Researchers from the University of Alabama at Birmingham (AL, US) presented a paper at Neuroscience 2010, the annual meeting of the Society for Neuroscience in which they reported that exposure to nicotine during pregnancy leads to a decrease in adult stem cells and a change in synaptic plasticity in the hippocampus of the offspring. The synaptic changes could have lifelong consequences for the offspring. According to Professor Robin Lester of the Department of Neurobiology and lead researcher on the project, “These problems could include various cognitive deficits, learning difficulties, [and] ADHD.”
These are very preliminary findings. They come from research conducted with rats and will require extensive additional work to make the connections to human learning. Note that the mother rats apparently were also ingesting nicotine while nursing (first 10 days after birth) as well as during pregnancy. My reporting here is based entirely on press releases from UAB and the Society for Neuroscience (with abstract).
852.18, Neurogenesis and LTP is altered in the rat dentate gyrus after chronic gestational exposure to nicotine
S. HYMAN1, A. KIDWELL2, R. A. J. LESTER1;
1Neurobio., 2Univ. of Alabama In Birmingham, Birmingham, AL
More than 20 percent of pregnant women in the United States smoke, despite FDA warnings that smoking during pregnancy is associated with a number of negative outcomes. Long-term effects of this behavior on the offspring include: a higher rate of drug abuse during adolescence and learning disabilitiesi. Here we evaluate how neuronal stem cells and synaptic plasticity in the dentate gyrus may be affected after gestational exposure to nicotine. Pregnant dams were implanted with osmotic minipumps on gestational day 4 with either saline or a moderate to high dose of nicotine [6mg/kg/day] for the duration of gestation and through post-natal day10 (PN 10). ii This time period after birth is analogous to the third trimester in human gestation. After injection of pups on PN 10 with BrdU we show that the rate of neurogenesis, as reported by BrdU activity, decreases after gestational exposure to nicotine by 75 +/- 20 percent (s.e.m.; n = 3 saline; n=5 nicotine) in PN 10 animals. The rate of survival for these stem cells is the same however, in both groups, over a four-day period [saline = 45 percent +/- 20 (s.e.m.; n = 3), nicotine = 37 percent +/- 20 (s.e.m.; n = 5)]. This change in neurogenesis rate is accompanied by an increase in synaptic activity as measured by a shift to the left on extracellular input-output curves; in addition to a decrease in LTP threshold. A decrease in LTP threshold was determined by a decrease in the number of stimuli necessary for LTP induction. Both the changes in excitability and neurogenesis in the dentate gyrus may contribute to the observed behavioral changes in the offspring of pregnant rats exposed to nicotine. i Abdel-Rahman, A, Dechkovskaia, AM, Sutton, JM, Chen WC, Guan X, Khan WA, Abou-Donia MB (2005) Maternal exposure of rats to nicotine via infusion during gestation produces neurobehavioral deficits and elevated expression of glial fibrillary acidic protein in the cerebellum and CA1 subfield in the offspring at puberty Toxicology 209:245-261 ii Fewell, JE, Smith, FG, Ng, VKY. (2001) Threshold level of Maternal Nicotine that Impairs Protective Responses of Newborn Rats to Intermittent Hypoxia. J Appl Physiol 90: 1968 -76