Early Recognition of Overweight Hyperglycaemia May Improve Clinical Outcomes in Type 2 Diabetes

Glucose Fluctuation Inhibits Nrf2 Signaling Pathway in Hippocampal Tissues and Exacerbates Cognitive Impairment in Streptozotocin-Induced Diabetic Rats

Background

This research investigated whether glucose fluctuation (GF) can exacerbate cognitive impairment in streptozotocin-induced diabetic rats and explored the related mechanism.

Methods

After 4 weeks of feeding with diets containing high fats plus sugar, the rat model of diabetes mellitus (DM) was established by intraperitoneal injection of streptozotocin (STZ). Then, GF was triggered by means of alternating satiety and starvation for 24 h. The weight, blood glucose level, and water intake of the rats were recorded. The Morris water maze (MWM) test was carried out to appraise the cognitive function at the end of week 12. Moreover, the morphological structure of hippocampal neurons was viewed through HE and Nissl staining, and transmission electron microscopy (TEM) was performed for ultrastructure observation. The protein expression levels of Nrf2, HO-1, NQO-1, Bax, Bcl-2, and Caspase-3 in the hippocampal tissues of rats were measured via Western blotting, and the mRNA expressions of Nrf2, HO-1, and NQO-1 were examined using qRT-PCR. Finally, Western blotting and immunohistochemistry were conducted to detect BDNF levels.

Results

It was manifested that GF not only aggravated the impairment of spatial memory in rats with STZ-induced type 2 DM but also stimulated the loss, shrinkage, and apoptosis of hippocampal neurons. Regarding the expressions in murine hippocampal tissues, GF depressed Nrf2, HO-1, NQO-1, Bcl-2, and BDNF but boosted Caspase-3 and Bax.

Conclusions

GF aggravates cognitive impairment by inhibiting the Nrf2 signaling pathway and inducing oxidative stress and apoptosis in the hippocampal tissues.

Obesity-Induced Hyperglycemia and Heart Failure Preserved Ejection Fraction: Uncharted Territories to Remission

Until the end of World War II, food security was a global challenge. Consequently, in 1948, type 2 diabetes was relatively uncommon, with the majority of cases being type 1 diabetes requiring insulin therapy. Since then, food has become increasingly palatable and readily available, leading to a rise in obesity across all age groups. Understanding the impact of obesity on our health has become crucial for optimizing healthcare. In this context, we draw attention to two significant, yet relatively uncharted pathogenic effects associated with obesity: Hyperglycemia and Heart Failure with Preserved Ejection Fraction (HFpEF). Thorough pathophysiologic, hemodynamic, and echocardiographic characterization have revealed the existence of a distinct phenotype known as "obese HFpEF" within the broader HFpEF population, and "obesity-induced hyperglycemia" within the diabetes population. In these phenotypes, patients often present with higher Body Mass Index and experience clinical symptoms decades earlier. Recent insights have enhanced our understanding of the mechanisms underlying obesity-mediated heart failure preserved ejection fraction and hyperglycemia. Early detection offers the potential for reversibility of many pathologies associated with obesity through adequate weight reduction. The objective of this review is to provide a deeper insight into these uncharted territories and explore the potential for improved outcomes by reframing these two narratives toward achieving remission. Such a shift has the potential to positively impact individual engagement with healthier lifestyles.