The individual and joint effects of methylmercury (MeHg; 1 mg/kg
body weight/day, GD7-PND7) and
PCB153 (20 mg/kg
body weight/day, GD10-GD16), administered orally to rat dams, were explored in 21-day-old rat offspring brain in terms of
monoamine oxidase B (
MAO-B) activity and regional content of
dopamine (DA),
serotonin (5-HT), 5-hydroxy-indole-3-acetic
acid (5-HIAA) and
homovanillic acid (HVA). Neither treatment altered
MAO-B in striatum, hippocampus, cerebellum and cerebral cortex of female pups. In males the cerebellum displayed a significantly reduced
enzyme activity (25-45%) following all treatments. Concerning
biogenic amines,
5-HT levels were decreased by 30-50% in the cerebral cortex of males and females by
PCB153 alone and combined with MeHg, without changes in
5-HIAA and dopaminergic endpoints. In cerebellum of all pups, MeHg enhanced
5-HIAA levels, whereas
PCB153, either alone or combined with MeHg, did not affect this endpoint. In striatum,
PCB153 reduced the content of DA, HVA and
5-HIAA (respective control values: 2-3; 60-80; 8-10 ng/mg
protein) to a similar extent when administered alone or together with MeHg (20-40%). Perinatal exposure to MeHg and/or
PCB153 results in regionally and/or gender-specific alterations in the central dopaminergic and serotonergic systems at weaning. The combined treatment with MeHg and
PCB153 does not exacerbate the neurochemical effects of the individual compounds.