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oai:www.ideals.illinois.edu:2142/71422 2023-07-11 col_2142_5131 col_2142_16508 com_2142_5130 com_2142_16507 com_2142_14793 com_2142_8903

Hartter, Daryl Edward 2014-12-16T06:45:42Z 2014-12-16T06:45:42Z 10000-01-01 1983 1983 The effect of a variety of experimental compounds on the release of immunoreactive luteinizing hormone-releasing hormone (LHRH) from rat hypothalamus was examined using an in vitro superfusion system and sensitive assays for LHRH measurement. High extracellular (60 mM) K('+) ion repeatedly stimulated in vitro LHRH release, an effect attributed to nerve membrane depolarization triggering influx of Na('+) and Ca('++) ions and resulting in exocytosis of LHRH. K('+)-evoked LHRH release was strongly Ca('++)-dependent; however, Na('+) influx was not obligatory in depolarization-induced release. In support of calcium's role in LHRH release, agents permitting influx of Ca('++) (inophore A23187) or increased Ca('++) leakage from intracellular Ca('++) stores (2,4-dinitrophenol) stimulated LHRH release. K('+)-evoked release of LHRH is also thought to involve a microtubular transport mechanism, since colchicine (10('-6) or 10('-5) M) inhibited K('+)-stimulated LHRH output. However, 10('-4) M colchicine dramatically increased LHRH release as well as hypothalamic LHRH content by an unknown mechanism. The release of LHRH is possibly mediated through adenyl cyclase/cyclic AMP, supported by the finding that adenyl cyclase activators (prostaglandin E, and elevated Mg('++) concentration) and cyclic AMP derivatives stimulated in vitro LHRH release. Employing intermittent delivery of dibutyryl cyclic AMP, mean LHRH release was repeatedly triggered, as assessed by specific assay employing Root anti-LHRH serum. This synchronous LHRH release was Ca('++)-dependent. Intriguingly, cyclic AMP-synchronized LHRH release was not observed when NETT or Chen-Ramirez anti-LHRH sera were used in LHRH measurement, in spite of the fact that spontaneous LHRH release and post-superfusion tissue LHRH content did not differ among the three LHRH assays. These results suggest the existence of immunologically distinct hypothalamic LHRH molecules, a fraction of which are released in response to intermittent cyclic AMP administration and recognized as immunogenic by Root anti-LHRH but to a lesser degree by Nett and Chen-Ramirez LHRH antibodies. Taken together, these results suggest that Ca('++) ion plays a crucial role in K('+)-stimulated LHRH release from rat hypothalamic fragments superfused in vitro. In addition, it can be postulated that a microtubular transport mechanism is an important component of the LHRH neurosecretory process. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI Made available in DSpace on 2014-12-16T06:45:42Z (GMT). No. of bitstreams: 1 8309952.pdf: 4754267 bytes, checksum: b7a0c606e5f1df68807ba7bc2ebd1fc4 (MD5) Previous issue date: 1983 Embargo set by: Seth Robbins for item 71588 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 128 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983. http://hdl.handle.net/2142/71422 (UMI)AAI8309952 Biology, Animal Physiology Characterization of Luteinizing Hormone - Releasing Hormone (Lhrh) Release From Rat Hypothalamus Using an in Vitro System text Physiology and Biophysics Physiology University of Illinois at Urbana-Champaign Dissertation Ph.D.