Developmental bisphenol A (BPA) exposure is associated with adverse behavioral
effects, although underlying modes of action remain unclear. Because BPA is a
suspected xenoestrogen, the objective was to identify sex-based changes in adult
zebrafish social behavior developmentally exposed to BPA (0.0, 0.1 or 1 μM) or one of
two control compounds (0.1 μM 17β-estradiol [E2], and 0.1 μM GSK4716, a synthetic
estrogen-related receptor γ ligand). A test chamber was divided lengthwise so each
arena held one fish unable to detect the presence of the other fish. A mirror was
inserted at one end of each arena; baseline activity levels were determined without mirror. Arenas were divided into 3, computer-generated zones to represent different
distances from mirror image. Circadian rhythm patterns were evaluated at 1-3 (= AM)
and 5-8 (= PM) hr postprandial. Adult zebrafish were placed into arenas and monitored
by digital camera for 5 min. Total distance traveled, % time spent at mirror image, and
number of attacks on mirror image were quantified. E2, GSK4716, and all BPA
treatments dampened male activity and altered male circadian activity patterns; there
was no marked effect on female activity. BPA induced non-monotonic effects (response
curve changes direction within range of concentrations examined) on male % time at
mirror only in AM. All treatments produced increased % time at the mirror during PM.
Male attacks on the mirror were reduced by BPA exposure only during AM. There were
sex-specific effects of developmental BPA on social interactions and time-of-day of
observation affected results.Keywords: social behavior, bisphenol A, agonistic behavior, developmental exposure, zebrafish, circadian rhythms, sex-specific behavio
