PhD Exit Seminar – Sophie St-Cyr (McGowan lab)

PhD Exit Seminar

Wednesday August 16^th, 3:00 pm – SW 403 – University of Toronto at Scarborough

Sophie St-Cyr (McGowan lab)

“Maternal Programming of Adult Rodent Integrative Phenotype by Prenatal Exposure to Predator Odour”

Abstract

Prenatal stress mediated through the mother can program the long-term phenotype of the offspring. The capacity for adaptation to adversity in early life depends in part on the life history of the animal. It is therefore likely that an early life ethologically relevant psychogenic stressor that has been present over evolutionary times could prime responses to an environment containing this stress via epigenetic mechanisms such as DNA methylation modifications. Pregnant C57BL/6 mice and, separately, Long-Evans rats were exposed daily to unpredictable and inescapable predator odors or distilled water control over the second half of pregnancy. I examined the effect of the prenatal predator odour exposure on the integrative phenotype of adult offspring at the level of behaviour, physiology, endocrinology, transcription and DNA methylation. Prenatally predator odour-exposed offspring exhibited an overall increase in stress-related behaviours on a variety of commonly-used and semi-naturalistic assessments of the response to stress, as well as modifications of energy consumption at baseline and under stress. These changes were accompanied by a sex-specific increase in endocrine responses to stress and an increase in circulating thyroid hormone. Additionally, I observed modifications in stress-related transcript abundance at birth and in adulthood accompanied by DNA methylation modifications in adulthood. Overall, assessments of the integrative phenotype of prenatal predator odour-exposed animals indicate a persistent increase in stress responsiveness across a variety of experimental conditions and phenotypic levels in the two rodent species. This phenotype supports the hypothesis that maternal programming allows developmental forecasting that shapes the individual developmental trajectory. Prenatal predator odour is therefore a potent programming stressor.