Social Isolation in rats affects inflammatory and stress markers across four generations.

Introduction: Prenatal maternal stress can result in adverse perinatal outcomes and lead to non-communicable diseases. Social isolation (SI), a characteristic of depressed individuals, is a stressor associated with altered brain development and behaviour in rodents. We hypothesized that SI before conception and during pregnancy predisposes rats to increased uterine inflammatory/stress markers across generations.

Methods: Female rats of the F0 parental and F1-F3 generations were assigned to SI or control groups. SI involved housing dams alone for two weeks before breeding and during pregnancy. This gave rise to three groups of F1-F3 dams: control, transgenerational- (TG) and multigeneration-stressed (MG). Uteri were collected at weaning of offspring. RT-qPCR was performed for mRNA abundance of uterine inflammatory/stress markers such as Il1b, Il1ra, corticotropin-releasing hormone (Crh) and 11β-hydroxysteroid dehydrogenase type 1 and 2 (Hsd11b1/2). Data were analyzed by Kruskal Wallis, n numbers: Controls: 31; F0-F3: 6-12.

Results: Analysis showed increased Il1b and Il1ra expression in F0 animals but a decrease in the offspring (F1-F3) in TG and MG groups. Crh expression was decreased in the F3 generation of the TG group. Similarly, Hsd11b1/2 mRNA abundance decreased in the F0 generation but increased in the offspring (F1-F3). Protein levels for IL1a, IL1b, lL6 in uterine tissues remained unchanged between control and stress animals.

Conclusion: SI during pregnancy differentially affects gene expression related to inflammatory/stress markers in postpartum uteri of F0-F3 generations. Stress in the TG group demonstrated transmission of traits across generations, altering proinflammatory cytokines and stress markers in the F3 TG animals. Since similar results were observed in the MG group, the data suggest stress effects can be ancestral, influencing biomarkers and altering programming across generations.