Therapeutic Potential of 4-Hexylresorcinol in Preserving Testicular Function in Streptozotocin-Induced Diabetic Rats

Abstract

It is known that many diabetic patients experience testicular atrophy. This study sought to investigate the effect of 4-hexylresorcinol (4HR) on testicular function in rats with streptozotocin (STZ)-induced diabetes, focusing on testicular weight, sperm motility, histological alterations, and serum testosterone levels to understand the efficacy of 4HR on testes. Our findings reveal that 4HR treatment significantly improves testicular health in diabetic rats. Notably, the STZ group exhibited a testicular weight of 1.22 ± 0.48 g, whereas the STZ/4HR group showed a significantly enhanced weight of 1.91 ± 0.26 g (p < 0.001), aligning closely with the control group's weight of 1.99 ± 0.17 g and the 4HR group's weight of 2.05 ± 0.24 g, indicating no significant difference between control and 4HR groups (p > 0.05). Furthermore, the STZ/4HR group demonstrated significantly improved sperm motility compared to the STZ group, with apoptotic indicators notably reduced in the STZ/4HR group relative to the STZ group (p < 0.05). These results underscore the therapeutic potential of 4HR for maintaining testicular function under diabetic conditions.

Keywords: 4-hexylresorcinol; apoptosis; diabetes; testis; testosterone.

Figure 1

The weight of testis in each group. When comparing the STZ group to the other groups, the difference was statistically significant (* p < 0.05).

Figure 2

The sperm motility assay. In the sperm motility assay, a statistically significant difference in sperm mobility was observed between the STZ group and the other groups (* p < 0.05). Specifically, the STZ group demonstrated fewer mobile sperm (arrows), as evidenced in Video S1.

Figure 3

Histological images. In the STZ group, abnormal sperm morphology was observed, characterized by sparsely distributed flagella (denoted by *) and a decreased sperm density within the seminiferous tubules (arrow). Additionally, the basement membranes of the seminiferous tubules were often thickened. Conversely, the STZ/4HR group displayed an increased flagella density, aligning closely with both the control and 4HR groups, with no significant differences noted among them (bar = 50 μm).

Figure 4

Immunostaining for cleaved caspase-3 (c-caspase-3) demonstrated a statistically significant difference in immunoreactivity intensity across the groups (** p < 0.001). Detailed analysis indicated a pronounced elevation in c-caspase-3 expression within the STZ group compared to the others, with the STZ group showcasing seminiferous tubules that were highly positive (*). Significantly, p-values of <0.001 for the STZ/4HR group and 0.002 for both the control and the 4HR group were observed, underscoring these differences (bar = 100 μm).

Figure 5

Immunostaining for p53. The figure depicts a high concentration of p53-positive cells in the STZ group, indicated by arrows. A comparison across groups reveals a significantly greater number of p53-positive cells in the STZ group relative to the other groups (** p < 0.001). The specimen was counterstained using methyl green, and the scale bar represents 20 μm.

Figure 6

The quantification of TUNEL-positive cells per square millimeter. The STZ group exhibited a considerably higher count of TUNEL-positive cells (arrows) in comparison to the other groups (* p < 0.001) (bar = 100 μm).

Figure 7

The Western blot for selected apoptosis marker. Fresh testes acquired from each group were used for protein extraction. The expression levels of p-caspase3 and c-caspase9 were higher in the STZ group than in other groups.

Figure 8

The testosterone level in the testes and the serum. (a) The testosterone-bound proteins were detected by Western blot in the testes. The level of testosterone was lower in the STZ group compared to the other groups (b) The serum testosterone level. STZ group showed significantly lower levels of serum testosterone compared to those of healthy models (p < 0.05).