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Expression of melatonin (MT1, MT2) and melatonin-related receptors in the adult rat testes and during development

  • Gaia Izzo (a1), Aniello Francesco (a2), Diana Ferrara (a1), Maria Rosaria Campitiello (a3), Ismene Serino (a1), Sergio Minucci (a4) and Michela d'Istria (a1)...


It is well known that melatonin provokes reproductive alterations in response to changes in hours of daylight in seasonally breeding mammals, exerting a regulatory role at different levels of the hypothalamic–pituitary–gonadal axis. Although it has also been demonstrated that melatonin may affect testicular activity in vertebrates, until now, very few data support the hypothesis of a local action of melatonin in the male gonads. The aim of this study was to investigate whether MT1, MT2 melatonin receptors and the H9 melatonin-related receptor, are expressed in the adult rat testes and during development. A semi-quantitative RT-PCR method was used to analyse the expression of MT1, MT2 and H9 receptors mRNAs in several rat tissues, mainly focusing on testes during development and adult life. Our results provide molecular evidences of the presence of both MT1 and, for the first time, MT2 melatonin receptors as well as of the H9 melatonin-related receptor in the examined tissues, including adult testes. During development MT1 and MT2 transcripts are expressed at lower levels in testes of rats from 1 day to 1 week of age, lightly increased at 2 weeks of age and remained permanently expressed throughout development until 6 months. These data strongly support the hypothesis that melatonin acts directly in male vertebrate gonads suggesting that rat testes may be a suitable model to verify the role of indolamine in vertebrate testicular activity.


Corresponding author

All correspondence to: Sergio Minucci. Dipartimento di Medicina Sperimentale-Sezione di Fisiologia Umana e Funzioni Biologiche Integrate ‘F. Bottazzi’, Seconda Università degli Studi di Napoli, via Costantinopoli 16, 80138 Napoli, Italy. Tel: +39 815665829. Fax: +39 815667500. e-mail:


