Reproductive Medicine, Chronobiology
and Human Ethology, ISSN 0172780X
Vol.24 Nos.3/4, Jun-Aug 2003
of central and peripheral administration of leptin on pain threshold
in rats and mice
of central and peripheral administration of leptin on pain
threshold in rats and mice
Kutlu, Sinan Canpolat, Suleyman Sandal,
Mete Ozcan, Mustafa Sarsilmaz & Haluk Kelestimur
University, The Institute of Health Science, Department of
Neuroendocrinology, Elazig, TURKEY.
July 27, 2002
Accepted: September 19, 2002
leptin, pain threshold
This study was planned to investigate the effects of exogenous
leptin on the pain threshold.
Adult male Wistar rats weighing 250300 g and mice weighing
2530 g were used in this study. Leptin was intracerebroventricularly
(i. c. v.) injected in a dose of 3.5 µg/rat. Mice were intraperitoneally
(i. p.) injected with leptin in a dose of 25 µg/mouse. Control
animals were injected with the respective vehicle. The pain
threshold test was performed using hot plate analgesia meter.
The experiments were performed during the day and at night.
The data were statistically analysed by Mann-Whitney U test.
Level of significance was set at p<0.05.
During the day, there were no significant changes in hot plate
latencies half an hour after i.c.v. injection of vehicle or
leptin in the control and leptin-treated rats, respectively.
At night, like during the day, i.c.v. injection of neither
vehicle nor leptin caused any significant change in pain sensitivity.
In mice, i.p. injection of leptin decreased latencies significantly
(p<0.05) during the day and at night. Thus, leptin caused
an increase in pain sensitivity during the day and at night.
These results clearly demonstrated that leptin has a decreasing-effect
on pain threshold if it is peripherally administered in mice.
Copyright © Neuroendocrinology Letters 2003
Society of Integrated Sciences
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.
latest statistics from the www.nel.edu