Elsevier

Physiology & Behavior

Volume 49, Issue 6, June 1991, Pages 1107-1118
Physiology & Behavior

Article
“Isolation stress” revisited: Isolation-rearing effects depend on animal care methods

https://doi.org/10.1016/0031-9384(91)90338-OGet rights and content

Abstract

Early reports of enhanced behavioral reactivity in isolation-reared rats attributed this syndrome to “isolation stress.” In the studies reported here, this “isolation stress syndrome” was reliably obtained in adult rats reared from weaning in individual hanging metal cages. Such isolates showed behavioral and adrenocortical symptoms of profound fear during open-field testing, unlike group-housed controls or littermate isolates reared singly in plastic cages. Animals in hanging metal cages are never touched by human caretakers, whereas rats reared in plastic cages are picked up and put in clean cages twice weekly. Handling hanging-cage isolates twice weekly to model the handling associated with cage changes completely protected against this syndrome. Further, there was no hormonal, neurochemical or anatomical evidence of chronic stress even in hanging-cage isolates. Littermates housed in social groupings (three rats per plastic cage) also froze and defecated in the open field at rates comparable to hanging-cage isolates if they were the first animals to be tested from their social group cage. It is probable that odor cues from familiar cagemates in the open field protected socially reared animals tested subsequently from the same cage from this syndrome. It is concluded that isolates are not chronically stressed, and that rearing effects are the result of a complex interaction between prior handling, social experience and test conditions.

References (57)

  • A.M. Hatch et al.

    Isolation syndrome in the rat

    Toxicol. Appl. Pharmacol.

    (1965)
  • R.R. Holson

    Feeding neophobia: A possible explanation for the differential maze performance of rats reared in enriched or isolated environments

    Physiol. Behav.

    (1986)
  • R.R. Holson et al.

    Adrenocortical, β-endorphin and behavioral responses to graded stressors in differentially reared rats

    Physiol. Behav.

    (1988)
  • O.H. Lowry et al.

    Protein measurement with folin phenol reagents

    J. Biol. Chem.

    (1951)
  • M.J. Morgan et al.

    Incentive motivation and behavioral inhibition in socially-isolated rats

    Physiol. Behav.

    (1975)
  • A. Morinan et al.

    Some anatomical and physiological correlates of social isolation in the young rat

    Physiol. Behav.

    (1980)
  • D.E. Redmond et al.

    New evidence for a locus coeruleus-norepinephrine connection with anxiety

    Life Sci.

    (1979)
  • B.J. Sahakian et al.

    The effects of psychomotor stimulants on stereotypy and locomotor activity in socially-deprived and control rats

    Brain Res.

    (1975)
  • D.S. Segal et al.

    The effects of environmental isolation on behavior and regional rat brain tyrosine hydroxylase and tryptophan hydroxylase activities

    Behav. Biol.

    (1973)
  • J.A. Stern et al.

    The effect of group vs. individual physiological responses to stress in the albino rats

    J. Psychosom. Res.

    (1960)
  • G.S. Wiberg et al.

    Methodology in long-term toxicity tests: A comparison of individual versus community housing

    Fed. Cosmet. Toxicol.

    (1966)
  • R. Ader

    Effects of early experience and differential housing on behavior and susceptibility to gastric erosions in rats

    J. Comp. Physiol. Psychol.

    (1963)
  • R. Ader et al.

    Social factors affecting emotionality and resistance to disease in animals. IV. Differential housing, emotionality, and Walker 256 carcinosarcoma in the rat

    Psychol. Rep.

    (1964)
  • R. Ader et al.

    Social environment, emotionality, and alloxan diabetes in the rat

    Psychosom. Med.

    (1963)
  • S.F. Ali et al.

    Cholinergic and dopaminergic alterations in the mouse central nervous system following acute trimethyltin exposure

    Acta Pharmacol. Toxicol.

    (1986)
  • G. Blanc et al.

    Response to stress of mesocortical-frontal dopaminergic neurons in rats after long-term isolation

    Nature

    (1980)
  • P. Brain et al.

    The interpretation of physiological correlates of differential housing in laboratory rats

    Life Sci.

    (1979)
  • Y. Claustre et al.

    Pharmacological studies on stress-induced increase in frontal cortical dopamine metabolism in the rat

    J. Pharmacol. Exp. Ther.

    (1986)
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