Reproductive Medicine, Chronobiology
and Human Ethology, ISSN 0172780X
Vol.24 Nos.3/4, Jun-Aug 2003
Melatonin stimulates lymphocytes
supplementation restores cellular proliferation and DNA synthesis
in the splenic and thymic lymphocytes of old rats
H. El-Sokkary,1 Russel J. Reiter 2 &
Sary Kh. Abdel-Ghaffar 3
Department of Zoology, Faculty of Science, Assiut University,
2. Department of Cellular and Strucural Biology, The University
of Texas Health Science Center, 7703 Floyd Curl Drive, San
Antonio, TX, USA.
3. Department of Pathology, Faculty of Veterinary Medicine,
Assiut University, Assiut, Egypt
March 28, 2003
Accepted: April 13, 2003
Autoradiography, 3H-thymidine, cell proliferation, DNA
synthesis, lymphocytes, histopathology.
In this study we investigated the effect of melatonin treatment
on the proliferative activity, the rate of DNA synthesis and
the histopathological changes of splenic and thymic lymphocytes
in old rats.
Two subgroups of old rats (25-months-old) were used in this
study. One subgroup was given melatonin in the drinking water
(250300 mg/day/rat) for 3 months while the second subgroup
was given water containing diluent. A third group consisted
of young rats (3-months-old) which served as an additional
A 3H-thymidine autoradiographic investigation showed a reduction
in both the proliferative activity and the rate of DNA synthesis
in splenic and thymic lymphocytes in old rats. In addition,
light and electron microscopy showed severe histopathological
changes in these cells from diluent-treated old rats. Melatonin
administration increased the proliferative activity and the
rate of DNA synthesis in the lymphocytes of both the spleen
and thymus of the old animals. Also, histopatholgical changes
were partially reversed by melatonin treatment with the tissues
appearing similar to those in the young rats.
The stimulation of the lymphocyte activity by melatonin is
a beneficial response, especially in old rats, since aging
results in an inhibition in lymphocytic functions.
Copyright © Neuroendocrinology Letters 2003
Society of Integrated Sciences
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