Table 1 Summary of studies on social isolation in rat models.
| Â | Strain | Sex | Isolation | Rehousing | Behavioral outcomes (isolated compared to group housed rats) |
|---|---|---|---|---|---|
SD | M | P21 to P42 | Yes | Open field test—Reduced locomotion and fewer entries to center in adulthood Free social interaction test—Increased social anxiety-like behaviors (increased latency for social approach, decreased number and duration of social contacts, and increased freezing behavior) in adulthood Habituation to novel dark open field—No differences | |
Meng et al.27 | SD | M | P21 to P48a | Yes | Open field test—Increased locomotor activity before but not after rehousing Free social interaction—Increased social interaction before but not after rehousing |
Weintraub et al.28 | SD | M & F | P30 to P50 | Yes | Elevated plus maze—Decreased anxiety-like behavior in males but not females |
Lukkes et al.29 | SD | F | P21 to P42 | Yes | Social interaction—No difference Habituation to novel dark open field—No difference |
Baarendse et al.30 | LS | M | P21 to P42 | Yes | 5-choice serial reaction time task—Disrupted impulse control Delayed reward task—No difference Rat gambling task—Impaired decision making |
Tulogdi et al.31 | W | M | P21 to P70b | Yes | Resident intruder test—No difference before rehousing but increased aggressive behavior after rehousing |
Bator et al.32 | WH | M | P30 to P40 | Yes | Home cage social behavior during resocialization—Decreased social investigation and contact behavior but no difference in play behaviors Locomotor activity using a fear conditioning chamber setup—No difference Free social interaction—No difference Novel object recognition test—No difference Acoustic startle response test—No difference |
Begni et al.33 | LH | M | P21 to P58 or P21 to P101c | Yes | Open field test—Increased locomotor activity following isolation from P21-101; no differences following rehousing Burrowing behavior—No differences following isolation from P21-101 or following rehousing |
Kinley et al.34 | LE | M & F | P21 to P42 | Yes | Open field test—No differences Social preference—Decreased social preference in males but not females Light–dark box—Decreased anxiety-like behavior in males but not females |
P Graf et al.35 | W | M & F | P21 to P42 or P42 to P63d | Yes | Open field test—No difference in distance traveled Elevated plus maze—No difference in either sex Novel object recognition task—No difference in either sex Free social interaction—No differences following early adolescence isolation but decreased social interaction following late adolescence isolation in both sexes Social recognition memory—Impaired social discrimination in both sexes following both early and late isolation Hotplate test—Increased thermal pain sensitivity in male isolated rats and decreased thermal pain sensitivity in female isolated rats |
Tanaka et al.36 | LE | M & F | P23 to P38—P48 | No | Elevated plus maze—Increased anxiety-like behavior in males but not females Social recognition test—Impairments in social recognition in both sexes |
Wall et al.37 | SD | M & F | P21 to P49—P52 | No | Free social interaction—Increased social interaction and aggressive grooming in both sexes |
Seffer et al.38 | W | M | P21 to P49 | Yese | Exposure to acoustic stimuli (pro-social USV, alarm USV, or background noise) and subsequent arm entries on a radial arm—Lack of deficits in approach behavior seen specifically in response to pro-social USV following isolation from P21-P49 rescued by rehousing |
Fontenot et al.39 | SD | M & F | P21 to P49 | No | Free social interaction—Increase in aggressive grooming behavior with no changes in non-aggressive social behavior in both sexes |
Novoa et al.40 | SD | M | P21 to P31 | No | Open field test—Increased time in center and distance traveled in isolated rats Elevated plus maze—Increased anxiety-like behavior (less time in open arms; more time in closed arms) |
Potrebic et al.41 | WH | M | P29 to P43f. | No | Three chamber test—Isolated rats showed increased approaches to social stimulus and more time spent more time in exploratory activity compared to GH rats at early adolescence (P36) but not at mid-adolescence (P43) |
Douglas et al.42 | SD | M & F | P23 to P38 or P21 to P70g | No | Social conditioned placed preference (CPP) -– Isolated adolescent and adult rats demonstrated CPP while GH adult rats did not display CPP Social behavior (play fighting, social investigation, social avoidance) tracked during social conditioned place preference -– Increased play fighting in adolescent but not adult rats; adult isolated rats spent more time engaging in social investigation than GH or adolescent isolated rats |
Yorgason et al.43 | LE | M | P28 to P77 or P28 to P174 | No | Elevated plus maze—Increased anxiety-like behavior in both age groups |
Toyoshima et al.44 | WI | M | P21 to P80 | No | Social discrimination task—Isolated rats were able to discriminate novel conspecific amongst 3 different conspecifics while group-housed rats were unable to discriminate Object discrimination task—No difference |
Oliveira et al.45 | W | M & F | P21 to P72 | No | Resident intruder test—Increased aggression in both sexes Elevated plus maze—No difference in either sex Social preference test—No difference in both sex Short-term social recognition memory/social discrimination test -– Impaired social discrimination in both sexes |
Amiri et al.46 | W | M | P21-28 to P77-84 | No | Open field test—Increased locomotor activity Free social interaction—Decreased social exploration behavior (rearing, anogenital sniffing, time spent with other rat) |
Shirenova et al.47 | W | F | P31 to 5.5 months or P35 to 9.5 monthsh | No | Open field test—Greater Increased locomotor activity (distance traveled) after 5.5 months of isolation Elevated plus maze—Decreased exploratory risk assessments (head dips from the open arms) and less time spent in open arms after 2 months of isolation but not at other time points Three chamber test—Increased preference for novel social stimulus and chamber containing novel social object in isolated rats at 9.5 months but not at 3 months Free social interaction—Increased duration of social contact (including aggressive interaction) after 2 and 5 months of isolation but not after 8 months of SI |
Harding et al.48 | LE | M & F | P28 to P64 | No | Open field test—No difference in male isolated rats.; Less distance traveled and time spent in center zone in female isolated rats Elevated plus maze—No difference in either sex Sociability test (novel rat vs. novel object)—Both male and female isolated rats displayed preference for social compared to the novel object stimulus (though difference in investigation time is not stated to be significantly different) Novel object location test—No difference in either sex |
