
Alexander SirotkinConstantine the Philosopher University in Nitra, Slovakia · Zoology and Anthropology
Alexander Sirotkin
Prof., Dr., PhD., DSc.
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173
Publications
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Introduction
Current research interests: regulators of female reproduction
Additional affiliations
May 1993 - February 1994
April 2014 - present
September 1989 - March 2016
Publications
Publications (173)
Context
The applicability of hormones in the prediction of meat production in non-ruminant species has been poorly examined.
Aims
To examine the applicability of plasma concentrations of leptin, estradiol, progesterone and insulin-like growth-factor I (IGF-I) for characterisation and early prediction of the production and quality of meat in gilts....
This review is to summarize and analyze the currently available knowledge concerning the action of oat (Avena sativa L.) consumption on obesity, as well as possible constituents and extra- and intracellular mediators responsible for its anti-obesity effect. The oat constituents could reduce fat storage via several mediatory mechanisms – brain cente...
Phytotherapy can be an efficient tool for prevention and treatment of disorders including obesity. The purpose of this narrative review is to summarize the available knowledge concerning the positive effects of peppers (Capsicum spp.) and their alkaloid capsaicin on human health, in particular on fat and obesity. Search for literature was performed...
The paper examines the recent trends in international mobility, attractivity for international students, and the number of publications of two universities (Constantine the Philosopher University in Nitra, Slovakia, CPU and Tbilisi State Medical University, Georgia, TSMU) to understand whether the COVID-19 pandemic affected these processes and whet...
Citation: Baláži, A.; Sirotkin, A.V.; Makovický, P.; Chrastinová, L'.; Makarevich, A.; Chrenek, P. Effect of Green Tea on Weight Gain and Semen Quality of Rabbit Males. Vet. Sci. 2022, 9, 321. https://doi.
The aim of this study was to investigate: (1) the ability of granulosa cells to produce amphiregulin (AREG), kisspeptin (KISS) and FSH receptor (FSHR); (2) the role of AREG and KISS in the control of ovarian functions; (3) the effect of FSH and KISS on AREG; and (4) the ability of KISS to affect FSHR and to modify FSH action on AREG output by human...
This review describes composition, general physiological and health effects, as well as the currently available knowledge concerning the action of Opuntia ficus-indica (L.) Miller (prickly pear, nopal cactus) on fat metabolism and its applicability for treatment of obesity. The available data demonstrates a number of positive physiological and ther...
The paper outlines the adverse consequences and challenges induced by COVID-19 pandemic for the whole world and for universities in particular. The example of Constantine the Philosopher University in Nitra illustrates the difficulties and challenges caused by the pandemic in relation to the two main activities arising from the university mission-t...
The present review summarizes the available knowledge concerning the action of curcumin, the best-known polyphenol among the rhizomes of Curcumas, on female reproductive processes and their dysfunctions. Curcumin affects a number of physiological processes, including female reproduction (puberty, reproductive aging, ovarian follicullogenesis and oo...
This review outlines the positive effects of konjac (Amorphophallus konjac K. Koch) and it polysaccharide glucomannan on human health, on fat metabolism and obesity. The available data demonstrate, that both konjac and glucomannan can reduce fat storage via several extra- and intracellular mechanisms. Despite some possible adverse effects and limit...
This paper reviews provenance, chemical composition and properties of tea (Camelia sinensis L.) and coffee (Coffee arabica, L. and Coffea caniphora, L.), their general health effects, as well as the currently available knowledge concerning their action on fat storage, physiological mechanisms of their effects, as well as their safety and recommende...
The objective of this study was to examine the direct effects of the medicinal plant fennel (Foeniculum vulgare Mill.) on basic functions of ovarian cells, including proliferation, apoptosis, and response to the physiological hormonal stimulator, ghrelin. In the first series of experiments, porcine ovarian granulosa cells were cultured with (1, 10,...
This non-systematic review outlines the current knowledge concerning provenance, chemical composition and properties of apple cider vinegar, its general health effects, as well as the currently available knowledge concerning its action on fat storage, physiological mechanisms of its effects, as well as its safety and recommended dosage for treatmen...
During the period of mass industrial production of plastic products, the quality of human health has decreased significantly, especially in children’s neurodevelopmental disorders. Phthalates are endocrine-disrupting chemicals that can induce neurological disorders. This review aims to compile evidence concerning the associations between neurologic...
