Meeting Abstract

146.1  Monday, Jan. 7  Season- and context-dependent sex differences in melatonin receptor activity in a forebrain song control nucleus: comparison of data from the laboratory and a semi-natural environment BENTLEY, GE*; PERFITO, N; CALISI, RM; UC Berkeley; UC Berkeley; UC Berkeley gb7@berkeley.edu

There are dense populations of melatonin receptors in large areas of the songbird brain, in particular in the visual system and the song control system. Melatonin has therefore been implicated in neuroplasticity of the song control system. Previously we demonstrated extremely large changes in activity of melatonin receptor in Area X, a forebrain song control nucleus that is important for song learning and production. In a laboratory environment, melatonin receptor activity was drastically down-regulated in male and female European starlings during photostimulation (a simulated breeding season). The functional significance of this large change in Area X is unclear, so we sought to elucidate it by tracking melatonin receptor activity in male and female starlings housed in a semi-natural environment and permitted to breed. Males and females all exhibited high melatonin receptor activity in Area X during short days at the start of the breeding season, and maintained this high activity during photostimulation until females laid eggs. At this point the females down-regulated melatonin receptor activity in Area X, whereas the males maintained high activity until later on in the breeding season. Overall, we observed a gradual termination of melatonin receptor activity in Area X as the breeding season progressed, but the timing of the termination was different between the sexes. Our data contrast with those collected in a laboratory environment, and highlight the need for studying brain and behavior of wild species in as natural an environment as possible if we are to understand the significance of any observed effects.