Possible roles for prostaglandins E2 and F2 alpha in seasonal changes in ovarian steroidogenesis in the frog (Rana esculenta).

Concentrations of PGE2, PGF2 alpha, androgens and oestradiol in plasma, and ovary weights were measured in the female frog, Rana esculenta, during the annual breeding cycle. Experiments were carried out in vivo to study the effects of PGE2 and PGF2 alpha on plasma sex steroids during the following stages: pre-reproduction (April), reproduction (May), post-reproduction (June) and recovery (October). Experiments were performed in vitro during these stages to evaluate the effects of these two prostaglandins on the secretion of ovarian steroids. Concentrations of PGE2 were low in plasma during winter hibernation, the reproduction and post-reproduction stages, whereas they were high during the pre-reproduction and recovery stages. PGE2 treatment in vivo increased androgen secretion in April, whereas PGF2 alpha treatment increased oestradiol secretion in June and October. In experiments in vitro, PGE2 increased androgen secretion and decreased oestradiol secretion from ovaries collected in April, whereas PGF2 alpha increased oestradiol secretion from ovaries collected in October. These results suggest that a seasonal increase in plasma PGE2 may inhibit breeding activity, probably by stimulating ovarian androgen secretion, whereas, as previously reported, a seasonal increase in plasma PGF2 alpha may inhibit breeding, by stimulating ovarian oestradiol secretion

Hormonal and cellular brain mechanisms regulating the amplexus of male and female water frog (Rana esculenta)

The role of nitric oxide (NO) synthase, prostaglandin E2-9-ketoreductase, and aromatase brain activities in regulating frog amplexus was assessed in the water frog (Rana esculenta). Plasma concentrations of testosterone were higher, and concentrations of 17beta-oestradiol lower, in amplexing males than in unamplexing males; while concentrations of testosterone and PGE2 were lower, and those of 17beta-oestradiol and PGF2alpha higher, in amplexing females compared to unamplexing females. Hormone release rescued from frog brains in vitro mirrored plasma hormone measures. Brain aromatase activity was lower in amplexing males; NO synthase was lower and PGE2-9-ketoreductase and aromatase were higher in amplexing females. In male brains, PGE2-9-ketoreductase inhibitor decreased PGF2alpha release and increased that of PGE2; aromatase inhibitor decreased 17beta-oestradiol and increased testosterone release. In female brains, NO donor and PGE2-9-ketoreductase inhibitor increased testosterone and PGE2 release and decreased that of 17beta-oestradiol and PGF2alpha; NO synthase inhibitor decreased testosterone release and PGE2 and increased 17beta-oestradiol and PGF2alpha release; PGF2alpha decreased testosterone release and increased 17beta-oestradiol release; aromatase inhibitor decreased 17beta-oestradiol release and increased testosterone release. In female brains, NO donor and PGE2-9-ketoreductase inhibitor decreased PGE2-9-ketoreductase and aromatase activities; PGF2alpha increased aromatase activity; NO synthase inhibitor increased PGE2-9-ketoreductase and aromatase activity. The data suggest that, in amplexing female brains, external and/or internal stimuli inhibit NO synthase, decreasing NO and activating PGE2-9-ketoreductase; in turn, PGF2alpha increases aromatase activity and 17beta-oestradiol release; while, in amplexing male brains, stimuli inhibit aromatase activity, thereby increasing testosterone production

Prisutnost imunoreaktivnih ciklooksigenaza u sjemenskim kanalićima i nuzjajima u alpaka prije spolne zrelosti i odraslih alpaka (Lama pacos).

