Exploring the interplay of glucose metabolism, insulin resistance, and neurodegenerative pathologies: insights from streptozotocin and hypoglycaemic in vitro models

Neurodegenerative diseases raise public health concerns. Recent evidence indicates that Alzheimer’s disease (AD) sufferers will triple by 2050. The rising incidence of dementia diagnoses raises concerns about the socio-economical and emotional impact of this uncurable illness, which reduces quality of life through cognitive decline. Although genetic and environmental factors may contribute to its aetiology, neuropathological mechanisms underlying these disorders are still under investigation. One is brain insulin resistance (BIR), which has been associated with clinical cognitive dysfunction and linked to mitochondrial dysfunction, neurogenesis deficits, and cell death. Not limited to neurodegeneration, these phenotypes have been associated with other neuropsychiatric disorders. Streptozotocin (STZ), a diabetes-causing drug that targets pancreatic β-cells, may imitate BIR in suitable models. From patients’ neuroimaging to in vitro approaches, scientists have been striving to understand the pathophysiology of such disorders at the behavioural, molecular, and cellular levels. Although animal models are useful for studying insulin resistance’s systemic effects, in vitro phenotypic research represents an alternative to study molecular and cellular aspects. STZ and hypoglycaemia-like scenarios have been successful for studying neurodegenerative disorders in primary cell culture (e.g., neuroblastoma cells) and patient-specific neural cell lines derived from pluripotent stem cells (iPSCs). Intriguingly, STZ treatment or hypoglycaemia-like conditions in a dish were able to induce AD pathological characteristics such Aβ plaque deposition and Tau protein hyperphosphorylation. Such approaches have shown potential in understanding molecular and cellular implications of metabolic changes in neuropsychiatric disorders, according to this review. Furthermore, these models may help identify novel treatment targets.