1. Introduction
Diabetes is one of the most important endocrine diseases in human society that has long been associated with specific side effects such as nephropathy, retinopathy, neuropathy, fertility decline, ovarian diameter decrease, erectile dysfunction, sperm motility, and testicular tissue changes [1].
The population with diabetes is on the rise and threatens developed countries such as the United States and, at the same time, threatens developing countries, causing cardiovascular disease, blindness, renal failure, and so on [2].
Nowadays, research on medicinal plants with the aim of achieving new and effective compounds is a top priority. Many plants are a rich source of natural antioxidants and can reduce the effects of oxidants and the effects of some diseases such as diabetes.
A study by Aricav et al. (2006) found that in diabetic rats, testosterone and LH levels were significantly decreased in alloxan-treated diabetic groups compared to the healthy control group, indicating an effect of diabetes on the reduction of male hormones [12]. Other research has also shown that high blood sugar levels can affect sperm quality and thus reduce the fertility potential in men [13].
2. Methods
In this experimental study, carried out in Payam-e-Noor University in 2018, 24 rats weighing 195±4 g and approximate age of 95±3 days were used. Animals were kept in standard polycarbonate cages (Razi Rad, Iran) at 24±3°C, 35±4% of relative humidity, and a 12-h light-dark period. They watered sufficiently in 500 ml plastic bottles and fed with a standard formula food for rats (Daneh-Daran Toes, Iran). In order to adapt to the environment, the experiments started at least 10 days after the animals were housed. 
In this study, all surgeries and sampling were performed under complete anesthesia. It was also attempted to use the least acceptable sample size. All laboratory animal rights in the study for human use based on international guidelines for the care and use of laboratory animals were respected.
3. Results
The results of the study showed that the tissue level of Bax indices and the amount of malondialdehyde in the diabetic control group were significantly increased compared to the healthy control group. The amount of Bcl2 and superoxide dismutase, glutathione peroxidase, and catalase were significantly decreased in the diabetic control group (P<0.05). Tissue expression of the Bcl2 index in treating diabetic groups with 50 mg/ml crocin was not significantly different from the control diabetic group, but the glutathione peroxidase enzyme increased significantly in treating diabetic group with 50 mg/ml crocin (P<0.05).


4. Discuss
In this study, the effect of crocin on sperm parameters in diabetic rats was investigated. Factors contributing to the increase in oxidative stress in diabetic patients include the reduction of antioxidants such as superoxide dismutase and glutathione peroxidase. The level of malondialdehyde in healthy subjects is lower than in diabetic subjects and the level of antioxidant enzymes is higher than in diabetic subjects [25].
Based on the results, crocin at a concentration of 100 mg/ml significantly increased the mean percentage of antioxidant enzymes such as catalase, superoxide dismutase, and glutathione peroxidase compared to the diabetic control group; it also significantly reduced the amount of malondialdehyde (P<0.05).
 Given that all mice in the experimental group were treated with crocin and the diabetic control group by streptozotocin, improvement in catalase, superoxide dismutase, glutathione peroxidase, and Bcl2 index tissue expression in the crocin-treated experimental group could be attributed to the effective compositions in this plant.
 Research has shown that crocin has high antioxidant properties and increases blood insulin levels and low blood sugar levels in diabetic samples, and so far no adverse effects of crocin on the liver and kidney tissue have been reported [6].
5. Conclusion
Crocin at a concentration of 100 mg/ml was able to decrease the tissue expression index of Bax and significantly increased the tissue expression of Bcl2 as well as antioxidant enzymes such as catalase, superoxide dismutase, and glutathione peroxidase compared to diabetic control group; it also improved the damages induced by diabetes in the testicular tissues of the rats.
Ethical Considerations
Compliance with ethical guidelines
This study has obtained its ethical approval from the Research Ethics Committee of Neyshabur University of Medical Sciences (code: IR.NUMS.REC.1395.47).  All experiments on animals in this study was according to the Guide for the Care and Use of Laboratory Animals.

References