Among glial cells, microglia are major component of the central nervous system (CNS), and play central roles in neuroimmune interactions and brain homeostasis. They are highly sensitive to physiological and pathological changes in the brain tissue regeneration and repair (Graeber, 2010; Nimmerjahn et al., 2005). When activated by inflammatory stimuli, microglial cells generate various endogenous mediators including cytokines, chemokines, nitric oxide (NO), growth factors, reactive oxygen species (ROS), and arachidonic acid-derived lipid mediators (De Smedt-Peyrusse et al., 2008; Gao et al., 2002). By releasing various endogenous mediators, microglial cells play key roles in coordinating brain innate immune response and exerting marked effects on the surrounding brain tissues (Hanisch and Kettenmann, 2007). Known as the main component of the brain immunity, and because of their strong phagocytic activity, microglial cells are considered as the first line of defense of the CNS. Their transient activation is required in the induction of brain adaptive immune response through the interaction with infiltrating immune cells (Mizuno, 2012); however, the chronic activation of microglial cells can lead to neurodegeneration, and consequently neurodegenerative diseases, such as Alzheimer's (Lehnardt et al., 2003).

Microglial cells express various receptors, notably Toll-like receptors (TLRs) that are involved in the initiation of the brain immune responses (Olson and Miller, 2004). In fact, TLR-4 has been reported to be the most cell surface molecule involved in microglial cell activation (Bsibsi et al., 2002; Lehnardt et al. (2002). Moreover, TLR-4 activation is triggered by LPS, the endotoxin of gram-negative bacteria and the most used prototypical inflammatory activator of microglial cells in vitro and in vivo (Carroll et al., 2021; He et al., 2021).

The specific response of microglial cells to environmental exposures may be an essential element in understanding the pathophysiology of the CNS. Among environmental factors, pesticides are a complex family of toxicants widely used for killing or damaging pests and vectors of diseases (Cohen, 2007). They are also used in hygienic purpose, industry and agricultural activities. Consequently, human and animals are inevitably exposed to the deleterious effects of these environmental toxic agents that acted as powerful disrupters of various biological systems (Keifer and Firestone, 2007; Maroni et al., 2000). Many experimental, clinical and epidemiological studies clearly reported the neurotoxic effects of various pesticides (Costa et al., 2008; Keifer and Firestone, 2007). These data are not surprising since many pesticides belonging to the organophosphate, strobilurine, carbamate, and organochlorine families, directly target nervous tissues due to their mechanism of neurotoxicity. Depending on their target, pesticides can be classified as insecticides, herbicides or fungicides. Among fungicides, Carbendazim (CBZ) is a benzimidazole belonging to the carbamate family, and widely used worldwide (De et al., 2014; Selmanoglu et al., 2001, WHO (World Health Organization), 2009). The wide-spread use of CBZ in industrial, agricultural and veterinary practices resulted in severe health risk for human and animals, and inescapably contributes to environmental contamination and pollution which constitute a major problem in many nations (Damalas and Eleftherohorinos, 2011; Ecobichon, 2001). Indeed, CBZ has been reported to be the most frequently compound detected in apples from the Greek market (Tzatzarakis et al., 2020). In addition, CBZ accumulation in brain tissues has been recently established in rat receiving the fungicide orally (Ebedy et al., 2022). At cellular levels, CBZ acts as an antimitotic factor by binding to fungal tubulin, inhibiting microtubule assembly and therefore cell division (Howard and Aist, 1980),

Several mechanisms and signaling pathways have been reported to be involved in fungicide-induced deleterious effects targeting all biological responses, such as immunity and inflammation (Voccia et al., 1999). The generation of oxidative stress is, among others, a potential mechanism by which pesticides induced immunotoxicity effects. Thus, the use of antioxidants, such as NAC reduced these effects (Naasri et al., 2021). In fact, it has been reported that NAC prevented pesticide-induced immunotoxicity by acting as a potent anti-inflammatory and antioxidant factor (Lasram et al., 2014). The antioxidant role of NAC has also been reported in murine oligodendrocytes (Zhou et al., 2020). Other beneficial effects of NAC were established in various studies (Dhouib et al., 2014; Zhou et al., 2021).

The effects of some fungicides, such as Mancozeb on the brain have mainly focused on the structure and the function of neurons (Domico et al., 2007). Indeed, fungicides interfere with neurotransmitters, alter the structure of myelin, induce the degradation of axons and induce the loss of neuron by apoptosis and/or necrosis (Costa et al., 2008; Regueiro et al., 2015). However, studies regarding fungicide-induced neuroimmunotoxicity targeting microglial cells are very limited. Although, microglial cells do not exert electrical signaling in the brain, they are profoundly involved in supporting the signaling ability of the neurone. In addition, by acting as scavenger cells, activated microglial cells eliminate cellular debris. This process can also amplify their activation, and therefore their ability to release various inflammatory factors involved in coordinating brain immunity. It is known that resting microglial cells did not produce proinflammatory factors, such as cytokines and NO; however, their activation is a prerequisite for neuro-immune interaction and brain homeostasis. Moreover, activated microglial cells exhibited a high sensitivity to chemicals and pathological changes in the brain. Thus, the aim of the present study was to investigate the impact of CBZ fungicide on LPS-activated microglial BV-2 cells which display characteristics of mature microglial cells, by measuring oxidative stress and inflammatory response in vitro in absence or presence of NAC.