title: Effects of aging on photoperiodic responsiveness and specific 2-[125I]-iodomelatonin binding sites in the pars tuberalis and suprachiasmatic nuclei of Siberian hamsters.
abstract: Siberian hamsters undergo reproductive quiescence during exposure to a short day photoperiod, but this response appears to diminish with age. This study investigated whether age-related losses in photoperiodic responsiveness may be related to decreases in specific 2-[125I]-iodomelatonin binding sites in the suprachiasmatic nuclei or pars tuberalis. Adult male Siberian hamsters (group 1: 3-6 months of age and group 2: 9-12 months of age) were exposed to short photoperiod (10 hr of light/day) for 10 weeks. Profound testicular regression was evident in the majority of the hamsters in group 1, but in only a few of the hamsters in group 2. There were no significant differences between the groups in the density or affinity of the specific 2-[125I]-iodomelatonin binding sites in either the suprachiasmatic nuclei or the pars tuberalis. These findings suggest that the failure of older hamsters to respond to short photoperiod is not caused by a loss of specific 2-[125I]-iodomelatonin binding sites in the suprachiasmatic nuclei or pars tuberalis.
authors: Department of Anatomy and Neurobiology, University of Kentucky, Chandler Medical Center, Lexington.
authors: M J
authors: MJ
authors: Duncan
authors: C C
authors: CC
authors: Purvis
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D001345:Autoradiography; D001665:Binding Sites; D006224:Cricetinae; D007457:Iodine Radioisotopes; D008027:Light; D008297:Male; D008550:Melatonin / Q000031:analogs & derivatives* / Q000378:metabolism; D017111:Phodopus; D017440:Photoperiod; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D013493:Suprachiasmatic Nucleus / Q000378:metabolism*; D013737:Testis / Q000502:physiology
chemical_list: D007457:Iodine Radioisotopes; C044556:2-iodomelatonin; D008550:Melatonin