Mechanism of retinoic acid in improving spermatogenesis in cryptorchid rats

Objective To explore the related mechanism of retinoic acid in improving spermatogesis in cryptorchidism rats. Methods A total of 30 pregnant rats were divided randomly into 3 groups.Normal control group (n=10): 1 mg/ml corn oil was hypodermically injected with a dose of 25 mg/kg between gestation 12-20 d. Flutamide-induced cryptorchidism group (n=10): flutamide was prepared with corn oil and hypodermically injected with a dose of 25 mg/kg between gestation 12-20 days.Retinoic acid group (n=10): basic intervention was same as flutamide-induced cryptorchidism group.Pup male rats were hypodermically injected with retinoic acid between 1-10 d and 28-30 d after birth.Postnatal 30 d and 60 d, testicular histopathology of offspring male rats, sperm count and sperm deformity rate were measured.The levels of oxidative stress protein, apoptosis protein and blood-testis barrier protein were analyzed with testicular immunohistology and Western blot. Results In normal control group, testicular weight was (0.56±0.17) g and testis volume (0.44±0.12) cm3.The sperm count was (2.25±0.14)/ml and the levels of SOD1, Ho-1, Gpx, Bax, Bcl-2, Cx43 and Zo-1 were 0.92±0.02, 0.62±0.06, 0.93±0.12, 0.67±0.06, 0.80±0.04, 1.44±0.07 and 3.84±0.10 respectively.In flu-induced cryptorchidism group, testicular weight was (0.13±0.03) g and testis volume (0.07±0.02) cm3.The sperm count was (0.65±0.17)/ml and the levels of SOD1, Ho-1, Gpx, Bax, Bcl-2, Cx43 and Zo-1 were 1.23±0.07, 0.90±0.09, 1.70±0.01, 0.87±0.01, 0.53±0.20, 0.51±0.07 and 1.48±0.25 respectively.As compared with control group, sperm count significantly declined, levels of oxidative stress protein and apoptosis increased markedly while blood-testis barrier protein significantly decreased.After retinoic treatment, the testicular weight was (0.29±0.11) g and volume (0.90±0.09) cm3.The sperm count was (1.49±0.31)/ml and the levels of SOD1, Ho-1, Gpx, Bax, Bcl-2, Cx43 and Zo-1 were 0.94±0.01, 0.76±0.02, 0.96±0.02, 0.68±0.02, 0.76±0.06, 1.12±0.04 and 2.07±0.17 respectively.As compared with control group, the expressions of proteins showed no significant difference.Significant differences existed between flu-induced cryptorchidism and RA treatment groups. Conclusions Retinoic acid can partially reverse flutamide-induced cryptrochidism spermatogenesis damage through regulating the levels of oxidative stress and apoptosis and repairing blood-testis barrier function. Key words: Cryptorchidism; Retinoic acid; Oxidative stress; Apoptosis; Blood-testis barrier