2-containing GlyRs and α3β heteromeric GlyR. Each column represents the average value of 6–11 neurons. ***P < 0.001, Paired Student's t-test, compared with the control without E2 treatment (dashed line).

Mentions: We further employed tamoxifen, a classical ER antagonist in the hippocampus [15], to examine whether membrane-localized classical ERs were involved in E2 inhibition of IGly. After incubation of 1 μM tamoxifen for 2 h, we examined the effects of E2on IGly in the continued presence of tamoxifen. Though, consistent with the previous study [32], the peak amplitude of IGly induced by 100 μM glycine was decreased after the treatment with tamoxifen (Figure 2A5, note the difference in the scale bar), the inhibitory effect of E2 on IGly was not affected (Figure 4A5 and 4B1, P > 0.05, Unpaired Student's t-test). Moreover, 17-α-estradiol (17-α-E2, 10 μM), the inactive stereoisomer of E2, mimicked the inhibitory effect of E2 on IGly (Figure 2A6 and 2B1, P > 0.05, Unpaired Student's t-test), suggesting that E2 inhibition on GlyR is independent of classical ERs.


Glycine receptor in rat hippocampal and spinal cord neurons as a molecular target for rapid actions of 17-beta-estradiol.

Jiang P, Kong Y, Zhang XB, Wang W, Liu CF, Xu TL - Mol Pain (2009)

Inhibitory effect of E2 on recombinant GlyRs. (A) Sample traces demonstrating the effects of 10 μM E2 on various homomeric and heteromeric GlyRs. (B) Summary of results from all experiments similar to those shown in A. E2 selectively inhibited the peak amplitude of IGly mediated by α2-containing GlyRs and α3β heteromeric GlyR. Each column represents the average value of 6–11 neurons. ***P < 0.001, Paired Student's t-test, compared with the control without E2 treatment (dashed line).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2651124&req=5

Figure 4: Inhibitory effect of E2 on recombinant GlyRs. (A) Sample traces demonstrating the effects of 10 μM E2 on various homomeric and heteromeric GlyRs. (B) Summary of results from all experiments similar to those shown in A. E2 selectively inhibited the peak amplitude of IGly mediated by α2-containing GlyRs and α3β heteromeric GlyR. Each column represents the average value of 6–11 neurons. ***P < 0.001, Paired Student's t-test, compared with the control without E2 treatment (dashed line).
Mentions: We further employed tamoxifen, a classical ER antagonist in the hippocampus [15], to examine whether membrane-localized classical ERs were involved in E2 inhibition of IGly. After incubation of 1 μM tamoxifen for 2 h, we examined the effects of E2on IGly in the continued presence of tamoxifen. Though, consistent with the previous study [32], the peak amplitude of IGly induced by 100 μM glycine was decreased after the treatment with tamoxifen (Figure 2A5, note the difference in the scale bar), the inhibitory effect of E2 on IGly was not affected (Figure 4A5 and 4B1, P > 0.05, Unpaired Student's t-test). Moreover, 17-α-estradiol (17-α-E2, 10 μM), the inactive stereoisomer of E2, mimicked the inhibitory effect of E2 on IGly (Figure 2A6 and 2B1, P > 0.05, Unpaired Student's t-test), suggesting that E2 inhibition on GlyR is independent of classical ERs.

Bottom Line: Here we show that, in cultured rat hippocampal (HIP) and spinal dorsal horn (SDH) neurons, 17-beta-estradiol (E2) rapidly and reversibly reduced the peak amplitude of whole-cell glycine-activated currents (IGly).Moreover, the E2 effect on IGly persisted in the presence of the calcium chelator BAPTA, the protein kinase inhibitor staurosporine, the classical ER (i.e. ERalpha and ERbeta) antagonist tamoxifen, or the G-protein modulators, favoring a direct action of E2 on GlyRs.In HEK293 cells expressing various combinations of GlyR subunits, E2 only affected the IGly in cells expressing alpha2, alpha2beta or alpha3beta subunits, suggesting that either alpha2-containing or alpha3beta-GlyRs mediate the E2 effect observed in neurons.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Neuroscience and State Key Laboratory of Neuroscience, Chinese Academy of Sciences, Shanghai 200031, PR China.

ABSTRACT
Glycine receptors (GlyRs) play important roles in regulating hippocampal neural network activity and spinal nociception. Here we show that, in cultured rat hippocampal (HIP) and spinal dorsal horn (SDH) neurons, 17-beta-estradiol (E2) rapidly and reversibly reduced the peak amplitude of whole-cell glycine-activated currents (IGly). In outside-out membrane patches from HIP neurons devoid of nuclei, E2 similarly inhibited IGly, suggesting a non-genomic characteristic. Moreover, the E2 effect on IGly persisted in the presence of the calcium chelator BAPTA, the protein kinase inhibitor staurosporine, the classical ER (i.e. ERalpha and ERbeta) antagonist tamoxifen, or the G-protein modulators, favoring a direct action of E2 on GlyRs. In HEK293 cells expressing various combinations of GlyR subunits, E2 only affected the IGly in cells expressing alpha2, alpha2beta or alpha3beta subunits, suggesting that either alpha2-containing or alpha3beta-GlyRs mediate the E2 effect observed in neurons. Furthermore, E2 inhibited the GlyR-mediated tonic current in pyramidal neurons of HIP CA1 region, where abundant GlyR alpha2 subunit is expressed. We suggest that the neuronal GlyR is a novel molecular target of E2 which directly inhibits the function of GlyRs in the HIP and SDH regions. This finding may shed new light on premenstrual dysphoric disorder and the gender differences in pain sensation at the CNS level.

Show MeSH
Related in: MedlinePlus