In search of new paradigms for epididymal health and disease: innate immunity, inflammatory mediators, and steroid hormones

The primary job of the epididymis is to mature and protect the luminally transiting spermatozoa. Mounting evidence is showing that innate immune components [including Toll-like receptors (TLRs) and antimicrobial proteins, among which are β-defensins] and inflammatory mediators, under the primary influence of androgens, participate in the cellular and molecular processes that define this tissue. Here, we present an overview of the contributions of these signaling pathway components during epididymal homeostasis and discuss the hypotheses as to their involvement in epididymitis, the most common urological inflammatory condition in men, frequently impairing their fertility. Drawing primarily from rodent models, we also focus on how the distribution and functional expression of innate immune components are differentially regulated in the prenatal developing epididymis, providing new insights into the disruption of these signaling pathways throughout the lifespan. Male infertility is caused by a variety of conditions, such as congenital malformations, genetic and endocrine disorders, exposure to environmental toxicants, and inflammatory/infectious conditions. More than one-third of infertile men with an idiopathic condition cannot currently be adequately diagnosed. Thinking about the innate immunity and inflammation context of the epididymis may provide new insights and directions as to how these systems contribute to male fertility, as well as also uncover urological and andrological outcomes that may aid clinicians in diagnosing and preventing epididymal pathologies.

Impact of adrenalectomy and dexamethasone treatment on testicular morphology and sperm parameters in rats: insights into the adrenal control of male reproduction

Here we investigated the hypothesis that normal levels of glucocorticoids, a class of adrenal steroid hormones, are required for normal testicular and epididymal functions. We examined the effects of the manipulation of glucocorticoid plasma levels by bilateral adrenalectomy (1, 2, 7 and 15 days) alone or in combination with daily treatment with the synthetic glucocorticoid dexamethasone (DEX; 5 μg/kg, i.p., 6 days) on the morphology of the testis and sperm parameters in rats. We showed that adrenalectomy led to a reduction in testicular sperm count and daily sperm production starting 2 days after surgery and a differential decrease in sperm count in the epididymis, according to the region and time post-adrenalectomy analysed. In parallel, testes from 7-day adrenalectomized (ADX) rats displayed a higher frequency of damaged seminiferous tubules and the presence of elongated spermatids retained in the basal epithelial compartment in stages IX-XVII, which is indicative of defective spermiation. The alkaline comet assay revealed a late effect of adrenalectomy on epididymal sperm DNA fragmentation, which was increased only 15 days after surgery. DEX treatment prevented the changes in testicular and epididymal sperm count observed in 7-day ADX rats, but failed to protect the testis from ADX-induced morphological abnormalities. Thus, our results indicated that glucocorticoids may be involved in events related to the maintenance of spermatogenesis and sperm maturation during adulthood. These findings provide new insights into the importance of adrenal steroids to male fertility.

Influence of N-methyl-D-aspartate receptors on ouabain activation of nuclear factor-κB in the rat hippocampus

It has been shown that ouabain (OUA) can activate the Na,K-ATPase complex and mediate intracellular signaling in the central nervous system (CNS). Inflammatory stimulus increases glutamatergic transmission, especially at N-methyl-D-aspartate (NMDA) receptors, which are usually coupled to the activation of nitric oxide synthase (NOS). Nuclear factor-κB (NF-κB) activation modulates the expression of genes involved in development, plasticity, and inflammation. The present work investigated the effects of OUA on NF-κB binding activity in rat hippocampus and the influence of this OUA-Na,K-ATPase signaling cascade in NMDA-mediated NF-κB activation. The findings presented here are the first report indicating that intrahippocampal administration of OUA, in a concentration that did not alter Na,K-ATPase or NOS activity, induced an activation of NF-κB, leading to increases in brain-derived neurotrophic factor (Bdnf), inducible NOS (iNos), tumor necrosis factor-α (Tnf-α), and B-cell leukemia/lymphoma 2 (Bcl2) mRNA levels. This response was not linked to any significant signs of neurodegeneration as showed via Fluoro-Jade B and Nissl stain. Intrahippocampal administration of NMDA induced NF-κB activation and increased NOS and α(2/3) -Na,K-ATPase activities. NMDA treatment further increased OUA-induced NF-κB activation, which was partially blocked by MK-801, an antagonist of NMDA receptor. These results suggest that OUA-induced NF-κB activation is at least in part dependent on Na,K-ATPase modulatory action of NMDA receptor in hippocampus. The interaction of these signaling pathways could be associated with biological mechanisms that may underlie the basal homeostatic state linked to the inflammatory signaling cascade in the brain.