In this study, we report the cell specific expression of cyclooxygenase (COX) enzymes, COX1 and COX2, in the ductuli efferentes and epididymis of prepubertal and adult alpaca. COX1 weakly stained the cytoplasm of epithelial cells lining the ductuli efferentes and the epididymal corpus, whereas these cells were immunonegative in the epididymal caput and cauda. In adults, we observed an increase in the immunsignals for COX1 in the cytoplasm of epithelial cells lining the ductuli efferentes and all the epididymal regions. In prepubertal alpaca, immunoreactivity for COX2 was not revealed in the epithelial cells lining the ductuli efferentes and epididymal regions, whereas it was evidenced in adult animals. The apical rich mithocondria cells immunoreacted only with COX1 in the epididymis of prepubertal animals, whereas they expressed both COX1 and -2 in the adult alpaca. Our results suggest that COXs may play a role in the pubertal development of the excurrent duct system of the alpaca.Istražena je stanično specifična ekspresija enzima ciklooksigenaza COX1 i COX2 u sjemenim kanalićima i nuzjaju u alpaka prije spolne zrelosti i odraslih alpaka. Slaba aktivnost COX1 dokazana je u citoplazmi epitelnih stanica sjemenih kanalića i tijela nuzjaja dok su iste stanice bile imunološki negativne u glavi i repu nuzjaja. U odraslih je opaženo povećanje imunosnog signala za COX1 u citoplazmi bazalnih epitelnih stanica sjemenih kanalića i cijelog područja nuzjaja. U alpaka prije spolne zrelosti, imunoreaktivnost za COX2 se nije vidjela u epitelnim stanicama sjemenih kanalića i nuzjajima kao što je to bilo kod odraslih životinja. Apikalne stanice bogate mitohondrijima reagirale su samo na COX1 u nuzjajima životinja prije spolne zrelosti dok je ekspresija i COX1 i COX2 opažene u odraslih alpaka. Rezultati ukazuju na moguću ulogu ciklooksigenaza u razvoju razgranatog sustava kanalića prije spolne zrelosti u alpaka

Nitric oxide synthase acutely regulates progesterone production by in vitro cultured rabbit corpora lutea

We examined the presence and the regulation of nitric oxide (NO) synthase (NOS) using in vitro cultured corpora lutea (CL) obtained from rabbits at days 4 and 9 of pseudopregnancy. The role of NO and NOS on steroidogenesis was also investigated using the same CL preparations after short-term incubations (30 min and 2 h) with the NO donor, sodium nitroprusside (NP), the NOS inhibitor, Nomega-nitro-l-arginine methyl ester (l-NAME) and prostaglandin (PG) F-2alpha. The basal NOS activity was greater in CL at day 4 than at day 9, and was also differently modulated by PGF-2alpha, depending on the age of the CL. The addition of PGF-2alpha to day 4 CL had no effect, but PGF-2alpha on day 9 caused a threefold increase in NOS activity. NP caused a two- to fivefold decrease in release of progesterone from CL of both ages, and this inhibitory effect on steroidogenesis was reversed by l-NAME. All treatments failed to modify basal androgens and 17beta-oestradiol was not detectable in either control or treated CL. These results suggest that NO is effectively involved in the regulation process of steroidogenesis, independently of 17beta-oestradiol. PGF-2alpha had no effect on day 4, but induced luteolysis on day 9, by reducing progesterone (P</=0. 01) to about 18% of control. The luteolytic action of PGF-2alpha was completely reversed by co-incubation with l-NAME, thus supporting the hypothesis that luteolysis is mediated by NO. The addition of NP or l-NAME did not modify the in vitro release of PGF-2alpha. We hypothesised that PGF-2alpha upregulates NOS activity and, consequently, the production of NO, which acutely inhibits progesterone release from day 9 CL of pseudopregnant rabbits

Prisutnost imunoreaktivnih ciklooksigenaza u sjemenskim kanalićima i nuzjajima u alpaka prije spolne zrelosti i odraslih alpaka (Lama pacos).

