Cognition- and anxiety-related behavior, synaptophysin and MAP2 immunoreactivity in the adult rat treated with a single course of antenatal betamethasone.

We investigated the effects of a single course of antenatal betamethasone on cognition- and anxiety-related behavior and synaptophysin and microtubule-associated protein 2 (MAP2) immunoreactivity in the adult rat hippocampus. On d 20 of gestation, pregnant rats were injected with either 1) 170 microg/kg body weight of betamethasone ("clinically equivalent dose," equivalent to 12 mg twice, 24 h apart); 2) half this dose; or 3) vehicle. Cognition- and anxiety-related behavior of the offspring was analyzed at an age of 5 mo using the Morris water maze, object recognition task, and open field test. Subsequently, synaptophysin and MAP2 immunoreactivity were measured in the hippocampus. We report no detrimental effects of antenatal betamethasone on cognition- and anxiety-related behavior and synaptophysin immunoreactivity in the adult rat. On the other hand, MAP2 immunoreactivity was decreased by betamethasone in males, suggesting a permanent impairment in the hippocampus. Interestingly, the lower dose appears to have less influence in terms of growth restriction, known to be associated with an increased risk of disease in adulthood. Further research might elucidate whether the betamethasone effect on hippocampal neurons persists later in life and could affect the aging process increasing the risk for neuropathology of the adult.