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VOLUME 4, NUMBER 3
ABSTRACTS
The Role of Calcium in Signal Transduction Processes in Sertoli Cells
Eleonora Gorczynska-Fjalling1
Summary
Sertoli cells play a pivotal role in regulation and maintenance of spermatogenesis. They are hormonally regulated predominantly by follicle-stimulating hormone (FSH) and testosterone (T). Although FSH and T have distinct mechanisms of action they act synergistically in promoting spermatogenesis. Stimulation of freshly isolated Sertoli cells with FSH evokes a prompt rise in cytosolic calcium which is quantitatively reproduced by cAMP. The cytosolic calcium response to FSH in Sertoli cells is predominantly attributable to serial signaling after the generation of endogenous cAMP. Calcium homeostasis of Sertoli cells may also be regulated by cAMP-independent metabolism. Vasoactive testicular paracrine hormones such as angiotensin II (AII) and vasopressin acting via inositol triphosphate generation induce cytosolic calcium rise predominantly derived from the thapsigargin-sensitive endoplasmic reticulum. Investigations involving androgens action on cytosolic calcium reveal a common mechanism of action between the peptide and steroid regulators of Sertoli cell function, indicating that cytosolic calcium ions may represent a unifying biochemical mechanism that could explain the synergism of FSH and T. Androgens rapidly and specifically increase cytosolic calcium, consistent with a plasma membrane site of action. This argues for the possible existence of a short term non-genomic signaling pathway in hormonal regulation of Sertoli cell function in addition to the classical longer term, slower genomic response.
Reproductive Biology 2004 4 (3): 219-241
1Corresponding author: Department of Obstetrics and Gynaecology (Building DO2), University of Sydney, Sydney 2006, New South Wales, Australia;
e-mail: eleanora.fjalling@alconlabs.com
Potential roles of the aryl hydrocarbon receptor in female reproductive senescence
Kelli E. Valdez2,3, Brian K. Petroff1,2,3
2Center for Reproductive Sciences University of Kansas Medical Center, Kansas City, KS 66160
3Department of Internal Medicine, University of Kansas Medical Center, Kansas City, KS 66160
Summary
The transition to reproductive senescence involves changes in neuroendocrine and ovarian functions, and is accelerated by activation of the aryl hydrocarbon pathway by environmental toxicants such as 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD). In this article, studies which provide evidence as to the possible mechanisms by which the aryl hydrocarbon receptor (AhR) acts in this capacity (i.e. disruption of ovarian, hypothalamic or suprachiasmatic nucleus function, or any combination of these) are reviewed, along with the normal physiological changes that occur during the transition to reproductive senescence in female humans and rodents. Based on findings that the AhR is evolutionarily conserved and necessary for normal fertility, we suggest that the AhR has not only a pathological but also a physiological role in the process of aging. Studies of realistic lifelong AhR activation by dioxins on the hypothalamic-pituitary-ovarian axis and its impact on the transition to reproductive senescence in the aging female are a previously neglected area of research that warrants further consideration.
Reproductive Biology 2004 4 (3): 243-258
1Breast Cancer Prevention Center, Department of Internal Medicine, University of Kansas Medical Center, MS 3003; 3901 Rainbow Boulevard, Kansas City, KS 66160;
e-mail: bpetroff@kumc.edu
Growth hormone gene expression in oocytes and zygotes produced by cows heterozygous (Leu127Val) at GH locus
Ewelina Warzych, Jakub Namysl, Michal Kubiatowicz, Dorota Lechniak1
August Cieszkowski Agricultural University of Poznan, Department of Genetics and Animal Breeding, Poznan, Poland
Summary
The present work describes analysis of the growth hormone gene (GH) expression in non-matured and in vitro matured bovine oocytes as well as zygotes after in vitro fertilization. The Leu/Val polymorphism described in the 5th exon of the bovine GH gene was applied to investigate the expression of genetic variants in the analyzed material. Experiments were performed on oocytes collected from heterozygous (LV) cows. Since developmental stages analyzed in this study are not transcriptionally active with regard to the GH gene, the analyzed transcripts were exclusively of maternal origin. According to our findings, GH transcript was observed in each analyzed sample. The expected heterozygous pattern of GH gene expression was found in non-matured oocytes. However, an unexpected variation in allelic distribution was noticed in matured oocytes and zygotes. A tendency was observed of a gradual disappearance of the heterozygous pattern (variant LV) ranging from 100% in non-matured oocytes, 70% in matured cells and 20% in zygotes. In some of analyzed samples, the expected heterozygous pattern was replaced by the VV variant in matured oocytes and either by VV or LL variants in zygotes. Possible mechanisms underlying the described phenomenon (in vitro culture conditions, transcript polyadenylation) are discussed. These results indicate a possible influence of sub-optimal in vitro culture conditions on the distribution of genetic variants of GH gene transcripts in bovine oocytes and zygotes.
Reproductive Biology 2004 4 (3): 259-269
1August Cieszkowski Agricultural University of Poznan, Department of Genetics and Animal Breeding, Wolynska 33, 60-637 Poznan, Poland;
e-mail: lechniak@jay.au.poznan.pl
Effects of dietary supplementation with polyunsaturated fatty acids and antioxidants on biochemical characteristics of boar semen
Jerzy Strzezek1, Leyland Fraser, Magda Kuklinska, Anna Dziekonska, Marek Lecewicz.
