Possible molecular mechanisms of cryoablation-induced impotence in a rat model

Insulin-Like Growth Factor-1-Loaded Polymeric Poly(Lactic-Co-Glycolic) Acid Microspheres Improved Erectile Function in a Rat Model of Bilateral Cavernous Nerve Injury

BACKGROUND

Previous studies have documented improvement in erectile function after bilateral cavernous nerve injury (BCNI) in rats with the use of pioglitazone. Our group determined this improvement to be mediated by the insulin-like growth factor-1 (IGF-1) pathway.

AIM

To eliminate the systemic effects of pioglitazone and evaluate the local delivery of IGF-1 by polymeric microspheres after BCNI in the rat.

METHODS

Male Sprague-Dawley rats aged 10-12 weeks were assigned at random to 3 groups: sham operation with phosphate buffered saline (PBS)-loaded microspheres (sham group), crush injury with PBS-loaded microspheres (crush group), and crush injury with IGF-1-loaded microspheres (IGF-1 group). Poly(lactic-co-glycolic) acid microspheres were injected underneath the major pelvic ganglion (MPG). IGF-1 was released at approximately 30 ng/mL/day per MPG per rat.

OUTCOMES

Functional results were demonstrated by maximal intracavernosal pressure (ICP) normalized to mean arterial pressure (MAP). Protein-level analysis data of IGF-1 receptor (IGF-1R), extracellular signal-regulated kinase (ERK)-1/2, and neuronal nitric oxide synthase (nNOS) were obtained using Western blot analysis and immunohistochemistry for both the cavernosal tissue and the MPG and cavernous nerve (CN).

RESULTS

At 2 weeks after nerve injury, animals treated with IGF-1 demonstrated improved erectile functional recovery (ICP/MAP) at all voltages compared with BCNI (2.5V, P = .001; 5V, P < .001; 7.5V, P < .001). Western blot results revealed that up-regulation of the IGF-1R and ERK-1/2 in both the nervous and erectile tissue was associated with improved erectile function recovery. There were no significant between-group differences in nNOS protein levels in cavernosal tissue, but there was an up-regulation of nNOS in the MPG and CN. Immunohistochemistry confirmed these trends.

CLINICAL TRANSLATION

Local up-regulation of the IGF-1R in the neurovascular bed at the time of nerve injury may help men preserve erectile function after pelvic surgery, such as radical prostatectomy, eliminating the need for systemic therapy.

STRENGTHS & LIMITATIONS

This study demonstrates that local drug delivery to the MPG and CN can affect the CN tissue downstream, but did not investigate the potential effects of up-regulation of the growth factor receptors on prostate cancer tissue.

CONCLUSION

Stimulating the IGF-1R at the level of the CN has the potential to mitigate erectile dysfunction in men after radical prostatectomy, but further research is needed to evaluate the safety of this growth factor in the setting of prostate cancer. Haney NM, Talwar S, Akula PK, et al. Insulin-Like Growth Factor-1-Loaded Polymeric Poly(Lactic-Co-Glycolic) Acid Microspheres Improved Erectile Function in a Rat Model of Bilateral Cavernous Nerve Injury. J Sex Med 2019;16:383-393.

Homocysteine, insulin-like growth factor one and oestrogen levels in patients with erectile dysfunction-associated chronic hepatitis C virus infection

We assessed the change of homocysteine (Hcy), insulin-like growth factor one (IGF-Ι) and oestrogen (E2) levels in patients with erectile dysfunction (ED) associated with chronic hepatitis C virus (HCV) infection. Eighty-five male patients with chronic HCV and/or ED were enrolled in this study. Seventy-five men were assigned to three equal groups (n = 25/each); Group A: patients who had chronic HCV and ED. Group B: patients who had chronic HCV and had no ED complaint. Group C: patients who had ED with no chronic HCV. In addition to 10 control patients with no ED or chronic HCV (Group D). All patients were subjected to: detailed medical and sexual history, complete physical examination, laboratory assessment including measurement of serum Hcy, IGF-1 and E2. The means of international index of erectile function scores were 8 and 16 in groups A and C respectively. There were significant differences in Hcy, IGF-I and E2 among study groups (p < 0.05 for each). There were significant differences in Hcy between patients with Child B and Child C. A strong association between severity of ED and chronic HCV was demonstrated. There was statistically significant increase of Hcy and E2 levels and reduction in IGF-I level in patients with ED associated with chronic HCV infection.

