Antioxidant Potential and Improvement Activities of Sterculia setigera Delile on Insulin Resistance in Type 2 Diabetic Rats Induced by High-Fat Diet and Low Dose of Streptozotocin

A Review on the Phytochemistry and Pharmacology of the Genus Sterculia

The Sterculia genus is comprised of approximately 300 species, which have been widely used as traditional medicines to treat inflammation, snake bites, gastrointestinal diseases, skin diseases, microbial infections and many other diseases. To gain a comprehensive understanding of the therapeutic potential of Sterculia plants, an extensive literature search was conducted in CNKI, Bing, Wanfang Database, Springer Database, Elsevier Database, Google Scholar, Baidu Scholar, PubMed, and other similar websites from January 1971 to March 2024. The research indicated that Sterculia species predominantly contain flavonoids, terpenoids, phenylpropanoids, fatty acids, alkaloids and other chemical components. A wide range of pharmacologic activities such as anti-inflammatory, antioxidant, antibacterial and other biological activities have been reported. Nevertheless, there isn't much scholarly research on the therapeutic material basis of the genus Sterculia. This review reports the ethnobotany, phytochemicals, and biological activities of the plants in the Sterculia genus as herbal remedies.

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.