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Aleandri, V., Spina, V. & Morini, A. (1996). The pineal gland and reproduction. Hum. Reprod. Update 2, 225–35.
Anton-Tay, F., Chou, C., Anton, S. & Wurtman, R.J. (1968). Brain serotonin concentration: elevation following intraperitoneal administration of melatonin. Science 162, 277–8.
Arendt, J. (1986). Role of the pineal gland and melatonin in seasonal reproductive function in mammals. Oxf. Rev. Reprod. Biol. 8, 266320.
Bartness, T.J., Powers, J.B., Hastings, M.H., Bittman, E.L. & Goldman, B.D. (1993). The timed infusion paradigm for melatonin delivery: what has it taught us about the melatonin signal, its reception and the photoperiodic control of seasonal responses? J. Pineal Res. 15, 161–90.
Bittman, E.L., Kaynard, A.H., Olster, D.H., Robinson, J.E., Yellon, S.M. & Karsch, F.J. (1985). Pineal melatonin mediates photoperiodic control of pulsatile luteinizing hormone secretion in the ewe. Neuroendocrinology 40, 409–18.
Cardinali, D.P., Vacas, M.I. & Boyer, E.E. (1979). Specific binding of melatonin in bovine brain. Endocrinology 105, 437–41.
Cassone, V.M., Warren, W.S., Brooks, D.S. & Lu, J. (1993). Melatonin, the pineal gland and circadian rhythms. J. Biol. Rhythms Suppl. S73–S81.
Chomczynski, P. & Sacchi, N. (1987). Single-step method of RNA isolation by acid guanidinium thiocyanate–phenol–chloroform extraction. Anal. Biochem. 162, 156–9.
Clemens, J.W., Jarzynka, M.J. & Witt-Enderby, P.A. (2001). Down-regulation of mt1 melatonin receptors in rat ovary following estrogen exposure. Life Sci. 69, 2735.
d'Istria, M., Palmiero, C., Serino, I., Izzo, G. & Minucci, S. (2003). Inhibition of the basal and oestradiol-stimulated mitotic activity of primary spermatogonia by melatonin in the testes of frog, Rana esculenta, in vivo and in vitro. Reproduction 126, 8390.
d'Istria, M., Serino, I., Izzo, G., Ferrara, D., De Rienzo, G. & Minucci, S. (2004). Effects of melatonin treatment on Leydig cell activity in the testes of the frog Rana esculenta. Zygote 12, 293–9.
Diaz, B., Diaz, E., Colmenero, M.F., Arce, A., Esquifino, A. & Marìn, B. (1999). Maternal melatonin influences rates of somatic and reproductive organs postnatal development of male rat offspring. Neuro. Endocrinol. Lett. 20, 6976.
Drew, J.E., Barrett, P., Mercer, J.G. et al. (2001). Localization of the melatonin-related receptor in the rodent brain and peripheral tissues. J. Neuroendocrinol. 13, 453–8.
Dubocovich, M.L., Masana, M.I., Iacob, S. & Sauri, D.M. (1997). Melatonin receptor antagonists that differentiate between the human Mel1a and Mel1b recombinant subtypes are used to assess the pharmacological profile of the rabbit retina ML1 presynaptic heteroreceptor. Naunyn Schmiedebergs Arch. Pharmacol. 355, 365–75.
Duncan, M.J., Takahashi, J.S. & Dubocovich, M.L. (1988). 2-[125I]iodomelatonin binding sites in hamster brain membranes: pharmacological characteristics and regional distribution. Endocrinology 122, 1825–33.
Frungieri, M.B., Mayerhofer, A., Zitta, K., Pignataro, O.P., Calandra, R.S. & Gonzalez-Calvar, S.I. (2005). Direct effect of melatonin on Syrian hamster testes: melatonin subtype 1a receptors, inhibition of androgen production and interaction with the local corticotropin-releasing hormone system. Endocrinology 146, 1541–52.
Fu, Z., Kato, H., Kotera, N., Noguchi, T., Sugahara, K. & Kubo, T. (2001). Regulation of hydroxyindole-O-methyltransferase gene expression in Japanese quail (Coturnix coturnix japonica). Biosci. Biotechnol. Biochem. 65, 2504–11.
Gubitz, A.K. & Reppert, S.M. (1999). Assignment of the melatonin-related receptor to human chromosome X (GPR50) and mouse chromosome X (Gpr50). Genomics 55, 248–51.
Hazlerigg, D.G., Morgan, P.J. & Messager, S. (2001). Decoding photoperiodic time and melatonin in mammals: what can we learn from the pars tuberalis? J. Biol. Rhythms 16, 326–35.
Izzo, G., d'Istria, M., Serino, I. & Minucci, S. (2004). Inhibition of the increase 17β-estradiol-induced mast cell number by melatonin in the testes of the frog Rana esculenta, in vivo and in vitro. J. Exp. Biol. 207, 437–41.
Kato, H., Fu, Z., Kotera, N., Sugahara, K. & Kubo, T. (1999). Regulation of the expression of serotonin N-acetyltransferase gene in Japanese quail (Coturnix japonica): I. Rhythmic pattern and effect of light. J. Pineal Res. 27, 2433.
Kus, I., Sarsilmaz, M., Ogetürk, M., Yilmaz, B., Keleştimur, H. & Oner, H. (2000). Ultrastructural interrelationship between the pineal gland and the testes in the male rat. Arch. Androl. 45, 119–24.
Kuş, I., Akpolat, N., Ozen, O.A., Songur, A., Kavakli, A. & Sarsilmaz, M. (2002). Effects of melatonin on Leydig cells in pinealectomized rat: an immunohistochemical study. Acta Histochem. 104, 93–7.
Morgan, P.J., Barrett, P., Howell, H.E. & Helliwell, R. (1994). Melatonin receptors: localization, molecular pharmacology and physiological significance. Neurochem. Int. 24, 101–46.
Niedziela, M., Lerchl, A. & Nieschlag, E. (1995). Direct effects of the pineal hormone melatonin on testosterone synthesis of Leydig cells in Djungarian hamsters (Phodopus sungorus) in vitro. Neurosci. Lett. 201, 247–50.
