Meeting Abstract

64.5  Thursday, Jan. 6  Season- and context-dependent sex differences in melatonin receptor activity in a forebrain song control nucleus: studies from the lab and semi-natural environments CALISI, RM; BENTLEY, GE*; Univ. of California, Berkeley; Helen Wills Neuroscience Institute, Univ. of California, Berkeley beccacalisi@gmail.com

In stark contrast to mammals, changes in reproductive state in birds appear to be independent of daily or seasonal changes in secretion of the pineal hormone melatonin. Despite this, the avian brain expresses dense populations of melatonin receptors in multiple brain areas. Area X, one such brain area, is part of the forebrain circuitry involved in song production and vocal learning. Seasonal changes in the volumes of song control nuclei, such as Area X, largely depend on seasonal changes in circulating gonadal steroids. Based on data from laboratory-housed male birds, there also appears to be a role for melatonin in functional plasticity within this forebrain circuitry. However, male birds in non-laboratory environments and females in any environment are woefully understudied in this regard. To understand better the interaction of melatonin in Area X of both male and female European starlings (Sturnus vulgaris) we examined changes in melatonin receptor binding in the lab under artificial lighting and in semi-natural enclosures exposed to natural photoperiod. We report a complex interaction of photoperiod, sex and housing environment upon melatonin receptor activity within Area X. Our data are the first to demonstrate an influence of housing environment upon melatonin receptor activity in the brain. Furthermore, this effect of housing environment is dependent upon sex and season. These data imply that studies on melatonin receptor activity in the central nervous system of vertebrates need to take into account sex and housing environment prior to interpretation of results.