Therapeutic And Preventive Effects Of Lycium Barbarum Polysaccharides On Erectile Dysfunction in Diabetic Rats Via The NO–cGMP Pathway
May 06, 2025
2 Results
2.1 Modeling Time and Blood Glucose Levels in Rats
The modeling time and pre- and post-treatment blood glucose levels were statistically analyzed for each group of rats. The results showed that the modeling time was significantly prolonged in the rats that received preventive treatment with Lycium barbarum polysaccharides (LBP), and LBP could effectively reduce blood glucose levels before and after treatment.
There were significant differences in pre- and post-treatment blood glucose levels between the DM group, LBP treatment group, and LBP prevention group compared to the normal control group (P < 0.05). Additionally, the modeling time and blood glucose levels before and after treatment in the LBP prevention group were significantly different from those in the LBP treatment group and the DM group (P < 0.05).
(See Table 1)
Table 1. Modeling Time and Blood Glucose Levels in Rats
| Group | n | Modeling Time (days) | Pre-Treatment Glucose (mmol/L) | Post-Treatment Glucose (mmol/L) |
|---|---|---|---|---|
| DM Group | 18 | 4.24 ± 0.43 | 27.68 ± 3.81★ | 28.87 ± 3.54★ |
| LBP Treatment Group | 18 | 4.18 ± 0.52 | 28.14 ± 4.06★ | 24.23 ± 3.67★ |
| LBP Prevention Group | 18 | 6.39 ± 0.75▲▲ | 22.46 ± 5.27★▲▲ | 20.31 ± 4.16★▲▲ |
| Normal Control Group | 20 | – | 6.21 ± 0.85 | 6.28 ± 0.78 |
Note:
★ Compared with the normal control group, P < 0.05, indicating significant difference.
▲ Compared with the DM group, P < 0.05, indicating significant difference.
▲▲ Compared with the LBP treatment group, P < 0.05, indicating significant difference.
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2.3 NOS Activity, NO Content, and cGMP Levels After Treatment
The levels of NOS activity, NO content, and cGMP after treatment were measured in all groups. The results indicated that the DM group, LBP treatment group, and LBP prevention group all had significantly lower levels of NOS, NO, and cGMP after treatment compared to the normal control group (P < 0.05).
Furthermore, the LBP treatment group and LBP prevention group showed significantly higher levels of NOS, NO, and cGMP compared to the DM group (P < 0.05).
(See Table 3)
Table 2. Comparison of Erectile Function in Rats Before and After Treatment
| Group | Before Treatment | After Treatment | ||||
|---|---|---|---|---|---|---|
| Erected Rats (n) | Total Rats (n) | Erection Rate (%) | Erected Rats (n) | Total Rats (n) | Erection Rate (%) | |
| DM Group | 4 | 5 | 22.22★ | 4 | 4 | 22.22★ |
| LBP Treatment Group | 4 | 4 | 22.22★ | 8 | 9 | 44.44★ |
| LBP Prevention Group | 9 | 11 | 50.00★ | 11 | 12 | 61.11★▲ |
| Normal Control Group | 20 | 22 | 100.00 | 20 | 21 | 100.00 |
Notes:
★ Compared with the normal control group, P < 0.05, indicating significant difference.
▲ Compared with the LBP treatment group, P < 0.05, indicating significant difference.
Table 3. NOS Activity, NO Content, and cGMP Levels After Treatment
| Group | NOS (U/mg) | NO (μmol/g) | cGMP (pmol/g) |
|---|---|---|---|
| DM Group | 0.29 ± 0.11★ | 3.26 ± 0.33★ | 0.85 ± 0.31★ |
| LBP Treatment Group | 0.47 ± 0.12★△ | 5.74 ± 0.46★△ | 1.95 ± 0.37★△ |
| LBP Prevention Group | 0.54 ± 0.15★△ | 6.15 ± 0.64★△ | 2.07 ± 0.74★△ |
| Normal Control Group | 0.67 ± 0.12 | 7.76 ± 0.89 | 2.48 ± 0.86 |
Notes:
★ Compared with the normal control group, P < 0.05, indicating significant difference.
△ Compared with the DM group, P < 0.05, indicating significant difference.
