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Dexmedetomidine Modulates Histamine-induced Ca(2+) Signaling and Pro-inflammatory Cytokine Expression.

Yang D, Hong JH - Korean J. Physiol. Pharmacol. (2015)

Bottom Line: Dexmedetomidine itself did not trigger Ca(2+) peak or increase in the presence or absence of external Ca(2+).Histamine stimulated IL-6 mRNA expression not IL-8 mRNA within 2 hrs, however this effect was attenuated by dexmedetomidine.Collectively, these findings suggest that dexmedetomidine modulates histamine-induced Ca(2+) signaling and IL-6 expression and will be useful for understanding the antagonistic properties of dexmedetomidine on histamine-induced signaling beyond its sedative effect.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, College of Medicine, Gachon University, Incheon 406-799, Korea.

ABSTRACT
Dexmedetomidine is a sedative and analgesic agent that exerts its effects by selectively agonizing α2 adrenoceptor. Histamine is a pathophysiological amine that activates G protein-coupled receptors, to induce Ca(2+) release and subsequent mediate or progress inflammation. Dexmedetomidine has been reported to exert inhibitory effect on inflammation both in vitro and in vivo studies. However, it is unclear that dexmedetomidine modulates histamine-induced signaling and pro-inflammatory cytokine expression. This study was carried out to assess how dexmedetomidine modulates histamine-induced Ca(2+) signaling and regulates the expression of pro-inflammatory cytokine genes encoding interleukin (IL)-6 and -8. To elucidate the regulatory role of dexmedetomidine on histamine signaling, HeLa cells and human salivary gland cells which are endogenously expressed histamine 1 receptor were used. Dexmedetomidine itself did not trigger Ca(2+) peak or increase in the presence or absence of external Ca(2+). When cells were stimulated with histamine after pretreatment with various concentrations of dexmedetomidine, we observed inhibited histamine-induced [Ca(2+)]i signal in both cell types. Histamine stimulated IL-6 mRNA expression not IL-8 mRNA within 2 hrs, however this effect was attenuated by dexmedetomidine. Collectively, these findings suggest that dexmedetomidine modulates histamine-induced Ca(2+) signaling and IL-6 expression and will be useful for understanding the antagonistic properties of dexmedetomidine on histamine-induced signaling beyond its sedative effect.

No MeSH data available.


Related in: MedlinePlus

Histamine-induced [Ca2+]i signals were inhibited by dexmedetomidine in HSG cells. (A) Expression levels of histamine receptor mRNA (H1R to H4R) in HSG cells. (B) Changes in [Ca2+]i induced by 30 µM histamine. (C) Changes in [Ca2+]i after pretreatment with 100 ng/mL dexmedetomidine (Dex) and subsequent treatment with 30 µM histamine (His). (D) Evoked [Ca2+]i (Δ Ca2+) calculated by the peak value of 30 µM histamine stimulation in the presence or absence of 100 ng/mL dexmedetomidine. The upper bars indicate the extracellular solutions applied to the cells and traces were represented with average value. (E, F) After pre-treatment with 100 ng/mL dexmedetomidine for 30 min, HSG cells were stimulated with PBS or with 30 µM histamine for 90 min and then total RNAs were extracted and amplified with primers specific for IL-6, IL-8, and GAPDH. Data are from one of three experimental replicates. IL-6 and IL-8 mRNA expressions were quantified after normalizing to GAPDH levels as a loading control. Results are the mean±SEMs of three independent experiments. (-): no RNA, M: DNA ladder (bp), *p<0.01 was considered statistically significant.
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Figure 5: Histamine-induced [Ca2+]i signals were inhibited by dexmedetomidine in HSG cells. (A) Expression levels of histamine receptor mRNA (H1R to H4R) in HSG cells. (B) Changes in [Ca2+]i induced by 30 µM histamine. (C) Changes in [Ca2+]i after pretreatment with 100 ng/mL dexmedetomidine (Dex) and subsequent treatment with 30 µM histamine (His). (D) Evoked [Ca2+]i (Δ Ca2+) calculated by the peak value of 30 µM histamine stimulation in the presence or absence of 100 ng/mL dexmedetomidine. The upper bars indicate the extracellular solutions applied to the cells and traces were represented with average value. (E, F) After pre-treatment with 100 ng/mL dexmedetomidine for 30 min, HSG cells were stimulated with PBS or with 30 µM histamine for 90 min and then total RNAs were extracted and amplified with primers specific for IL-6, IL-8, and GAPDH. Data are from one of three experimental replicates. IL-6 and IL-8 mRNA expressions were quantified after normalizing to GAPDH levels as a loading control. Results are the mean±SEMs of three independent experiments. (-): no RNA, M: DNA ladder (bp), *p<0.01 was considered statistically significant.

