Background: Type 1 diabetes (T1D) is a chronic autoimmune disease which results from autoimmune destruction of insulin-producing pancreatic beta cells. Diabetic nephropathy (DN) is the most important outcome of microvascular implications in diabetes and currently the most common cause of end-stage renal disease in Western countries. Numerous studies have shown that the inflammation induced by hyperglycemia is the main mechanism of the pathogenesis of diabetic nephropathy (DN). The relationship between inflammation and diabetic nephropathy progression included the processes and complex molecular networks. There is compelling evidence that the innate immune system plays a key role in early mechanisms triggering diabetes. Toll-like receptors (TLRs) are the key receptors that activate the innate immunity following the recognition of Danger-associated molecular patterns (DAMPs) that involved in DN. Methods: In this study, the time course expression of TLR4 in the kidney cortex tissue of rats following induced hyperglycemia was studied. Hyperglycemia was induced in male wistar rats with intraperitoneal (I.P.) injection of Streptozotocin. In different time points (4, 6, 8 and 20 weeks) post diabetes type 1 induction, rats were euthanized and cortex kidney tissues was removed for further analysis. One of cortex kidney samples was fixed in Formaldehyde (10%) for histological examinations. The fixed samples were then embedded in paraffin, stained with Periodic acid Schiff (PAS), and observed under the light microscope. Histological results showed an increased level of glomerular volumes in diabetic rats as compared to the control group. RNA was isolated from another kidney cortex sample from the same rat followed by cDNA synthesization using oligo-dT primers. Exon specific TLR4 primers were used to amplify TLR4 cDNA. After performing RT-PCR, the expression level of TLR4 mRNA was quantified by real time quatitative PCR (qPCR). Results: Expression level of TLR4 as quantified by qPCR and statistically analyzed results showed a significant up-regulation of TLR4 transcripts during the time course after diabetes induction as compared to the control healthy rats. Conclusion: Increased understanding of the role of these molecules may provide insight into site-specific immunoregulatory mechanisms in the kidney cortex. Enhanced TLR4 expression might be linked to the development and maintenance of pathogenic conditions in kidney cortex.

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