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TRPV1 in Salivary Gland Epithelial Cells Is Not Involved in Salivary Secretion via Transcellular Pathway.

Choi S, Shin YH, Namkoong E, Hwang SM, Cong X, Yu G, Park K - Korean J. Physiol. Pharmacol. (2014)

Bottom Line: However, capsaicin (CAP), TRPV1 agonist, had little effect on intracellular free calcium concentration ([Ca(2+)]i) in these cells, although carbachol consistently increased [Ca(2+)]i.Saliva flow rate also showed insignificant change in the mice treated with PILO plus CAP compared with that in mice treated with PILO alone.Taken together, our results suggest that although TRPV1 is expressed in SGEC, it appears not to play any direct roles in saliva secretion via transcellular pathway.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul 110-749, Korea.

ABSTRACT
Transient receptor potential vanilloid subtype 1 (TRPV1) was originally found in sensory neurons. Recently, it has been reported that TRPV1 is expressed in salivary gland epithelial cells (SGEC). However, the physiological role of TRPV1 in salivary secretion remains to be elucidated. We found that TRPV1 is expressed in mouse and human submandibular glands (SMG) and HSG cells, originated from human submandibular gland ducts at both mRNA and protein levels. However, capsaicin (CAP), TRPV1 agonist, had little effect on intracellular free calcium concentration ([Ca(2+)]i) in these cells, although carbachol consistently increased [Ca(2+)]i. Exposure of cells to high temperature (>43℃) or acidic bath solution (pH5.4) did not increase [Ca(2+)]i, either. We further examined the role of TRPV1 in salivary secretion using TRPV1 knock-out mice. There was no significant difference in the pilocarpine (PILO)-induced salivary flow rate between wild-type and TRPV1 knock-out mice. Saliva flow rate also showed insignificant change in the mice treated with PILO plus CAP compared with that in mice treated with PILO alone. Taken together, our results suggest that although TRPV1 is expressed in SGEC, it appears not to play any direct roles in saliva secretion via transcellular pathway.

No MeSH data available.


Related in: MedlinePlus

Calcium response to capsaicin in salivary gland epithelial cells (SGEC). [Ca2+]i responses induced by capsaicin (CAP) in mouse dorsal root ganglion (DRG) (A), mSMG (B), hSMG (C), and HSG cells (D). (A) CAP 1 µM in DRG as positive control. (B) CAP 10 µM (a), acidic solution with pH 5.4 (b), and hot temperature of 42℃ (c) in the acinar cells from mSMG. CAP 10 µM in the acinar cells from hSMG (C) and HSG cells (D). It is of note that 10 µM carbachol (CCh) applied at the end of each experiment consistently increased [Ca2+]i. Data for each trace were obtained from ≥30 cells in at least 5 separate experiments.
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Figure 3: Calcium response to capsaicin in salivary gland epithelial cells (SGEC). [Ca2+]i responses induced by capsaicin (CAP) in mouse dorsal root ganglion (DRG) (A), mSMG (B), hSMG (C), and HSG cells (D). (A) CAP 1 µM in DRG as positive control. (B) CAP 10 µM (a), acidic solution with pH 5.4 (b), and hot temperature of 42℃ (c) in the acinar cells from mSMG. CAP 10 µM in the acinar cells from hSMG (C) and HSG cells (D). It is of note that 10 µM carbachol (CCh) applied at the end of each experiment consistently increased [Ca2+]i. Data for each trace were obtained from ≥30 cells in at least 5 separate experiments.

Mentions: It is well known that activation of TRPV1 results in the elevation of intracellular free calcium concentration ([Ca2+]i) via calcium influx [5]. Thus, we examined Ca2+ mobilization mediated by TRPV1 in these cells. In mouse DRG, 1 µM capsaicin (CAP) markedly increased [Ca2+]i. After the [Ca2+]i peak, [Ca2+]i was sustained at a plateau, which was higher than basal levels for about 2 min (Fig. 3A). In contrast, the same concentration of CAP did not evoke [Ca2+]i increase in mSMG acinar cells (Fig. 3B). 10 µM CAP has little effect on [Ca2+]i, either (Fig. 3Ba). Neither acidic condition (pH 5.4) nor heating, raising temperature from 37℃ to 42℃ in bath solution, evoked [Ca2+]i increase (Figs. 3Bb, 3Bc). We confirmed that the cells we tested are healthy, since 10µM carbachol (CCh) consistently increased [Ca2+]i in these cells. The effect of CAP on [Ca2+]i in hSMG acinar cells and HSG cells were similar to those in mSMG (Fig. 3C, D). In most of the cells, capsaicin had little effect on the [Ca2+]i in hSMG. The results demonstrate that CAP did not evoke an increase of [Ca2+]i in acinar cells from mSMG, hSMG, and HSG cells we have tested.


