Behavioral, Cardiovascular, and Neuroinflammatory Effects of 3-Aminobenzamide in a Rodent Model of Chronic Psychological Stress

Background: Major depressive disorder (MDD) affects approximately 20% of the population, with over 30% of cases demonstrating treatment resistance. Postmortem analyses have revealed increased poly (ADP-ribose) polymerase 1 (PARP-1) expression in prefrontal cortical white matter of individuals with MDD, suggesting PARP-1 as a potential therapeutic target. Chronic stress, a major risk factor for depression, affects multiple physiological domains including behavior, cardiovascular function, neuroinflammation, and gut-brain axis signaling. Methods: We conducted a comprehensive multi-system investigation of PARP inhibition effects on stress-induced pathophysiology using the social defeat stress/chronic unpredictable stress (SDS+CUS) rodent model. In the primary study, male Sprague-Dawley rats (N=32) underwent 10 days of SDS+CUS while receiving daily treatment with the PARP inhibitor 3-aminobenzamide (3-AB; 40mg/kg), selective serotonin reuptake inhibitor fluoxetine (FLX; 10mg/kg), or saline (0.9% NaCl), with non-stressed controls included. Behavioral outcomes were assessed via sucrose preference and social interaction tests. Neurobiological analyses examined PARP-1 expression, microglial morphology, and proinflammatory cytokine levels (IL-1{beta}, TNF-, IL-6) in relevant brain regions. In a parallel cardiovascular study, a separate cohort of stressed rats (N=8) received either saline or 3-AB treatment while hemodynamic parameters were monitored via telemetry before, during, and after stress exposure. Results: Saline-treated stressed rats demonstrated significantly reduced sucrose preference compared to the 3-AB/Stress rats and social avoidance compared to the 3-AB/Stress and Control/ No-Stress groups. Cardiovascular monitoring showed increases in systolic and mean arterial pressure and a decrease in heart rate across the paradigm; Treatment x Time interations for blood pressure were not significant, while heart rate decline was greater in saline-treated rats. Neurobiological analyses of PARP-1 expression in PFC did not reveal significant group differences. Microglial morphological analysis revealed a shift toward more prolate soma morphology in the saline-treated stressed rats compared to the non-stressed controls. Additionally, 3-AB-treated rats showed significantly more oblate microglia than saline-treated rats. Saline-treated stressed rats exhibited significantly increased hippocampal proinflammatory cytokines, with 3-AB treatment specifically attenuating TNF- and IL-1{beta} levels. Conclusion: 3-AB treatment provided multi-system protection against chronic stress effects, preventing behavioral deficits and attenuating select markers of neuroinflammation, without significantly altering blood pressure. These findings suggest that 3-AB, and potentially PARP-1 inhibition, warrants further investigation as a therapeutic approach for stress-related disorders.