Serotonin modulation of the release of sequestered [3H]serotonin from nerve terminals in an insect neurohemal organ in vitro.
Exogenous tritiated serotonin ([3H]5-HT) is taken up by and released from serotonin-containing fibers within abdominal nerves of Rhodnius prolixus during in vitro incubations. Sequestered [3H]5-HT behaves as expected of an endogenous neurosecretory product in this system. Release is Ca2+-dependent during both K+-induced and physiologically induced secretory episodes. The kinetics of the release of sequestered label parallels the kinetics of release of endogenous neurohormones. Preloaded preparations which are washed with unlabeled 5-HT release label in two fashions; 5-HT itself induces a release of label and, at lower concentrations, 5-HT facilitates the release of label induced by high K+ washes. Facilitatory effects appear to be mediated through receptors within the neurohemal organ (NHO).
D000818:Animals; D002118:Calcium / Q000502:physiology; D066298:In Vitro Techniques; D007700:Kinetics; D007814:Larva; D009411:Nerve Endings / Q000378:metabolism; D009490:Neurosecretory Systems / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D012239:Rhodnius / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism* / Q000494:pharmacology; D014225:Triatominae / Q000378:metabolism*
D012701:Serotonin; D011188:Potassium; D002118:Calcium