Year-end Sale % OFF 
Abstract
The early actions of thyrotropin-releasing hormone (TRH) have been studied in hormone-responsive clonal GH3 rat pituitary cells. Previous studies had demonstrated that TRH promotes a "phosphatidylinositol response" in which increased incorporation of [32P]orthophosphate into phosphatidylinositol and phosphatidic acid was observed within minutes of hormone addition. The studies described here were designed to establish whether increased labeling of phosphatidylinositol and phosphatidic acid resulted from prior hormone-induced breakdown of an inositol phosphatide. GH3 cells were prelabeled with [32P]orthophosphate or myo-[3H]inositol. Addition of TRH resulted in the rapid disappearance of labeled polyphosphoinositides, whereas levels of phosphatidylinositol and other phospholipids remained unchanged. TRH-promoted polyphosphoinositide breakdown was evident by 5 S and maximal by 15 s of hormone treatment. Concomitant appearance of inositol polyphosphates in [3H]inositol-labeled cells was observed. In addition, TRH rapidly stimulated diacylglycerol accumulation in either [3H]arachidonic- or [3H]oleic acid-labeled cultures. These results indicate that TRH rapidly causes activation of a polyphosphoinositide-hydrolyzing phospholipase C-type enzyme. The short latency of this hormone effect suggests a proximal role for polyphosphoinositide breakdown in the sequence of events by which TRH alters pituitary cell function.
Highlights
RESULTSFor TLC analysis of phospholipids, oxalate-impregnated Silica Gel TRH Stimulates [32P]OrthosphosphateIncorporation into 60 plates were prepared by the method of Jolles et al [19]
The early actions of thyrotropin-releasing hormone cell-surface membrane localization has been presented [2, 3]. (TRH)have been studied in hormone-responsive clonaHlowever, the means by which TRH receptor occupancy genGH3 rat pituitary cells
Additional evidence pholipidsremainedunchanged.TRH-promotedpoly- has suggested possible effects of TRH on cell-surface calcium phosphoinositide breakdown was evident by 5 s and [7], intracellular membrane-bound calcium [6],or receptormaximal by 15 s of hormone treatment
Summary
For TLC analysis of phospholipids, oxalate-impregnated Silica Gel TRH Stimulates [32P]OrthosphosphateIncorporation into 60 plates were prepared by the method of Jolles et al [19]. For TLC analysis of neutral lipids, Silica Gel 60 plates were two-dimensional TLC showed that the stimulation of incorporation, at treatment times beyond 60 s, was restricted to PtdIns and PA. A similar study using oxalate-impregnatedTLC plates with a molybdenum blue spray for phospholipids, or by staining with to resolve PtdIns-4,5-P2 and PtdIns-4-P is presented in Fig. a phosphomolybdic acid spray for neutral lipids [20]. TRH Promotes the Rapid Breakdown of PtdIns-4,5-P2 and pholipids was constant.PtdIns,PtdIns-4,5-P2,PtdIns-4-P, Ptdlns-4-P and the Accumulation of Phosphatidic Acid in 32P- and PA represented about10,0.4,0.3, and0.2%,respectively, prelabeled Cells-The above results suggested the operation of phospholipid pools in unstimulated cells. Phospholipids determined were: PtdIns (0)P, tdIns-4,5-P2(O), PtdIns-4-P (A), and PA (0)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
