Short photoperiods reduce vascular endothelial growth factor in the testes of Peromyscus leucopus

Hypoxia, NSAIDs, and autism: A biocultural analysis of stressors in gametogenesis

Cultural and generational trends have increasingly favored "anti-inflammatory" action, innovating a new class of analgesic, non-steroidal anti-inflammatory drugs (NSAIDs) in the 20th century. The modern human body has been molded over evolutionary time and while acknowledging inflammation can be pathologically entwined, it also serves an important role in healthy folliculogenesis and ovulation, shaping cues that drive needed vascular change. This review argues that because of anti-inflammatory action, the cultural invention of NSAIDs represents a particular stressor on female reproductive-age bodies, interacting with natural, underlying variation and placing limits on healthy growth and development in the follicles, creating potential autism risk through hypoxia and mutagenic or epigenetic effects. Since testes are analogs to ovaries, the biological grounding extends naturally to spermatogenesis. This review suggests the introduction of over-the-counter NSAIDs in the 1980s failed to recognize the unique functioning of reproductive-age bodies, challenging the cyclical inflammation needed for healthy gamete development. NSAIDs are framed as one (notable) stressor in an anti-inflammatory era focused on taming the risks of inflammation in modern human life.

Vascular endothelial growth factor (VEGF-A) and fibroblast growth factor (FGF-2) as potential regulators of seasonal reproductive processes in male European bison (Bison bonasus, Linnaeus 1758)

Growth factors: vascular endothelial growth factor A (VEGF-A) and fibroblast growth factor (FGF-2) were reported to affect normal physiological reproductive processes in human, domestic and free living animals. Moreover, some reports suggest that VEGF-A and FGF-2 may be directly involved in the control of the annual reproductive cycle of seasonally breeding animals but detailed knowledge is still missing. Our study aimed to demonstrate the expression of mRNA and protein for both factors in the tissues of testis and epididymis (caput, corpus, cauda) at different periods of the year (March, June, November, December) in European bison as a model of seasonally breeding animal. Results suggest, that VEGF-A expression was more pronounced in testis than in epididymis and the highest expression was noted in December and June. Surprisingly, the highest protein accumulation was observed in June at the same level in all tissues analyzed. On the other hand, the highest FGF-2 mRNA expression was noted in testis in June and in epididymis in March. However, no differences in protein expression of FGF-2 were found between analyzed groups. The results indicate that both factors are necessary for proper functioning of the reproductive system and their levels differ seasonally. Perhaps, it is linked to increased need of these factors in the testis as well as epididymis during preparation for the reproductive functions. Moreover, VEGF-A and FGF-2 not only may regulate reproductive functions by affecting vascularization and cell nutrition, but it also may be possible that they possess protective functions by stabilizing the reproductive cells. Therefore, obtained results provide new insight into mechanisms underlying seasonal breeding of the male European bison.

Matrix metalloproteinase inhibition influences aspects of photoperiod stimulated ovarian recrudescence in Siberian hamsters

