Role of perceived neighbourhood crime in the longitudinal association between perceived built environment and type 2 diabetes mellitus: a moderated mediation analysis.

BACKGROUND: We examined to what extent perceived neighbourhood crime moderates, associations between type 2 diabetes mellitus (T2DM) and perceived local amenities, recreational facilities, footpaths and public transit, and potential mediation of environmental characteristics-T2DM association by physical activity, social contact, sleep and body mass index (BMI). METHODS: The 45 and Up Study data of 36, 224 individuals collected from 2010 to 2015 were analysed in 2019 using multilevel logistic regression to examine the association between T2DM and clustering of unfavourable built environment, and any difference in the association with increasing unfavourable environment and area disadvantage. We performed causal mediation analyses stratified by crime to examine whether crime moderated the strength of identified local amenities-T2DM pathways. RESULTS: The results showed that irrespective of crime, perceived lack of local amenities was associated with increased odds of developing T2DM, and BMI mediated 40% and 30.3% of this association among those who reported unsafe and safe daytime crime, respectively. The proportion mediated by BMI among those who reported unsafe and safe night-time crime was 27.3% and 35.1%, respectively. Walking mediated 5.7% of the local amenities-T2DM association among those who reported safe daytime crime. The odds of T2DM increased with rising unfavourable environment and area disadvantage. CONCLUSIONS: The results suggest that the availability of neighbourhood amenities may lower T2DM risk by increasing walking and reducing BMI regardless of area crime. Policies to enhance access to local amenities and prevent crime, especially in disadvantaged areas, may support healthy behaviour and physical health that can potentially reduce T2DM risk.

Genome-wide expression changes induced by bisphenol A, F and S in human stem cell derived hepatocyte-like cells.

The debate about possible adverse effects of bisphenol A (BPA) has been ongoing for decades. Bisphenol F (BPF) and S (BPS) have been suggested as "safer" alternatives. In the present study we used hepatocyte-like cells (HLCs) derived from the human embryonic stem cell lines Man12 and H9 to compare the three bisphenol derivatives. Stem cell-derived progenitors were produced using an established system and were exposed to BPA, BPF and BPS for 8 days during their transition to HLCs. Subsequently, we examined cell viability, inhibition of cytochrome P450 (CYP) activity, and genome-wide RNA profiles. Sub-cytotoxic, inhibitory concentrations (IC50) of CYP3A were 20, 9.5 and 25 µM for BPA, BPF and BPS in Man12 derived HLCs, respectively. The corresponding concentrations for H9-derived HLCs were 19, 29 and 31 µM. These IC50 concentrations were used to study global expression changes in this in vitro study and are higher than unconjugated BPA in serum of the general population. A large overlap of up- as well as downregulated genes induced by the three bisphenol derivatives was seen. This is at least 28-fold higher compared to randomly expected gene expression changes. Moreover, highly significant correlations of expression changes induced by the three bisphenol derivatives were obtained in pairwise comparisons. Dysregulated genes were associated with reduced metabolic function, cellular differentiation, embryonic development, cell survival and apoptosis. In conclusion, no major differences in cytochrome inhibitory activities of BPA, BPF and BPS were observed and gene expression changes showed a high degree of similarity.

Identification of Sertoli cell-specific transcripts in the mouse testis and the role of FSH and androgen in the control of Sertoli cell activity.

