Development of the oviduct in quail during sexual maturation in relation to plasma concentrations of oestradiol and progesterone

The disparate origins of ovarian cancers: pathogenesis and prevention strategies

Ovarian cancer is the fifth cause of cancer-related death in women and comprises a histologically and genetically broad range of tumours, including those of epithelial, sex cord-stromal and germ cell origin. Recent evidence indicates that high-grade serous ovarian carcinoma, clear cell carcinoma and endometrioid carcinoma primarily arise from tissues that are not normally present in the ovary. These histogenetic pathways are informing risk-reduction strategies for the prevention of ovarian and ovary-associated cancers and have highlighted the importance of the seemingly unique ovarian microenvironment.

Effects of 3-Methyl-4-Nitrophenol in Diesel Exhaust Particles on the Regulation of Reproductive Function in Immature Female Japanese Quail (Coturnix japonica)

In a previous study, we found that 3-methyl-4-nitrophenol (PNMC), a component of diesel exhaust particles and also a degradation product of the insecticide fenitrothion, exhibits reproductive toxicity in the adult male Japanese quail. The present study investigated the toxicity of PNMC in the female Japanese quail and its ability to influence reproduction in immature females. The quail (21-day-old) were injected intramuscularly (im) with PNMC at doses 0.1, 1 or 10 mg/kg body weight daily for 3 days. There was no significant difference in body growth between the PNMC-administered and control birds. However, the weights of the oviducts were significantly lower in the PNMC-treated birds at all doses. Furthermore, the plasma concentrations of luteinizing hormone (LH) and estradiol-17 beta were significantly decreased with 1 and 10 mg/kg of PNMC. These findings suggest that PNMC might influence the hypothalamo-pituitary-gonadal axis with decreasing in secretion of GnRH, LH and ovarian steroid hormones and subsequently disturb growth of the reproductive organs of immature female quail. This study indicates that PNMC induces reproductive toxicity at the central level and disrupts reproductive function in the immature female quail.

Lack of effects of atrazine on estrogen-responsive organs and circulating hormone concentrations in sexually immature female Japanese quail (Coturnix coturnix japonica)

The widely used herbicide, atrazine, has been reported to exhibit reproductive toxicity in rats and amphibians. The present studies investigate toxicity of atrazine in Japanese quail and its ability to influence reproduction in sexually immature females. Atrazine was administered in the diet at concentrations from 0.001 to 1000 ppm (approximately 109 mg kg-1 per day) or systemically via daily subcutaneous injections (1 and 10 mg kg-1) or Silastic implants. Atrazine did not cause overt toxicity in sexually immature female quail (no effects on change in body weight, feed intake, mortality or on circulating concentrations of the stress hormone, corticosterone). It was hypothesized that if atrazine were to have estrogenic activity or to enhance endogenous estrogen production, there would be marked increases in the weights of estrogen sensitive tissues including the oviduct, the liver and the ovary together with changes in gonadotropin secretion. However, atrazine had no effect on either liver or ovary weights. Atrazine in the diet increased oviduct weights at 0.1 and 1 ppm in some studies. These effects were not consistently observed and were not significant when data from studies were combined. Systemic administration of atrazine had no effect on oviduct weights. Dietary (concentrations from 0.001 to 1000 ppm) and systemically administered atrazine had no effect on circulating concentrations of luteinizing hormone (LH). The present studies provide evidence for a lack of general or reproductive toxicity of atrazine in birds.

Immunohistochemical localization of the progesterone and oestrogen receptors in the shell gland of sexually immature ostriches (Struthio camelus) with active or inactive ovaries

The immunohistochemical localization of progesterone and oestrogen receptors was studied in the shell gland of the immature ostrich (Struthio camelus) during periods of ovarian activity and inactivity. In birds with active ovaries moderate to strong immunostaining for the progesterone receptor was observed in the surface epithelium and tubular glands. In contrast faint progesterone receptor immunostaining was observed in the surface epithelium of the shell gland in ostriches with inactive ovaries. In addition, bud-like invaginations of the surface epithelium, which signaled tubular gland development, were negative for the progesterone receptor. Oestrogen receptor immunostaining, which was seen only in birds with active ovaries, was weak and restricted to nuclei of the surface epithelium. These results suggest that steroid hormones secreted by the active ovary regulate the differentiation of the shell gland. Furthermore, the influence of these hormones on the shell gland appears to be mediated predominantly through the activation of the progesterone receptor.