Blocking matrix metalloproteinase (MMP) activity in vivo with inhibitor GM6001 impedes photostimulated ovarian recrudescence in photoregressed Siberian hamsters. Since direct and indirect effects of MMPs influence a myriad of ovarian functions, we investigated the effect of in vivo MMP inhibition during recrudescence on ovarian mRNA expression of steroidogenic acute regulatory protein (StAR), 3β-hydroxysteroid dehydrogenase (3β-HSD), Cyp19a1 aromatase, epidermal growth factor receptor (EGFR), amphiregulin (Areg), estrogen receptors (Esr1 and Esr2), tissue inhibitors of MMPs (TIMP-1,-2,-3), proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor A (VEGFA), its receptor VEGFR-2, and angiopoietin-2 (Ang-2). Female Siberian hamsters were randomly assigned to one of four photoperiod groups: stimulatory long (LD) or inhibitory short (SD) photoperiods, or transferred from SD to LD for 2 weeks (post-transfer, PT). Half of the PT hamsters were injected (ip) daily with GM6001 (PTG). SD exposure reduced ovarian StAR, 3β-HSD, Cyp19a1, Esr1, Esr2, TIMPs 2-3, PCNA, VEGFR-2 and Ang-2 mRNA expression (p<0.05), and 2 weeks of photostimulation restored mRNA expression of 3β-HSD and PCNA and increased Areg and VEGFA mRNA expression in the PT group. GM6001 treatment during photostimulation (PTG) increased TIMP-1, -2 and -3 and PCNA mRNA, but inhibited Areg mRNA expression compared to PT. Neither photoperiod nor GM6001 altered EGFR expression. Results of this study suggest that in vivo inhibition of MMP activity by GM6001 may impede ovarian recrudescence, particularly follicular growth, in two ways: (1) directly by partially inhibiting the release of EGFR ligands like Areg, thereby potentially affecting EGFR activation and its downstream pathway, and (2) indirectly by its effect on TIMPs which themselves can affect proliferation, angiogenesis and follicular growth.

Seasonal Changes in Testes Vascularisation in the Domestic Cat (Felis domesticus): Evaluation of Microvasculature, Angiogenic Activity, and Endothelial Cell Expression

Some male seasonal breeders undergo testicular growth and regression throughout the year. The objective of this study was to understand the effect of seasonality on: (i) microvasculature of cat testes; (ii) angiogenic activity in testicular tissue in vitro; and (iii) testicular endothelial cells expression throughout the year. Testicular vascular areas increased in March and April, June and July, being the highest in November and December. Testes tissue differently stimulated in vitro angiogenic activity, according to seasonality, being more evident in February, and November and December. Even though CD143 expression was higher in December, smaller peaks were present in April and July. As changes in angiogenesis may play a role on testes vascular growth and regression during the breeding and non-breeding seasons, data suggest that testicular vascularisation in cats is increased in three photoperiod windows of time, November/December, March/April and June/July. This increase in testicular vascularisation might be related to higher seasonal sexual activity in cats, which is in agreement with the fact that most queens give birth at the beginning of the year, between May and July, and in September.

Vascular endothelial growth factor A is a putative paracrine regulator in seasonally controlled spermatogenesis: insights from a ruminant model, the roe deer

Vascular endothelial growth factor A (VEGFA) influences spermatogenesis, but its impact on seasonally regulated sperm production is still not fully understood. Thus, we investigated both expression levels and localisation of VEGFA and its receptors VEGFR1 and 2 in roe buck testis via real-time reverse transcription polymerase chain reaction and immunohistochemistry in relation to seasonal changes in the cellular composition of the testis. VEGFA was expressed by interstitial cells while its receptors were found on endothelial and perivascular cells. Inside the tubules, VEGFA was located in spermatogonia and spermatocytes, VEGFR1 was present on elongating spermatids and VEGFR2 on Sertoli cells. VEGFR1 mRNA was expressed tenfold lower than VEGFR2 and VEGF mRNAs. Relative VEGF and VEGFR2 expression (divided by the number of VEGFA and VEGFR2 expressing cells) showed an increase towards the rut (July/August) and a decrease thereafter. The results suggest involvement of VEGFA in the adjustment of vascular permeability as well as in spermiogenesis and the proliferation of spermatogonia.

