The effect of the degree of left renal vein constriction on the development of adolescent varicocele in Sprague-Dawley rats

Lycopene Attenuates Hypoxia-Induced Testicular Injury by Inhibiting PROK2 Expression and Activating PI3K/AKT/mTOR Pathway in a Varicocele Adult Rat

Purpose

The aim of this study was to evaluate the effect of lycopene on hypoxia-induced testicular injury in rat model and explore the underlying mechanism.

Methods

Six-week-old male Wistar rats (n = 36) were randomly divided into three groups (n = 12/group): a normal group (NG, sham control), a varicocele group (VG), and a varicocele treated by lycopene group (VLG). Bilateral renal veins constriction was performed on rats in VG and VLG. Simultaneously, rats in VLG were treated to lycopene by intragastric administration. Four weeks later, sperm was collected for sperm analysis. Testes and epididymides were harvested for morphological change analysis, histologic analysis, ELISA, qRT-PCR, and western blot.

Results

Our observations were that lycopene improved the hypoxia-induced testicular injury in vivo. Prokineticin 2(PROK2) and prokineticin receptor 2 (PROKR2) were overexpressed in VG (P < 0.01), and lycopene inhibited the PROK2 expression (P < 0.01). Proliferating cell nuclear antigen (PCNA) and sex hormones were increased by lycopene in VLG (P < 0.05). Lycopene restored the quality and activity of sperm by blocking PROK2 expression (P < 0.05). The expression of VEGF was increased, as HIF-1/NF-κB pathway was upregulated in VLG (P < 0.05). Meanwhile, expression of pAKT/AKT in VLG was higher than that in VG (P < 0.05). In addition, lycopene reduced levels of interleukin-1β (IL-1β) and interleukin-2 (IL-2) in VLG (P < 0.05), compared to NG.

Conclusions

Lycopene improved the hypoxia-induced testicular injury by inhibiting the expression of PROK2 and decreasing levels of IL-1β and IL-2, which might show us a novel and promising treatment for varicocele testicular injury.

Down regulating PHGDH affects the lactate production of sertoli cells in varicocele

BACKGROUND

Although varicocele is considered to be one of the leading causes of male infertility, the precise mechanism underlying how varicocele leads to male infertility is not completely understood. We found the lactate concentration on the varicocele side of the patients was decreased compare with peripheral venous blood. In the testicles, the lactate produced by the sertoli cells through the glycolysis pathway provides most of the energy needed for spermatogenesis, the reduction of lactate will affect spermatogenesis. The objective of this study was to investigate the mechanism of this abnormal energy metabolism phenomenon in varicocele.

METHODS

In this study, we collected the testicular tissue from patients with varicocele, the glycolysis related proteins PHGDH was identified by iTRAQ proteomics technology. Experimental rat varicocele model was constructed according to our new clip technique, the mRNA and protein expression levels of PHGDH were examined with qRT-PCR and Western blotting. We constructed a sertoli cell of PHGDH down-regulation model, and then detected the glucose consumption, LDH activities and lactate production in the sertoli cells. Western blot was conducted to investigate the effects of PHGDH on the expression of phosphoserine phosphatase (PSPH) and Pyruvate kinase M2 (PKM2). Flow cytometry was used to detect the cell apoptosis and cell cycle in sertoli cells.

RESULTS

The results showed that testicular protein PHGDH was down-regulated in patients with varicocele and in experimental rat varicocele model. Down-regulation of PHGDH in sertoli cells significantly decreased the glucose consumption, LDH activities and lactate production in the sertoli cells, indicating that the low expression of PHGDH ultimately led to a decrease in lactate production by affecting the glycolysis. The Western blot results showed that the down-regulation of PHGDH significantly reduced the expression of pathway protein PSPH and PKM2, leading to the reduction of lactate production. Moreover, PHGDH knockdown can promote apoptosis and inhibit cell cycle to affect cell growth.

CONCLUSIONS

Overall, we conformed that varicocele lead to the decreasing of testis lactate production. Down-regulation of PHGDH in sertoli cells may mediate the process of abnormal glucose metabolism. Our study provide new insight into the mechanisms underlying metabolism-associated male infertility and suggests a novel therapeutic target for male infertility.

Sertoli Cell Alterations in Peripubertal Varicocelized Rats: Evidence of Primary Damage on Spermatogenesis

Idiopathic varicocele is closely associated with male infertility or subfertility. Sertoli cell is a very important regulator of spermatogenesis. We investigated the morphofunctional alterations in the Sertoli cell and its possible involvement in the establishment of testicular primary lesion in experimental left-sided varicocele, induced from peripuberty. Twenty-five male peripubertal rats (44 days postpartum [dpp]) were distributed into two groups: control (C) and varicocele (V). Experimental left varicocele was induced in rats through the partial ligature of the left renal vein. Euthanasia was performed at 100 dpp. Testicular histopathology and testosterone plasmatic level were evaluated. Transferrin and vimentin proteins were, respectively, used as immunomarkers of Sertoli cell function and structure. Significant reductions in vimentin and transferrin expressions were noticed in androgen-dependent stages (VII and VIII) of the seminiferous epithelium cycle in V rats; testosterone plasmatic level was also reduced. Bilateral testicular histopathological alterations were found in V rats, mainly massive germ cell desquamation. The histological damage and changes in protein expressions occurred bilaterally. The relevant impairment of the functional and structural characteristics of the Sertoli cell, together with the typical massive germ cell desquamation, indicates that Sertoli cell changes can primarily contribute to the significant testicular dysfunction associated with varicocele.

With a new clip technique surgically inducing varicocele in Sprague-Dawley rats

BACKGROUND

We introduced and recreated a more consistent and effective experimental varicocele rat model by a new clip technique.

METHODS

A total of 40 rats were numbered and randomly assigned to 5 groups of 8 each, including sham surgery (Group I), conventional (Group II) and clip groups with 0.7, 0.8, 0.9 mm gap widths, respectively (Group III, IV, V). All of the rats in each group were sacrificed at 8 weeks after initial surgery, and the rats forming out with less than 1 mm diameter of left spermatic vein or no presence of the pampiniform plexus dilation were excluded from the experimental groups. The left spermatic vein (LSV) diameter, testicular weight, left kidney weight to body weight coefficients, kidney and testicular histology were determined.

RESULTS

The baseline mean diameter of the LSV in Group I, II and III was 0.22 ± 0.02, 0.23 ± 0.02 and 0.22 ± 0.03 mm, respectively (P = 0.7504). At 8 weeks after initial surgery, varicocele was successfully created in 6/8 (75%), 7/8 (87.5%), 3/8 (37.5%), 3/8 (37.5%) in GroupII-V, no varicocele was observed in Group I. In Group I, II and III, no pathological changes were observed and the left kidney weight to body weight coefficients showed no significant differences. The diameter of LSV was remarkably increased both in Group II and III compared to Group I (1.72 ± 0.13, 1.57 ± 0.19 and 0.25 ± 0.02, respectively), and Group II and III had a smaller testicular weight than the rats in Group I (1.67 ± 0.05, 1.62 ± 0.06, and 1.92 ± 0.12, respectively).

CONCLUSIONS

With a new clip technique, surgically inducing varicocele rat model becomes convenient and safe. This appears to improve the effectiveness of the model and this innovation may allow us to further understand the pathophysiology of varicocele.