Gonadal Proliferation Research Articles

Irinotecan (CPT-11) Treatment Induces Mild Gonadotoxicity.

Background:Gonadal toxicity following chemotherapy is an important issue among the population of young cancer survivors. The inhibitor of DNA topoisomerase I, irinotecan (CPT-11), is widely used for several cancer types. However, little is known about the effect of irinotecan on the fertility of both genders. Thus, the aim of the present study was to evaluate irinotecan gonadotoxicity, using a mouse model.MethodsMature male and female mice were injected intraperitoneally with either saline (), irinotecan (100 mg/kg) or cyclophosphamide (100 mg/kg); and sacrificed one week or three months later for an acute or long-term toxicity assessment, respectively. We used thorough and advanced fertility assessment by already established methods: Gonadal and epididymal weights, as well as sperm count and sperm motility were determined; serum anti-Müllerian hormone (AMH) was measured by ELISA. Immunohistochemistry (Ki-67), immunofluorescence (PCNA, CD34), terminal transferase-mediated deoxyuridine 5-triphosphate nick-end labeling (TUNEL) and computerized analysis were performed to examine gonadal proliferation, apoptosis and vascularization. qPCR was used to assess the amount of testicular spermatogonia (Id4 and Gafra1 mRNA) and ovarian primordial oocytes reserves (Sohlh2, Nobox and Figla mRNA).ResultsFemales: Irinotecan administration induced acute ovarian apoptosis and decreased vascularity, as well as a mild, statistically significant, long-term decrease in the number of growing follicles, ovarian weight, and ovarian reserve. Males: Irinotecan administration caused an acute testicular apoptosis and reduced testicular spermatogenesis, but had no effect on vascularity. Irinotecan induced long-term decrease of testicular weight, sperm count and testicular spermatogonia and caused elevated serum AMH.ConclusionOur findings imply a mild, though irreversible effect of irinotecan on mice gonads.

Seasonal variations in gonad morphology and hypothalamic GnRH-I and GnIH in Eurasian Tree Sparrow, a multi-brooded passerine

The hypothalamic-pituitary-gonadal (HPG) axis ubiquitously regulates seasonal reproduction, following the rhythmicity of a suite of environmental cues. Birds display prominent seasonal variations in gonad size regulated by two hypothalamic peptides, gonadotropin-releasing hormone-1 (GnRH-I) and gonadotropin-inhibiting hormone (GnIH). How multi-brooded avian species adjust GnRH-I and GnIH to regulate gonadal morphology seasonally remains largely unknown. Here, we studied the variations in the hypothalamic immunoreactivity (ir) of GnRH-I and GnIH, gonadal proliferation, and apoptosis in a typical multi-brooded species, the Eurasian Tree Sparrow (Passer montanus), across the pre-breeding (PB), first breeding (FB), second breeding (SB), pre-basic molt (PM), and wintering stages (WS). Our results showed that both sexes had higher preoptic area (POA)-GnRH-I-ir but lower paraventricular nucleus (PVN)-GnIH-ir neurons during the breeding stages (FB and SB) relative to other life-history stages, with no significant differences between two broods. The testes and ovaries were significantly larger during the breeding stages. Testicular volume increased during the two broods due to anincreased diameter of seminiferous tubules. Furthermore, there were more testicular apoptotic cells in PB and WS stages than in breeding stages, and in PB stage than in PM stage. Males had higher POA-GnRH-I expression than females during the breeding stages, but both sexes had comparable PVN-GnIH expression throughout the annual cycle. Both sexes of the sparrows may undergo a similar pattern of life-history stage-dependent variation in the hypothalamic GnRH-I, GnIH, and gonadal morphology, except that during breeding stages, males may display higher expression of POA-GnRH-I relative to females. The higher expression of POA-GnRH-I-ir in breeding male sparrows may be critical for male-dependent parental care.

