Friday, May 16, 2014

Housing Lab Rats in Pairs

ressaure / Foter
Individual housed rats animal are widely considered to experience a syndrome called ‘isolation stress’.[1][2]. This syndrome includes hyper-reactivity to stimuli,[3] deficits in learning performance,[4] and altered reactivity to pharmaceuticals.[5]

When compared to other rodent species, rats are particularly susceptible to isolation stress, especially as juveniles (up to 50 days of age).[6][7] While housing in larger groups is often desirable, pair housing is sufficient to abolish the worst effects of isolation stress. Use of social contact substitutes such as mirrors has not been successful.[1]

 Social housing permits the display of highly-motivated social behaviors and helps moderate the effect of experimental or incidental stressors. When confronted with a novel or aversive event, paired animals experience significantly less distress as indicated by measures such as open field activity,[1] ethanol intake[8] and adrenal gland size.[4]

 As such, differences in social housing should be considered as a potential source of experimental confounds. Social housing is preferred as producing rats that display less severe physical and behavioral abnormalities[9] and are less susceptible to stressors.

  •  [1] Wiberg, G. S., and H. C. Grice. "Long term isolation stress in rats." Science (New York, NY) 142 (1963): 507.
  •  [2] Baer, Hf. "Long-term isolation stress and its effects on drug response in rodents." Laboratory animal science 21.3 (1971): 341. 
  •  [3] Lapiz, M. D. S., et al. "Influence of postweaning social isolation in the rat on brain development, conditioned behavior, and neurotransmission." Neuroscience and behavioral physiology 33.1 (2003): 13-29. 
  • [4] Reed, Phil, et al. "Effects of isolation rearing and mirror exposure on social and asocial discrimination performance." Learning and Motivation 27.2 (1996): 113-129. 
  •  [5] Jones, G. H., et al. "Dopaminergic and serotonergic function following isolation rearing in rats: study of behavioural responses and postmortem and in vivo neurochemistry." Pharmacology Biochemistry and Behavior 43.1 (1992): 17-35. 
  •  [6] Einon, Dorothy F., et al. "Isolation has permanent effects upon the behavior of the rat, but not the mouse, gerbil, or guinea pig." Developmental psychobiology 14.4 (1981): 343-355. 
  • [7] Lukkes, Jodi L., et al. "Adult rats exposed to early-life social isolation exhibit increased anxiety and conditioned fear behavior, and altered hormonal stress responses." Hormones and behavior 55.1 (2009): 248-256.
  • [8] Parker, Lorne F., and Barbara L. Radow. "Isolation stress and volitional ethanol consumption in the rat." Physiology & behavior 12.1 (1974): 1-3. 
  •  [9] Muchimapura, S., et al. "Isolation rearing in the rat disrupts the hippocampal response to stress." Neuroscience 112.3 (2002): 697-705.

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