2.4 Intracavernosal Pressure (ICP) and Mean Arterial Pressure (MAP) After Treatment
The ICP and ICP/MAP ratio were statistically analyzed after treatment. The results showed that the DM group, LBP treatment group, and LBP prevention group had significantly reduced ICP and ICP/MAP compared to the normal control group (P < 0.05).
Both the LBP treatment group and LBP prevention group had significantly improved ICP and ICP/MAP values compared to the DM group (P < 0.05). Moreover, the ICP/MAP ratio in the LBP prevention group was significantly different from that in the LBP treatment group (P < 0.05).
(See Table 4)
Table 4. Intracavernosal Pressure (ICP) and ICP/MAP Ratios in Rats After Treatment
| Group | Intracavernosal Pressure (ICP) (mmHg) | ICP/MAP Ratio |
|---|---|---|
| DM Group | 34.67 ± 5.82★ | 0.27 ± 0.03★ |
| LBP Treatment Group | 48.32 ± 6.92★△ | 0.44 ± 0.06★△ |
| LBP Prevention Group | 55.79 ± 7.61★△▲ | 0.58 ± 0.03★△▲ |
| Normal Control Group | 63.41 ± 8.06 | 0.81 ± 0.04 |
Notes:
★ Compared with the normal control group, P < 0.05, indicating significant difference.
△ Compared with the DM group, P < 0.05, indicating significant difference.
▲ Compared with the LBP treatment group, P < 0.05, indicating significant difference.
3 Discussion
Diabetes can lead to dysfunction in multiple organs, and approximately 35% to 75% of patients with diabetes develop erectile dysfunction (ED). In clinical practice, diabetic ED is mostly treated with medications, but the clinical efficacy is often unsatisfactory and short-lasting [3].
The Diabetes Control and Complications Trial (DCCT) [4] confirmed that controlling blood glucose in diabetic patients can reduce the risk of diabetes-related complications.
The pathogenesis of diabetic erectile dysfunction is not yet fully understood. Some researchers believe that diabetes can reduce the activity of nitric oxide synthase (NOS) in the body, indirectly leading to reduced levels of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) in the corpus cavernosum, thereby resulting in erectile dysfunction [5–7].
The NO–cGMP signaling pathway plays a key role in the physiological process of penile erection, and it is also a critical target for the treatment of erectile dysfunction [8,9]. Research has shown that NO is produced from L-arginine under the catalysis of NOS, and acts as an endothelium-derived relaxing factor. NO can activate soluble guanylate cyclase (sGC) within cells, which then catalyzes the conversion of guanosine triphosphate (GTP) into cGMP. cGMP can significantly inhibit intracellular Ca²⁺ concentration in the smooth muscle cells of the corpus cavernosum, resulting in smooth muscle relaxation, increased blood flow in the corpus cavernosum, and thereby facilitating penile erection [10].
In diabetic patients, the levels of NOS and NO are suppressed, which contributes to the onset of diabetic erectile dysfunction.
Lycium barbarum (goji berry) is a traditional Chinese medicinal herb known for its tonic, anti-fatigue, and sexual health-enhancing properties. Its main active ingredient is Lycium barbarum polysaccharides (LBP). Studies have shown that LBP has multiple biological effects such as lowering blood sugar and lipids, anti-fatigue, anti-aging, and anti-tumor activities [11,12].
Animal experiments have demonstrated that LBP can significantly reduce the latency of penile erection and mounting behavior in partially castrated rats, increase the percentage of mounting behavior, and improve sexual function [13]. Li Jingjing et al. [14] used LBP to treat low-dose radiation-induced sexual dysfunction in male rats and found that LBP had protective and restorative effects on sexual function. Liu Hongjing et al. [15] treated diabetic male rats with LBP and found that it had a protective effect on diabetes-induced reproductive damage.
In this study, LBP was used to treat diabetic rats to observe its therapeutic and preventive effects on erectile dysfunction. The results showed that LBP could lower blood glucose levels and prevent hyperglycemia, help restore erectile function, and significantly improve the levels of NOS, NO, cGMP, ICP, and ICP/MAP in diabetic rats. These findings indicate that LBP has a significant preventive and therapeutic effect on diabetic erectile dysfunction, and provides a new direction and potential pharmacological candidate for the clinical treatment of this condition.
References
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Podlasek CA, Zetner DJ, Bervig TR, et al. Characterization and localization of nitric oxide synthase isoforms in the BB/WOR diabetic rat. J Urol, 2001, 166(2): 746–755.
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