BACKGROUND: The Sertoli cells act to induce testis differentiation and subsequent development in fetal and post-natal life which makes them key to an understanding of testis biology. As a major step towards characterisation of factors involved in Sertoli cell function we have identified Sertoli cell-specific transcripts in the mouse testis and have used the data to identify Sertoli cell-specific transcripts altered in mice lacking follicle-stimulating hormone receptors (FSHRKO) and/or androgen receptors (AR) in the Sertoli cells (SCARKO). RESULTS: Adult iDTR mice were injected with busulfan to ablate the germ cells and 50 days later they were treated with diphtheria toxin (DTX) to ablate the Sertoli cells. RNAseq carried out on testes from control, busulfan-treated and busulfan + DTX-treated mice identified 701 Sertoli-specific transcripts and 4302 germ cell-specific transcripts. This data was mapped against results from microarrays using testicular mRNA from 20 day-old FSHRKO, SCARKO and FSHRKO.SCARKO mice. Results show that of the 534 Sertoli cell-specific transcripts present on the gene chips, 85% were altered in the FSHRKO mice and 94% in the SCARKO mice (mostly reduced in both cases). In the FSHRKO.SCARKO mice additive or synergistic effects were seen for most transcripts. Age-dependent studies on a selected number of Sertoli cell-specific transcripts, showed that the marked effects in the FSHRKO at 20 days had largely disappeared by adulthood although synergistic effects of FSHR and AR knockout were seen. CONCLUSIONS: These studies have identified the Sertoli cell-specific transcriptome in the mouse testis and have shown that most genes in the transcriptome are FSH- and androgen-dependent at puberty although the importance of FSH diminishes towards adulthood.

Evaluation of a sprinkler cooling system on inhalable dust and ammonia concentrations in broiler chicken production.

Workers are exposed to dust in broiler chicken production during daily work activities. Poultry dust may contain inflammatory agents (e.g., endotoxin) and inhalation exposure has been associated with pulmonary symptoms. Current practice to reduce worker exposure to poultry dust is the use of respiratory protection (e.g., elastomeric face-piece respirator with a P100 and ammonia chemical cartridge). Limited research has been conducted to evaluate engineering controls to reduce dust and ammonia concentrations in broiler chicken production; therefore, the purpose of this research was to evaluate the effectiveness of a water sprinkling system to reduce inhalable dust and ammonia concentrations in a broiler chicken house. Inhalable dust and ammonia concentrations were measured daily for the production cycle of a flock of broiler chickens (63 days). Inhalable dust was measured gravimetrically using an inhalable sampler and ammonia was measured by a direct reading sensor. Sampling was performed on a stationary mannequin inside two broiler chicken houses. One house used a sprinkler cooling system to deliver a water mist throughout the house and the second house was an untreated control. The sprinkler system activated after day 5 of chicken placement, releasing water periodically from 6 am to 10 pm. The amount of sprinkling increased at day 10 and day 15 as recommended by the manufacturer. Geometric mean (GM) inhalable dust concentrations measured in the treatment house (5.5 mg/m3) were not different (p = 0.33) than those found in the control house (6.0 mg/m3). The GM ammonia concentrations were also not different (p = 0.34) across the treatment and control house [10.6 ppm (GSD: 1.80); GM 9.51 ppm (GSD: 1.77)], respectively. The use of cost effective engineering, administrative and personal exposure controls are needed in the poultry industry to effectively reduce worker's exposure to hazardous concentrations of dust and ammonia.

Love, faith and hope - a secondary analysis of prostate cancer survivors and their partners.

BACKGROUND: Men's experience of recovery from treatment for prostate cancer has been extensively researched with reports highlighting the physical side effects of treatments such as erectile dysfunction and incontinence. The psychological, emotional and spiritual burden of prostate cancer on men and their partners has received far less attention. DESIGN: In this study, a secondary thematic analysis of data from a series of separate but related qualitative studies with prostate cancer survivors and their partners was conducted to further explore themes of love, hope and faith within this population. RESULTS: This study identified unresolved needs related to the emotive concepts of love, hope and faith. The findings from this study can be employed to refine psychosocial assessments of men with prostate cancer, and provide a more comprehensive understanding of prostate cancer survivors supportive care needs.

Cell-specific ablation in the testis: what have we learned?

