The protective effects of Crocin on testopathy in fat-fed and streptozotocin-treated diabetic rats: An experimental study

Advances on the anti-tumor mechanisms of the carotenoid Crocin

Saffron is located in the upper part of the crocus stigma of iridaceae, which has a long history of medicinal use. Crocin (molecular formula C44H64O24) is a natural floral glycoside ester compound extracted from saffron, which is a type carotenoid. Modern pharmacological studies have shown that crocin has multiple therapeutic effects including anti-inflammatory, anti-oxidant, anti-hyperlipidemic and anti-stone effects. In recent years, crocin has been widely noticed due to its considerable anti-tumor effects manifested by the induction of tumor cell apoptosis, inhibition of tumor cell proliferation, inhibition of tumor cell invasion and metastasis, enhancement of chemotherapy sensitivity and improvement of immune status. The anti-tumor effects have been shown in various malignant tumors such as gastric cancer, liver cancer, cervical cancer, breast cancer and colorectal cancer. In this review, we compiled recent studies on the anti-tumor effects of crocin and summarized its anti-tumor mechanism for developing ideas of treating malignancies and exploring anti-tumor drugs.

The protective effect of crocin on cisplatin-induced testicular impairment in rats

BACKGROUND

Side effects of cisplatin (CIS) such as testicular toxicity restrict its clinical use. Instead, evidence indicates that crocin (CR) has synergistic anti-cancer potential with CIS and exhibited beneficial effects on CIS-induced hepatorenal damage. The aim of this study was to investigate the protective potential of CR against CIS-induced testicular toxicity in rats.

METHODS

Fifty adult male Wistar rats randomly assigned to five equal groups including control, CIS, and CIS plus CR at doses of 6.25 mg/kg (CIS + CR6.25), 25 mg/kg (CIS + CR25), and 100 mg/kg (CIS + CR100). CIS and CIS + CR groups received a single intraperitoneally (i.p.) injection of CIS (7 mg/kg). CR (6.25-100 mg/kg i.p.) injections were started three days before the CIS injection and continued once a day for up to 13 days. On the 14th day, all animals were sacrificed and their blood samples and testes were removed for biochemical and histological analyses.

RESULTS

Compared to the control group, CIS significantly decreased relative testis weight (0.28 vs. 0.39, p < 0.001), testosterone level (0.3 vs. 2.31 ng/mL, p < 0.001), germinal layer area (25,886 vs. 35,320 µm2, p < 0.001), superoxide dismutase (SOD) (0.9 vs.1.73 U/mg, p < 0.001) and increased testicular lipid peroxidation (3.05 vs. 15.35 nmol/mg, p < 0.001). CR at 25 mg/kg ameliorated testicular lipid peroxidation and enhanced SOD activity compared to CIS group (p < 0.05). Besides, CR treatment at the maximum dose (100 mg/kg) resulted in reversing CIS effects on testis weight, testosterone level, SOD, lipid peroxidation, and germinal layer area.

CONCLUSIONS

These findings demonstrated that CR co-treatment could prevent CIS-induced testicular toxicity in rats.

Crocin Improves Insulin Sensitivity and Ameliorates Adiposity by Regulating AMPK-CDK5-PPARγ Signaling

Crocin is a carotenoid compound which possesses multiple biological activities. Our and other laboratory's previous findings show that crocin alleviates obesity and type 2 diabetes-related complications. We have found that crocin activates AMP-activated protein kinase (AMPK) signaling and inhibition of AMPK suppresses crocin-induced protective effects. However, the causal role of AMPK activation in the biological role of crocin is still not verified. In the present study, we showed that crocin markedly inhibits the changes of glucose metabolic parameters and serum lipid profiles in wild type diabetic mice. In AMPKα KO diabetic mice, those protective effects of crocin against glucose and lipid metabolic dysfunction were abolished. These results demonstrated AMPK activation was responsible for the beneficial effects of crocin on metabolic dysfunction. Moreover, we have shown that the antiobese effect of crocin has been abolished by the deficiency of AMPKα. We also showed that crocin induced a significant decrease of CDK5 protein level in wild type diabetic mice, while this effect was abolished in AMPKα KO diabetic mice. The regulation of downstream targets of CDK5/PPARγ by crocin was abolished by the deficiency of AMPK. In conclusion, our study verified that activation of AMPK is involved in crocin-induced protective effects against glucose and lipid metabolic dysfunction. Activation of AMPK downregulates the protein level of CDK5, followed by the decrease of PPARγ phosphorylation, leading to the inhibition of adipose formation and metabolic dysfunction. Our study provides new insights into the mechanism of protective effects of crocin and interaction of AMPK and CDK5/PPARγ signaling.