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Antinociception produced by Thalassia testudinum extract BM-21 is mediated by the inhibition of acid sensing ionic channels by the phenolic compound thalassiolin B.

Garateix A, Salceda E, Menéndez R, Regalado EL, López O, García T, Morales RA, Laguna A, Thomas OP, Soto E - Mol Pain (2011)

Bottom Line: Thalassiolin B reduced the licking behavior during both the phasic and tonic phases in the formalin test.It was also found that BM-21 and thalassiolin B selectively inhibited the fast desensitizing (τ < 400 ms) ASIC currents in DRG neurons obtained from Wistar rats, with a nonsignificant action on ASIC currents with a slow desensitizing time-course.The antinociceptive effects of BM-21 and thalassiolin B may be partially because of this action on the ASICs.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centro de Bioproductos Marinos, Agencia de Medio Ambiente, Ministerio de Ciencia, Tecnología y Medio Ambiente, Loma y 37, Alturas del Vedado, CP 10600 La Habana, Cuba.

ABSTRACT

Background: Acid-sensing ion channels (ASICs) have a significant role in the sensation of pain and constitute an important target for the search of new antinociceptive drugs. In this work we studied the antinociceptive properties of the BM-21 extract, obtained from the sea grass Thalassia testudinum, in chemical and thermal models of nociception in mice. The action of the BM-21 extract and the major phenolic component isolated from this extract, a sulphated flavone glycoside named thalassiolin B, was studied in the chemical nociception test and in the ASIC currents of the dorsal root ganglion (DRG) neurons obtained from Wistar rats.

Results: Behavioral antinociceptive experiments were made on male OF-1 mice. Single oral administration of BM-21 produced a significant inhibition of chemical nociception caused by acetic acid and formalin (specifically during its second phase), and increased the reaction time in the hot plate test. Thalassiolin B reduced the licking behavior during both the phasic and tonic phases in the formalin test. It was also found that BM-21 and thalassiolin B selectively inhibited the fast desensitizing (τ < 400 ms) ASIC currents in DRG neurons obtained from Wistar rats, with a nonsignificant action on ASIC currents with a slow desensitizing time-course. The action of thalassiolin B shows no pH or voltage dependence nor is it modified by steady-state ASIC desensitization or voltage. The high concentration of thalassiolin B in the extract may account for the antinociceptive action of BM-21.

Conclusions: To our knowledge, this is the first report of an ASIC-current inhibitor derived of a marine-plant extract, and in a phenolic compound. The antinociceptive effects of BM-21 and thalassiolin B may be partially because of this action on the ASICs. That the active components of the extract are able to cross the blood-brain barrier gives them an additional advantage for future uses as tools to study pain mechanisms with a potential therapeutic application.

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The effect of thalassiolin B on the pH versus amplitude and steady state desensitization curve of the ASIC current. A) No significant influence of 100 μM thalassiolin B on the pH dependence of the ASIC current amplitude was found. B) The use of thalassiolin B also did not significantly modify the steady-state desensitization of ASIC currents. C) Analysis of the thalassiolin B effect as function of pH used to activate the current shows no significant correlation (P > 0.05). Line shows the linear regression (slope = 0.27); dotted lines show confidence intervals at P ≤ 0.05. D) Amiloride (30 μM) decreased the current 64 ± 4%. The coapplication of 30 μM amiloride and 100 μM thalassiolin B produced an additional nonsignificant 10.8 ± 3.8% decrease of the current (P ≥ 0.05 Student's t-test; thalassiolin B preapplied 20 s before coapplication of amiloride and thalassiolin B). Effects were fully reversible.
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Figure 7: The effect of thalassiolin B on the pH versus amplitude and steady state desensitization curve of the ASIC current. A) No significant influence of 100 μM thalassiolin B on the pH dependence of the ASIC current amplitude was found. B) The use of thalassiolin B also did not significantly modify the steady-state desensitization of ASIC currents. C) Analysis of the thalassiolin B effect as function of pH used to activate the current shows no significant correlation (P > 0.05). Line shows the linear regression (slope = 0.27); dotted lines show confidence intervals at P ≤ 0.05. D) Amiloride (30 μM) decreased the current 64 ± 4%. The coapplication of 30 μM amiloride and 100 μM thalassiolin B produced an additional nonsignificant 10.8 ± 3.8% decrease of the current (P ≥ 0.05 Student's t-test; thalassiolin B preapplied 20 s before coapplication of amiloride and thalassiolin B). Effects were fully reversible.

