Changes in the Behavior and Body Weight of Mature, Adult Male Wistar Han Rats after Reduced Social Grouping and Social Isolation

Guinea pigs (Cavia porcellus) are a commonly used species in biomedical research. As social creatures, compatible guinea pigs should be housed together unless scientific objectives or veterinary care require otherwise. Extensive literature suggests that adult male guinea pigs are highly aggressive in the presence of females, but data are lacking regarding the compatibility of cohoused adult males in the absence of females. Most studies that use adult males do not report housing densities. We used serial wound scoring and observations of behavior to determine whether unfamiliar adult male guinea pigs will develop stable, prosocial isosexual pairs. Wound scoring was performed before and 24 h after pairing. Serial behavioral observations assessed affiliative and agonistic behaviors at 0.5, 2, 24, and 48 h after pairing. Wound scoring and behavioral observations continued weekly for 1 mo and monthly thereafter. Wound scores were significantly higher at 24 h after pairing as compared with baseline and all other time points. Wounding was rare after week 2, indicating reduced aggression. Furthermore, affiliative behaviors significantly increased over time while agonistic behaviors were rare. Together, these data suggest that unfamiliar adult male guinea pigs establish stable prosocial pairs after an acclimation period. As was done in the present study, providing ample space, separate shelters for each animal, and the absence of female guinea pigs will likely facilitate successful pairing. We recommend consideration of a social housing program for adult male guinea pigs to provide companionship and enrich their housing environment.

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Alterations in the Hypothalamic–Pituitary–Adrenal Axis as a Response to Experimental Autoimmune Encephalomyelitis in Dark Agouti Rats of Both Sexes

Milosevic,

Zivkovic

et al. 2024

Biomolecules

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Multiple sclerosis (MS) is a chronic inflammatory disease that affects the central nervous system, usually diagnosed during the reproductive period. Both MS and its commonly used animal model, experimental autoimmune encephalomyelitis (EAE), exhibit sex-specific features regarding disease progression and disturbances in the neuroendocrine and endocrine systems. This study investigates the hypothalamic–pituitary–adrenal (HPA) axis response of male and female Dark Agouti rats during EAE. At the onset of EAE, Crh expression in the hypothalamus of both sexes is decreased, while males show reduced plasma adrenocorticotropic hormone levels. Adrenal gland activity is increased during EAE in both males and females, as evidenced by enlarged adrenal glands and increased StAR gene and protein expression. However, only male rats show increased serum and adrenal corticosterone levels, and an increased volume of the adrenal cortex. Adrenal 3β-HSD protein and progesterone levels are elevated in males only. Serum progesterone levels of male rats are also increased, although testicular progesterone levels are decreased during the disease, implying that the adrenal gland is the source of elevated serum progesterone levels in males. Our results demonstrate a sex difference in the response of the HPA axis at the adrenal level, with male rats showing a more pronounced induction during EAE.

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Changes in the Behavior and Body Weight of Mature, Adult Male Wistar Han Rats after Reduced Social Grouping and Social Isolation

Cited by 4 publications

References 63 publications

How to Enrich/Refine Lab Animal’s Housing and Environment by Environmental Enrichment Programs and Training?

How to Enrich/Refine Lab Animal’s Housing and Environment by Environmental Enrichment Programs and Training?

Establishing New Isosexual Pairs in Adult Male Guinea Pigs (Cavia porcellus) to Facilitate Social Housing

Alterations in the Hypothalamic–Pituitary–Adrenal Axis as a Response to Experimental Autoimmune Encephalomyelitis in Dark Agouti Rats of Both Sexes

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