Polyphosphoinositide breakdown to inositol phosphates is an important postreceptor mechanism in various ligand-stimulated cell types. LiCl is a commonly used tool to study inositol phosphate accumulation since it inhibits inositol phosphate metabolism and is a widely distributed drug in neurology. In the present study the conditions of LiCl application have been characterized in rat pituitary cells to allow further investigations of GnHR-induced gonadotropin release regarding the involvement of inositol phosphate production. In rat anterior pituitary cells radiolabelled with myo-(2-3H)-inositol, LiCl (10 mM) enhances the amount of intracellular inositol phosphates (IP) in stimulated and unstimulated cells. The production rates of inositol monophosphate (IP1) and inositol biphosphate (IP2) are maximally stimulated at a different concentration of LiCl (1 mM 890% and 10 mM 493% resp.). Preincubation times shorter than 30 min with 10 mM LiCl provide the highest production rate concerning IP1 (2.7 fold) and 2 h the highest production rate concerning IP2 (10.2 fold). GnRH-induced LH release over 4 h is stimulated by preincubation with LiCl for 10 min and this provides evidence for a role of inositol phosphate production in the mechanism of GnRH. In addition, the methods developed in this paper allow the determination of inositol phosphates under more accurately defined conditions.
|Number of pages||7|
|Journal||Aktuelle Endokrinologie und Stoffwechsel|
|Publication status||Published - Jan 1 1988|
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