Mentions: To evaluate whether the modulatory effect of dexmedetomidine was mediated through the histamine receptor activation, experiments were performed in HSG cells which expressed H1R [25]. HSG cells were tested and confirmed histamine receptor subtype expression (Fig. 5A). HSG cells did not exhibit an altered Ca2+ response at less than 10 µM histamine despite predominant H1R expression. Cells were stimulated with 30 µM histamine, and histamine-triggered [Ca2+]i responses were inhibited in the presence of 100 ng/mL dexmedetomidine (Fig. 5B and 5C; 81 and 78 cells from three independent experiments, respectively). In HSG cells, dexmedetomidine reduced Ca2+ signals to 67% compared to histamine-treated cells. To assess the effect of dexmedetomidine on histamine-mediated IL-6 and IL-8 production, HSG cells were pretreated with 100 ng/mL dexmedetomidine for 30 min and then treated with 30 µM histamine for 90 min. Histamine increased IL-6 mRNA level (Fig. 5E), whereas dexmedetomidine pretreatment suppressed histamine-mediated IL-6 mRNA expression to 81.6% compared to histamine-treated cells (Fig. 5E and 5F). Histamine stimulation also did not alter IL-8 mRNA expression within 2 hrs in HSG cells. Dexmedetomidine itself did not affect pro-inflammatory cytokines expression. These findings confirmed that dexmedetomidine potently inhibited histamine signaling by suppressing histamine-induced expression of the pro-inflammatory cytokine IL-6. These results suggested that the ability of dexmedetomidine suppressed histamine-induced Ca2+ signals is not cell type specific.


Dexmedetomidine Modulates Histamine-induced Ca(2+) Signaling and Pro-inflammatory Cytokine Expression.

Yang D, Hong JH - Korean J. Physiol. Pharmacol. (2015)

