Induction of varicocele in the dog: I. Partial ligation of the left renal vein does not induce a varicocele in the dog

Characterization of varicocele-induced animal models: Potential role of inflammasome complex in the varicocele pathophysiology

Varicocele mechanisms and its impact in testicular dysfunction has been studied in order to understand the pathophysiology involved in this disease. However, study designs using testicular tissues from varicocele patients are restricted due to ethical limitations. Therefore, the use of animal models, mainly rats, that mimics varicocele and its effects is an option to develop new approaches. The surgical technique, that induces the varicocele in rats, is based on the partial obstruction of the left renal vein, leading to a dilation in the left spermatic vein and consequently to the pampiniform plexus, resulting in varicocele-induced condition. Thus, the study of the cellular and molecular mechanisms involved in varicocele development can be addressed in depth. Besides the animal model goal to uncover the exact varicocele pathophysiology, varicocele induced models are the best options to develop new non-surgical and less invasive therapies. Various animal model studies designed and investigated antioxidant and anti-inflammatory agents to face varicocele conditions. Minding this fact, we tried to discuss a newly uncovered complex in varicocele condition, known as inflammasome complex. Taking into consideration the possible inflammatory state present in varicocele, the inflammasome complex has been proposed to be involved in the pathophysiology of this disease.

The role of animal models in the study of varicocele

Varicocele is the most common correctible cause of male infertility and is present in 15% to 20% of the male population. Despite its prevalence, the pathophysiology of varicocele remains under investigation. One of the largest obstacles in studying varicocele is that it is almost exclusively found in humans. This has necessitated the creation of an animal model of varicocele. The most commonly used animal model involves the creation of a varicocele in a rodent by partially occluding the left renal vein. This model has provided a significant amount of data on varicocele, and a modification of this model utilizing microsurgery appears even more promising. Animal models have proven critical to investigating the pathophysiology of varicocele.

The comparison of two experimental rat varicocele models and their effect on sperm quality

OBJECTIVE

To develop a modified rat varicocele model.

METHODS

300 male Sprague-Dawley rats were selected. In 82 rats (classic group, CG), this was achieved by dissecting the left renal vein and ligating it using a 0.8-mm metal clip and 3-0 silk suture proximal to the inferior vena cava, followed by removal of the bar. In 118 rats (modified group, MG), in addition to the partial ligation of the left renal vein, the communicating branch was fully ligated. In 100 rats (sham operation group, SG), the left renal vein and communicating branches were dissected, but not ligated. The seminal fluid was aspirated and the diameters of the left spermatic veins were analyzed. Three months later, the examination was performed again.

RESULTS

The diameters were 0.16 ± 0.1 mm and 1.88 ± 0.1 mm before and after operation, respectively, in the CG (p < 0.01), and 0.15 ± 0.05 mm and 2.0 ± 0.1 mm in the MG (p < 0.01). Postsurgical diameters in the CG and MG were 1.88 ± 0.1 mm and 2.0 ± 0.1 mm (p > 0.5), and 0.16 ± 0.1 mm and 0.16 ± 0.11 mm in the SG (p > 0.5). Semen parameters in the CG had significant differences before and after the operation (p < 0.01), were significantly lower in the MG (p < 0.01), and had no significant differences in the SG (p > 0.5).

CONCLUSION

Simple partial ligation of the renal vein combined with ligation of the communicating branch leads to acceptable models for varicocele.

Ligation of the left renal vein in epm1-Wistar rats: functional and morphologic alterations in the kidneys, testes and suprarenal glands

OBJECTIVE

The ligation of the left renal vein (LLVR) in man is a controversial procedure in view of the risks of lesion to the renal parenchyma. With the objective of studying the morphologic and functional alterations caused by these lesions, we conducted experimental research with rats.

MATERIAL AND METHODS

64 male adult EPM1-WISTAR rats were used, divided into 8 groups-4 for LLRV and four for control. Each LLRV group and corresponding control group were sacrificed progressively on the 7th, 15th, 30th and 60th day after the initial surgery.

RESULTS

We found morphofunctional alterations only in animals that underwent LLRV in the four periods of sacrifice. The proteinuria creatinine in serum, testosterone in serum and serum corticosterone in serum showed practically no alteration in relation to the normal values for rats. Statistically significant severe histological lesions were found in the kidneys and testes of the LLRV groups. Lesions in the suprarenal glands were also present in these groups, but no sufficient to demonstrate statistical significance.

CONCLUSION

Based on these results we can conclude that the ligation of the left renal vein is a procedure of high risk in these animals.

Total ligation of the left renal vein in the dog: an inappropriate model for varicocele

Induction of varicocele was attempted by ligation of the left renal vein (LRV) in male dogs (Group I). Before the operation and in the 4-month post-operative period, sperm count, sperm motility, and sperm morphology of Group I (n = 8) dogs were compared to sham operated animals (Group II, n = 5). Furthermore, haemodynamics as well as testicular and vascular morphology were studied. In Group I, changes in diameter and consistency of the spermatic cord were temporary. Semen quality was reduced significantly during the second month after ligation of the LRV, but improved thereafter. Haemodynamic studies revealed that LRV blood pressure was increased significantly in Group I dogs. An extensive venous collateral network replaced the occluded LRV. Retrograde blood flow in the left testicular vein (LTV) was observed only in the proximal part of the LTV of Group I dogs. In Group II dogs numerous pairs of sufficient valves prevented reflux into the LTV. Histological examination revealed that spermatogenesis was not impaired and that the left pampiniform plexus had not changed. The number of Leydig cells was decreased slightly in Group I dogs. Sufficient valves in the LTV prevented formation of a permanent varicocele.