In vivo effects of GnRH peptide on gonadal proliferation and related gene expression of Pacific abalone, Haliotis discus hannai

Gonadotropin-releasing hormone (GnRH) is a key hypothalamic neuropeptide regulating the reproductive function of vertebrates and invertebrates. In the present study, we report the role of GnRH in gamete cell proliferation of Pacific abalone, Haliotis discus hannai using BrDU incorporation, and analyzed the expression of reproductive responsive genes. In vivo injection of buserelin and H. discus hannai GnRH peptides (GnRH-I and GnRH-II) at doses of 250 and 500 ng/g BW resulted in a significant increases in the number of testicular and ovarian proliferating cells. Administration of GnRH peptide at higher doses was less effective in stimulating gonadal cell proliferation. A qPCR analysis revealed that the mRNA expression of GnRH, GnRH-R, and serotonin-R was elevated in the male gonad compared with female gonad in all treatment groups. Compared with control and other treatment groups, the expression profile of GnRH, GnRH-R, and serotonin-R was significantly higher after treatment with buserelin and synthetic GnRH peptides at doses of 250 ng/g BW in both male and female gonad. However, the gonadal tissues expressed lower levels of mRNA following the treatment with GnRH peptide at the higher dose (1000 ng/g BW). Furthermore, the results of comet assay demonstrated that gonadal cells did not show significant differences in the average level of fragmented DNA and tail length between control and treated groups. Taken together, these findings suggest that administration of GnRH peptide at a concentration of 250 ng/g BW effectively accelerated the gametogenesis of abalone. This strategy will enhance the benefits of breeding technology in this species, or may useful for increasing the aquaculture production.

Nr0b1 (DAX1) mutation in zebrafish causes female-to-male sex reversal through abnormal gonadal proliferation and differentiation

Sex determinations are diverse in vertebrates. Although many sex-determining genes and pathways are conserved, the mechanistic roles of these genes and pathways in the genetic sex determination are not well understood. DAX1 (encoded by the NR0B1 gene) is a vertebrate specific orphan nuclear receptor that regulates gonadal development and sexual determination. In human, duplication of the NR0B1 gene leads to male-to-female sex reversal. In mice, Nr0b1 shows both pro-testis and anti-testis functions. We generated inheritable nr0b1 mutation in the zebrafish and found the nr0b1 mutation caused homozygous mutants to develop as fertile males due to female-to-male sex reversal. The nr0b1 mutation did not increase Caspase-3 labeling nor tp53 expression in the developing gonads. Introduction of a tp53 mutation into the nr0b1 mutant did not rescue the sex-reversal phenotype. Further examination revealed reduction in cell proliferation and abnormal somatic cell differentiation in the nr0b1 mutant gonads at the undifferentiated and bi-potential ovary stages. Together, our results suggest nr0b1 regulates somatic cell differentiation and cell proliferation to ensure normal sex development in the zebrafish.

Melatonin control of oogenesis and metabolic resources in Zebrafish

Summary The aim of this manuscript is to study the effects of two different doses of melatonin (100 nm and 1 μm) on fecundity in zebrafish females. In addition, an overview of the mechanisms controlling the energy balance and reproduction in fish was provided. At molecular level the expression of cyclo-oxygenase 2A (Cox2A) gene, involved in ovulation control, Leptin and GHrelin, apparently involved in gonadal proliferation and steroidogenesis control, were evaluated by Real Time PCR in class IIIb oocytes. Besides, melatonin role in metabolic resources regulation was here assessed through FT-IR Spectroscopy. Fecundity was positively affected by both doses of exogenous melatonin and the improvement was associated to the increase of Cox2A gene expression. The improvement of fecundity was concomitant with the increase of Leptin gene expression in class IIIb oocyte, the increase was significantly higher only with the higher dose of melatonin, while a significant increase of GHrelin gene expression was found with the lower dose of melatonin. Moreover, a modulation on carbohydrates and lipids metabolism was observed in muscle tissue after melatonin treatment.

