Lay Abstract EDMONDS, Kent 98-128224 The goals of the proposed studies are to examine the roles of photoperiod, the circadian system, melatonin, the pineal gland, and food intake in regulating the magnitude of compensatory gonadal hypertrophy (CGH) in a reproductively photoperiodic rodent, the marsh rice rat (Oryzomys palustris). Compensatory gonadal hypertrophy results when the surgical removal of one gonad produces a dramatic increase in the size of the remaining gonad. Studies will be conducted on hemi-castrated male and female marsh rice rats housed under different photoperiodic regimes, or melatonin treatment conditions. Dr. Edmunds will also examine the extent to which CGH is mediated by the circadian system by conducting "resonance" experiments. Because CGH has only been studied in laboratory strains of rodents, this work is important to discover the effects of photoperiod on CGH. The results of this work may provide insights into the mechanisms underlying CGH and the possible ramifications of melatonin treatment on CGH processes.
