NOTE: This item is not available outside the Texas A&M University network. Texas A&M affiliated users who are off campus can access the item through NetID and password authentication or by using TAMU VPN. Non-affiliated individuals should request a copy through their local library's interlibrary loan service.
Association of intracellular calcium oscillations with release of gonadotropin-releasing hormone (GnRH) from GT1-1 neuronal cells
Abstract
GnRH is released from its nerve terminals via a calcium (Ca²⁺)-dependent mechanism. Oscillation in the intercellular Ca²⁺ [Ca²⁺][] concentration may encode signals that result in the release of GnRH. The objective of this study was to investigate the relationship of GnRH release with [Ca²⁺][] oscillations using the GT1-1 neuronal cell line. GnRH release was measured by radioimmunoassay of media incubated with GT1-1 neuronal cells for 1 hr with control or test substances to induce release of GnRH. [Ca[]][] oscillations were analyzed by confocal microscopy of fluorescence intensities, at 3 sec intervals, of GT1-1 neuronal cells loaded with fluo-3,AM dye. Depolarization (60 mMK+) induced a consistent 2-fold increase in GnRH release. The response of GT1-1 neuronal cells to treatment with NMDA varied between experiments. Studies with either PGE[] or PGE[] released GnRH in a dose-dependent manner, with PGE[] being more potent than PGE[]. 90% of GT1-1 neuronal cells examined exhibited intrinsic oscillations of [Ca²⁺][]. The frequency or pattern of [Ca²⁺][] oscillations was synchronized within an isolated aggregate of neuronal cells, but varied between unconnected aggregates of neuronal cells. Intrinsic [Ca²⁺][] oscillations disappeared when EGTA was added to the media. Depolarization evoked a transient spike in the [Ca²⁺][] at followed by a sustained elevated plateau of [Ca²⁺][]. NMDA did not significantly alter the frequency of [Ca²⁺][] oscillations. Both PGE[] and PGE[] induced an immediate increase in the frequency of [Ca²⁺][] oscillations. In summary, GT1-1 neuronal cells exhibit intrinsic [Ca²⁺][] oscillations whose frequency or pattern is synchronized between interconnected neuronal cells but vary between unconnected cells. Extracellular Ca²⁺ appears important for [Ca²⁺][] oscillations. Both PGE[] and PGE[], at doses that induce release of GnRH, induce a dramatic increase in the frequency of [Ca²⁺][] at oscillations. These results indicate that release of GnRH is associated with an increase frequency of [Ca²⁺][] oscillations and suggest that [Ca²⁺][] oscillations may be invovled in GnRH release.
Description
Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references (leaves 43-57).
Issued also on microfiche from Lange Micrographics.
Collections
Citation
Gilmore, Chrystal Dawn (1999). Association of intracellular calcium oscillations with release of gonadotropin-releasing hormone (GnRH) from GT1-1 neuronal cells. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1999 -THESIS -G652.
Request Open Access
This item and its contents are restricted. If this is your thesis or dissertation, you can make it open-access. This will allow all visitors to view the contents of the thesis.