Antiseizure medications and fetal nutrients: Effects on choline transporters in a human placental cell line.

OBJECTIVE: Many nutrients essential to the fetus and for proper function of the placenta itself cannot freely diffuse across membrane barriers, and their transplacental transfer depends on transporters. Our previous studies provided evidence for altered expression of transporters for folic acid in trophoblasts exposed to antiseizure medications (ASMs). The goal of the current study was to explore the effects of older and newer ASMs on the expression and function of uptake transporters for choline, which interacts with folate at pathways for methyl group donation. METHODS: BeWo cells were incubated for 2 or 5 days with valproate (42, 83, or 166 µg/ml), carbamazepine (6 or 12 µg/ml), levetiracetam (10 or 30 µg/ml), lamotrigine (3 or 12 µg/ml), lacosamide (5, 10, or 20 µg/ml), or their vehicles (n = 6/treatment group). Quantitative polymerase chain reaction (PCR) analysis was utilized to study the effects of ASMs on the transcript levels of the choline transporters SLC44A1 (CTL1) and SLC44A2 (CTL2). Transporter protein expression in valproate-treated cells was assessed by western blot analysis. Choline and acetylcholine were quantified in cell lysates by a choline/acetylcholine assay kit. RESULTS: Compared with controls, valproate and levetiracetam at high therapeutic concentrations (83 and 30 µg/ml, respectively) lowered choline transporter transcript levels by up to 42% and 26%, and total choline levels by 20% and 21%, respectively (p < .05). At 83 µg/ml, valproate additionally reduced CTL1 and CTL2 protein expression, by 39 ± 21% and 61 ± 13% (mean ± SD), respectively (p < .01). Carbamazepine reduced SLC44A1 transcript levels, whereas lacosamide modestly decreased the expression of SLC44A2. Lamotrigine did not alter choline transporter expression. SIGNIFICANCE: Antiseizure medications, particularly at high therapeutic concentrations, can interfere with the placental uptake of choline. In line with current knowledge from pregnancy registries and clinical studies, the present in vitro findings further support careful adjustment of maternal ASM doses during pregnancy.

The Placental Barrier: the Gate and the Fate in Drug Distribution.

Optimal development of the embryo and the fetus depends on placental passage of gases, nutrients, hormones, and waste products. These molecules are transferred across the placenta via passive diffusion, carrier-mediated cellular uptake and efflux, and transcytosis pathways. The same mechanisms additionally control the rate and extent of transplacental transfer of drugs taken by the pregnant mother. Essentially all drugs cross the placenta to a certain extent, and some accumulate in the placenta itself at levels that can even exceed those in maternal plasma. Hence, even drugs that are not efficiently transferred across the placenta may indirectly affect fetal development by interfering with placental function. In this article, we describe key properties of the placental barrier and their modulation by medications. We highlight implications for pharmacotherapy and novel approaches for drug delivery in pregnant women and their fetuses.