The future of testis research is turning 6! Six years of international network for young researchers in male fertility.

The 'International Network for Young Researchers in Male Fertility' has now turned 6 years old and offers a platform that stimulates scientific exchange as well as the development of international cooperation for young researchers. We report on our scope and the exciting achievements, amongst others, the continually increasing number of participants and the growing success of our annual meetings.

Influence of long-term dietary administration of procymidone, a fungicide with anti-androgenic effects, or the phytoestrogen genistein to rats on the pituitary-gonadal axis and Leydig cell steroidogenesis.

Procymidone is a fungicide with anti-androgenic properties, widely used to protect fruits from fungal infection. Thereby it contaminates fruit products prepared for human consumption. Genistein-containing soy products are increasingly used as food additives with health-promoting properties. Therefore we examined the effects of long-term dietary administration (3 months) of the anti-androgen procymidone (26.4 mg/animal per day) or the phytoestrogen genistein (21.1 mg/animal per day) to rats on the pituitary-gonadal axis in vivo, as well as on Leydig cell steroidogenesis and on spermatogenesis ex vivo. The procymidone-containing diet elevated serum levels of LH and testosterone and, furthermore, Leydig cells isolated from procymidone-treated animals displayed an enhanced capacity for producing testosterone in response to stimulation by hCG or dibutyryl cAMP, as well as elevated expression of steroidogenic acute regulatory protein (StAR), cytochrome P450 side-chain cleavage (P450 scc) and cytochrome P450 17alpha (P450c17). In contrast, the rate of DNA synthesis during stages VIII and IX of spermatogenesis in segments of seminiferous tubules isolated from genistein-treated rats was decreased without accompanying changes in the serum level of either LH or testosterone. Nonetheless, genistein did suppress the ex vivo steroidogenic response of Leydig cells to hCG or dibutyryl cAMP by down-regulating their expression of P450 scc. Considered together, our present findings demonstrate that long-term dietary administration of procymidone or genistein to rats exerts different effects on the pituitary-gonadal axis in vivo and on Leydig cell steroidogenesis ex vivo. Possibly as a result of disruption of hormonal feedback control due to its anti-androgenic action, procymidone activates this endocrine axis, thereby causing hyper-gonadotropic activation of testicular steroidogenesis. In contrast, genistein influences spermatogenesis and significantly inhibits Leydig cell steroidogenesis ex vivo without altering the serum level of either LH or testosterone.

Molecular identity, expression and functional analysis of interleukin-1alpha and its isoforms in rat testis.

Interleukin-1alpha (IL-1alpha) is a proinflammatory cytokine that has also been found to act as a paracrine mediator involved in the regulation of testicular functions. The present review provides an overview of the role of IL-1alpha in testicular physiology. Bioactive IL-1alpha isolated from adult rat testis was found to consist of three distinct immunoreactive protein species with apparent sizes of 45, 24 and 19 kDa. These isoforms showed bioactivity in a thymocyte proliferation and steroidogenesis assays with different biopotencies. The background of the molecular heterogeneity and processing, secretion and regulation of the isoforms of testicular IL-1alpha are discussed. All three isoforms have been found to be secreted into the testis tubular lumen and interstitial space. We have provided evidence that IL-1alpha is a paracrine factor that may be of importance in, e.g., the regulation of Leydig cell steroidogenesis. Pathophysiologically, testicular IL-1alpha may contribute to testicular relapse of acute lymphocytic leukemia in boys.

The paracrine role played by interleukin-1 alpha in the testis.

Interleukin-1alpha (IL-1alpha) plays an important role(s) in the regulation of immune and inflammatory responses. The testis is an immunologically privileged organ and the variety of effects exerted by IL-1alpha on this organ have yet to be explored in detail. The aim of the present review is to describe our current view of the paracrine role played by IL-1alpha in testicular physiology. Testicular IL-1alpha is expressed during development, primarily in Sertoli cells, appearing in rats for the first time 20 days after birth. This cytokine is microheterogeneous, consisting of three molecular species with molecular weights of 45, 24 and 17 KDa. The 17 KDa form represents mature IL-1alpha, while the 24-KDa IL-1alpha has been shown by our research group to be an alternately spliced form of the 45-KDa pro-IL-1alpha. IL-1alpha was observed to stimulate the proliferation of immature Sertoli cells with higher efficacy than FSH. IL-1alpha was also found to exert mitogenic effects both on isolated peritubular cells and germ cells. Furthermore, isoforms of IL-1alpha were seen to stimulate basal testosterone production in immature Leydig cells, but not in the corresponding adult cells. This effect involved induction of the steroidogenic acute regulatory (StAR) protein and positively regulation by p38 MAPK. Recently, we have observed positive interactions between IL-1alpha and hormones of the GH/IGF-I system that lead to enhanced androgen production by the Leydig cell. In conclusion, our findings suggest that isoforms of IL-1alpha may serve as paracrine mediators, alone or in concert with other factors, that support proper testicular cell functioning and, thereby, reproduction and fertility.

Constitutive production of interleukin-1alpha mRNA and protein in the developing rat testis.

Interleukin-1 (IL-1), a multifunctional cytokine produced mainly by activated macrophages, is also produced in the intact testis. Rat testicular IL-1 was found to be identical to IL-1alpha, judged by immunoneutralization of the bioactive protein and sequence comparison of cloned rat testicular and macrophage pro-IL-1alpha cDNA. Testicular IL-1alpha mRNA was first demonstrated on postnatal day 15, and the corresponding bioactive protein from day 20. IL-1alpha mRNA was still low on day 20, but then increased rapidly in parallel with the bioactive protein to establish a plateau level from day 25. In adult testes, IL-1alpha mRNA and immunoreactive protein were low in stage VII of the seminiferous epithelial cycle, whereas other stages showed a clearly detectable expression. In the adult testis, the concentration of IL-1alpha was 75 pg/mg testicular protein (approximately 200 pM). In conclusion, production of testicular IL-1alpha is developmentally and stage-dependently regulated, probably at the transcriptional level, emphasizing an important paracrine role in testicular function.

The interleukin-1 system in the testis.

The interleukin-1 (IL-1) family consists of two agonist proteins, IL-1 alpha and IL-1 beta, and one antagonist, IL-1 receptor antagonist (IL-1ra), which blocks the action of the agonists by binding and competing at the IL-1 receptor level. IL-1 beta and to a lesser extent IL-1 alpha were originally described as rapidly inducible proinflammatory cytokines released by activated macrophages. However, IL-1 alpha has been found to be constitutively produced by certain tissues, and noninflammatory functions have been proposed for this protein, although they have not yet been well elucidated. Consistent with this suggestion, we previously showed that the intact rat testis constitutively produces large amounts of IL-1 alpha at both the mRNA and protein levels. The expression of IL-1 alpha was found to be confined to Sertoli cells, with evidence of a developmental as well as a stage-dependent production pattern. In more recent studies, we have found indications that the testis can also initiate production of IL-1 beta upon stimulation with inflammatory inducers such as endotoxin. Further, we have detected constitutive testicular expression of IL-1ra, opening up the possibility that IL-1 action in the testis may be specifically regulated by paracrine mechanisms. Recent data have demonstrated that the testis can produce more than one isoform of IL-1 alpha with indications of both post-transcriptional and post-translational modifications, resulting in at least three distinct bio- and immunoreactive IL-1 alpha proteins. We conclude that all three classical IL-1 ligands and novel IL-1 alpha isoforms are present in the testis and may serve as paracrine mediators under physiological or pathophysiological conditions. The function of this testicular IL-1 agonist-antagonist network is a current focus of investigation.