Expression and hormonal modulation of the thromboxane A2 receptor gene in mammalian testicular arteries

Objective: Thromboxane A2 (TXA2) is a biologically potent arachidonate metabolite which causes vasoconstric- tion and platelet aggregation. This study aimed to evaluate the presence of TXA2 receptors in mammalian testicular arteries and the influence of exogenous gonadotropin administration on their expression. Design: Experimental study. Setting: Experimental animals in an academic research environment. Animal(s): Seven rams aged 4–6 years, weighing 60–90 kg. Intervention(s): Both testicular arteries of seven rams were extracted before (from one testis) and after (from the opposite testis) IV administration of 5,000 IU human chorionic gonadotropin (hCG). Main Outcome Measure(s): The expression of the TXA2 receptor gene was investigated by the real-time polymerase chain reaction. Data were analyzed by means of Student t test. Results were expressed as mean standard deviation. A P value of .01 was considered statistically significant. Result(s): Polymerase chain reaction revealed the presence of TXA2 messenger RNA receptor in all the basal samples, but the expression of TXA2 receptor gene was undetectable in all the arteries obtained 24 h after the administration of hCG. Conclusion(s): These preliminary results demonstrated for the first time the presence of TXA2 receptors in mammalian testicular arteries. Results also showed that their expression was down-regulated after hCG administration.