Effect of androgen deprivation on penile ultrastructure

<abstract>Aim: To investigate the ultrastructural changes of penile corpus cavernosum and tunica albuginea in rats treated with castration or finasteride. Methods: Eighteen male Sprague-Dawley rats of nine weeks old were randomly divided into three groups with 6 rats each. Group A served as the control, Group B was castrated and Group C, treated with finasteride. Four weeks later, rats were anesthetized and blood samples obtained for the determination of serum testosterone (T) and dihydrotestosterone (DHT) levels; penile tissues were taken for scanning electron microscopy. Results: The T, free T and DHT levels in Group B and the DHT level in Group C were significantly lower than those in Group A (P<0.05). The tunica albuginea was significantly thinner in Group B than that in Group A (P<0.05), but there was no significant difference between Group C and Group A (P>0.05). Elastic fibers in the tunica albuginea of Group A were very rich and arranged regularly and undulatedly, but in Group B, most of the elastic fibers were replaced by collagenous fibers. In Group C, the tunica albuginea was mainly composed of thick and irregular-arranged collagenous fibers. In Group A, there were abundant smooth muscle fibers in the trabeculae of corpus cavernosum, but they were much less in Group C and scarce or even disappeared in Group B. In Groups B and C, the diminished/disappeared smooth muscle fibers were replaced by irregularly arranged collagenous fibers. Conclusion: In rats, androgen is essential for maintaining the normal structure of penile tunica albuginea and corpus carvenosum.

Ultrastructural changes of penile tunica albuginea in diabetic rats

Aim: To clarify the ultrastructural changes of penile tunica albuginea (TA) in streptozotocin (STZ)-induced diabetic rats. Methods: Intraperitoneal injection of STZ was used to induce diabetes mellitus (DM) in 12 Sprague Dawley rats. Ten rats (age and weight-matched) were used as control. Blood samples from the tail snips of the rats were used for the determination of serum glucose levels with SureStep Plus Blood Meter. At week 4 and 10 after the injection, half of the rats in each group were sacrificed and penile samples were obtained from the middle third of the penile shaft for the examination of TA under scanning electron microscopy. Results: In the diabetic group, the serum glucose levels were higher (P<0.01 at both time points) and the TA were thinner (P<0.05) than those of the controls. In the control group, the fibers of TA were rich and arranged regularly and undulated, while in the diabetic group, the fibers were diminished, lost the undulations and were arranged irregularly. Conclusion: In rats, DM appeared to impair the penile TA ultrastructures and this impairment could contribute to diabetic erectile dysfunction in part by impairing the veno-occlusive function.

Preliminary study on androgen dependence of calcitonin gene-related peptide in rat penis

Aim: To study the androgen dependence of the neurotransmitter, calcitonin gene-related peptide (CGRP) in rat penis. Methods: Forty-four Sprague-Dawley rats were randomly divided into Group A (intact controls), Group B (castrated) and Group C (gavaged with finasteride 4.5 mg·kg^(-1).day^(-1)). Four and ten weeks later respectively, half of rats in each group were anaesthetized. Blood samples were taken for the measurement of serum testosterone and dihydrotestosterone (DHT) by means of radioimmunoassay. Penile samples were harvested for the investigation of calcitonin gene related peptide (CGRP)-immunoreactive nerve fibers with immunohistochemistry. The computer-assisted imaging analysis system was applied to calculate the area proportion of the CGRP-positive nerve fibers (CGRP-PNF) in each group. Results: 1) Both 4 and 10 weeks later, testosterone and DHT levels in Group B decreased significantly compared with those in Group A, (P < 0.05, P < 0.01, respectively); DHT level in Group C was also significantly decreased in comparison with that in Group A for both 4- and 10- week animals (P < 0.05); 2) There was no significant differences in area proportion of CGRP-PNF among Groups A, B and C 4 weeks after treatments (P > 0.05); However, 10 weeks later, the proportion of CGRP-PNF in Groups B and C was significantly less than that in Group A (P < 0.01);3) The proportion of CGRP-PNF of 4-week animals in Groups B and C was significantly higher than that of 10-week animals (P < 0.05). Conclusion: The expression of neurotransmitter, CGRP may depend on androgens, including testosterone and DHT in rat penis.