Testicular development and function is the culmination of a complex process of autocrine, paracrine and endocrine interactions between multiple cell types. Dissecting this has classically involved the use of systemic treatments to perturb endocrine function, or more recently, transgenic models to knockout individual genes. However, targeting genes one at a time does not capture the more wide-ranging role of each cell type in its entirety. An often overlooked, but extremely powerful approach to elucidate cellular function is the use of cell ablation strategies, specifically removing one cellular population and examining the resultant impacts on development and function. Cell ablation studies reveal a more holistic overview of cell-cell interactions. This not only identifies important roles for the ablated cell type, which warrant further downstream study, but also, and importantly, reveals functions within the tissue that occur completely independently of the ablated cell type. To date, cell ablation studies in the testis have specifically removed germ cells, Leydig cells, macrophages and recently Sertoli cells. These studies have provided great leaps in understanding not possible via other approaches; as such, cell ablation represents an essential component in the researchers' tool-kit, and should be viewed as a complement to the more mainstream approaches to advancing our understanding of testis biology. In this review, we summarise the cell ablation models used in the testis, and discuss what each of these have taught us about testis development and function.

Effects of probiotic Enterococcus faecium and Saccharomyces cerevisiae on the faecal microflora of pet rabbits.

OBJECTIVES: Probiotics are frequently used in the treatment of gastrointestinal diseases in pet rabbits based largely on anecdotal evidence of a beneficial effect. However, there has been little work performed to assess any such benefit in health or disease. The aim of this study was to determine the effect of probiotics on faecal levels of four important candidate gastrointestinal bacteria (Bacteroides species, Enterococcus faecium, Fibrobacter succinogenes and Clostridium spiroforme) in pet rabbits. Additional aims were to evaluate the effect of probiotics on bodyweight and faecal weight and diameter. MATERIALS AND METHODS: Double-blind triple cross-over study in six healthy rabbits orally administered two probiotic strains, Saccharomyces cerevisiae NCYC Sc47 and E. faecium NCIMB 30183. Levels of bacteria in faecal pellets were subsequently determined by real-time quantitative polymerase chain reaction. RESULTS: Oral administration of probiotic E. faecium NCIMB 30183 was associated with a significant (P = 0 · 042) increase in faecal levels of E. faecium. However, probiotic treatment did not affect faecal levels of Bacteroides species, F. succinogenes or C. spiroforme, bodyweight, or faecal weight and diameter. CLINICAL SIGNIFICANCE: The inclusion of dietary probiotic supplementation using E. faecium NCIMB 30183 can increase faecal levels of certain bacterial flora of healthy adult rabbits. Further work is required to investigate the effects of probiotics in animals affected with gastrointestinal disease.

Identification of Leydig cell-specific mRNA transcripts in the adult rat testis.

The adult population of Leydig cells acts to secrete testosterone which is essential for reproductive health and fertility in the adult male. However, other physiological functions of these cells are uncertain, and to address this issue a cell ablation model has been used to identify Leydig cell-specific mRNA transcripts. Ethane dimethane sulphonate (EDS) was synthesised by a novel process and was used to ablate Leydig cells in adult male rats previously treated with butane dimethane sulphonate (busulphan) to delete the germ cell population. Levels of mRNA transcripts were measured in the testis using microarrays 1, 3, 5, 8 and 12 days after EDS injection. During this period, there was a significant change in the levels of 2200 different transcripts with a marked decline in the levels of canonical Leydig cell transcripts, such as Cyp11a1, Cyp17a1 and Insl3. A total of 95 transcripts showed a similar decline in expression after EDS treatment, suggesting that they have a Leydig cell-specific origin. Analysis of selected transcripts confirmed that they were expressed specifically in Leydig cells and showed that most had a late onset of expression during adult Leydig cell development. Apart from transcripts encoding components of the steroidogenic apparatus, the most common predicted function of translated proteins was endogenous and xenotoxicant metabolism. In addition, a number of transcripts encode acute-phase proteins involved in reduction of oxidative stress. Results show that, in addition to androgen secretion, Leydig cells may have a critical role to play in protecting the testis from damage caused by toxicants or stress.

Outcomes and costs of autologous stem cell mobilization with chemotherapy plus G-CSF vs G-CSF alone.

