Plasminogen activator is involved in the hCG-induced neutrophil extravasation and vasopermeability increase in the rat testis

The changes in testicular vascular permeability during progression of the experimental varicocele

OBJECTIVES

The vascular permeability of testicular capillaries which play a role in controlling the formation of testicular interstitial fluid was studied during the progressive course of experimental varicocele.

MATERIALS AND METHODS

The pathology was developed through partial ligation of left renal vein in four groups of rats. Controls of each group were subjected to sham surgery. After different periods of varicocele creation (1, 3, 6 and 14 weeks), animals' testes per one of the study groups were extirpated and weighed. The volume density percentages of polymorphnuclear leukocytes (PMN) per testicular blood vessels; which are markers of the increase in vascular permeability, were also estimated in both testes. To further verify the obtained findings, another group of animals received human chorionic gonadotrophin (hCG) treatment 6 weeks after varicocele creation and their histopathological sections were examined.

RESULTS

Animal testes' of (1 and 3 weeks) groups were found to be significantly heavier (p<0.05) than their controls. PMN showed accumulation in testicular blood vessels and their volume density percentages per these blood vessels in both testes were significantly higher in each study group than in those of its controls. However, these percentages showed gradual significant decline as the duration of varicocele bearing gradually increased. The hCG-treated animals revealed more accumulation of the PMN in their histopathological sections.

CONCLUSION

The present results suggest that experimental varicocele may induce an increase in testicular vascular permeability, which then decreases gradually with time. It is supposed that parallel changes in the rate of formation of testicular interstitial fluid may be accompanied. The results have also showed that the vasculature of the testis with experimental varicocele can still respond to hCG.

The time-response and magnitude of hCG-induced vascular changes are different in scrotal and abdominal testes

Adult unilaterally cryptorchid rats were injected with 50 IU human chorionic gonadotrophin (hCG). At 4, 8, 24 and 72 h after treatment, testicular vascular permeability was studied by injecting colloidal carbon intravenously. The number of blood vessel profiles labelled with carbon was increased by hCG in both types of testes, but the response was more sustained in abdominal than in scrotal testes. The number of polymorphonuclear leucocytes (PMNs) accumulating in testicular blood vessels and migrating into the interstitial space in response to hCG treatment was also measured. The volume density of intravascular and interstitial PMNs was increased in both types of testes but the peak response was larger in scrotal than in abdominal testes. PMN accumulation and vascular leakage were apparently correlated in the scrotal but not in the abdominal testes. Testicular interstitial fluid (IF) was collected from intact and unilaterally cryptorchid adult rats. The IF was diluted with sterile buffer and injected intracutaneously in test animals. The vascular permeability response was assessed by measuring the leakage of Evans blue into the injection sites. IF from scrotal and abdominal testes increased vascular permeability in the skin. The response was rapid and transient. IF collected from rats given hCG 24 h earlier did not increase vascular permeability. The vascular permeability response to IF was reduced slightly in neutrophil-depleted animals. The inflammation mediator present in IF cannot explain the kinetics and magnitude of the hCG-induced changes in vascular permeability in intact or unilaterally cryptorchid rats.