In this study, we report the cell specific expression of cyclooxygenase (COX) enzymes, COX1 and COX2, in the ductuli efferentes and epididymis of prepubertal and adult alpaca. COX1 weakly stained the cytoplasm of epithelial cells lining the ductuli efferentes and the epididymal corpus, whereas these cells were immunonegative in the epididymal caput and cauda. In adults, we observed an increase in the immunsignals for COX1 in the cytoplasm of epithelial cells lining the ductuli efferentes and all the epididymal regions. In prepubertal alpaca, immunoreactivity for COX2 was not revealed in the epithelial cells lining the ductuli efferentes and epididymal regions, whereas it was evidenced in adult animals. The apical rich mithocondria cells immunoreacted only with COX1 in the epididymis of prepubertal animals, whereas they expressed both COX1 and -2 in the adult alpaca. Our results suggest that COXs may play a role in the pubertal development of the excurrent duct system of the alpaca.Istražena je stanično specifična ekspresija enzima ciklooksigenaza COX1 i COX2 u sjemenim kanalićima i nuzjaju u alpaka prije spolne zrelosti i odraslih alpaka. Slaba aktivnost COX1 dokazana je u citoplazmi epitelnih stanica sjemenih kanalića i tijela nuzjaja dok su iste stanice bile imunološki negativne u glavi i repu nuzjaja. U odraslih je opaženo povećanje imunosnog signala za COX1 u citoplazmi bazalnih epitelnih stanica sjemenih kanalića i cijelog područja nuzjaja. U alpaka prije spolne zrelosti, imunoreaktivnost za COX2 se nije vidjela u epitelnim stanicama sjemenih kanalića i nuzjajima kao što je to bilo kod odraslih životinja. Apikalne stanice bogate mitohondrijima reagirale su samo na COX1 u nuzjajima životinja prije spolne zrelosti dok je ekspresija i COX1 i COX2 opažene u odraslih alpaka. Rezultati ukazuju na moguću ulogu ciklooksigenaza u razvoju razgranatog sustava kanalića prije spolne zrelosti u alpaka

Immunopresence and functional activity of prostaglandin-endoperoxide synthases and nitric oxide synthases in bovine corpora lutea during diestrus.

The aim of this study was to evaluate the occurrence and the activity of prostaglandin- endoperoxide synthase 1 (PTGS1), PTGS2, and endothelial, neuronal, and inducible nitric oxide synthase (e-, n-, and iNOS) in early, mid, late, and regressive corpora lutea (CL) of bovines during diestrus. PTGS1 immunoreactivity was localised mainly in the cytoplasm of small luteal cells, whereas PTGS2 was detected in the cytoplasm of large luteal cells during early, mid, and late stages. The immunoexpression of all NOS isoforms was observed in the nuclei of luteal cells in the CL stages examined. PTGS1 enzyme activity was higher in late CL and lower in regressive ones; PTGS2 increased from early to late CL and lowered in regressive ones. Constitutive NOS enzymatic activity (eNOS plus nNOS) was higher in late CL and lower in regressive ones; iNOS was lower in regressive CL. These results support the idea that PTGSs and NOSs regulate the bovine CL life span mainly during the transition from the luteotrophic to the luteolytic phase

Relationships among GnRH, substance P, prostaglandins, sex steroids and aromatase activity in the brain of the male lizard Podarcis sicula sicula during reproduction.

The release of PGF2 alpha and PGE2, progesterone, androgens and oestradiol in vitro, and the aromatase activity in the brain of the male lizard Podarcis sicula sicula during three different phases of the reproductive period were evaluated. In addition, the effects of salmon GnRH, substance P, salmon GnRH antagonist, substance P antagonist, PGF2 alpha, PGE2 and acetylsalicylic acid on the release of prostaglandins and sex steroids and on aromatase activity in the brain were evaluated during the same three phases. PGF2 alpha, oestradiol and aromatase activity were higher during the refractory phase, androgens during the fighting phase, and progesterone during the mating phase, while PGE2 was lower during the refractory phase. Treatment with salmon GnRH increased PGF2 alpha, oestradiol and aromatase activity, but decreased the amount of androgens released. Substance P decreased PGF2 alpha, oestradiol and aromatase activity, but increased the amount of androgens released. PGF2 alpha increased oestradiol and aromatase activity, but decreased the amount of androgens released. Acetylsalicylic acid decreased PGF2 alpha, oestradiol and aromatase activity, but increased the amount of androgens released. These data suggest that salmon GnRH and substance P have different roles in reproductive processes, with opposite mechanisms, in the central nervous system of this male lizard: salmon GnRH seems to be involved in regulating the refractory phase, while substance P plays a role in regulating the fighting phase

Prostaglandin receptors and role of G protein-activated pathways on corpora lutea of pseudopregnant rabbit in vitro

