ECE2011 Poster Presentations Neuroendocrinology (36 abstracts)
Effects of orexin–monoaminergic interactions on vasopressin secretion in rat neurohypophyseal cell cultures
G K Kis 1 , M Gálfi 2 , M Radács 2 , K Kádár 3 , Z Molnár 2 , A H Molnar 4 , F László 4 , C Varga 1 & F A László 1
1Department of Physiology, Anatomy and Neuroscience, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary; 2Department of Environmental Biology, Gyula Juhász Faculty of Education, University of Szeged, Szeged, Hungary; 3Department of Medical Chemistry, Faculty of Medicine, University of Szeged, Szeged, Hungary; 4Gyula Juhász Faculty of Education, Institute of Physical Education and Sport Sciences, University of Szeged, Szeged, Hungary.
Introduction: The effects of dopamine (DA), serotonin (5-HT), histamine (HA) adrenaline (ADR), noradrenaline (NADR) and K+ administration on vasopressin (VP) secretion were studied in 13–14 days cultures of rat neurohypophyseal (NH) cells, and it was examined whether orexin (ORX) can modify the VP release enhancement induced by these monoaminergic compounds.
Methods: An enzymatic dissociation technique was used to prepare the rat NH cell cultures. The VP contents of the supernatants were determined by RIA.
Results: Following administration of ORX-A or ORX-B in increasing doses (10−10–10−4 M), significant changes were not observed in the VP levels (pg VP/mg protein; avarage±S.E.M.) of the supernatant media (controll: 50.14±0.9; ORX-A: 51.6±0.67; ORX-B: 52.30±0.86). VP level substantially increased after NADR (222.98±2.45), ADR (208.68±2.36) or 5-HT (194.9±2.69) treatment, while the enhancing effects of DA (166.74±2.33), HA (143.56±13.75) or K+ (123.77±2.51) administration were more moderate. Preincubation with ORX-A or ORX-B reduced the NADR (197.06±3.35; 202.14±1.61) or HA-induced (107.30±1.63; 110.12±2.03) VP level increases. Following ADR, 5-HT or DA administration, the VP level enhancement was slightly decreased (195.32±2.22;181.36±1.8;158.22±0.89 in ORX-A; 194.62±1.61; 181.16±2.3; 160.94±0.53 in ORX-B preincubation), though the differences proved to be significant (P<0.05), but the VP concentrations of the supernatant media remained above the control level. There was no significant difference in decreasing effect between ORX-A and ORX-B. ORX had no influence on the VP level increase induced by K+, which causes non-specific hormone secretion. ORX-A or B did not induce any changes in VP release following monoaminergic treatment.
Conclusions: The results indicate that the changes in VP secretion induced by the monoaminergic system can be directly influenced by the ORX system. The interactions between the monoaminergic and ORX systems regarding VP secretion occur at the level of the posterior pituitary.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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