TRPV1 in Salivary Gland Epithelial Cells Is Not Involved in Salivary Secretion via Transcellular Pathway.

Choi S, Shin YH, Namkoong E, Hwang SM, Cong X, Yu G, Park K - Korean J. Physiol. Pharmacol. (2014)

Calcium response to capsaicin in salivary gland epithelial cells (SGEC). [Ca2+]i responses induced by capsaicin (CAP) in mouse dorsal root ganglion (DRG) (A), mSMG (B), hSMG (C), and HSG cells (D). (A) CAP 1 µM in DRG as positive control. (B) CAP 10 µM (a), acidic solution with pH 5.4 (b), and hot temperature of 42℃ (c) in the acinar cells from mSMG. CAP 10 µM in the acinar cells from hSMG (C) and HSG cells (D). It is of note that 10 µM carbachol (CCh) applied at the end of each experiment consistently increased [Ca2+]i. Data for each trace were obtained from ≥30 cells in at least 5 separate experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4296043&req=5

Figure 3: Calcium response to capsaicin in salivary gland epithelial cells (SGEC). [Ca2+]i responses induced by capsaicin (CAP) in mouse dorsal root ganglion (DRG) (A), mSMG (B), hSMG (C), and HSG cells (D). (A) CAP 1 µM in DRG as positive control. (B) CAP 10 µM (a), acidic solution with pH 5.4 (b), and hot temperature of 42℃ (c) in the acinar cells from mSMG. CAP 10 µM in the acinar cells from hSMG (C) and HSG cells (D). It is of note that 10 µM carbachol (CCh) applied at the end of each experiment consistently increased [Ca2+]i. Data for each trace were obtained from ≥30 cells in at least 5 separate experiments.
Mentions: It is well known that activation of TRPV1 results in the elevation of intracellular free calcium concentration ([Ca2+]i) via calcium influx [5]. Thus, we examined Ca2+ mobilization mediated by TRPV1 in these cells. In mouse DRG, 1 µM capsaicin (CAP) markedly increased [Ca2+]i. After the [Ca2+]i peak, [Ca2+]i was sustained at a plateau, which was higher than basal levels for about 2 min (Fig. 3A). In contrast, the same concentration of CAP did not evoke [Ca2+]i increase in mSMG acinar cells (Fig. 3B). 10 µM CAP has little effect on [Ca2+]i, either (Fig. 3Ba). Neither acidic condition (pH 5.4) nor heating, raising temperature from 37℃ to 42℃ in bath solution, evoked [Ca2+]i increase (Figs. 3Bb, 3Bc). We confirmed that the cells we tested are healthy, since 10µM carbachol (CCh) consistently increased [Ca2+]i in these cells. The effect of CAP on [Ca2+]i in hSMG acinar cells and HSG cells were similar to those in mSMG (Fig. 3C, D). In most of the cells, capsaicin had little effect on the [Ca2+]i in hSMG. The results demonstrate that CAP did not evoke an increase of [Ca2+]i in acinar cells from mSMG, hSMG, and HSG cells we have tested.

Bottom Line: However, capsaicin (CAP), TRPV1 agonist, had little effect on intracellular free calcium concentration ([Ca(2+)]i) in these cells, although carbachol consistently increased [Ca(2+)]i.Saliva flow rate also showed insignificant change in the mice treated with PILO plus CAP compared with that in mice treated with PILO alone.Taken together, our results suggest that although TRPV1 is expressed in SGEC, it appears not to play any direct roles in saliva secretion via transcellular pathway.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul 110-749, Korea.

ABSTRACT
Transient receptor potential vanilloid subtype 1 (TRPV1) was originally found in sensory neurons. Recently, it has been reported that TRPV1 is expressed in salivary gland epithelial cells (SGEC). However, the physiological role of TRPV1 in salivary secretion remains to be elucidated. We found that TRPV1 is expressed in mouse and human submandibular glands (SMG) and HSG cells, originated from human submandibular gland ducts at both mRNA and protein levels. However, capsaicin (CAP), TRPV1 agonist, had little effect on intracellular free calcium concentration ([Ca(2+)]i) in these cells, although carbachol consistently increased [Ca(2+)]i. Exposure of cells to high temperature (>43℃) or acidic bath solution (pH5.4) did not increase [Ca(2+)]i, either. We further examined the role of TRPV1 in salivary secretion using TRPV1 knock-out mice. There was no significant difference in the pilocarpine (PILO)-induced salivary flow rate between wild-type and TRPV1 knock-out mice. Saliva flow rate also showed insignificant change in the mice treated with PILO plus CAP compared with that in mice treated with PILO alone. Taken together, our results suggest that although TRPV1 is expressed in SGEC, it appears not to play any direct roles in saliva secretion via transcellular pathway.

No MeSH data available.


Related in: MedlinePlus