Abstract
Glutamate transporters are expressed throughout the CNS where their major role is to clear released glutamate from presynaptic terminals. Here, we report a novel function of the transporter in rat pinealocytes. This electrogenic transporter conducted inward current in response to L-glutamate and L- or D-aspartate and depolarized the membrane in patch-clamp experiments. Ca 2+ imaging demonstrated that the transporter-mediated depolarization induced a significant Ca2+ influx through voltage-gated Ca 2+ channels. The Ca2+ rise finally evoked glutamate exocytosis as detected by carbon-fiber amperometry and by HPLC. In pineal slices with densely packed pinealocytes, glutamate released from the cells effectively activated glutamate transporters in neighboring cells. The Ca2+ signal generated by KCl depolarization or acetylcholine propagated through several cell layers by virtue of the regenerative "glutamate-induced glutamate release." Therefore, we suggest that glutamate transporters mediate synchronized elevation of L-glutamate and thereby efficiently downregulate melatonin secretion via previously identified inhibitory metabotropic glutamate receptors in the pineal gland.
| Original language | English |
|---|---|
| Pages (from-to) | 10852-10863 |
| Number of pages | 12 |
| Journal | Journal of Neuroscience |
| Volume | 28 |
| Issue number | 43 |
| DOIs | |
| Publication status | Published - Oct 22 2008 |
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Keywords
- Calcium
- Depolarization
- Glutamate transporters
- Patch clamp
- Pineal
- Secretion
ASJC Scopus subject areas
- Neuroscience(all)
Cite this
Glutamate transporter-mediated glutamate secretion in the mammalian pineal gland. / Kim, Mean Hwan; Uehara, Shunsuke; Muroyama, Akiko; Hille, Bertil; Moriyama, Yoshinori; Koh, Duk Su.
In: Journal of Neuroscience, Vol. 28, No. 43, 22.10.2008, p. 10852-10863.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Glutamate transporter-mediated glutamate secretion in the mammalian pineal gland
AU - Kim, Mean Hwan
AU - Uehara, Shunsuke
AU - Muroyama, Akiko
AU - Hille, Bertil
AU - Moriyama, Yoshinori
AU - Koh, Duk Su
PY - 2008/10/22
Y1 - 2008/10/22
N2 - Glutamate transporters are expressed throughout the CNS where their major role is to clear released glutamate from presynaptic terminals. Here, we report a novel function of the transporter in rat pinealocytes. This electrogenic transporter conducted inward current in response to L-glutamate and L- or D-aspartate and depolarized the membrane in patch-clamp experiments. Ca 2+ imaging demonstrated that the transporter-mediated depolarization induced a significant Ca2+ influx through voltage-gated Ca 2+ channels. The Ca2+ rise finally evoked glutamate exocytosis as detected by carbon-fiber amperometry and by HPLC. In pineal slices with densely packed pinealocytes, glutamate released from the cells effectively activated glutamate transporters in neighboring cells. The Ca2+ signal generated by KCl depolarization or acetylcholine propagated through several cell layers by virtue of the regenerative "glutamate-induced glutamate release." Therefore, we suggest that glutamate transporters mediate synchronized elevation of L-glutamate and thereby efficiently downregulate melatonin secretion via previously identified inhibitory metabotropic glutamate receptors in the pineal gland.
AB - Glutamate transporters are expressed throughout the CNS where their major role is to clear released glutamate from presynaptic terminals. Here, we report a novel function of the transporter in rat pinealocytes. This electrogenic transporter conducted inward current in response to L-glutamate and L- or D-aspartate and depolarized the membrane in patch-clamp experiments. Ca 2+ imaging demonstrated that the transporter-mediated depolarization induced a significant Ca2+ influx through voltage-gated Ca 2+ channels. The Ca2+ rise finally evoked glutamate exocytosis as detected by carbon-fiber amperometry and by HPLC. In pineal slices with densely packed pinealocytes, glutamate released from the cells effectively activated glutamate transporters in neighboring cells. The Ca2+ signal generated by KCl depolarization or acetylcholine propagated through several cell layers by virtue of the regenerative "glutamate-induced glutamate release." Therefore, we suggest that glutamate transporters mediate synchronized elevation of L-glutamate and thereby efficiently downregulate melatonin secretion via previously identified inhibitory metabotropic glutamate receptors in the pineal gland.
KW - Calcium
KW - Depolarization
KW - Glutamate transporters
KW - Patch clamp
KW - Pineal
KW - Secretion
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UR - http://www.scopus.com/inward/citedby.url?scp=58149347136&partnerID=8YFLogxK
U2 - 10.1523/JNEUROSCI.0894-08.2008
DO - 10.1523/JNEUROSCI.0894-08.2008
M3 - Article
VL - 28
SP - 10852
EP - 10863
JO - Journal of Neuroscience
JF - Journal of Neuroscience
SN - 0270-6474
IS - 43
ER -