Type 2 diabetes represents a mounting global health challenge, with its impact extending beyond traditional complications to impair central nervous system function (Biessels and Despa, 2018). This includes diabetes-associated cognitive impairment (DACI), characterized by progressive deterioration in memory, learning, and executive capacities (Moheet et al., 2015). DACI pathogenesis arises from a confluence of metabolic, vascular, and direct neuronal insults (McCrimmon et al., 2012). The lack of therapies that effectively halt or reverse this decline constitutes a significant unmet need.

Brain regions essential for memory processes, particularly the hippocampus and cortical networks, are particularly vulnerable to the diabetic environment (Muth and Park, 2021). Persistent hyperglycemia stimulates the overproduction of reactive oxygen species (ROS), leading to oxidative stress that exceeds cellular antioxidant capacity (Chen et al., 2021). This redox imbalance damages neuronal lipids, proteins, and DNA, ultimately impairing synaptic function and activating cell death mechanisms (Cobley et al., 2018). Simultaneously, a chronic, low-grade inflammatory response permeates the diabetic brain. Microglial cells activate, and production of pro-inflammatory mediators, including interleukin-1β (IL-1β) and IL-18, increases substantially (Guzman-Martinez et al., 2019).

As a primary inflammatory regulator, the transcription factor nuclear factor-kappa B (NF-κB) is activated in diabetic conditions, promoting the expression of numerous inflammatory genes (Lawrence, 2009). The NLRP3 inflammasome, a multi-protein complex that processes and activates IL-1β and IL-18, represents another key player (Swanson et al., 2019). Inflammasome activation propagates inflammatory cascades that disrupt synaptic integrity and contribute to neuronal loss (Heneka et al., 2018). Importantly, oxidative stress and NLRP3 activation interconnect, as ROS can directly trigger inflammasome assembly (Abais et al., 2015).

Netrin-3 is a secreted laminin-related protein belonging to the netrin family of guidance molecules. First identified for their roles in directing axonal navigation during nervous system development, netrins now demonstrate functions in diverse biological contexts (Lai Wing Sun et al., 2011). In adults, these proteins influence processes including blood vessel formation, cancer development, and immune modulation (Wu et al., 2017). Netrin-3 is expressed in various adult tissues, including the brain, where it is detected in neurons (Seaman and Cooper, 2001). Whereas Netrin-1 is expressed in the adult central nervous system and supports plasticity and survival (Manitt et al., 2001), the role of Netrin-3 in the healthy adult brain is less defined, with its functions more extensively characterized during development or following injury. Accordingly, recent evidence indicates that Netrin-3 expression decreases following spinal cord injury, and its restoration reduces neuroinflammation by suppressing the inflammasome (Li et al., 2025a). While Netrin-1 has been widely studied in contexts of neurological injury (Ranganathan et al., 2013; Ramkhelawon et al., 2014), the specific roles of Netrin-3 in metabolic disease represent a potential area for future investigation.

Growing evidence suggests possible connections between netrins and metabolic control. Some investigations indicate that Netrin-1 can influence insulin sensitivity and adipose tissue inflammation (van Gils et al., 2012). However, the expression and function of Netrin-3 in the diabetic brain and its potential role in cognitive impairment remain unknown. Considering its structural relationship to Netrin-1 and its documented involvement in inflammatory regulation in other systems, we speculated that Netrin-3 might also mediate effects within the diabetic brain (Lai Wing Sun et al., 2011; Seaman and Cooper, 2001; Li et al., 2025a). It remains unclear whether diabetes affects Netrin-3 expression and whether this protein contributes to pathways underlying cognitive impairment.

We hypothesized that reduced brain Netrin-3 contributes to diabetic cognitive impairment, and that its restoration would protect cognition by targeting both oxidative stress and NLRP3 neuroinflammation. Using db/db mice, we assessed cortical Netrin-3 levels and employed adenoviral gene delivery to overexpress Netrin-3 in vivo, evaluating its effects on metabolism, cognitive behavior, and relevant hippocampal pathways. Our work introduces novelty by first identifying Netrin-3 as a previously uncharacterized factor downregulated in the diabetic brain. We specifically test whether its restoration provides multi-faceted protection against diabetes-induced cognitive deficits. This study uniquely investigates whether Netrin-3 restoration can protect against diabetes-induced cognitive deficits by concurrently targeting hippocampal oxidative stress and the NF-κB/NLRP3 inflammasome axis.