Olivares, A.N., Valladares, L.E., Bustos-Obregón, E. & Núñez, S.M. (1989). Testicular function of sexually immature rats chronically treated with melatonin. Arch. Biol. Med. Exp. 22, 387–93.
Pandi-Perumal, S.R., Trakht, I., Srinivasan, V., et al. (2008). Physiological effects of melatonin: role of melatonin receptors and signal transduction pathways. Prog. Neurobiol. 853, 335–53.
Paul, P., Lahaye, C., Delagrange, P., Nicolas, J.P., Canet, E. & Boutin, J.A. (1999). Characterization of 2-[125I]iodomelatonin binding sites in Syrian hamster peripheral organs. J. Pharmacol. Exp. Ther. 290, 334–40.
Pickering, D.S. & Niles, L.P. (1990). Pharmacological characterization of melatonin binding sites in Syrian hamster hypothalamus. Eur. J. Pharmacol. 175, 71–7.
Redins, C.A., Redins, G.M. & Novaes, J.C. (2002). The effects of treatment with melatonin on the ultrastructure of mouse Leydig cells: a quantitative study. Braz. J. Biol. 62, 517–23.
Reiter, R.J. (1980). Photoperiod: its importance as an impeller of pineal and seasonal reproductive rhythms. Int. J. Biometeorol. 24, 5763.
Reiter, R.J. (1981). Pineal control of reproduction. Prog. Clin. Biol. Res. 59, 349355.
Reiter, R.J. (1991a). Melatonin: the chemical expression of darkness. Mol. Cell Endocrinol. 79, 153–8.
Reiter, R.J. (1991b). Pineal melatonin: cell biology of its synthesis and of its physiological interactions. Endocr. Rev. 12, 151–80.
Reiter, R.J. (1991c). Neuroendocrine effects of light. Int. J. Biometeorol. 35, 169–75.
Reiter, R.J. (1993). The melatonin rhythm: both a clock and a calendar. Experientia 49, 654–64.
Reppert, S.M., Godson, C., Mahle, C.D., Weaver, D.R., Slaugenhaupt, S.A. & Gusella, J.F. (1995). Molecular characterization of a second melatonin receptor expressed in human retina and brain: the Mel1b melatonin receptor. Proc. Natl. Acad. Sci. USA 92, 8734–8.
Reppert, S.M., Weaver, D.R., Ebisawa, T., Mahle, C.D. & Kolakowski, L.F. Jr (1996). Cloning of a melatonin-related receptor from human pituitary. FEBS Lett. 386, 219–24.
Sallinen, P., Saarela, S., Ilves, M., Vakkuri, O. & Leppäluoto, J. (2005). The expression of MT1 and MT2 melatonin receptor mRNA in several rat tissues. Life Sci. 76, 1123–34.
Sanger, F., Donelson, J.E., Coulson, A.R., Kössel, H. & Fischer, D. (1974). Determination of a nucleotide sequence in bacteriophage f1 DNA by primed synthesis with DNA polymerase. J. Mol. Biol. 90, 315–33.
Shiu, S.Y., Li, L., Siu, S.W., Xi, S.C., Fong, S.W. & Pang, S.F. (2000). Biological basis and possible physiological implications of melatonin receptor-mediated signaling in the rat epididymis. Biol. Signals Recept. 9, 172–87.
Stankov, B. & Reiter, R.J. (1990). Melatonin receptors: current status, facts and hypotheses. Life Sci. 46, 971–82.
Stefulj, J., Hörtner, M., Ghosh, M., et al. (2001). Gene expression of the key enzymes of melatonin synthesis in extrapineal tissues of the rat. J. Pineal Res. 30, 243–7.
Tijmes, M., Pedraza, R. & Valladares, L. (1996). Melatonin in the rat testes: evidence for local synthesis. Steroids 61, 65–8.
Valenti, S., Guido, R., Giusti, M. & Giordano, G. (1995). In vitro acute and prolonged effects of melatonin on purified rat Leydig cell steroidogenesis and adenosine 3′,5′-monophosphate production. Endocrinology 136, 5357–62.
Valenti, S., Giusti, M., Guido, R. & Giordano, G. (1997). Melatonin receptors are present in adult rat Leydig cells and are coupled through a pertussis toxin-sensitive G-protein. Eur. J. Endocrinol. 136, 633–9.
Valenti, S., Thellung, S., Florio, T., Giusti, M., Schettini, G. & Giordano, G. (1999). A novel mechanism for the melatonin inhibition of testosterone secretion by rat Leydig cells: reduction of GnRH-induced increase in cytosolic Ca2+. J. Mol. Endocrinol. 23, 299306.
Valenti, S., Fazzuoli, L., Giordano, G. & Giusti, M. (2001). Changes in binding of iodomelatonin to membranes of Leydig cells and steroidogenesis after prolonged in vitro exposure to melatonin. Int. J. Androl. 24, 80–6.
Vanecek, J. & Watanabe, K. (1998). Melatonin inhibits the increase of cyclic AMP in rat suprachiasmatic neurons induced by vasoactive intestinal peptide. Neurosci. Lett. 252, 21–4.
Vera, H., Tijmes, M. & Valladares, L.E. (1997). Melatonin and testicular function: characterization of binding sites for 2-[125I]-iodomelatonin in immature rat testes. Steroids 62, 226–9.
Weaver, D.R. (1999). The roles of melatonin in development. Adv. Exp. Med. Biol. 460, 199214.
Wiechmann, A.F., Campbell, L.D. & Defoe, D.M. (1999). Melatonin receptor RNA expression in Xenopus retina. Brain Res. Mol. Brain Res. 63, 297303.
Wu, C.C., Chiao, C.W., Hsiao, G., Chen, A. & Yen, M.H. (2001). Melatonin prevents endotoxin-induced circulatory failure in rats. J. Pineal Res. 30, 147–56.
Wurtman, R.J. & Axelrod, J. (1966). The physiologic effects of melatonin and the control of its biosynthesis. Probl. Actuels Endocrinol. Nutr. 10, 189200.



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