Transgenerational consolidation of schizophrenia-relevant behavioral phenotypes reveals sex-specific trajectories and individual heterogeneity

Modeling schizophrenia in rodents is challenging because of the disorder's complexity and multifactorial etiology. This study aimed to elucidate the transgenerational consolidation of schizophrenia-relevant behavioral alterations in a triple-hit rat model (Lisket) developed on the behaviorally active Long Evans (LE). The Lisket line was established by combining post-weaning social isolation, repeated ketamine exposure, and selective breeding based on behavioral traits across 13 generations. A total of 1154 rats were assessed using repeated tail-flick test to measure pain sensitivity and the reward-based Ambitus test to evaluate locomotor activity, exploratory behavior and reward-guided task performance. Detailed sex-specific and individual-level analyses were performed in the final generation. Over six years, Lisket rats showed a gradual emergence of decreased pain sensitivity, reduced behavioral activity, and altered reward-guided task performance, potentially reflecting a combination of motivational, exploratory, and cognitive influences. Most parameters were significantly associated with generation, and the phenotype was generally more pronounced in males. In the final generation, principal component analysis showed a clear separation between the two lines, consistent with a more consolidated behavioral phenotype in Lisket rats. Altered response dynamics across repeated trials were also observed in the Lisket animals, while individual-level profiling showed that even animals with relatively preserved task performance often displayed deficits in other behavioral domains. These findings suggest that the Lisket line may provide a useful preclinical model for studying neurobiological mechanisms and interventions relevant to schizophrenia-associated behavioral alterations, particularly negative symptom-like and reward-guided performance-related domains. • Triple-hit schizophrenia-like rat substrain was developed through 14 generations. • Prolonged breeding with two other hits resulted in impairments in Lisket rats. • Negative and cognitive signs and hypoalgesia were detected in Lisket rats. • The male animals had higher level of impairments compared to females. • Individual heterogeneity was demonstrated in behavioral changes.