Prenatal phencyclidine induces heightened neurodegeneration in rats in some brain regions, especially during 2nd trimester, but possible anti-apoptotic effects in others.

Phencyclidine administered to the developing rat brain at high doses for a few hours during late foetal life induces apoptotic neurodegeneration in several brain regions. We sought to investigate whether prolonged, low level foetal exposure to phencyclidine during different gestational periods (2nd trimester versus 3rd trimester) would have different effects on several brain regions showing neurodegeneration as assessed using silver stains. Pregnant rats were treated with phencyclidine (5.45 mg/day) continuously for 5 days via minipumps, and the pups were either perfused immediately after birth and silver-stained for degeneration, or allowed to mature and then tested for behavioural deficits. In the newborn pups, there was a substantial increase in the number of agrophilic cells in entorhinal cortex and subiculum; this effect was greater when the drug was given during 2nd trimester. However, in the ventromedial nucleus of the hypothalamus, both the 2nd and 3rd trimester phencyclidine pups had significantly fewer degenerating cells than the controls. Behavioural tests of rotorod and open field performance in the pups allowed to mature indicated decreased motor coordination and hyperactivity in the 3rd trimester phencyclidine pups, but minimal alterations in the 2nd trimester pups. Thus, prenatal exposure to phencyclidine can have either neurodegenerative or antiapototic effects depending upon brain region, and there is a discrepancy between persisting behavioural deficits and amount of cell loss for time of maximal prenatal effect of the drug.