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Mutation Research 449 2000 33–39
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Effect of exogenous melatonin on the ovarian follicles in
g-irradiated mouse
Jin Kyu Kim
)
, Chang Joo Lee
Korea Atomic Energy Research Institute, 150 Dukjin-dong, Yusong-gu, Taejon 305-353, South Korea
Received 25 August 1999; received in revised form 11 January 2000; accepted 3 February 2000
Abstract
The present study was performed to obtain the evidence of the radioprotective function of melatonin on g-radiation-in-
duced follicular atresia in mouse ovary. Three-week-old immature mice received 10 and 100 mg of melatonin dissolved in
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100 ml of the alcoholic saline. Two hours after the treatments, they were whole-body irradiated with a dose of LD 8.3
80
Ž30.
.
Gy . The ovaries were dissected out of the animals at y2, 2, 8, 14 h after the onset of irradiation. The total number of
follicles including the normal and atretic follicles examined in the largest cross sections was 125. The number was reduced
to 103 in the irradiated group. The number of primordial follicles of the irradiation group or the melatonin-treated group was
smaller than that of the control group. However, the number of primary, preantral, and antral follicles was not different from
that of the control group. In the group pretreated with 100 mg of melatonin before irradiation, the ratio of normal primordial
follicles was significantly higher than that of the irradiation group at any time point after irradiation. The high concentration
of melatonin also reduced the radiation-induced degeneration of the primary follicles at 14 h after irradiation. On the other
hand, the pretreatment of 10 mg of melatonin had little or no effect on the radiation-induced degeneration of primary
follicles. However, it gave a protective effect on the radiation-induced degeneration in the primordial follicles at 2 h after
irradiation, and 14 h after irradiation in preantral and antral follicles. From the above results, it is concluded that the
exogenous melatonin has different functions depending on the follicle stages, and that the radioprotective effect of
exogenous melatonin on the follicular degeneration is related to its concentration. q 2000 Elsevier Science B.V. All rights
reserved.
Keywords: Melatonin; g-Radiation; Follicular atresia; Mouse ovary
1. Introduction
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Melatonin N-acetyl-5-methoxytrptamine; MW s
.
232 is an endogenous compound secreted by the
)
Corresponding author. Tel.: q82-42-868-8763; fax: q82-42-
868-2091.
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E-mail address: jkkim@nanum.kaeri.re.kr J.K. Kim .
pineal gland. It is generally accepted that melatonin
influences reproduction via its action on the hypo-
wx wx
thalamus 1,2 and hypophysis 3 , and that mela-
tonin may modulate the secretion of gonadotropins
wx
4 . However, there are many evidences for the exis-
wx wx
tence of melatonin receptors in rat 5 , mouse 6 ,
wx
and human 7,8 . Furthermore, melatonin has been
reported to participate in the regulation of a number
0027-5107r00r$ - see front matter q 2000 Elsevier Science B.V. All rights reserved.
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PII: S0027-510 7 00 00027-0