Developmental pathway alterations in the stress axis of chickens exposed in ovo to an emerging environmental contaminant

Abstract

Pharmaceutical and personal care products are present in the natural environment by way of the wastewater stream. They are persistent in the environment and have bioaccumulative abilities that threaten the health of both humans and animals. Triclosan is an emerging contaminant of concern given its extensive use in personal care products. While past studies have focused on its ability to cause neuroendocrine dysfunction through the reproductive axis, this study focuses on disruption to the stress axis. The stress axis is vital in regulating various body processes, and irreversible modifications to the axis can result from the induction of stress during development. Alterations are measured via stress related endpoints such as plasma corticosterone concentration and glucocorticoid receptor abundance, as well as other common developmental endpoints. This study demonstrates that at the environmentally relevant doses tested, developmental endpoints relevant to the stress axis were not altered in chickens exposed in ovo. Notable trends were observed, however, that support previous research, such as: activation of the reserve capacity protects some endpoints such as somatic growth but not others like pipping and hatching, exposure to environmental pollutants may increase variance in population level responses to stressors, and developmental stressors may impair brain formation and lead to behavioral changes such as fear and other anxiety-like behaviors.