| Title: |
Mechanisms of Cytosolic Ca 2+ Suppression By Prostaglandin E 2 Receptors in Rat Melanotrophs |
| Authors: |
Nagata, T.; Harayama, N.; Sasaki, N.; Inoue, M.; Tanaka, K.; Toyohira, Y.; Uezono, Y.; Maruyama, T.; Yanagihara, N.; Ueta, Y.; Shibuya, I. |
| Source: |
Journal of Neuroendocrinology ; volume 15, issue 1, page 33-41 ; ISSN 0953-8194 1365-2826 |
| Publisher Information: |
Wiley |
| Publication Year: |
2003 |
| Collection: |
Wiley Online Library (Open Access Articles via Crossref) |
| Description: |
We have previously reported that voltage‐dependent Ca 2+ (VDC) channels of rat melanotrophs are inhibited by prostaglandin E 2 (PGE 2 ). In this study, mechanisms involved in the inhibitory actions of PGE 2 receptors of rat melanotrophs were analysed using reverse transcriptase‐polymerase chain reaction (RT‐PCR), Ca 2+ ‐imaging and whole‐cell, patch‐clamp techniques with recently developed EP agonists, each of which is selective for the known four subclasses of EP receptors (EP 1–4 ). PGE 2 reversibly suppressed the cytosolic Ca 2+ concentration ([Ca 2+ ] i ). The maximum reduction in [Ca 2+ ] i by PGE 2 was comparable to that by dopamine or to that by extracellular Ca 2+ removal. RT‐PCR analysis of all four EP receptors revealed that EP 3 and EP 4 receptor mRNAs were expressed in the intermediate lobe. The effects of PGE 2 to suppress [Ca 2+ ] i were mimicked by the selective EP 3 agonist, ONO‐AE‐248, whereas three other EP agonists, ONO‐DI‐004 (EP 1 ), ONO‐AE1‐259 (EP 2 ) and ONO‐AE1‐329 (EP 4 ), had little or no effect on [Ca 2+ ] i . All four G‐protein activated inward rectifying K + (GIRK) channel mRNAs were identified in intermediate lobe tissues by RT‐PCR. Dopamine concentration‐dependently activated GIRK currents, whereas PGE 2 did not activate GIRK currents, even at the concentration causing maximal inhibition of VDC channels. These results suggest that PGE 2 acts on EP 3 receptors to suppress Ca 2+ entry of rat melanotrophs by selectively inhibiting VDC channels of these cells. We have compared the possible cellular and molecular mechanisms of inhibition by dopamine and PGE 2 . |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| DOI: |
10.1046/j.1365-2826.2003.00864.x |
| Availability: |
https://doi.org/10.1046/j.1365-2826.2003.00864.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1365-2826.2003.00864.x; https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-2826.2003.00864.x |
| Rights: |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
| Accession Number: |
edsbas.3DA97001 |
| Database: |
BASE |