Aggression and deficient cognitive control problems are widespread in psychiatric disorders, including major depressive disorder (MDD). These abnormalities are known to contribute significantly to the accompanying functional impairment and the global burden of disease. Progress in the development of targeted treatments of excessive aggression and accompanying symptoms has been limited, and there exists a major unmet need to develop more efficacious treatments for depressed patients. Due to the complex nature and the clinical heterogeneity of MDD and the lack of precise knowledge regarding its pathophysiology, effective management is challenging. Nonetheless, the aetiology and pathophysiology of MDD has been the subject of extensive research and there is a vast body of the latest literature that points to new mechanisms for this disorder. Here, we overview the key mechanisms, which include neuroinflammation, oxidative stress, insulin receptor signalling and abnormal myelination. We discuss the hypotheses that have been proposed to unify these processes, as many of these pathways are integrated for the neurobiology of MDD. We also describe the current translational approaches in modelling depression, including the recent advances in stress models of MDD, and emerging novel therapies, including novel approaches to management of excessive aggression, such as anti-diabetic drugs, antioxidant treatment and herbal compositions.

The phenomenon of individual variability in susceptibility/resilience to stress and depression, in which the hippocampus plays a pivotal role, is attracting increasing attention. We investigated the potential role of hippocampal cyclooxygenase-2 (COX-2), which regulates plasticity, neuroimmune function, and stress responses that are all linked to this risk dichotomy. We used a four-week-long chronic mild stress (CMS) paradigm, in which mice could be stratified according to their susceptibility/resilience to anhedonia, a key feature of depression, to investigate hippocampal expression of COX-2, a marker of microglial activation Iba-1, and the proliferation marker Ki67. Rat exposure, social defeat, restraints, and tail suspension were used as stressors. We compared the effects of treatment with either the selective COX-2 inhibitor celecoxib (30 mg/kg/day) or citalopram (15 mg/kg/day). For the celecoxib and vehicle-treated mice, the Porsolt test was used. Anhedonic (susceptible) but not non-anhedonic (resilient) animals exhibited elevated COX-2 mRNA levels, increased numbers of COX-2 and Iba-1-positive cells in the dentate gyrus and the CA1 area, and decreased numbers of Ki67-positive cells in the subgranular zone of the hippocampus. Drug treatment decreased the percentage of anhedonic mice, normalized swimming activity, reduced behavioral despair, and improved conditioned fear memory. Hippocampal over-expression of COX-2 is associated with susceptibility to stress-induced anhedonia, and its pharmacological inhibition with celecoxib has antidepressant effects that are similar in size to those of citalopram.

Sciendo provides publishing services and solutions to academic and professional organizations and individual authors. We publish journals, books, conference proceedings and a variety of other publications.

Neurodevelopmental disorders stemming from maternal immune activation can significantly affect a child’s life. A major limitation in pre-clinical studies is the scarcity of valid animal models that accurately mimic these challenges. Among the available models, administration of lipopolysaccharide (LPS) to pregnant females is a widely used paradigm. Previous studies have reported that a model of ‘emotional stress’, involving chronic exposure of rodents to ultrasonic frequencies, induces neuroinflammation, aberrant neuroplasticity, and behavioral deficits. In this study, we explored whether this model is a suitable paradigm for maternal stress and promotes neurodevelopmental abnormalities in the offspring of stressed females. Pregnant dams were exposed to ultrasound stress for 21 days. A separate group was injected with LPS on embryonic days E11.5 and E12.5 to mimic prenatal infection. The behavior of the dams and their female offspring was assessed using the sucrose test, open field test, and elevated plus maze. Additionally, the three-chamber sociability test and Barnes maze were used in the offspring groups. ELISA and qPCR were used to examine pro-inflammatory changes in the blood and hippocampus of adult females. Ultrasound-exposed adult females developed a depressive-like syndrome, hippocampal overexpression of GSK-3β, IL-1β, and IL-6 and increased serum concentrations of IL-1β, IL-6, IL-17, RANTES, and TNFα. The female offspring also displayed depressive-like behavior, as well as cognitive deficits. These abnormalities were comparable to the behavioral changes induced by LPS. The ultrasound stress model can be a promising animal paradigm of neurodevelopmental pathology associated with prenatal ‘emotional stress’.

Fibromyalgia, a syndrome characterized by hyperalgesia and ‘negative emotionality’, and major depressive disorder (MDD) demonstrate substantial overlaps in clinical, neurobiological, and therapeutic domains. Currently, treatment options for fibromyalgia remain limited; however, the epidemiology of this syndrome continues to grow worldwide. The use of animal models is indispensable for developing new treatment strategies for fibromyalgia. Meanwhile, the choice of animal paradigms is limited. Here, we used the ultrasound exposure of emotional stress on CBA, BALB/c, and C57BL/6 mouse strains to model this condition and to identify new molecular targets of fibromyalgia treatment. We exposed young male mice of three common strains to a three-week ultrasound stress (US) comprising emotionally negative and neutral frequencies of 20–25 kHz and 25–45 kHz, resulting in the development of altered pain sensitivity and signs of ‘negative emotionality’. Specifically, mice were studied for timid-like/aggressive behaviors and the tail flick response. Serum levels of corticosterone, cortisol, β-Endorphin, and brain-derived neurotrophic factor (BDNF), as well as brain gene expression of interleukin-33 (Il-33), Bdnf, and its receptor Trkb were investigated. Among the stressed mouse strains, C57BL/6 mice displayed augmented pain sensitivity, allodynia, and suppressed dominant behavior, whereas CBA and BALB/c mice demonstrated opposing changes. Glucocorticoid levels were increased in all stressed groups. Stressed C57BL/6 mice showed downregulated gene and protein expression of functionally inter-related BDNF and IL-33 molecules in the hippocampus, amygdala, and striatum, significantly correlating with behavioral outcomes, as well as lowered blood levels of β-Endorphin and elevated cortisol concentrations. Altogether, our study identified the BDNF/IL-33 regulatory pathway as a molecular correlate of fibromyalgia, and the use of US-exposed young C57BL/6 mice as a potential model that recapitulates this syndrome.