Comparison of penile size and erectile function after high-intensity focused ultrasound and targeted cryoablation for localized prostate cancer: a prospective pilot study

INTRODUCTION

Erectile dysfunction (ED) represents a common quality-of-life issue of any treatment used for prostate cancer, including high-intensity focused ultrasound (HIFU) and targeted cryoablation of the prostate (TCAP). There is a paucity of comparative studies regarding the difference in the erectile function and penile size of patients undergoing HIFU or TCAP.

AIM

The aim of this study is to compare the erectile function and penile size of patients undergoing HIFU or TCAP.

METHODS

Patients with a preoperative erectile function domain of the International Index of Erectile Function (IIEF-EF) score ≥ 26 were prospectively included. All patients were preoperatively evaluated by IIEF-EF and penile color Doppler ultrasound. Penile length and circumference were measured in flaccidity and at maximum erection. At 6, 12, 18, 24, 36 months after surgery, patients were assessed with the same protocol.

MAIN OUTCOME MEASURES

IIEF-EF score, penile color Doppler ultrasound, penile length, and circumference at different time points.

RESULTS

There were 55 patients in the HIFU group and 47 in the TCAP group. At each time point, there were significant differences in mean IIEF-EF scores and penile color Doppler results between the two groups. At 36 months, TCAP patients experienced lower erectile function recovery rate compared with HIFU patients (TCAP=46.8%; HIFU=65.5%; P=0.021). No significant decreases in penile length and circumference were found in the two groups (all P values ≥ 0.05).

CONCLUSIONS

Our data demonstrate TCAP caused significantly decreased erectile function than HIFU. We found no change in penile size after HIFU or TCAP. The option of HIFU may be more attractive to the patient who wants to avoid ED afterward, to maintain their quality of life.

Effect of insulin-like growth factor-1 and insulin-like growth factor binding protein-3 complex in cavernous nerve cryoablation

The purpose of this work was to study the effect of insulin-like growth factor 1 (IGF-1) and its binding protein (IGFBP-3) on the recovery of erectile function in a rat model for neurogenic impotence. In all, 28 male Sprague-Dawley rats were divided into four groups: seven underwent a sham operation; seven underwent bilateral cavernous nerve freezing (control group); seven underwent bilateral cavernous nerve freezing followed by intraperitoneal injection of IGF-1; and seven underwent bilateral cavernous nerve freezing followed by intraperitoneal injection of IGFBP-3. Erectile response was assessed by cavernous nerve electrostimulation at 3 months, and samples of penile tissue were evaluated histochemically for nitric oxide synthase (NOS)-containing fibers. In the sham and IGF-1 group, there were significantly higher maximal intracavernous pressures compared to the IGFBP-3 complex and the control group. Correspondingly in the cavernosum, there were significantly more NOS-containing nerve fibers in the sham and IGF-1 groups. In conclusion, administration of IGF-1 can facilitate the regeneration of NOS-containing nerve fibers in penile tissue and enhance the recovery of erectile function after bilateral cavernous nerve cryoablation. The reverse effect was noted with the IGFBP-3 complex injection.

Neurogenic erectile dysfunction

Penile erection is a neurovascular event modulated by psyche and hormones. Erectile dysfunction (ED) has been classified as psychogenic, arteriogenic, neurogenic, endocrinologic, and cavernosal, based on the organs that are involved in penile erection. Among these types, neurogenic ED may be the most common, probably because a deficiency of neurotransmitters is the final common pathway in many diseases and conditions. This review discusses the physiology, pathophysiology, diagnosis, and treatment of erectile function and dysfunction, as well as strategies for future research.

Neurologic erectile dysfunction

Neurologic erectile dysfunction presents a diagnostic and treatment challenge to the internist and urologist. Multiple chronic disease modalities and traumatic etiologies exist. Education regarding these conditions and a detailed and thorough history and office work-up are the best resources for the clinician. Treatment can follow the model of proceeding from the least to most invasive procedure (process of care), taking into account patient and partner satisfaction. Because the psychology of grief and loss may enter into treatment of some neurologic conditions (e.g., erectile dysfunction after radical retropubic prostatectomy, spinal cord injury, or chronic diseases), a whole-patient approach encompassing psychotherapy is warranted.