tailieunhanh - Reproductive response of adult Siberian hamsters to one hour melatonin infusions

The pineal hormone melatonin is known to play an important role in mediating photoperiodic messages to the reproductive system in seasonal breeding animals. In this study, we investigated whether a 1 h subcutaneous infusion of 50 ng of melatonin at 2000-2100 hours, effective in causing inhibition of testicular development in the juvenile Siberian hamsters would cause testicular regression in adults of this species housed on a long photoperiod (LD16:8). | Turk J Biol 27 (2003) 57-63 © TÜB‹TAK Reproductive Response of Adult Siberian Hamsters to One-Hour Melatonin Infusions Bülent GÜNDÜZ* Department of Biology, Abant Izzet Baysal University, 14280, Bolu - TURKEY Milton H. STETSON Physiology and Anatomy Section, Department of Biological Sciences, University of Delaware, Newark, DE 19716 USA Received: Abstract: The pineal hormone melatonin is known to play an important role in mediating photoperiodic messages to the reproductive system in seasonal breeding animals. In this study, we investigated whether a 1 h subcutaneous infusion of 50 ng of melatonin at 2000-2100 hours, effective in causing inhibition of testicular development in the juvenile Siberian hamsters (Phodopus sungorus), would cause testicular regression in adults of this species housed on a long photoperiod (LD16:8). Pinealectomized adult hamsters received programmed subcutaneous infusions of 50 or 500 ng of melatonin or vehicle ( ml) at 2000-2100 hours each day for 8 weeks. We found that the testicular weights of infused animals receiving melatonin or vehicle were not different from each other; all animals retained large testes. These results show that a 50 ng melatonin infusion at a particular time point (20002100 hours) is not effective in altering the functional status (size) of the testes of adults. Key Words: Melatonin, Siberian hamster, Photoperiod, Testes, Infusion Bir-Saat Melatonin ‹nfüzyonlar›na Yetiflkin Sibirya Hamsterlerinin Üreme Yan›t› Özet: Pineal bezi hormonu olan melatonin mevsimsel üreyen hayvanlarda fotoperiyodik mesajlar› üreme sistemine iletmede önemli bir role sahiptir. Bu çal›flmada, yavru Sibirya hamsterlar›nda (Phodopus sungorus) etkili oldu¤unu buldu¤umuz 50 ng melatoninin 2000-2100 saatleri aras›nda 1 saat infüze edildi¤inde uzun fotoperiyotta (LD16:8) tutulan yetiflkin erkek Sibirya hamsterlar›nda etkili olup olmad›¤› araflt›r›ld›. Pineal bezleri al›nm›fl (pinealektomi) yetiflkin hamsterler 8 hafta .