Long-term social isolation impairs learning in a two-way active avoidance task in female rats

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In socially living species, including humans, social contacts’ deficit provokes chronic stress development, leading to disorders in the psychoemotional sphere, cognitive impairment, etc. Previously, we showed that spatial memory and passive avoidance impairments in rats exposed to months-long social isolation (SI) from an early age are more pronounced in females compared to males. There is lack research on females. This study aimed to evaluate learning in the two-way avoidance paradigm using the conditioned active avoidance reflex (CAAR) test and to assess skill retention in female rats exposed to SI, which started after the pups were taken from their dams and lasted for up to ten months. After 6.5 months of SI, rats were trained in the CAAR test when their anxiety level and grooming expression were lower than in rats housed in groups. Rats exposed to SI performed fewer avoidance but more escape responses and were less likely to achieve the learning criterion. In isolated rats compared to control rats, the escape latency was heightened, and the maximum number of avoidance reactions in a row was less after 24 hours after training. After 2 months after training, no differences in CAAR retention were revealed between rats kept in different housing conditions. After 10 months of SI, rat blood serum corticosterone levels were lower than in rats in the control group. The findings show worse learning and skill retention one day following training in the CAAR test in rats under the influence of long-term SI.