Clinical and preclinical evidence indicates that prenatal exposure to
glucocorticoids may induce detrimental effects in the offspring, including reduction in fetal growth and alterations in the CNS. On this basis, the present study investigated whether in utero exposure to high levels of
glucocorticoids is a risk factor that may lead to an exacerbation of the central noxious effects induced by
psychoactive drugs consumed later in life. To this end, pregnant C57BL6/J dams were treated with
dexamethasone (DEX, 0.05 mg/kg per day) from gestational day 14 until delivery. Thereafter, the male offspring were evaluated to ascertain the magnitude of dopaminergic damage,
astrogliosis and microgliosis elicited in the nigrostriatal tract by the
amphetamine-related drug 3,4--methylenedioxymethamphetamine (
MDMA, 4 × 20 mg/kg, 2 h apart, sacrificed 48 h later) administered at either adolescence or adulthood. Immunohistochemistry was performed in the substantia nigra pars compacta (SNc) and striatum, to evaluate dopaminergic degeneration by measuring
tyrosine hydroxylase (TH), as well as
astrogliosis and microgliosis by measuring
glial fibrillary acidic protein (GFAP) and ionized
calcium-binding adapter molecule 1 (IBA-1), respectively. Moreover, immunohistochemistry was used to ascertain the co-localization of IBA-1 with either the pro-inflammatory
interleukin (IL) IL-1β or the anti-inflammatory IL
IL-10, in order to determine the microglial phenotype. In utero administration of DEX induced dopaminergic damage by decreasing the density of TH-positive fibers in the striatum, although only in adult mice.
MDMA administration induced dopaminergic damage and glia activation in the nigrostriatal tract of adolescent and adult mice. Mice exposed to DEX in utero and treated with
MDMA later in life showed a more pronounced loss of dopaminergic neurons (adolescent mice) and
astrogliosis (adolescent and adult mice) in the SNc, compared with control mice. These results suggest that prenatal exposure to
glucocorticoids may induce an age-dependent and persistent increase in the susceptibility to central toxicity of
amphetamine-related drugs used later in life.