Alzheimer's disease (AD) is a crucial area for biomedical study because it is one of the most prevalent neurodegenerative illnesses. It is the most common cause of dementia, attributing to 60–70% of all cases worldwide (Leng and Edison, 2021). Over 55 million individuals worldwide currently have dementia and an estimated 10 million new cases are reported annually (WHO, 2021). In the United States, many individuals suffer from AD or another form of dementia. In 2050, 88 million Americans aged 65 and older will suffer from this disease, an increase from 58 million in 2021. A significant proportion of Americans aged 65 and over are considered to be part of the “baby boom generation” and are at the greatest risk of developing AD as a result of their advanced age (A.s. Association, 2022).

AD is a slowly progressing brain disease that begins long before symptoms develop. AD patients exhibit a progressive loss of memory and mental abilities in the linguistic, visuospatial, and executive domains (McKhann et al., 2011). The buildup of the protein beta-amyloid (Aβ) peptide (plaques) outside of neurons and the development of neurofibrillary (tangles) (NFTs) by hyperphosphorylated Tau protein inside of neurons in the brain are the hallmark diseases of AD. Neuronal loss and brain tissue damage accompany these alterations (Roda et al., 2022). The amyloid precursor protein (APP) gene is sequentially cleaved to produce the Aβ, while the microtubule associated protein Tau (MAPT) gene is the encoded gene for Tau protein (Roda et al., 2022; Zhang et al., 2011).

According to several studies, the buildup of pathogenic Aβ aggregates and hyperphosphorylated Tau protein in neurofibrillary plaques, as well as neuroinflammation, oxidative stress, and other characteristics of AD, have all been linked to mitogen-activated protein kinases (MAPKs) activation (Ahmed et al., 2020) (Kirouac et al., 2017; Sun and Nan, 2017). While extracellular regulated kinases (ERK1/2) activities are altered at all stages of this illness, including those with minimal clinical symptoms, MAPK activity is only related with mild and severe stages of AD (Zhu et al., 2001).

The primary route through which extracellular signals, such as inflammatory cytokines and reactive oxygen species, are transferred from the plasma membrane to the nucleus is MAPK pathways. Among them, the central nervous system benefits from the ERK1/2 pathway (Albert-Gasco et al., 2020). The cytosolic targets of ERK, which participate in the creation of pathological hallmarks and in neurodegeneration, include several of the proteins that result in pathological deposits in the brain during AD, such as Tau protein and Aβ (Gerfen et al., 2002; Spillantini et al., 1998). Furthermore, Dr. Faucher and his colleagues have demonstrated that in the early stages of AD, Aβ aggregates can activate the ERK1/2 signaling pathway (SP) in the brain (Faucher et al., 2015; Muraleva et al., 2021).

The fact that Tau pathology and toxicity are complex and cell-type-specific is demonstrated by the protection against Tau-mediated cognitive deficits through the inactivation of microglial nuclear factor kappa β (NF-κβ) despite increased Tau inclusions. Importantly, microglial NF-κβ activation leads to Tau-accumulation, which mediates neuronal toxicity and cognitive impairments (Wang et al., 2022a). NF-κβ, a transcriptional regulator, expresses several genes that code for proteins important for immune response, inflammation, cell proliferation, survival, and apoptosis (Qin et al., 2007; Chen et al., 2012). An inflammatory response and oxidative stress play a role in some pathological circumstances, including ischemic stroke, autoimmune diseases, and neurodegenerative diseases like AD (Camandola and Mattson, 2007; Kaltschmidt et al., 1993; O'Neill and Kaltschmidt, 1997). The transcription of certain genes occur in response to the activation of NF-κβ by a variety of cellular stress stimuli that amplify the cellular stress response, such as the production of cytokines (tumor necrosis factor TNFα, Interleukin-1, growth factors), neurotrophic factors, or viral infections (Thanos and Maniatis, 1995). Consequently, NF-κβ signaling plays a crucial role in a variety of physiological activities, as well as in several pathological conditions, where it is negatively regulated through either activating or suppressing its target genes (Camandola and Mattson, 2007).

Small chemical compounds such as U-0126 (1,4-Diamino-2,3-dicyano-1,4-bis(2-aminophenylthio) butadiene), which is the ‘code’ name for a compound. It is a non-ATP competitive inhibitor of mitogen-activated protein kinase (MEK) isoforms MEK1 and MEK2. Some researchers have utilized it as a means of deactivating the MAPK pathway (Ashabi et al., 2012; Favata et al., 1998; Namura et al., 2001; Ong et al., 2015; Satoh et al., 2000; Scherle et al., 1998). While PAF C-16, also known as platelet-activating factor C-16, is an activator of PAF-R, MAP kinase, and MAP kinase kinase. In response to inflammation, immune cells, such as monocytes and macrophages, produce this naturally occurring phospholipid. Researchers have reported that human macrophages produce IL-6 and reactive oxygen species as a result of their interaction with PAF G-protein-coupled receptors (PAFR). Other researchers have also used it to activate the MAPK pathway. (Song et al., 2022; Wu et al., 2022; Wang et al., 2022b; Bogershausen et al., 2015; Ji et al., 2020).

Furthermore, QNZ ((E)-3-(2-(4-cyanostyryl)-4-oxoquinazolin-3(4H)-yl) benzoic acid), which is a quinazoline derivative that inhibits NF-κβ activation. NF-κβ enhances the transcription of pro-inflammatory cytokines, and QNZ inhibits lipopolysaccharide (LPS)-stimulated TNFα production in mouse splenocytes, as well as CXCL1-mediated pro-inflammatory increase in potassium currents in adult rat neurons (Choi et al., 2006; Tobe et al., 2003; Wu et al., 2011; Yang et al., 2009). In contrast, Betulinic Acid (BetA), which is a cytotoxic compound isolated from naturally occurring pentacyclic triterpenoids. Several biological activities have been associated with it; it has been used by many researchers as an activator for the NF-κβ pathway (Preciado et al., 2018; Oloyede et al., 2017; Kim et al., 2012).

The ineffectiveness of medications used to treat neurodegenerative illnesses reflects their complicated pathophysiology and etiology. Multiple risk factors, such as genetic predispositions and environmental triggers, combined with aging, contribute to their susceptibility. To determine the underlying molecular pathways and associated pharmaceutical targets, more research is needed. The recent failure of several clinical trials aimed at neurodegenerative diseases has raised questions about the applicability of animal disease models to human patients, in addition to the ethical issues surrounding their use in medical research. This has led to a demand for better research tools in this area (Cummings et al., 2014; Schneider et al., 2014).

By bridging the gap between present pre-clinical animal models and humans using novel in vitro models, it may be possible to identify promising therapeutic targets that can be examined in upcoming clinical trials. In vitro testing can also shorten the time and expense of translation by assisting in the identification of the mechanism of action and any potential dangers (Slanzi et al., 2020). In light of these factors, our aim is to simulate the onset of AD in mouse microglial (SIM-A9) and neuroblast Neuro-2a (N2a) cell lines by triggering the MAPK and NF-κβ signaling pathways with the aid of small chemical compounds (PAF C-16 and BetA), respectively, since the MAPK kinase pathway targets APP activation, then β. Amyloid protein activation leading to Aβ accumulation, while the NF-κβ pathway targets Tau protein activation, which leads to Tau phosphorylation accumulation.