Efeitos da laminarina sobre domínios afetivos e cognitivos em camundongos submetidos a estresse repetido imprevisível

Abstract

Major Depressive Disorder (MDD) is a common neuropsychiatric condition that affects a substantial proportion of people worldwide, many of whom do not respond a satisfactory therapeutic response with current drug treatments. Given the therapeutic limitations of current antidepressants for the MDD, laminarin (LAM) emerges as an important beta-glucan with immunomodulatory potential, which interacts with the Dectin-1 receptor, a pattern recognition receptor (PRR) found in immune system cells. In the neuropsychiatric field, this beta-glucan has been investigated in preclinical studies as a therapeutic strategy for depression due to its applicability in modulating the neuroimmune axis. In this regard, the purpose of this study was to evaluate the behavioral and neurochemical effects of LAM administered to BALB/c mice in an animal model of depression induced by repeated unpredictable stress (ERI). To this end, male BALB/c mice were subjected to a stress-inducing protocol for a period of 21 days. Subsequently, they were treated with saline (SAL, intraperitoneally), desvenlafaxine (DSV, 10 mg/kg orally), or laminarin (LAM, 20 mg/kg intraperitoneally). Behavioral analysis included the open field test (OFT), tail suspension test (TST), splash test, Y-maze, and object recognition test (ORT). The findings revealed that the stress model used was unable to induce a consistent depressive-like phenotype, as evidenced by the TSC and splash test, nor did it affect the animals’ memory, body weight, or locomotor activity. Similarly, LAM did not alter locomotor and exploratory activity in the OFT, nor did it demonstrate an antidepressant effect in the TSC. In contrast, LAM reversed the effects of ERI on the parameters of grooming time and frequency in the splash test, suggesting a possible pro-motivational effect on the animals’ self-care behavior. Regarding for memory, LAM did not improve or impair recognition ability in the TRO, possibly due to the absence of a prior deficit in the model used. In the Y-Maze test, no changes in short-term memory induced by LAM were observed. Furthermore, LAM did not alter the animals’ weight variation. With regard to oxidative stress, LAM did not exhibit a neuroprotective profile under the conditions used, reducing GSH levels in the HC and contributing to increased lipid peroxidation in the CE.