Studies were conducted to characterize receptors for prostaglandin (PG) F(2alpha) (PGF(2alpha)) and PGE(2), and the signalling pathways regulating total nitric oxide synthase activity and progesterone production in rabbit corpora lutea (CL) of different luteal stages. CL were obtained at days 4, 9 and 13 of pseudopregnancy and cultured in vitro for 2 h with PGF(2alpha) or PGE(2) and with activators and inhibitors of G protein (Gp), phospholipase C (PLC), protein kinase C (PKC), adenylate cyclase (AC) and protein kinase A (PKA). High affinity PGF(2alpha) receptor (K(d)=1.9+/-0.6 nM mean+/-s.e.m. ) concentrations increased (P< or =0.01) four- to five-fold from early to mid- and late-luteal phases (50.6+/-8.5, 188.3+/-36.1 and 231.4+/-38.8 fmol/mg protein respectively). By contrast, PGE(2) receptor (K(d)=1.6+/-0.5 nM) concentrations decreased (P< or =0.01) from day 4 to day 9 and 13 (27.5+/-7.7, 12.4+/-2.4 and 16.5+/-3.0 fmol/mg protein respectively). The Gp-dependent AC/PKA pathway was triggered only on day 4 CL, mimicking the PGE(2) treatment and increasing progesterone production. In both day 9 and day 13 CL, the Gp-activated PLC/PKC pathway evoked a luteolytic effect similar to that induced by PGF(2alpha). The time-dependent selective resistance to PGF(2alpha) and PGE(2) by rabbit CL is mediated by factors other than a lack of luteal receptor-ligand interactions

Lectin-binding sites in the seminal vesicles of entire and castrated horses

This research was undertaken to determine the glycoconjugates secreted by the glandular epithelium of the seminal vesicles in the entire and castrated horses using lectin histochemistry in combination with sialidase digestion and deglycosylation pre-treatments. The following lectins were used: Con-A, UEA-I, LTA, WGA, GSA-IB4, SBA, PNA, ECA and DBA. In the entire stallion, the glandular cells expressed the following sugar residues: a-Fuc, internal GlcNAc, terminal b- and a-GalNAc, b-D-Gal-(1-4)-GlcNAc and a-Gal included in O-linked oligosaccharides; b-Gal-(1-3)-GalNAc belonged to both O- and N-oligosaccharides whereas terminal GlcNAc to N-linked glycans. Additionally, a-Gal and b-Gal acted as acceptor sugars for sialic acid moieties. In castrated horses, the glandular epithelium showed a different lectin labelling pattern. In particular, we evidenced internal GlcNAc, a-GalNAc, b-Gal-(1-3)-GalNAc in both O- and N-linked glycoproteins whereas b-GalNAc and b-Gal-(1-3)-GalNAc in O-linked glycoproteins. The differences evidenced in the lectin profile between the stallion and castrated horse suggested an hormonal regulation of the glycoconjugate production. Additionally, the plurality of glycomolecules detected in the secretions of the stallion may be involved in spermatozoa maturatio

Ovulation induction in rabbit does: current knowledge and perspectives

The profitability of rabbit farms has increased in recent years due primarily to improvements in the management of reproduction and genetic selection. This review summarizes the most important scientific papers relating to ovulation in rabbit does dealing in particular with: (a) studies from 1905 to the present day relating to ovulatory mechanisms in rabbit does; (b) research on the primary gonadotrophin-releasing hormone (GnRH), its analogues and their functions; and (c) descriptions of parenteral and intravaginal (iv.) treatments for induction of ovulation in does and their reported efficacies. The addition of GnRH analogues via the seminal dose (iv.) fulfils the need for a welfare-orientated method of inducing ovulation in rabbits. The structure, tissues, secretions, contractions, and innervations of the vagina in rabbits that can affect absorption profiles are reviewed in the context of recent reports of the achievement of high ovulation rates obtained by adding GnRH analogues directly to the seminal dose. This review demonstrates the possibility of ovulation induction in rabbits by the addition of GnRH synthetic analogues to the seminal doses and provides new perspectives for simplifying the AI technique