Cloning of complementary deoxyribonucleic acids encoding quail (Coturnix coturnix japonica) retinoic acid receptor ss isoforms and changes in their gene expression during gonadotropic growth

Retinoids have important effects on the development of the reproductive system, where they act via their specific nuclear receptors: retinoic acid receptors (RARalpha, ss, gamma) and retinoid X receptors (RXRalpha, ss, gamma). The research reported here was conducted in an effort to clone quail RARbeta+ cDNA (qRARbeta) and to evaluate the expression of qRARbeta+ mRNAs in different tissues and during the development of gonadotropic organs. Two complete cDNAs of qRARbeta1 and qRARbeta2 were isolated by a combination of reverse transcription-polymerase chain reaction and 5'- and 3'-rapid amplification of cDNA ends techniques. An RNase protection assay revealed the widespread expression of qRARbeta1 and beta2 with large tissue-specific variations. The qRARbeta1 isoform was predominant in the testis, whereas qRARbeta2 was dominant in the other tissues examined with the exception of the brain, where both isoforms were almost equally expressed. In the developing testes, the qRARbeta1 mRNA level was high between 30 and 40 days of age, the period during which the testes grew rapidly. The level declined thereafter to its initial level. In contrast, qRARbeta2 mRNA did not exhibit obvious changes. In the developing oviducts, both qRARbeta1 and beta2 mRNAs reached their peak levels by 30 days of age, just before the rapid development of the oviduct occurred, and then decreased to almost undetectable levels when the oviduct developed to the laying stage (over 2.88 g in weight). Similar expression patterns of qRARbeta1 and beta2 were also observed in the developing follicles from the prehierarchical (<2-mm diameter) to the largest preovulatory follicle. In contrast, neither qRARbeta1 nor beta2 mRNA exhibited developmental changes in the brain. These results suggest that RARbeta+ may play an important role in the development of the reproductive systems of birds.

Oestradiol-induced changes in the composition of phospholipid classes of quail oviduct: specific replacement of arachidonic acid by docosahexaenoic acid in alkenylacyl-glycerophosphoethanolamine

The phospholipid composition and the molecular species of the major subclasses of ethanolamine and choline glycerophospholipids were determined during the natural or oestradiol-induced development of the quail oviduct. The phospholipid concentration increased significantly during oviduct development, and the proportion of ethanolamine glycerophospholipids (EPL) remained constant while that of choline glycerophospholipids increased. The immature oviduct contained the majority of its endogenous arachidonic acid mass (71%) in EPL, mainly in alkenylacyl-glycerophosphoethanolamine (alkenylacyl-GPE) (49% of the total). Oestrogen treatment induced the depletion of 20:4,n-6 specifically from this pool, which indicates the biological importance of 20:4,n-6 molecular species in alkenylacyl-GPE as substrates for the oviduct phospholipases activated by oestradiol, and suggests that this EPL subclass is involved in the oestrogen-induced cell proliferation. Another striking result was the marked increase in 22:6,n-3 EPL molecular species following the oestradiol treatment and more particularly the strict substitution of 20:4,n-6 by 22:6,n-3 in alkenylacyl-GPE. We speculate that alkenylacyl-GPE molecular species containing 22:6,n-3 may participate in the arrest of oestrogen-induced proliferation.

Changes in plasma concentrations of reproductive steroids in female Japanese quail (Coturnix coturnix japonica) raised on long or short photoperiods

Plasma concentrations of progesterone, testosterone, estradiol, and estrone were measured by radioimmunoassay in female Japanese quail 22 to 70 days of age. The birds were raised on long (16 hr light per day) or short (8 hr light per day) photoperiods. Only the birds raised on the long photoperiod layed eggs, starting between 42 and 49 days of age. The concentration of each reproductive steroid increased between 28 and 35 days of age, but the increases were more substantial in the birds raised on long days than in the birds raised on short days. Changes in plasma progesterone and testosterone concentrations showed similar trends: the concentrations increased before the onset of lay and were maintained at a high level in the laying birds. In contrast, plasma concentrations of estradiol and estrone increased to a peak at 35-42 days and declined once egg laying became established. The short-day birds also showed increased plasma estrogen levels, maximal at 35-42 days, with estrone being at a higher concentration than estradiol. The increases in plasma steroid levels occurred during the period of rapid growth of the ovaries and oviducts in the long-day birds, although in the short-day birds the growth of these organs was much less substantial.