Seminal insulin-like growth factor-I may be involved in the pathophysiology of infertility among patients with clinical varicocele

Abstract

Varicocele, the most common cause of male infertility, is defined as abnormal dilation of the pampiniform plexus. Although different mechanisms have been proposed to explain the pathophysiology of infertility caused by varicocele, it is still open to debate. Previous studies have demonstrated the effect of insulin-like growth factor-I (IGF-I) on semen quality in animals and humans, but there are no studies on the probable role of seminal IGF-I in the pathophysiology of infertility among patients with clinical varicocele. We therefore aimed to examine the seminal IGF-I concentration in 49 patients with varicocele and primary infertility before and after varicocelectomy and compare the results with those of 50 healthy fertile men (in the control group). Mean seminal IGF-I level of patients before varicocelectomy (93.7 ± 67.2 ng/mL) was significantly different (P < 0.001) from that following varicocelectomy (58 ± 35.1 ng/mL) and from that of the controls (57.6 ± 22.1 ng/mL). However, mean seminal IGF-I levels of patients after varicocelectomy and the controls were not significantly different. Seminal IGF-I level was not correlated with grade and side of varicocele, and semen quality. We conclude that locally secreted IGF-I in the semen may be involved in the pathophysiology of infertility in patients with varicocele or semen.

Association of decreased sperm motility and increased seminal plasma IGF-I, IGF-II, IGFBP-2, and PSA levels in infertile men

“…Early human studies have shown the presence of IGF-I, IGF-II, IGFBP-2, IGFBP-3 fragments, IGFBP-4, IGFBP-5, IGFBP-protease activities and PSA in SP [14,18,19,27,[37][38][39], while recent studies have reported that SP IGF-I levels do not differ between men with normal and abnormal semen parameters [15,20]. Evidence that vasectomized patients had lower SP IGF-I levels than intact patients suggests that SP IGF-I is mainly of testicular origin [39], whereas in patients with varicocele (a common cause of male infertility), higher SP IGF-I levels than healthy fertile men have been observed implying a role of localized IGF-I in the pathogenesis of male infertility [17].…”

“…Conversely, the role of IGFs and IGFBPs in the male reproductive system has been less well studied. Although the presence of IGFs and IGFBPs have been demonstrated in SP [14][15][16][17][18][19][20], it remains unclear what these levels are in infertile men with low sperm motility versus those with low sperm counts, and if they exert a speci c functional role in affecting sperm characteristics.…”

Association between male Infertility and seminal plasma levels of growth hormone and insulin-like growth factor-1

“…In addition, IGF‐1 receptor (IGF‐1R) was shown to be absent from the seminal plasma of patients with a history of failed fertilisation, although IGF‐1R was present both in fertile and infertile men (Sánchez‐Luengo, Fernández, & Romeu, ). IGF‐1 levels in seminal plasma from patients with varicocele‐a common cause of male infertility were significantly different compared with those following varicocelectomy and those of the control group, although IGF‐1 was not correlated with semen quality (Naderi, Mohseni Rad, Tabassomi, & Latif, ). With regard to animal models, IGF‐binding protein‐1 (IGFBP‐1) overexpression in transgenic mice showed an alteration of spermatogenesis resulting in lower production and quality of sperm (Froment et al., ).…”

Decreased Sperm Motility is Associated with Increased Seminal Plasma IGF-I, IGF-II, IGFBP-2 and PSA Levels in Male Infertility

“…Early human studies have shown the presence of IGF-I, IGF-II, IGFBP-2, IGFBP-3 fragments, IGFBP-4, IGFBP-5, IGFBP-protease activities and PSA in SP [14,18,19,27,[37][38][39], while recent studies have reported that SP IGF-I levels do not differ between men with normal and abnormal semen parameters [15,20]. Evidence that vasectomized patients had lower SP IGF-I levels than intact patients suggests that SP IGF-I is mainly of testicular origin [39], whereas in patients with varicocele (a common cause of male infertility), higher SP IGF-I levels than healthy fertile men have been observed implying a role of localized IGF-I in the pathogenesis of male infertility [17].…”