Elsevier

Tissue and Cell

Volume 45, Issue 6, December 2013, Pages 402-406
Tissue and Cell

Co-expression pattern of dopamine beta-hydroxylase (DβH) and neuropeptide Y (NPY) within sympathetic innervation of ovary and umbilical cord of the European bison (Bison bonasus L.)

https://doi.org/10.1016/j.tice.2013.07.002Get rights and content

Abstract

Co-expression of dopamine β-hydroxylase (DβH) and neuropeptide Y (NPY) has never been examined in ovary (OV) and umbilical cord (UC) of the European bison (Eb), the endangered wild species. The OV and UC samples were harvested from seasonally eliminated Eb females (45–120 days post coitum). Frozen histological sections were examined by double fluorescent immunohistochemistry (dF-IHC), using the primary mouse anti-DβH monoclonals and rabbit anti-NPY polyclonals and then the immunocomplexes were visualized with FITC and CY3 fluorophores, respectively. Numerous DβH immunoreactive nerve fibers (DβH-IRs) and a little less frequent NPY-IRs were found in the bundle-like structures, innervating mainly perivascular regions of the OV. The NPY-IRs constantly co-expressed DβH, while some DβH-IRs did not express NPY. This specific pattern of innervation was observed both in the stromal and cortical regions of the OV. The simultaneous co-expression of DβH and NPY were also detected in the UC, in which specific single or bundle-like structures ran along the smooth muscles of blood vessels. The spatial-specific co-expression of DβH and NPY in OV and UC, may suggest that these markers are involved in the control of vascularization that regulates nourishing blood circulation required for proper pregnancy maintenance and efficient embryo/fetus development in the Eb.

Introduction

The sympathetic activity of female reproductive system has a great impact on reproduction since noradrenaline (NA) influences the ovarian, oviductal, uterine (Czaja et al., 1996, Klukovits et al., 2002, Marzioni et al., 2004) and also umbilical cord (Kobayashi et al., 2003, Marzioni et al., 2004) functions. The mutual co-expression of DβH and NPY, which enhances catecholaminergic activity, is a crucial key to maintain the fertility (Jovanovic et al., 2000, Stjernquist et al., 1991). The dopamine β-monooxygenase (EC 1.14.17.1) is 578 amino acids protein involved in oxidative hydroxylation of the dopamine conversion to NA – a dominating sympathetic neurotransmitter. The neuropeptide Y (NPY) is known as the most common co-transmitter peptide, which intensifies and prolongs of NA activity (Thomas et al., 1995). Both, NA together with NPY regulate the blood vessel contraction influencing mainly the fetal, UC and OV circulation (Silva et al., 2005, Wang et al., 1999). Several studies regarding sympathetic and peptidergic innervations of female reproductive tract have been performed in rodents (Ducza et al., 2002, Houdeau et al., 1998, Klukovits et al., 2002), pigs (Czaja et al., 1996, Lakomy et al., 1994), cattle (Lakomy et al., 1995, Majewski et al., 1995), horses (Bae et al., 2001) and human (Petraglia et al., 1989). However, some information regarding the innervation pattern of reproductive system (i.e. OV and UC) of various wild mammalian species, including the European bison (Eb) classified as the endangered taxon (Red List: EN A2ce, C2a), is very sparse. This is due to the scanty availability of the biological material from wild mammals, especially reproductive system – the crucial element for survival of rare and internationally protected and endangered wild species. Some data are available regarding the specific sympathetic innervations, i.e. DβH expression have been, in part already, identified within the nerve fibers supplying the placentome structures of the synepitheliochorial Eb placenta (Skobowiat et al., 2009) and also in the unique abnormal tissues (vestigial uteri) of some Eb bulls from the Polish population (Skobowiat et al., 2010). Such information is critical for the fertility of endangered species like the Eb. This study aimed to identify the physiological existence and tissue-specific localization of the DβH/NPY co-expression within the OV and UC of the Eb, examined by double fluorescent immunohistochemistry (dF-IHC).

Section snippets

Animals, OV and UC collection

The OV and UC samples were harvested from seasonally eliminated Eb females (N = 6) in the Bialowieza National Park (BNP), located in Northeastern region of Poland. These samples were harvested post mortem from the hunted very early and middle pregnant Eb females (approx. 45–150 gestation days), according to double agreements of the governmental (Ministry of the Environment) and local ethical authorities (ME/DLOPIK-op/ogiz-4200/IV.A-3/3609/06; and UWM/LKE-23/2009, respectively). In many wild

Results

Both immunofluorescent signals (DβH – green; NPY – red) were identified by dF-IHC in the sympathetic nerve fibers, appearing as single fibers, network- or bundle-like structures, surrounding mainly various perivascular regions of the examined bison OV and UC sections (Fig. 1). There were no statistically significant differences in the number of immunopositive nerve fibers’ density between specimens studied, nevertheless, generally DβH positive nerve fibers predominated over NPY ones.

Numerous

Discussion

Our study demonstrates the DβH and the NPY co-expression (by dF-IHC) in OV and UC of the pregnant European bison. The detected abundant noradrenergic and peptidergic innervation of OV and UC in the Eb suggests that NA and NPY may play an important role in functioning of these structures. The rare availability of tissues from reproductive system from wild and especially endangered species, like the Eb, forced us to discuss our results and compare them to data obtained in other species (mainly

Conflict of interest

All authors disclose none financial, personal or organizational conflicts of interest.

Acknowledgements

The authors are grateful to all workers of the Bialowieza National Park (PL) for their passionate help during seasonal tissue-collection of the European bison. This study was supported by the State Committee for Scientific Research (UWM 528-0206-0806 granted to B. Szafranska, PL). The authors also thank Dr. Natalia Schlabritz-Loutsevitch (Department of Obstetrics and Gynecology, University of Tennessee Health Science Center in Memphis, TN) for her critical comments regarding this manuscript.

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