Presence of mRNA of muscle nicotinic acetylcholine receptor subunits and an epsilon-subunit splice variant in the mouse brain

Transcripts encoding for alpha1, beta1, delta, gamma and epsilon (and its splice variant epsilon(s)) subunits of the muscle-type nicotinic acetylcholine receptor (nAChR) were assessed using reverse transcription followed by polymerase chain reaction (RT-PCR) assays, with RNA extracted from the mouse skeletal muscle (diaphragm) and brain regions (cortex, hippocampus and cerebellum). The presence of alpha1, beta1, delta, gamma, epsilon and epsilon(s) transcripts was confirmed in the diaphragm muscle, used as positive control. mRNAs coding for muscle alpha1, beta1, delta, epsilon, epsilon(s), but not gamma subunits, were detected in adult mouse brain regions. An epsilon-subunit sequence variant, named epsilon(t), was also detected in all brain regions examined, but not in skeletal muscle. This new epsilon-subunit splice variant lacks a 115 bp cassette corresponding to exon 8 in the first intracellular transmembrane domain of the subunit, leading to a truncated protein. The data provide evidence for the presence of muscle-type nAChR subunits in the mouse central nervous system.

237 EXPRESSION OF THE FULL-LENGTH AND ALTERNATIVELY SPLICED BOVINE LH RECEPTOR mRNAs IN GRANULOSA CELLS FROM FOLLICLES ≥ 7 mm IN DIAMETER

The objective of this study was to characterize the pattern of gene expression of LH receptor (LHR) transcripts from bovine antral follicles from 5 to 14 mm in diameter (theca and granulosa cells, TC and GC, respectively) in crossbreed cattle and from cultured GC. From ovaries collected in abattoir (Bos indicus � B. taurus cattle), antral follicles were dissected, and samples of TC and GC were obtained for total RNA extraction (Trizol protocol). Steroid concentrations in the follicular fluid were determined by RIA. Samples of GC cultured for 6 days (obtained from B. taurus follicles), were treated with FSH (0 (control), 1, or 10 ng) and processed for total RNA extraction. Total RNA (1 �g) was utilized in the RT reaction (SuperScript III; Invitrogen, Brasil Ltd., S�o Paulo, Brazil). The PCR conditions were 29 cycles of 95�C, 60�C, and 70�C (1 min each) for denaturation, annealing, and extension (PTC200 thermocycler; MJ Research, Biozym, Landgraaf, The Netherlands). Gene expression of LHR was measured by semiquantitative RT-PCR with specific primers to amplify the fragment from exon 9 to exon 11 (LHRBC; full-length amplicon with 1240 bp). To investigate a putative site of alternative splicing on exon 3 specific primers were utilized to amplify a fragment containing the exons 2 to 9 (LHRA). As an internal control of the PCR, GAPDH expression was used. After sequencing, four isoforms were detected from the LHRBC fragment two with deletion of exon 10 (M2 and M4) and two with deletion of part of exon 11 (M3 and M4) as well as the fragment without deletions (M1). There was no correlation (P > 0.05; Spearman correlation) between LHRBC isoform expression and steroid hormones or follicular diameter (TC). However, estradiol and progesterone concentrations (r > 0.51 and P < 0.01) and follicular diameter (r > 0.82 and P < 0.01) were correlated with expression of the four LHRBC isoforms (GC). Expression of isoforms from fragment LHRBC was observed in GC from follicles with a diameter of 7 mm. In six follicles with a diameter of 7 mm, only one (16.7%) expressed LHR in GC, whereas most of the follicles e 8 mm expressed LHR (87.5%, 21/24). No LHR isoforms were detected in GC from follicles (n = 7) d 6 mm in diameter. From LHRA fragment amplification, an alternative transcript with a deletion of 75 bp, homologous to the rat exon 3, was detected by sequencing. In cultured GC (without FSH treatment), only a weak LHR expression (in vitro control) was observed when compared with the in vivo control (TC sample). The treatment with FSH (1 or 10 ng) was effective to induce LHR expression in cultured GC, however, with a different pattern of expression (lower M1/M2 ratio) when compared to in vivo GC samples (0.8 � 0.14 vs. 3.5 � 0.66; mean � SEM, P < 0.01, unpaired t-test). It is concluded that, in GC from follicles with a diameter e 7 mm, the gene expression of the LHR was positively correlated with follicular diameter and with estradiol and progesterone concentration in the follicular fluid. Treatment with FSH was effective in inducing LHR expression in cultured GC, however, with a different pattern than in the in vivo control. Additionally, sites of alternative splicing were detected in exons 3, 10, and 11 from the bovine LHR gene. This work was supported by a Fellowship from FAPESP.