Chemotherapy plus G-CSF (C+G) and G-CSF alone are two of the most common methods used to mobilize CD34(+) cells for autologous hematopoietic SCT (AHSCT). In order to compare and determine the real-world outcomes and costs of these strategies, we performed a retrospective study of 226 consecutive patients at 11 medical centers (64 lymphoma, 162 multiple myeloma), of whom 55% of lymphoma patients and 66% of myeloma patients received C+G. Patients with C+G yielded more CD34(+) cells/day than those with G-CSF alone (lymphoma: average 5.51 × 10(6) cells/kg on day 1 vs 2.92 × 10(6) cells/kg, P=0.0231; myeloma: 4.16 × 10(6) vs 3.69 × 10(6) cells/kg, P<0.00001) and required fewer days of apheresis (lymphoma: average 2.11 vs 2.96 days, P=0.012; myeloma: 2.02 vs 2.83 days, P=0.0015), although nearly all patients ultimately reached the goal of 2 × 10(6) cells/kg. With the exception of higher rates of febrile neutropenia in myeloma patients with C+G (17% vs 2%, P<0.05), toxicities and other outcomes were similar. Mobilization with C+G cost significantly more (lymphoma: median $10,300 vs $7300, P<0.0001; myeloma: $8800 vs $5600, P<0.0001), although re-mobilization adds $6700 for drugs alone. Our results suggest that although both C+G and G-CSF alone are effective mobilization strategies, C+G may be more cost-effective for patients at high risk of insufficient mobilization.

Plerixafor and G-CSF for autologous stem cell mobilization in patients with NHL, Hodgkin's lymphoma and multiple myeloma: results from the expanded access program.

Before US regulatory approval, an expanded access program provided plerixafor to patients with non-Hodgkin's lymphoma (NHL), Hodgkin's lymphoma (HD) or multiple myeloma (MM) who had not previously failed mobilization and were otherwise candidates for auto-SCT. Patients received granulocyte-CSF (G-CSF) 10 mcg/kg daily and plerixafor 0.24 mg/kg starting on day 4 with apheresis on day 5; all repeated daily until collection was complete. Overall, 104 patients received 1 dose of plerixafor. The addition of plerixafor to G-CSF resulted in a median threefold increase in peripheral blood CD34+ cell count between days 4 and 5. Among 43 NHL patients, 74% met the target of 5 × 10(6) CD34+ cells/kg (median, 1 day apheresis, range 1-5 days); among 7 HD patients, 57% met the target of 5 × 10(6) CD34+ cells/kg (median, 2 days apheresis, range 1-3); and among 54 MM patients, 89% met the target of 6 × 10(6) CD34+ cells/kg (median, 1 day apheresis, range 1-4). Overall, 93% of patients had 2 × 10(6) CD34+ cells/kg collected within 1-3 days. Plerixafor-related toxicities were minimal. Engraftment kinetics, graft durability and transplant outcomes demonstrated no unexpected outcomes. Efficacy and safety results were similar to results in phase II and III clinical trials.

Steroidogenic enzyme expression in the human fetal liver and potential role in the endocrinology of pregnancy.

The human feto-maternal unit produces large amounts of steroid hormones, particularly estrogens, during the second and third trimesters. The fetal adrenal gland and the placenta are considered the principal tissues driving steroid production but the fetal liver is likely to play an essential role in this process. This study was designed to measure transcript expression of proteins involved in steroid synthesis, metabolism, conjugation and signalling in the human fetal liver and to examine sex differences and effects of maternal smoking. Liver samples were taken from 55 normal fetuses from women undergoing second trimester elective termination. Levels of 23 mRNA transcripts encoding steroid synthesis/metabolic/conjugation enzymes and steroid receptors were measured by real-time PCR. The expression of representative proteins was confirmed by western blotting and immunohistochemistry. The human fetal livers expressed high levels of CYP19A1, SULT2A1, SULT1E1, HSD17B2, SRD5A3 and CYP3A7. Lower levels of SULT1A1, STS, UGT2B17, GPER, AKR1C3, UGT2B15, AR, CYP11A1, CYP21A2, HSD17B3, HSD17B1 and SRD5A1 were also detectable. The expression of ESR, ESR2, CYP17A1 and HSD3B transcripts was undetectable in most fetal livers, although HSD3B was shown to be present by western blotting. Sex differences were limited to SRD5A3 (lower in females) and UGT2B17 (higher in females). Maternal smoking increased the expression of CYP19A1, SULT2A1, UGT2B17, HSD17B2 and AKR1C3 and reduced the expression of SRD5A3 in the male fetal liver. This study shows that the human fetal liver is likely to have an extensive effect on circulating steroid levels in the human fetus and mother. The most important of these effects will be alterations to the species, conjugation and availability of estrogens in the fetus. Maternal smoking is likely to reduce circulating androgen bioactivity in male fetuses.