Experimental ischaemia-reperfusion injury induces vascular endothelial growth factor expression in the rat testis

Testicular torsion causes ischaemia-reperfusion (I-R) injury of testis and might lead to male infertility. Its injury initiates a pathophysiological cascade, including an activation of inflammatory cytokines and generation of nitric oxide and other reactive oxygen species. Vascular endothelial growth factor (VEGF) mediates angiogenesis and promotes endothelial cell survival. The aim of our study was to investigate the time course expression of VEGF, VEGF-receptor (R)1, VEGF-R2, nitric oxide synthases (NOS) in experimental I-R injury of rat testis. In torsion side testis, the expression of VEGF protein and mRNA significantly increased in a time-dependent manner (P < 0.001 and P < 0.001, respectively). Although the expression of VEGF-R1 mRNA was increased in a similar way (P < 0.001), VEGF-R2 mRNA expression was not detected. In immunohistochemistry, the increase in VEGF protein staining was observed in testicular vascular endothelial cells and germ cells at 24 h after reperfusion. Significant activation of inducible NOS and endothelial NOS was investigated at 12 and 24 h after reperfusion (P < 0.01 and P < 0.001, respectively). This is the first report to show the time course expression of VEGF in experimental I-R rat testis.

Sertoli cells enhance formation of capillary-like structures in vitro

Sertoli cells isolated from the testis (referred to as extratesticular Sertoli cells) have been shown to facilitate allo- and xenogeneic cell transplantations. It appears likely that the ability of these cells to enhance the success of cell engraftment is due, in part, to the retention of their intratesticular functions of trophic support and immunoprotection. Sertoli cells also are involved in the regulation of angiogenesis in the testis, which may also contribute to enhanced cell engraftment success facilitated by extratesticular Sertoli cells. Because the maintenance of the cell's intratesticular angiogenic function has not yet been evaluated for extratesticular Sertoli cells, this study examined the cell's ability to enhance angiogenesis in vitro. Sertoli cell conditioned media were derived from isolated rat Sertoli cell cultures and used in a rat aortic model of induced angiogenesis, in endothelial and smooth muscle cell monocultures, and in endothelial smooth muscle cocultures. An angiogenic rat cytokine array identified angiogenic factors in the control and conditioned media. Aorta sections incubated with Sertoli cell conditioned media showed a marked increase in the formation of capillary-like structures when compared to controls. Likewise, endothelial cells incubated in conditioned media organized into capillary-like structures not observed when incubated in control media. In coculture, smooth muscle cells were associated with endothelial cell-derived capillary-like structures only when incubated in conditioned media. Cytokine arrays indicated the presence and a qualitative increase of specific angiogenic growth factors in Sertoli cell conditioned media not observed in control media. Results indicate that extratesticular Sertoli cells retain their intratesticular angiogenic function in vitro.

Short photoperiod-induced ovarian regression is mediated by apoptosis in Siberian hamsters (Phodopus sungorus)

Siberian hamster reproduction is mediated by photoperiod-induced changes in gonadal activity. However, little is known about how photoperiod induces cellular changes in ovarian function. We hypothesized that exposing female hamsters to short (inhibitory) as opposed to long (control) photoperiods would induce an apoptosis-mediated disruption of ovarian function. Ovaries and plasma from hamsters exposed to either long (LD, 16 h light:8 h darkness) or short (SD, 8 h light:16 h darkness) days were collected during diestrus II after 3, 6, 9 and 12 weeks and processed for histology or RIA respectively. Apoptosis was assessed by in situ TUNEL and active caspase-3 protein immunolabeling. No significant differences were observed among LD hamsters for any parameter; therefore, these control data were pooled. SD exposure induced a decline in preantral follicles (P < 0.05), early antral/antral follicles (P < 0.01) and corpora lutea (P < 0.01) by week 12 as compared with LD. Terminal atretic follicles appeared by SD week 9; by week 12, these had become the predominant ovarian structures. Estradiol concentrations decreased by weeks 9 and 12 SD when compared with both LD and week-3 SD hamsters (P < 0.05); however, no changes were observed for progesterone. TUNEL-positive follicles in SD ovaries increased at week 3 and subsequently declined by week 12 as compared with LD ovaries (P < 0.01). Active capsase-3 protein immunostaining peaked at SD week 3 as compared with all other groups (P < 0.01). TUNEL and capsase-3 immunolabeling were localized to granulosa cells of late-preantral and early-antral/antral follicles. These data indicate that SD exposure rapidly induces follicular apoptosis in Siberian hamsters, which ultimately disrupts both estradiol secretion and folliculogenesis, resulting in the seasonal loss of ovarian function.

