Abstract
Pinealocytes, the neuroendocrine cells that produce melatonin, accumulate glutamate in microvesicles through a specific vesicular transporter energetically coupled with vacuolar-type proton ATPase. The glutamate is secreted into the extracellular space through microvesicle- mediated exocytosis and then stimulates neighboring pinealocytes, resulting in inhibition of norepinephrine-dependent melatonin synthesis. In this study, we identified and characterized the plasma membrane-type glutamate transporter in rat pinealocytes. The [3H]-glutamate uptake by cultured pinealocytes was driven by extracellular Na+, saturated with the [3H]glutamate concentration used, and significantly inhibited by L- glutamate, L-aspartate, β-threo-hydroxyaspartate, pyrrolidine dicarboxylate, and L-cysteine sulfinate, substrates or inhibitors of the plasma membrane glutamate transporter. Consistently, the clearance of extracellular glutamate, as measured by HPLC, was also dependent on Na+ and inhibited by β-threo-hydroxyaspartate and L-cysteine sulfinate. Immunological studies with site-specific antibodies against three isoforms of the Na+-dependent glutamate transporter (GLT-1, GLAST, and EAAC1) revealed the expression of only the GLT-1 type transporter in pineal glands. Expression of the GLT-1 type transporter in pineal glands was further demonstrated by means of reverse transcription-polymerase chain reaction with specific DNA probes. Immunohistochemical analysis indicated that the immunological counterpart(s) of the GLT-1 is localized in pinealocytes. These results suggested that the GLT-1-type Na+-dependent transporter is expressed and functions as a reuptake system for glutamate in rat pinealocytes. The physiological role of the transporter in the termination of the glutamate signal in the pineal gland is discussed.
| Original language | English |
|---|---|
| Pages (from-to) | 1491-1498 |
| Number of pages | 8 |
| Journal | Journal of Neurochemistry |
| Volume | 69 |
| Issue number | 4 |
| Publication status | Published - Oct 1997 |
| Externally published | Yes |
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Keywords
- Endocrine cell
- GLT-1
- L- glutamate
- Microvesicle
- Na-dependent glutamate transporter
- Pineal gland
- Pinealocyte
- Reuptake
ASJC Scopus subject areas
- Biochemistry
- Cellular and Molecular Neuroscience
Cite this
Functional expression of a GLT-1 type Na+-dependent glutamate transporter in rat pinealocytes. / Yamada, Hiroshi; Yatsushiro, Shouki; Yamamoto, Akitsugu; Hayashi, Mitsuko; Nishi, Tsuyoshi; Futai, Masamitsu; Yamaguchi, Akihito; Moriyama, Yoshinori.
In: Journal of Neurochemistry, Vol. 69, No. 4, 10.1997, p. 1491-1498.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Functional expression of a GLT-1 type Na+-dependent glutamate transporter in rat pinealocytes
AU - Yamada, Hiroshi
AU - Yatsushiro, Shouki
AU - Yamamoto, Akitsugu
AU - Hayashi, Mitsuko
AU - Nishi, Tsuyoshi
AU - Futai, Masamitsu
AU - Yamaguchi, Akihito
AU - Moriyama, Yoshinori
PY - 1997/10
Y1 - 1997/10
N2 - Pinealocytes, the neuroendocrine cells that produce melatonin, accumulate glutamate in microvesicles through a specific vesicular transporter energetically coupled with vacuolar-type proton ATPase. The glutamate is secreted into the extracellular space through microvesicle- mediated exocytosis and then stimulates neighboring pinealocytes, resulting in inhibition of norepinephrine-dependent melatonin synthesis. In this study, we identified and characterized the plasma membrane-type glutamate transporter in rat pinealocytes. The [3H]-glutamate uptake by cultured pinealocytes was driven by extracellular Na+, saturated with the [3H]glutamate concentration used, and significantly inhibited by L- glutamate, L-aspartate, β-threo-hydroxyaspartate, pyrrolidine dicarboxylate, and L-cysteine sulfinate, substrates or inhibitors of the plasma membrane glutamate transporter. Consistently, the clearance of extracellular glutamate, as measured by HPLC, was also dependent on Na+ and inhibited by β-threo-hydroxyaspartate and L-cysteine sulfinate. Immunological studies with site-specific antibodies against three isoforms of the Na+-dependent glutamate transporter (GLT-1, GLAST, and EAAC1) revealed the expression of only the GLT-1 type transporter in pineal glands. Expression of the GLT-1 type transporter in pineal glands was further demonstrated by means of reverse transcription-polymerase chain reaction with specific DNA probes. Immunohistochemical analysis indicated that the immunological counterpart(s) of the GLT-1 is localized in pinealocytes. These results suggested that the GLT-1-type Na+-dependent transporter is expressed and functions as a reuptake system for glutamate in rat pinealocytes. The physiological role of the transporter in the termination of the glutamate signal in the pineal gland is discussed.
AB - Pinealocytes, the neuroendocrine cells that produce melatonin, accumulate glutamate in microvesicles through a specific vesicular transporter energetically coupled with vacuolar-type proton ATPase. The glutamate is secreted into the extracellular space through microvesicle- mediated exocytosis and then stimulates neighboring pinealocytes, resulting in inhibition of norepinephrine-dependent melatonin synthesis. In this study, we identified and characterized the plasma membrane-type glutamate transporter in rat pinealocytes. The [3H]-glutamate uptake by cultured pinealocytes was driven by extracellular Na+, saturated with the [3H]glutamate concentration used, and significantly inhibited by L- glutamate, L-aspartate, β-threo-hydroxyaspartate, pyrrolidine dicarboxylate, and L-cysteine sulfinate, substrates or inhibitors of the plasma membrane glutamate transporter. Consistently, the clearance of extracellular glutamate, as measured by HPLC, was also dependent on Na+ and inhibited by β-threo-hydroxyaspartate and L-cysteine sulfinate. Immunological studies with site-specific antibodies against three isoforms of the Na+-dependent glutamate transporter (GLT-1, GLAST, and EAAC1) revealed the expression of only the GLT-1 type transporter in pineal glands. Expression of the GLT-1 type transporter in pineal glands was further demonstrated by means of reverse transcription-polymerase chain reaction with specific DNA probes. Immunohistochemical analysis indicated that the immunological counterpart(s) of the GLT-1 is localized in pinealocytes. These results suggested that the GLT-1-type Na+-dependent transporter is expressed and functions as a reuptake system for glutamate in rat pinealocytes. The physiological role of the transporter in the termination of the glutamate signal in the pineal gland is discussed.
KW - Endocrine cell
KW - GLT-1
KW - L- glutamate
KW - Microvesicle
KW - Na-dependent glutamate transporter
KW - Pineal gland
KW - Pinealocyte
KW - Reuptake
UR - http://www.scopus.com/inward/record.url?scp=0030885247&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0030885247&partnerID=8YFLogxK
M3 - Article
VL - 69
SP - 1491
EP - 1498
JO - Journal of Neurochemistry
JF - Journal of Neurochemistry
SN - 0022-3042
IS - 4
ER -