title: Behavioral and endocrine evaluation of the stressfulness of single-pen housing compared to group-housing and social isolation conditions.
abstract: Regulation of neuroendocrine responses is often studied in animals housed indoors in individual contiguous pens. In sheep, these housing conditions are used to control the environment, facilitate biological sampling and limit social stress. However, this type of housing also prevents exploratory behaviors and could induce stereotypies, non-compliant with welfare and possibly associated with a state of stress. In this context, we investigated the impact of housing in a single-pen, with other familiar conspecifics, on emotional state by evaluating behavioral, hormonal and neuronal measures in adult ewes. We hypothesized that emotional state would be more negative in animals housed in a single-pen for one week (Pen) than in freely moving animals (Free) but less negative than in socially isolated subjects (Isol). We tested our hypothesis in ovariectomized ewes to avoid the interaction with sexual steroid variations. Our behavioral, endocrine and neuronal (Fos activation of the corticotropin-releasing hormone neurons in the paraventricular nucleus of the hypothalamus) measures confirmed that withdrawing familiar conspecifics was sufficient to induce strong stress responses in Isol ewes, but there was no indication that Pen ewes were stressed. However, the latter showed less mastication activity than Free ewes, probably due to limited accessibility to straw. The highest plasma prolactin levels were observed in Isol and Free animals, which might result from stress and physical activity, respectively. In Free ewes, plasma dopamine was low, consistent with its inhibitory control of prolactin. However, Isol animals had both high levels of prolactin and dopamine, suggesting a dysregulated balance in socially stressed ewes. As in other species, we suggest that the regulation of prolactin by dopamine varies with stress and/or social context. Overall, this study shows that the impact of housing conditions on different neuroendocrine systems should be considered more in the future.
authors: ISA Lille, 48 bd Vauban, F-59046 Lille cedex, France.
authors: Vanessa
authors: V
authors: Guesdon
authors: INRA, UMR85 Physiologie de la Reproduction et des Comportements, F-37380 Nouzilly, France; CNRS, UMR 6175, F-37380 Nouzilly, France; Université de Tours, F-37041 Tours, France; IFCE, F-37380 Nouzilly, France.
authors: Maryse
authors: M
authors: Meurisse
authors: INRA, UMR85 Physiologie de la Reproduction et des Comportements, F-37380 Nouzilly, France; CNRS, UMR 6175, F-37380 Nouzilly, France; Université de Tours, F-37041 Tours, France; IFCE, F-37380 Nouzilly, France.
authors: Didier
authors: D
authors: Chesneau
authors: INRA, UMR85 Physiologie de la Reproduction et des Comportements, F-37380 Nouzilly, France; CNRS, UMR 6175, F-37380 Nouzilly, France; Université de Tours, F-37041 Tours, France; IFCE, F-37380 Nouzilly, France.
authors: Sophie
authors: S
authors: Picard
authors: INRA, UMR85 Physiologie de la Reproduction et des Comportements, F-37380 Nouzilly, France; CNRS, UMR 6175, F-37380 Nouzilly, France; Université de Tours, F-37041 Tours, France; IFCE, F-37380 Nouzilly, France.
authors: Frédéric
authors: F
authors: Lévy
authors: INRA, UMR85 Physiologie de la Reproduction et des Comportements, F-37380 Nouzilly, France; CNRS, UMR 6175, F-37380 Nouzilly, France; Université de Tours, F-37041 Tours, France; IFCE, F-37380 Nouzilly, France. Electronic address: elodie.chaillou@tours.inra.fr.
authors: Elodie
authors: E
authors: Chaillou
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D004703:Endocrine System / Q000503:physiopathology*; D005260:Female; D006728:Hormones / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D016761:Oncogene Proteins v-fos / Q000378:metabolism; D012756:Sheep; D012931:Social Environment; D012934:Social Isolation / Q000523:psychology*; D018709:Statistics, Nonparametric; D013315:Stress, Psychological / Q000097:blood* / Q000473:pathology / Q000503:physiopathology*; D014828:Vocalization, Animal / Q000502:physiology
chemical_list: D006728:Hormones; D016761:Oncogene Proteins v-fos
keywords: CRF; Cortisol; Dopamine; Emotion; Fos; Prolactin