Hormonal Regulation and Functional Role of Vascular Endothelial Growth Factor A in the Rat Testis1

Vascular endothelial cell growth factor (VEGF-A) is synthesized in the testis but its role and regulation in this organ have not been examined. VEGF and its receptors (VEGF-R) were quantified using reverse transcription-polymerase chain reaction and Western blot. VEGF, VEGF-R1, and VEGF-R2 mRNAs and VEGF protein were increased after treatment with 50 IU hCG. Injection of 100 ng human recombinant VEGF 165 into the testis caused an increase in endothelial cell proliferation, but only a moderate increase in testicular interstitial fluid volume. In contrast with systemic hCG treatment, local VEGF injection did not increase the permeability to intravenously injected colloidal carbon particles. However, if VEGF was given locally in the testes of animals pretreated with hCG 4 or 8 h earlier, VEGF acted in synergy with hCG to increase vascular carbon leakage by forming interendothelial cell gaps. Testicular blood flow was unaffected by local VEGF 165 injection. Treatment with a specific VEGF-R2 tyrosine kinase inhibitor blocked the hCG-induced increase in endothelial cell proliferation but did not affect the hCG-induced accumulation of polymorphonuclear leukocytes in testicular blood vessels or the increase in the testicular interstitial space. The present study demonstrated that testicular VEGF secretion is increased by hormonal stimulation of Leydig cells and that VEGF, through effects mediated via VEGF-R2, regulates endothelial cell proliferation in the rat testis. VEGF does not appear to regulate testicular blood flow and it is not involved in inducing the hCG-induced inflammation-like response in the testicular microvasculature. The permeability-increasing effect of VEGF is low in the testis under basal conditions but is apparently up-regulated by hCG treatment.

Stage-specific and tissue-specific expression characteristics of differentially expressed genes during mouse spermatogenesis

Spermatogenesis occurs in successive mitotic, meiotic, and post-meiotic phase, and involves a number of unique processes including meiosis and dramatic morphological changes. The unique differentiation mechanisms of spermatogenesis suggest the existence of germ-cell-specific molecules. The most straight forward strategy to elucidate differentiation mechanisms is to identify and characterize differentiation-specific molecules and their associated genes in germ cells. However, only a few genes specifically involved in spermatogenesis have been studied. In the present study, six different types of spermatogenic cells (primitive type A spermatogonia, type B spermatogonia, preleptotene spermatocytes, pachytene spermatocytes, round spermatids, and elongating spermatids) were isolated from Balb/c mice testes using velocity sedimentation and Atlas cDNA arrays containing 1,176 known mouse genes were used to determine the gene expression profiles of the spermatogenic cells. The expression of 260 genes were detected in six different stages of spermatogenic cells and a number of genes showed differential expression. The 23 differentially expressed genes were further analysed by reverse transcription polymerase chain reaction (RT-PCR) for their stage-specific and tissue-specific expression characteristics. Based on the results of RT-PCR, six genes highly express in both primitive type A and type B spermatogonia, four genes up-regulate in type B spermatogonia, two genes up-regulate in spermatocytes, two genes up-regulate in spermatids, three genes express constantly from primitive A spermatogonia to elongating spermatids, two genes express constantly from primitive A spermatogonia to round spermatids, two genes do not change in their expression during spermatogenesis, two genes can be detected highly in adult testis, but are undetectable in spermatogenic cells. The tissue-specific expression characteristics of the 23 genes showed that some of them specifically expressed in testes or other tissues. These data provide new information for further studies into spermatogenesis-related genes and may lead to the identification of genes with potential relevance to the differentiation of spermatogenic cells. In addition, some of these genes could be considered to be used as the molecular markers for different stages of spermatogenic cells.