Maternal Preconception Nicotine and Enriched Housing

The Effects on Offspring Anxiety Behaviour

Abstract

A mother’s environment can affect her offspring even before conception. Both positive factors, such as an enriched environment, and negative factors, such as drug use, have the potential to shape offspring development. The influence of psychoactive drugs is especially concerning because of the role they play in modulating important survival instincts, such as anxiety; therefore, strategies to counteract the changes induced by drug use are of particular interest. One possible way to counteract the transgenerational effects of drugs may be through enriching the maternal environment, which has been previously shown to attenuate the effects of nicotine. Enriched environments have huge beneficial effects on individuals, and hopefully these benefits can be passed down to offspring as a protective factor. In this experiment, female rats received moderate levels of nicotine in their drinking water (15mg/L sweetened with 1% sucralose) while being housed in either standard lab conditions or an enriched environment. The rats undergoing enriched housing were placed in a larger cage with multiple levels, more cage mates, and a rotation of stimulating objects. Control females received water sweetened with 1% sucralose while living in either environment. The offspring underwent behavioural testing in adolescence and adulthood to look for changes in elevated plus maze behaviours, a test that measure anxiety-like behaviours. Cortical thickness and thalamic size were also examined to look for effects on brain morphology. The results showed significant effects of preconception nicotine and enriched housing in the anxiety-like behaviours of the offspring in both adolescence and adulthood, dependent on sex. Results suggest that maternal preconception nicotine use lowers the amount of anxiety present in offspring. When the mothers are kept in enriched housing, however, the anxiety levels in the nicotine cohort return to levels near that of the control group. These results have important implications in the ability of the offspring to survive their environment, as differences in anxiety levels affect the survival strategies used by the offspring. Additionally, the return to control levels in the offspring whose mothers lived in an enriched environment does in fact suggest that maternal enrichment acts as a protective factor against preconception nicotine use. These results are not surprising as nicotinic acetylcholine receptors play a major role in the modulation of anxiety pathways, evidenced by both increases and decreases in anxiety due to nicotine use.