Effect of melatonin on the onset of puberty in male juvenile rats

다국어 초록 (Multilingual Abstract)

Melatonin or N-acetyl-5-methoxytryptamine, the fascinating molecule secreted by the pineal gland. Melatonin has a close interaction with hypothalamic-pituitary-gonadal axis. In non-seasonal breeders like rat its exact role in reproduction is controvertible. So it is worth to explore the possible role of melatonin on the onset of puberty in male albino rats. Two groups of male rats aged 5 and 10 days were used for the study. In each group, there were three subgroups, each receiving melatonin for 5 days, 10 days or till the day of descent of testes. Similar subgroups were used as controls. Without handling, animals were observed daily for the onset of puberty. On the day of descent of testes, body weight of the animal was noted, blood was collected, serum was separated and used for radio immunoassay. For histomorphometric analysis, all morphometric measurements were done using an occular micrometer. Volume fraction of seminiferous tubules, intertubular connective tissue of testes, cortex and medulla of thymus were estimated by point count method. In both the age groups melatonin advanced the age on descent of testes, increased the body weight, organ weight. It also increased the serum hormone levels. So, in conclusion this study indicates that exogenous melatonin advances the onset of puberty in male albino wistar rats and this effect is more pronounced in the younger animals.

참고문헌 (Reference)

1 Farris EJ, "The rat: in laboratory investigation" J.B.Lippincott Co 1949

2 Vaněcek J, "The melatonin receptors in rat ontogenesis" 48 : 201-203, 1988

3 Jevdjovic T, "The effect of hypophysectomy on pancreatic islet hormone and insulin-like growth factor I content and mRNA expression in rat" 123 : 179-188, 2005

4 Olivares AN, "Testicular function of sexually immature rats chronically treated with melatonin" 22 : 387-393, 1989

5 Acuña-Castroviejo D, "Similarity between the effects of suprachiasmatic nuclei lesions and of pinealectomy on gonadotropin release in ovariectomized, sulpiride-treated and melatonin-replaced rats" 49 : 797-801, 1993

6 Moreno ML, "Serum prolactin and luteinizing hormone levels and the activities of hypothalamic monoamine oxidase A and B and phenylethanolamine-N-methyl transferase are changed during sexual maturation in male rats treated neonatally with melatonin" 13 : 167-173, 1992

7 "Rat Behavior and Biology (Anne's rat page). Biological statistics of the Norway rat" Rat Behavior and Biology

8 Oner H, "Possible effects of melatonin on thymus gland after pinealectomy in rats" 25 : 115-118, 2004

9 Edmonds KE, "Photoperiod and melatonin affect testicular growth in the marsh rice rat(Oryzomys palustris)" 17 : 86-93, 1994

10 Leja-Szpak A, "Modulation of pancreatic enzyme secretion by melatonin and its precursor: L-tryptophan. Role of CCK and afferent nerves" 55 (55): 33-46, 2004

11 Yilmaz B, "Melatonin inhibits testosterone secretion by acting at hypothalamo-pituitary-gonadal axis in the rat" 21 : 301-306, 2000

12 Tijmes M, "Melatonin in the rat testis : evidence for local synthesis" 61 : 65-68, 1996

13 Das UN, "Melatonin in human health and disease" 45 : 133-139, 1996

14 Vera H, "Melatonin and testicular function : characterization of binding sites for 2-[125I]-iodomelatonin in immature rat testes" 62 : 226-229, 1997

15 Jaworek J, "Melatonin and its precursor, L-tryptophan : influence on pancreatic amylase secretion in vivo and in vitro" 36 : 155-164, 2004

16 Weaver DR, "Melatonin after Four Decades" Kluwer Academic/Plenum Publishers 199-214, 2000

17 Kostoglou-Athanassiou I, "Melatonin administration and pituitary hormone secretion" 48 : 31-37, 1998

18 Lerner AB, "Isolation of melatonin and 5-methoxyindole-3-acetic acid from bovine pineal glands" 235 : 1992-1997, 1960

19 van Haeften TW, "Insulin-like growth factors and pancreas beta cells" 34 : 249-255, 2004

20 Ostrowska Z, "Influence of pinealectomy and long-term melatonin administration on GH-IGF-I axis function in male rats" 22 : 255-262, 2001

21 Lang U, "Influence of exogenous melatonin on melatonin secretion and the neuroendocrine reproductive axis of intact male rats during sexual maturation" 112 : 1578-1584, 1983

22 Daftary SS, "IGF-1 in the brain as a regulator of reproductive neuroendocrine function" 230 : 292-306, 2005

23 Smythe GA, "Growth hormone responses to melatonin in man" 184 : 1373-1374, 1974

24 Alonso-Solís R, "Gonadal steroid modulation of neuroendocrine transduction : a transynaptic view" 16 : 357-382, 1996

25 Minneman KP, "Effects of pineal compounds on mammals" 17 : 1189-1199, 1975

26 Herradon PG, "Effects of early partial decapitation on the ontogenic development of chicken lymphoid organs. I. Thymus" 191 : 57-66, 1991

27 Valcavi R, "Effect of oral administration of melatonin on GH responses to GRF 1-44 in normal subjects" 26 : 453-458, 1987

28 Mandal H, "Effect of dihydrotestosterone on serum concentrations of alpha 2u-globulin and on spermatogenesis in melatonin-treated rats" 126 : 431-435, 1990

29 Esquifino AI, "Development of 24-hour rhythms in serum prolactin and luteinizing hormone levels in rats neonatally administered melatonin" 15 : 21-28, 1998

30 Rasmussen DD, "Daily melatonin administration at middle age suppresses male rat visceral fat, plasma leptin, and plasma insulin to youthful levels" 140 : 1009-1012, 1999

31 Mahmoud I, "Continuous darkness and continuous light induce structural changes in the rat thymus" 185 (185): 143-149, 1994

32 Peschke D, "Circannual rhythm and increase of body weight and food intake in the young wistar rat following pinealectomy and ganglionectomy" 9 : 321-327, 1987

33 Pierpaoli W, "Circadian melatonin and young-to-old pineal grafting postpone aging and maintain juvenile conditions of reproductive functions in mice and rats" 32 : 587-602, 1997

34 Drury RA, "Carleton's histological technique" Oxford University Press 1967

35 Kennedy GC, "Body weight and food intake as initiating factors for puberty in the rat" 166 : 408-418, 1963

36 Relkin R, "Absence of alteration in puberal onset in male rats following amygdaloid lesioning" 88 : 1272-1274, 1971