Mentions: To study the influence of thalassiolin B on the gating of the ASIC current, the pH dependence of the current amplitude was studied in the control and with the use of 100 μM thalassiolin B. The pH50 in the control was 6.12 ± 0.1 (n = 7) and with the use of thalassiolin B was 6.15 ± 0.1 (n = 7; P ≥ 0.05; Figure 7A). This result indicates no interaction with the proton gating of the channel. To further characterize the potential influence of the occupation of proton-binding sites on the actions of thalassiolin B, the effects of the drug were studied while the pH of the bath solution was varied between 7.0 and 8.0 with 0.2 pH increments (steady-state desensitization curves). The pH of the preconditioning bath produced a significant effect over the current produced by perfusion at pH 6.1. The preconditioning pH-effect relationships were constructed in control (pH50 = 7.19 ± 0.04, n = 5) and in the presence of 30 μM thalassiolin B (pH50 = 7.27 ± 0.03, n = 7; Figure 7B), indicating that its action is not dependent on the state, closed or inactivated, of the ASICs. The relationship between the effect of 100 μM thalassiolin B and the pH used to activate the ASIC current showed no significant pH dependence (pH 4 n = 22; pH 5 n = 8; pH 6.1 n = 8; pH 6.5 n = 9; Figure 7C). The interaction of amiloride and thalassiolin B was also studied. We found that the effect of 100 μM thalassiolin B on the ASIC current activated by pH 6.1 was occluded by the use of 30 μM amiloride (n = 5; Figure 7D). Finally, no significant influence of holding voltage (-20 mV versus -60 mV) on the thalassiolin B action was observed (n = 4; data not shown).


Antinociception produced by Thalassia testudinum extract BM-21 is mediated by the inhibition of acid sensing ionic channels by the phenolic compound thalassiolin B.

Garateix A, Salceda E, Menéndez R, Regalado EL, López O, García T, Morales RA, Laguna A, Thomas OP, Soto E - Mol Pain (2011)

The effect of thalassiolin B on the pH versus amplitude and steady state desensitization curve of the ASIC current. A) No significant influence of 100 μM thalassiolin B on the pH dependence of the ASIC current amplitude was found. B) The use of thalassiolin B also did not significantly modify the steady-state desensitization of ASIC currents. C) Analysis of the thalassiolin B effect as function of pH used to activate the current shows no significant correlation (P > 0.05). Line shows the linear regression (slope = 0.27); dotted lines show confidence intervals at P ≤ 0.05. D) Amiloride (30 μM) decreased the current 64 ± 4%. The coapplication of 30 μM amiloride and 100 μM thalassiolin B produced an additional nonsignificant 10.8 ± 3.8% decrease of the current (P ≥ 0.05 Student's t-test; thalassiolin B preapplied 20 s before coapplication of amiloride and thalassiolin B). Effects were fully reversible.
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Figure 7: The effect of thalassiolin B on the pH versus amplitude and steady state desensitization curve of the ASIC current. A) No significant influence of 100 μM thalassiolin B on the pH dependence of the ASIC current amplitude was found. B) The use of thalassiolin B also did not significantly modify the steady-state desensitization of ASIC currents. C) Analysis of the thalassiolin B effect as function of pH used to activate the current shows no significant correlation (P > 0.05). Line shows the linear regression (slope = 0.27); dotted lines show confidence intervals at P ≤ 0.05. D) Amiloride (30 μM) decreased the current 64 ± 4%. The coapplication of 30 μM amiloride and 100 μM thalassiolin B produced an additional nonsignificant 10.8 ± 3.8% decrease of the current (P ≥ 0.05 Student's t-test; thalassiolin B preapplied 20 s before coapplication of amiloride and thalassiolin B). Effects were fully reversible.
Mentions: To study the influence of thalassiolin B on the gating of the ASIC current, the pH dependence of the current amplitude was studied in the control and with the use of 100 μM thalassiolin B. The pH50 in the control was 6.12 ± 0.1 (n = 7) and with the use of thalassiolin B was 6.15 ± 0.1 (n = 7; P ≥ 0.05; Figure 7A). This result indicates no interaction with the proton gating of the channel. To further characterize the potential influence of the occupation of proton-binding sites on the actions of thalassiolin B, the effects of the drug were studied while the pH of the bath solution was varied between 7.0 and 8.0 with 0.2 pH increments (steady-state desensitization curves). The pH of the preconditioning bath produced a significant effect over the current produced by perfusion at pH 6.1. The preconditioning pH-effect relationships were constructed in control (pH50 = 7.19 ± 0.04, n = 5) and in the presence of 30 μM thalassiolin B (pH50 = 7.27 ± 0.03, n = 7; Figure 7B), indicating that its action is not dependent on the state, closed or inactivated, of the ASICs. The relationship between the effect of 100 μM thalassiolin B and the pH used to activate the ASIC current showed no significant pH dependence (pH 4 n = 22; pH 5 n = 8; pH 6.1 n = 8; pH 6.5 n = 9; Figure 7C). The interaction of amiloride and thalassiolin B was also studied. We found that the effect of 100 μM thalassiolin B on the ASIC current activated by pH 6.1 was occluded by the use of 30 μM amiloride (n = 5; Figure 7D). Finally, no significant influence of holding voltage (-20 mV versus -60 mV) on the thalassiolin B action was observed (n = 4; data not shown).