Direct action through the sertoli cells is essential for androgen stimulation of spermatogenesis.

Androgens act to stimulate spermatogenesis through androgen receptors (ARs) on the Sertoli cells and peritubular myoid cells. Specific ablation of the AR in either cell type will cause a severe disruption of spermatogenesis. To determine whether androgens can stimulate spermatogenesis through direct action on the peritubular myoid cells alone or whether action on the Sertoli cells is essential, we crossed hypogonadal (hpg) mice that lack gonadotrophins and intratesticular androgen with mice lacking ARs either ubiquitously (ARKO) or specifically on the Sertoli cells (SCARKO). These hpg.ARKO and hpg.SCARKO mice were treated with testosterone (T) or dihydrotestosterone (DHT) for 7 d and testicular morphology and cell numbers assessed. Androgen treatment did not affect Sertoli cell numbers in any animal group. Both T and DHT increased numbers of spermatogonia and spermatocytes in hpg mice, but DHT has no effect on germ cell numbers in hpg.SCARKO and hpg.ARKO mice. T increased germ cell numbers in hpg.SCARKO and hpg.ARKO mice, but this was associated with stimulation of FSH release. Results show that androgen stimulation of spermatogenesis requires direct androgen action on the Sertoli cells.

Effect of FSH on testicular morphology and spermatogenesis in gonadotrophin-deficient hypogonadal mice lacking androgen receptors.

FSH and androgen act to stimulate and maintain spermatogenesis. FSH acts directly on the Sertoli cells to stimulate germ cell number and acts indirectly to increase androgen production by the Leydig cells. In order to differentiate between the direct effects of FSH on spermatogenesis and those mediated indirectly through androgen action, we have crossed hypogonadal (hpg) mice, which lack gonadotrophins, with mice lacking androgen receptors (AR) either ubiquitously (ARKO) or specifically on the Sertoli cells (SCARKO). These hpg.ARKO and hpg.SCARKO mice were treated with recombinant FSH for 7 days and testicular morphology and cell numbers were assessed. In untreated hpg and hpg.SCARKO mice, germ cell development was limited and did not progress beyond the pachytene stage. In hpg.ARKO mice, testes were smaller with fewer Sertoli cells and germ cells compared to hpg mice. Treatment with FSH had no effect on Sertoli cell number but significantly increased germ cell numbers in all groups. In hpg mice, FSH increased the numbers of spermatogonia and spermatocytes, and induced round spermatid formation. In hpg.SCARKO and hpg.ARKO mice, in contrast, only spermatogonial and spermatocyte numbers were increased with no formation of spermatids. Leydig cell numbers were increased by FSH in hpg and hpg.SCARKO mice but not in hpg.ARKO mice. Results show that in rodents 1) FSH acts to stimulate spermatogenesis through an increase in spermatogonial number and subsequent entry of these cells into meiosis, 2) FSH has no direct effect on the completion of meiosis and 3) FSH effects on Leydig cell number are mediated through interstitial ARs.

Extracorporeal photopheresis for the prevention of acute GVHD in patients undergoing standard myeloablative conditioning and allogeneic hematopoietic stem cell transplantation.

