Prostaglandin E2-induced luteinizing hormone-releasing hormone release involves mobilization of intracellular Ca+2

Sergio Ojeda, A. Negro-Vilar

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

The present in vitro experiments were performed to examine the involvement of Ca+2 in the mechanism by which prostaglandin E2 (PGE2) induces LHRH release from the median eminence (ME) of the hypothalamus. Stepwise decreases in the Ca+2 concentration of the incubation medium reduced the LHRH response to PGE2. Nevertheless, neither complete omission of Ca+2 (residual Ca+2 concentration, 3.5 μM) nor chelation of residual Ca+2 with EGTA prevented the stimulatory effect of the PG, suggesting that a significant portion of the PGE2 effect on LHRH release is independent of extracellular Ca+2. Blockade of Ca+2 influx with verapamil, a Ca+2 entry blocker, demonstrated that this component of the PGE2 effect is completely independent of inward Ca+2 movement. Depletion of intraterminal Ca+2 stores by exposure of the MEs to the Ca+2 ionophore A23187 in medium without Ca+2 containing EGTA almost completely obliterated the subsequent LHRH response to PGE2, indicating that normal intraterminal Ca+2 levels are important for the PGE2 effect to occur. Preloading the ME terminals with 45Ca+2 and subsequent stimulation with PGE2 demonstrated that even in the absence of extracellular Ca+2 PGE2 stimulates Ca+2 efflux from the terminals, and this Ca+2 movement occurs temporarily associated with LHRH release. Depolarization of ME terminals with 56 mM K+ in the presence of normal Ca+2 concentration resulted in massive efflux of 45Ca+2 and a greater LHRH response than that produced by PGE2, suggesting that the effect of PGE2 is not the consequence of a nonspecific general depolarization of ME nerve terminals. Thus, although a full LHRH response to (exogenous) PGE2 necessitates normal extraterminal Ca+2 concentrations, the results indicate that translocation of Ca+2 from intracellular stores is an event involved in the mechanism by which PGE2 releases LHRH.

Original languageEnglish (US)
Pages (from-to)1763-1770
Number of pages8
JournalEndocrinology
Volume116
Issue number5
StatePublished - 1985
Externally publishedYes

Fingerprint

Dinoprostone
Gonadotropin-Releasing Hormone
Median Eminence
Egtazic Acid
Median Nerve
Ionophores
Calcimycin
Verapamil
Hypothalamus

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Prostaglandin E2-induced luteinizing hormone-releasing hormone release involves mobilization of intracellular Ca+2 . / Ojeda, Sergio; Negro-Vilar, A.

In: Endocrinology, Vol. 116, No. 5, 1985, p. 1763-1770.

Research output: Contribution to journalArticle

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