Using cortical thickness and elevated plus maze as a means to assess brain and behaviour in adolescent rodents

Paternal preconception nicotine exposure and enriched housing

Abstract

The effect of maternal experience on the prenatal environment is well researched, however, comprehensive examination of father experience is lacking. This project aims to gain insight into paternal nicotine exposure and complex housing on offspring brain and behaviour. In this study, four experimental groups were used; nicotine enriched, nicotine pair housed, control enriched and control pair housed. Male Long Evans rats were either kept in pair houses or enriched in complex housing at P45 for 96 days and administered the appropriate solution (nicotine/control) during the last 48 days. Rats were then immediately mated with female Long Evan rats following cessation of enrichment and treatment administration. Offspring were then born to the mothers, never coming into contact with the fathers. A subset of the offspring were perfused on P21 for anatomical analysis while the remaining underwent behavioral testing on P36 and were subsequently perfused. Cortical thickness measurements were completed on the animals perfused at P21 and elevated plus maze (EPM) behavioral task - a measure of anxiety - was conducted on the remaining animals at P36. An increased amount of time spent in the closed arms of the EPM is used as a measure of anxiety in these rodents. Nicotine pair housed males as well as control enriched males were found to have significantly thicker cortexes. However, when these treatments were combined in the nicotine enrichment males, this observed thickness in the cortex seemed to be nullified as the cortex thickness was now comparable to the control pair housed males. Male and female offspring of enriched fathers and male offspring of nicotine exposed fathers spent significantly more time in the closed arms of the EPM, thus being considered more anxious than the controls. *Indicates presenter