GVHD is partly mediated by host APCs that activate donor T cells. Extracorporeal photopheresis (ECP) can modulate APC function and benefit some patients with GVHD. We report the results of a study using ECP administered before a standard myeloablative preparative regimen intended to prevent GVHD. Grades II-IV acute GVHD developed in 9 (30%) of 30 recipients of HLA-matched related transplants and 13 (41%) of 32 recipients of HLA-matched unrelated or HLA-mismatched related donor transplants. Actuarial estimates of overall survival (OS) at day 100 and 1-year post transplant were 89% (95% CI, 78-94%) and 77% (95% CI, 64-86%), respectively. There were no unexpected adverse effects of ECP. Historical controls receiving similar conditioning and GVHD prophylaxis regimens but no ECP were identified from the database of the Center for International Blood and Marrow Transplant Research and multivariate analysis indicated a lower risk of grades II-IV acute GVHD in patients receiving ECP (P=0.04). Adjusted OS at 1 year was 83% in the ECP study group and 67% in the historical control group (relative risk 0.44; 95% CI, 0.24-0.80) (P=0.007). These preliminary data may indicate a potential survival advantage with ECP for transplant recipients undergoing standard myeloablative hematopoietic cell transplantation.

Effects of FSH on testicular mRNA transcript levels in the hypogonadal mouse.

FSH acts through the Sertoli cell to ensure normal testicular development and function. To identify transcriptional mechanisms through which FSH acts in the testis, we have treated gonadotrophin-deficient hypogonadal (hpg) mice with recombinant FSH and measured changes in testicular transcript levels using microarrays and real-time PCR 12, 24 and 72 h after the start of treatment. Approximately 400 transcripts were significantly altered at each time point by FSH treatment. At 12 h, there was a clear increase in the levels of a number of known Sertoli cell transcripts (e.g. Fabp5, Lgals1, Tesc, Scara5, Aqp5). Additionally, levels of Leydig cell transcripts were also markedly increased (e.g. Ren1, Cyp17a1, Akr1b7, Star, Nr4a1). This was associated with a small but significant rise in testosterone at 24 and 72 h. At 24 h, androgen-dependent Sertoli cell transcripts were up-regulated (e.g. Rhox5, Drd4, Spinlw1, Tubb3 and Tsx) and this trend continued up to 72 h. By contrast with the somatic cells, only five germ cell transcripts (Dkkl1, Hdc, Pou5f1, Zfp541 and 1700021K02Rik) were altered by FSH within the time-course of the experiment. Analysis of canonical pathways showed that FSH induced a general decline in transcripts related to formation and regulation of tight junctions. Results show that FSH acts directly and indirectly to induce rapid changes in Sertoli cell and Leydig cell transcript levels in the hpg mouse but that effects on germ cell development must occur over a longer time-span.

Role of androgen and gonadotrophins in the development and function of the Sertoli cells and Leydig cells: data from mutant and genetically modified mice.

Development and maintenance of the male phenotype and establishment of fertility are all dependent upon the activity of the Sertoli cells and Leydig cells of the testis. This review examines the regulation and function of these cell during fetal and post-natal development. Fetal Leydig cells are sensitive to both luteinising hormone (LH) and adrenocorticotrophic hormone (ACTH) but Leydig cell function appears normal in fetal mice lacking both hormones or their receptors. Post-natally, the Sertoli cells and Leydig cells are reliant upon the pituitary gonadotrophins. Leydig cells are critically dependent on LH but follicle-stimulating hormone (FSH), presumably acting through the Sertoli cell, can also affect Leydig cell function. Testosterone secreted by the Leydig cells acts with FSH to stimulate Sertoli cell activity and spermatogenesis. Study of animals lacking FSH-receptors and androgen-receptors shows that both hormones can act to maintain the meiotic germ cell population but that androgens are critical for completion of meiosis.

Leydig cell re-generation and expression of cell signaling molecules in the germ cell-free testis.

