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NeuroendocrinologyİLetters incl. Psychoneuroimmunology & Chronobiology,
ISSNİ0172ñ780X Copyrightİ©İ1999 NeuroendocrinologyİLetterss

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NEL VOL. 20 1/2
ORIGINAL ARTICLE

1999; 20:77–81
Full text pdf (101kb)

Effects of oxytocin and vasopressin on retrieval of passive avoidance response in melatonin-treated and/or pinealectomized male rats
Marlena Juszczak, Edgar Appenrodt, Jan W. Guzek & Helmut Schwarzberg

Key words:
oxytocin, vasopressin, melatonin, pinealectomy, behavior

Abstract
The role of the pineal gland and its hormone—melatonin—as to the impact of vasopressin (VP) and/or oxytocin (OT) on the regulation of behavior was studied, the passive avoidance task being chosen as an experimental model. The results showed that VP facilitated the avoidance latency during the first retention trial; after pinealectomy, however, VP was ineffective in this regard. Intraperitoneal application of OT was ineffective in modifying the passive avoidance latency when compared with respective saline-treated animals. Melatonin alone, when injected to sham operated animals 30 min before behavioral experiment, did not affect the passive avoidance response in SA- or OT-treated rats, but blocked the VP-induced lengthening of the passive avoidance latency in the first retention trial. In pinealectomized and OT-treated animals the passive avoidance latency during the second retention trial was severely diminished by melatonin when compared to respective control. We conclude that: a) VP needs a regulated pineal function for developing short-term effects on the passive avoidance response and b) the effect of OT on the avoidance latency in pinealectomized rats develops after melatonin treatment as a long-term effect.

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Copyright © Neuroendocrinology Letters 1999
All rights reserved. No part may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or ortherwise, without prior written permission from the Editor-in-Chief.