Expression of fibroblast growth factor-8 and its cognate receptors, fibroblast growth factor receptor (FGFR)-3c and-4, in fetal bovine preantral follicles

Paracrine cell signaling is thought to be important for ovarian follicle development, and a role for some members of the fibroblast growth factor (FGF) family have been suggested. In the present study, we tested the hypothesis that FGF-8 and its cognate receptors (FGFR-3c and FGFR-4) are expressed in bovine preantral follicles. Reverse transcription-polymerase chain reaction was used to amplify bovine FGF-8, FGFR-3c, and FGFR-4 from preantral follicle samples and a variety of fetal and adult tissues. All three genes were widely expressed in fetal tissues, with a restricted expression pattern in adult tissues. FGF-8 and FGFR-3c were expressed in secondary follicles in 70% of fetuses examined, whereas FGFR-4 expression was significantly less frequent (20%). FGFR-3c expression frequency was significantly lower in primordial compared to secondary follicles, and FGF-8 expression showed a similar trend. FGFR-4 was only observed when all follicle classes of an individual were expressing both FGF-8 and FGFR-3c. We conclude that FGF-8 and its receptors are expressed in preantral follicles in a developmentally regulated manner.

Prevalence of Y chromosome deletions in a Brazilian population of nonobstructive azoospermic and severely oligozoospermic men

We determined the prevalence of Y chromosome deletions in a population of 60 Brazilian nonobstructive azoospermic and severely oligozoospermic men. PCR-based screening of microdeletions was performed on lymphocyte DNA for the presence of 14 sequence-tagged sites (STS) located in the azoospermic factor (AZF) on the Yq chromosome. All STS were amplified efficiently in samples from 12 fertile men tested, but failed to be amplified in samples from fertile women, indicating the specificity of PCR conditions for Yq screening. Overall, 4 of the 60 infertile patients tested (6.7%) exhibited deletion of the Y chromosome, 2 of them being severely oligozoospermic patients (P10 and P32) and 2 azoospermic men (patients P47 and P57). Patients P47 and P57 presented larger deletions in the AZFa, AZFb and AZFc subregions, with apparent loss of Yq material evidenced by karyotype analysis. Patients P10 and P32 presented deletions confined to the AZFc region, involving the DAZ locus. Male relatives of patients P10 and P32 had no Y chromosome deletions and presented a normal karyotype, suggesting a de novo status of the deletions found. Our data add to the growing literature showing that microdeletions of the Y chromosome can be the cause of male idiopathic infertility.