Leydig cells in the rat testis can be specifically ablated with ethane dimethane sulfonate (EDS) and will subsequently re-generate. In this study, we have characterized Leydig cell re-generation and expression of selected cell-signaling molecules in a germ cell-free model of EDS action. This model offers the advantage that re-generation occurs on a stable background without confounding changes from the regressing and repopulating germ cell population. Adult rats were treated with busulfan to remove the germ cell population and Leydig cells were then ablated with EDS. Testicular testosterone levels declined markedly within 24 h of EDS treatment and started to recover after 8 days. After EDS treatment there were marked declines in levels of Leydig cell-specific mRNA transcripts coding for steroidogenic enzymes cytochrome P450 11a1 (Cyp11a1), cytochrome P450 17a1 (Cyp17a1), 3beta-hydroxysteroid dehydrogenase type 1 (Hsd3b1), 17beta-hydroxysteroid dehydrogenase type 3 (Hsd17b3) and the LH receptor. Levels of all transcripts recovered within 20 days of EDS treatment apart from Hsd17b3, which remained undetectable up to 20 days. Immunohistochemical localization of CYP11A1 during the phase of early Leydig cell re-generation showed that the Leydig cell precursors are spindle-shaped peritubular cells. Studies on factors which may be involved in Leydig cell re-generation showed there were significant but transient increases in platelet-derived growth factor A (Pdgfa), leukemia inhibitory factor (Lif), and neurofilament heavy polypeptide (Nefh) after EDS, while desert hedgehog (Dhh) levels declined sharply but recovered by 3 days. This study shows that the Leydig cell precursors are peritubular cells and that expression of Pdgfa and Lif is increased at the start of the re-generation process when precursor proliferation is likely to be taking place.

Effect of germ cell depletion on levels of specific mRNA transcripts in mouse Sertoli cells and Leydig cells.

It has been shown that testicular germ cell development is critically dependent upon somatic cell activity but, conversely, the extent to which germ cells normally regulate somatic cell function is less clear. This study was designed, therefore, to examine the effect of germ cell depletion on Sertoli cell and Leydig cell transcript levels. Mice were treated with busulphan to deplete the germ cell population and levels of mRNA transcripts encoding 26 Sertoli cell-specific proteins and 6 Leydig cell proteins were measured by real-time PCR up to 50 days after treatment. Spermatogonia were lost from the testis between 5 and 10 days after treatment, while spermatocytes were depleted after 10 days and spermatids after 20 days. By 30 days after treatment, most tubules were devoid of germ cells. Circulating FSH and intratesticular testosterone were not significantly affected by treatment. Of the 26 Sertoli cell markers tested, 13 showed no change in transcript levels after busulphan treatment, 2 showed decreased levels, 9 showed increased levels and 2 showed a biphasic response. In 60% of cases, changes in transcript levels occurred after the loss of the spermatids. Levels of mRNA transcripts encoding Leydig cell-specific products related to steroidogenesis were unaffected by treatment. Results indicate (1) that germ cells play a major and widespread role in the regulation of Sertoli cell activity, (2) most changes in transcript levels are associated with the loss of spermatids and (3) Leydig cell steroidogenesis is largely unaffected by germ cell ablation.

Spermatogenesis and sertoli cell activity in mice lacking sertoli cell receptors for follicle-stimulating hormone and androgen.

Spermatogenesis in the adult male depends on the action of FSH and androgen. Ablation of either hormone has deleterious effects on Sertoli cell function and the progression of germ cells through spermatogenesis. In this study we generated mice lacking both FSH receptors (FSHRKO) and androgen receptors on the Sertoli cell (SCARKO) to examine how FSH and androgen combine to regulate Sertoli cell function and spermatogenesis. Sertoli cell number in FSHRKO-SCARKO mice was reduced by about 50% but was not significantly different from FSHRKO mice. In contrast, total germ cell number in FSHRKO-SCARKO mice was reduced to 2% of control mice (and 20% of SCARKO mice) due to a failure to progress beyond early meiosis. Measurement of Sertoli cell-specific transcript levels showed that about a third were independent of hormonal action on the Sertoli cell, whereas others were predominantly androgen dependent or showed redundant control by FSH and androgen. Results show that FSH and androgen act through redundant, additive, and synergistic regulation of spermatogenesis and Sertoli cell activity. In addition, the Sertoli cell retains a significant capacity for activity, which is independent of direct hormonal regulation.