Warmia and Mazury University in Olsztyn, Faculty of Animal Bioengineering, Department of Animal Biochemistry and Biotechnology, Olsztyn, Poland
Summary
The aim of this study was to investigate the effect of providing a supplement containing polyunsaturated fatty acids and antioxidants (PROSPERM ) on the biochemical characteristics of boar semen. Two sexually mature boars were fed a standard diet with PROSPERM (250 g daily) for a 24-week period. Ejaculates collected prior to supplementation were used as the control. Semen quality and biochemical parameters were analyzed. The dietary supplementation enhanced sperm characteristics, including the percentage of spermatozoa with intact plasma membrane and osmotic resistance of the acrosomal membrane. Higher production of malondialdehyde was concurrent with increased activity of superoxide dismutase in the seminal plasma and spermatozoa after 8 weeks of supplementation. These changes were accompanied by a high content of total protein and low-molecular antioxidants of the seminal plasma. It was observed that PROSPERM supplementation enhanced the survivability of boar spermatozoa during storage in a standard semen extender supplemented with lipoprotein fractions, isolated from hen egg yolk or ostrich egg yolk, at 5 C and 16 C. These results indicate that PROSPERM supplementation of boars had a beneficial effect on the biological characteristics of the spermatozoa, which could be useful for semen preservation at different temperatures.
Reproductive Biology 2004 4 (3): 271-287
1Corresponding author: Institute of Animal Reproduction and Food Research of The Polish Academy of Sciences,
Tuwima 10, 10-747 Olsztyn, Poland;
e-mail: skrzym@pan.olsztyn.pl
Immunohistochemical localization of androgen receptor and aromatase in the ovary of the pregnant pig
Malgorzata Duda2, Malgorzata Burek2, Jerzy Galas2, Katarzyna Koziol3, Marek Koziorowski3, Maria Slomczynska1,2
2Laboratory of Endocrinology and Tissue Culture, Institute of Zoology, Jagiellonian University, Kraków.
3Department of Physiology and Reproduction of Animals, University of Rzeszów, Rzeszów, Poland
Summary
The distribution of androgen receptor (AR) and cytochrome P450 aromatase was investigated in paraffin sections of pregnant pig ovary. Ovarian follicles and corpora lutea were isolated from ovaries obtained on Days 10, 18, 32, 71 and 90 post coitum (p.c.). Androgen receptor was localized in the nuclei of granulosa cells of follicles of various sizes. In addition, some follicles demonstrated staining in the nuclei of theca interna cells. Stroma cells also exhibited a positive immunostaining. At early and mid pregnancy (up to Day 71) AR was expressed in the nuclei of luteal cells. Corpora lutea of Day 71 showed mainly cytoplasmic staining while on Day 90 almost all luteal cells showed staining exclusively in the cytoplasm. Immuno-staining for the presence of cytochrome P450aromatase was very faint in all investigated ovarian structures. The results could suggest that the process of androgen aromatization plays a negligible role in the ovary of the pregnant pig.
Reproductive Biology 2004 4 (3): 289-298
1Corresponding author: Laboratory of Endocrinology and Tissue Culture, Department of Animal Physiology, Institute of Zoology, Jagiellonian University, Ingardena 6, 30-060 Kraków, Poland; e-mail: slom@zuk.iz.uj.edu.pl
Testicular and blood steroid levels in aged men
Serge Carreau1,3, Sonia Bourguiba2,3, Eric Marie4
3Department of Biochemistry, University, Esplanade de la Paix, Caen; 4Department Gynaecology, CH Alencon-France
Summary
In this study, we have evaluated the hypophyso-gonadal axis in three groups of men aged 60-69, 70-79 and 80-91 years by measuring the intratesticular concentrations of several steroids (pregnenolone, progesterone, DHEA, DHEA-S, testosterone, estradiol) and serum levels of FSH, LH, testosterone, estradiol and sex hormone binding globulin (SHBG). The histological examination of testes revealed normal spermatogenesis in all examined samples. No significant changes in serum hormone and SHBG concentrations as well as in testicular steroid contents among the three groups of patients were found. However, the mean serum SHBG level was three times higher in the oldest men than in other groups and a positive correlation between patient's age and serum SHBG was observed. Therefore, the bioavailability of estradiol in the oldest men was likely diminished. Consequently, the hormonal status in aged men is rather unchanged but great variations observed between patients imply special cautious when the SHBG and estradiol levels are concerned
Reproductive Biology 2004 4 (3): 299-304
1Corresponding author: Serge Carreau, Biochimie, EA 2608 USC INRA, Universite, Esplanade de la Paix, 14032 CAEN Cedex, France; e mail : carreau@ibfa.unicaen.fr
2 In postoctoral position, University of Utretcht, Netherlands.
Expression of estrogen receptors α and β in term human myometrium
Piotr Laudanski1,2,3, Slawomir Redzko2, Jerzy Przepiesc2, Mariusz Koda5, Slawomir Wolczyński4, Stanisław Sulkowski5, Jan Urban2
2Department of Perinatology, 3Department of Pathophysiology of Pregnancy; 4Department of Gynecological Endocrinology; 5Department of Clinical Pathology, Medical University of Białystok, Białystok, Poland
Summary
We used immunohistochemistry to compare the expression of estrogen receptors (ERα and ERβ ) in term myometria of 32 pregnant women divided in two groups. Group I comprised of 16 women in labour and group II included 16 non-laboring gravidas. We observed cytoplasmatic localization of both ER isoforms and no differences in the ER expression between the two groups of patients. The abundance and specific localization of ERs in human term myometrium seems to be independent of its contractile activity which may point to the specific role of those receptors in late pregnancy myometrium.
Reproductive Biology 2004 4 (3): 305-311
1Corresponding author: Department of Pathophysiology of Pregnancy ul. Marii Sklodowskiej-Curie 24 A 15-276 Bialystok, Medical University of Bialystok, Poland, email: plauda@cksr.ac.bialystok.pl