Bottom Line: Thalassiolin B reduced the licking behavior during both the phasic and tonic phases in the formalin test.It was also found that BM-21 and thalassiolin B selectively inhibited the fast desensitizing (τ < 400 ms) ASIC currents in DRG neurons obtained from Wistar rats, with a nonsignificant action on ASIC currents with a slow desensitizing time-course.The antinociceptive effects of BM-21 and thalassiolin B may be partially because of this action on the ASICs.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centro de Bioproductos Marinos, Agencia de Medio Ambiente, Ministerio de Ciencia, Tecnología y Medio Ambiente, Loma y 37, Alturas del Vedado, CP 10600 La Habana, Cuba.

ABSTRACT

Background: Acid-sensing ion channels (ASICs) have a significant role in the sensation of pain and constitute an important target for the search of new antinociceptive drugs. In this work we studied the antinociceptive properties of the BM-21 extract, obtained from the sea grass Thalassia testudinum, in chemical and thermal models of nociception in mice. The action of the BM-21 extract and the major phenolic component isolated from this extract, a sulphated flavone glycoside named thalassiolin B, was studied in the chemical nociception test and in the ASIC currents of the dorsal root ganglion (DRG) neurons obtained from Wistar rats.

Results: Behavioral antinociceptive experiments were made on male OF-1 mice. Single oral administration of BM-21 produced a significant inhibition of chemical nociception caused by acetic acid and formalin (specifically during its second phase), and increased the reaction time in the hot plate test. Thalassiolin B reduced the licking behavior during both the phasic and tonic phases in the formalin test. It was also found that BM-21 and thalassiolin B selectively inhibited the fast desensitizing (τ < 400 ms) ASIC currents in DRG neurons obtained from Wistar rats, with a nonsignificant action on ASIC currents with a slow desensitizing time-course. The action of thalassiolin B shows no pH or voltage dependence nor is it modified by steady-state ASIC desensitization or voltage. The high concentration of thalassiolin B in the extract may account for the antinociceptive action of BM-21.

Conclusions: To our knowledge, this is the first report of an ASIC-current inhibitor derived of a marine-plant extract, and in a phenolic compound. The antinociceptive effects of BM-21 and thalassiolin B may be partially because of this action on the ASICs. That the active components of the extract are able to cross the blood-brain barrier gives them an additional advantage for future uses as tools to study pain mechanisms with a potential therapeutic application.

Show MeSH
Related in: MedlinePlus