Histamine-induced [Ca2+]i signals were inhibited by dexmedetomidine in HSG cells. (A) Expression levels of histamine receptor mRNA (H1R to H4R) in HSG cells. (B) Changes in [Ca2+]i induced by 30 µM histamine. (C) Changes in [Ca2+]i after pretreatment with 100 ng/mL dexmedetomidine (Dex) and subsequent treatment with 30 µM histamine (His). (D) Evoked [Ca2+]i (Δ Ca2+) calculated by the peak value of 30 µM histamine stimulation in the presence or absence of 100 ng/mL dexmedetomidine. The upper bars indicate the extracellular solutions applied to the cells and traces were represented with average value. (E, F) After pre-treatment with 100 ng/mL dexmedetomidine for 30 min, HSG cells were stimulated with PBS or with 30 µM histamine for 90 min and then total RNAs were extracted and amplified with primers specific for IL-6, IL-8, and GAPDH. Data are from one of three experimental replicates. IL-6 and IL-8 mRNA expressions were quantified after normalizing to GAPDH levels as a loading control. Results are the mean±SEMs of three independent experiments. (-): no RNA, M: DNA ladder (bp), *p<0.01 was considered statistically significant.
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Figure 5: Histamine-induced [Ca2+]i signals were inhibited by dexmedetomidine in HSG cells. (A) Expression levels of histamine receptor mRNA (H1R to H4R) in HSG cells. (B) Changes in [Ca2+]i induced by 30 µM histamine. (C) Changes in [Ca2+]i after pretreatment with 100 ng/mL dexmedetomidine (Dex) and subsequent treatment with 30 µM histamine (His). (D) Evoked [Ca2+]i (Δ Ca2+) calculated by the peak value of 30 µM histamine stimulation in the presence or absence of 100 ng/mL dexmedetomidine. The upper bars indicate the extracellular solutions applied to the cells and traces were represented with average value. (E, F) After pre-treatment with 100 ng/mL dexmedetomidine for 30 min, HSG cells were stimulated with PBS or with 30 µM histamine for 90 min and then total RNAs were extracted and amplified with primers specific for IL-6, IL-8, and GAPDH. Data are from one of three experimental replicates. IL-6 and IL-8 mRNA expressions were quantified after normalizing to GAPDH levels as a loading control. Results are the mean±SEMs of three independent experiments. (-): no RNA, M: DNA ladder (bp), *p<0.01 was considered statistically significant.
Mentions: To evaluate whether the modulatory effect of dexmedetomidine was mediated through the histamine receptor activation, experiments were performed in HSG cells which expressed H1R [25]. HSG cells were tested and confirmed histamine receptor subtype expression (Fig. 5A). HSG cells did not exhibit an altered Ca2+ response at less than 10 µM histamine despite predominant H1R expression. Cells were stimulated with 30 µM histamine, and histamine-triggered [Ca2+]i responses were inhibited in the presence of 100 ng/mL dexmedetomidine (Fig. 5B and 5C; 81 and 78 cells from three independent experiments, respectively). In HSG cells, dexmedetomidine reduced Ca2+ signals to 67% compared to histamine-treated cells. To assess the effect of dexmedetomidine on histamine-mediated IL-6 and IL-8 production, HSG cells were pretreated with 100 ng/mL dexmedetomidine for 30 min and then treated with 30 µM histamine for 90 min. Histamine increased IL-6 mRNA level (Fig. 5E), whereas dexmedetomidine pretreatment suppressed histamine-mediated IL-6 mRNA expression to 81.6% compared to histamine-treated cells (Fig. 5E and 5F). Histamine stimulation also did not alter IL-8 mRNA expression within 2 hrs in HSG cells. Dexmedetomidine itself did not affect pro-inflammatory cytokines expression. These findings confirmed that dexmedetomidine potently inhibited histamine signaling by suppressing histamine-induced expression of the pro-inflammatory cytokine IL-6. These results suggested that the ability of dexmedetomidine suppressed histamine-induced Ca2+ signals is not cell type specific.

Bottom Line: Dexmedetomidine itself did not trigger Ca(2+) peak or increase in the presence or absence of external Ca(2+).Histamine stimulated IL-6 mRNA expression not IL-8 mRNA within 2 hrs, however this effect was attenuated by dexmedetomidine.Collectively, these findings suggest that dexmedetomidine modulates histamine-induced Ca(2+) signaling and IL-6 expression and will be useful for understanding the antagonistic properties of dexmedetomidine on histamine-induced signaling beyond its sedative effect.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, College of Medicine, Gachon University, Incheon 406-799, Korea.

ABSTRACT
Dexmedetomidine is a sedative and analgesic agent that exerts its effects by selectively agonizing α2 adrenoceptor. Histamine is a pathophysiological amine that activates G protein-coupled receptors, to induce Ca(2+) release and subsequent mediate or progress inflammation. Dexmedetomidine has been reported to exert inhibitory effect on inflammation both in vitro and in vivo studies. However, it is unclear that dexmedetomidine modulates histamine-induced signaling and pro-inflammatory cytokine expression. This study was carried out to assess how dexmedetomidine modulates histamine-induced Ca(2+) signaling and regulates the expression of pro-inflammatory cytokine genes encoding interleukin (IL)-6 and -8. To elucidate the regulatory role of dexmedetomidine on histamine signaling, HeLa cells and human salivary gland cells which are endogenously expressed histamine 1 receptor were used. Dexmedetomidine itself did not trigger Ca(2+) peak or increase in the presence or absence of external Ca(2+). When cells were stimulated with histamine after pretreatment with various concentrations of dexmedetomidine, we observed inhibited histamine-induced [Ca(2+)]i signal in both cell types. Histamine stimulated IL-6 mRNA expression not IL-8 mRNA within 2 hrs, however this effect was attenuated by dexmedetomidine. Collectively, these findings suggest that dexmedetomidine modulates histamine-induced Ca(2+) signaling and IL-6 expression and will be useful for understanding the antagonistic properties of dexmedetomidine on histamine-induced signaling beyond its sedative effect.

No MeSH data available.


Related in: MedlinePlus