The development of the female gamete in the endosymbiont-bearing bivalve Loripes lucinalis

The development of the female gonad in Loripes lucinalis (Lamarck) from Brest Harbour (Brittany, France) was examined over a one-year period. Throughout the year, several size classes of eggs were observed, and spawning was seen to occur twice. A major spawning occurred in May leaving the gonad completely empty in June. A minor spawning is also thought to have occurred between the November and December sampling periods. These spawnings do not seem to correlate with the classical environmental factors often associated with gametogenesis and spawning, namely temperature and chlorophyll a levels. The energy for gametogenesis seems to be obtained from the transfer of metabolites to the oocytes via specialized follicle cells. These metabolites are believed to be of heterosynthetic origin. An inverse relationship exists between the thickness of the follicle cell epithelium and the occupancy level of the gametes. During periods of gonadal proliferation, these cells represent the nutritive cells of the gonad, but during periods of non-proliferation they make up a somatic tissue used for metabolite storage until conditions are adequate for gonadal development.

Reproductive cycle of the supralittoral gastropodLittorina kraussi(Rosewater, 1970)

The reproductive cycle of Littorina kraussi was determined on the basis of changes in gonadal histology over a 14-month period. This animal is dioecious, the sexes being evenly distributed both in terms of numbers and size. Despite some asynchrony within the population, L. kraussi showed a well defined reproductive cycle. Gonadal proliferation took place from August to January with peak spawning taking place from December to March.

Primordial germ cells and early stages of oogenesis in Ophryotrocha puerilis (Polychaeta, Dorvillediae)

Each setigerous segment of the protandric polychaete Ophryotrocha puerilis contains two primordial germ cells. A ventral furrow in the gut wall together with the peritoneal lining of the gut forms a genital blood vessel. The gonocytes are located within the peritoneum of this genital blood vessel. At sexual maturity the gonocytes undergo a proliferation cycle, the first division of which gives rise to a cell which is extruded into a forming outpocketing of the coelomic lining. The stem cell remains within the peritoneum. Inside the forming gonad the detached cell goes through a series of four mitotic divisions. The resulting 16 cells are interconnected by cytoplasmic bridges. These bridges are arranged in a very regular pattern which allows the mitotic cycles to be followed. While remaining still within the gonad the 16 cells begin to synthesize yolk and to take up exogenous yolk precursors. At this stage a differentiation into oocytes and nurse cells becomes visible. The oocytes deposit yolk platelets of the definitive size whereas the polyploid nurse cells produce only small yolk bodies that are passed to the adjacent oocytes. In a later stage the cell bridges between adjacent nurse cells are cut and pairs of one oocyte and one nurse cell are released to the coelomic cavity during breakdown of the gonadal sac. Oocyte-nurse cell-complexes then freely float in the coelomic fluid. The proliferation of gonadal cells is well synchronized within one segment. In anterior segments, however, gonadal proliferation usually begins earlier than in posterior segments but smaller oocytes in posterior segments catch up within a few days. Finally a batch of oocytes is produced in which all the oocytes are of the same size (120 μm). The origin of the primordial germ cells remains unknown.

EFFECTS OF TEMPERATURE AND LIGHT ON THE CYCLICAL CHANGES IN THE SPERMATOGENETIC ACTIVITY OF THE LAKE CHUB, COUESIUS PLUMBEUS (AGASSIZ)

Lake chub obtained from their natural habitat, at three different periods of their annual reproductive cycle, were subjected to four combinations of photoperiod and temperature. Temperature is the major environmental factor controlling spermatogenesis. Higher temperatures (16–21 °C) promote prespermatocytal changes (proliferation of spermatogonia) and hasten or terminate spermiation in prespawning fish; low temperatures (5–12 °C) are essential for normal gonadal proliferation and formation of the primary spermatocytes. Temperature effects are not overridden by either of the two contrasting photoperiods, but at lower temperatures a definite, although slight, photoperiodic effect is evident in the terminal part of all three experiments, Photoperiod does not appear to dominate spermatogenetic processes at any stage. Evidence is presented that an endogenous rhythm of activity is also present and may be partly responsible for the timing of the various testicular changes.