In the United States, one quarter of mothers who smoke continue to do so during pregnancy (or gestation). Numerous scientific studies have reported that gestational nicotine exposure can lead to shortfalls in learning (to acquire information) and memory (to retain and recall information), in children of mothers who smoked during pregnancy. Unfortunately, little information is currently available as to the reasons why this relationship exists, although human and animal studies are starting to provide more evidence that this link is due to the harmful effects of nicotine (the addictive drug in cigarettes) on the growing brain. Therefore, my proposal aims to determine the cause of gestational nicotine induced learning and memory impairments.
In the rat, nicotine can directly interact with certain types of cells (noradrenergic neurons) in the brain to release the compound, norepinephrine. This compound has been shown to be important in numerous brain functions (i.e. attention, arousal, stress, and learning and memory). The research in our lab has already shown that the children of rat mothers (offspring of dams), who were exposed to nicotine during pregnancy, release more norepinephrine than those that were not exposed. Moreover, this change in norepinephrine release in the nicotine exposed offspring can remain until adulthood. This result suggests that brain functions, dependent on the amount of norepinephrine around in the brain (i.e. attention, arousal, stress, and learning and memory), may be altered in the animal until adulthood, a finding that has been shown in human studies. In this proposal, the focus has been placed on learning and memory changes, allowing us to hypothesize that nicotine exposure during animal development can have harmful effects on the brain, altering the amount of norepinephrine around, thereby causing problems in an animals’ ability to learn and remember.
I am proposing to perform two behavioral experiments (an emotional memory task and a “smell” memory task) that have been shown to require a precise amount of norepinephrine for accurate animal performance. The aim is to (i) see whether a single exposure of nicotine can affect either one of the memory tasks, and (ii) determine whether continuous nicotine exposure during a dams’ pregnancy will affect the memory of the developing offspring.
If the hypothesis is correct, researchers can use this information to further understand the cause of learning and memory deficits seen in the children of mothers who smoke. Furthermore, the results can be used to educate the public, in more detail, about the harmful effects of smoking during pregnancy. Finally, the findings can also help scientists develop drugs that could prevent learning and memory problems that occur because of maternal cigarette smoking. |