This review presents an original hypothesis, which explains the existence of
current nationalism in the modern globalized society by biological rules of hierarchy
and competition between the genotypes. Due to its innate character, it cannot be
completely deleted from the social life, but the understanding its biological origin can
avoid its negativ...
This review presents an original hypothesis, which explains the existence of current nationalism in the modern globalized society by biological rules of hierarchy and competition between the genotypes. Due to its innate character, it cannot be completely deleted from the social life, but the understanding its biological origin can avoid its negativ...
The production of plastic products, which requires phthalate plasticizers, has resulted in the problems for human health, especially that of reproductive health. Phthalate exposure can induce reproductive disorders at various regulatory levels. The aim of this review was to compile the evidence concerning the association between phthalates and repr...
Intersexual individuals have both female and male genital tissues. We have described a case of an intersexual pig, which was identi-fied during veterinary inspection of pigs at slaughterhouse. This organ represented ovotestis. Half of its tissues was represented by ovarian tissue resembling ovary by poly-cystic ovary syndrome. Another half was repr...
The existing knowledge of the direct action of kisspeptin on the ovary needs to be expanded. In our study, the direct effects of kisspeptin on basic ovarian cell functions and their response to FSH was examined. We studied the effect of kisspeptin alone (0, 1, 10 and 100 ng.ml⁻¹) and of kisspeptin (1, 10 and 100 ng.ml⁻¹) in combination with FSH (10...
Background:
Cadmium is a non-essential heavy metal, which is toxic even in relatively low concentrations. Although the mechanisms of Cd toxicity are well documented, there is limited information concerning the recovery of plants after exposure to this metal.
Methods:
The present study describes the recovery of soybean plants treated for 48 h wit...
The involvement of the mTOR system/enzyme sirtuin 1 (SIRT1) intracellular signaling system in the control of ovarian functions and its role in mediating hormonal action on the ovary has been proposed, but this hypothesis should be supported by a demonstrated influence of hormones on mTOR/SIRT1. Therefore, the aim of our in vitro experiments was to...
The influence of environmental contaminant toluene and of plant fennel (Foeniculum vulgare Mill.) on reproduction are reported, but the mechanisms of their action and the protective effect of fennel on contaminant influence remain to be elucidated. In this study, we hypothesized that toluene and fennel directly affects basic ovarian cell functions,...
p>The bioflavonoid quercetin is a component of food with numerous biological effects, but its function in reproductive processes remains to be investigated. This study aimed to examine the direct action of quercetin on steroid hormone release in rabbit ovaries. We analysed the effect of quercetin (0, 1, 10, and 100 ng/mL) on cultured rabbit ovarian...
The present study investigated whether dietary turmeric (Curcuma longa L.) can improve rabbit reproduction, ovarian function, growth,
or viability. Female New Zealand White rabbits were either fed a standard diet (n=15) or a diet enriched with 5 g (group E1) or 20 g
(group E2) turmeric powder per 100 kg feed mixture (n=16 or 15, respectively). Afte...
The aim of the present study was to examine the role of cAMP response element-binding protein (CREB) and its phosphorylation in the regulation of ovarian cell proliferation and apoptosis, and of the response of proliferation and apoptosis to the upstream hormonal stimulators FSH and insulin-like growth factor (IGF) 1. In the first series of experim...
The polyphenol-rich plants rooibos and ginkgo are widely used in folk medicine and in preparation of foods and drinks, but their effect on reproduction has not been properly studied yet. The aim of our in vitro experiments was to examine the possible direct effect of rooibos and ginkgo on the basic ovarian cell functions—proliferation, apoptosis an...
T-2 toxin and its metabolite HT-2 toxin are one of the most toxic mycotoxins of type A-trichothecenes, which are produced mainly by Fusarium species. Therefore, study of Fusarium toxins T-2 toxin and HT-2 toxin is an essential issue because they could also play role in failures of reproductive functions as well as endocrine system of domestic anima...
It was supposed, that xylene as environmental contaminant and chia (Salvia hispanica L.) as a medicinal plant may affect ovarian cell functions, and that chia seed extract could modify the potentially adverse effect of xylene. So, the aim of our investigation was to study the effect of xylene, extract of chia seed and their combination on bovine ov...
Toxicity of organic chemical compounds, including benzene, toluene, ethyl benzene and xylene (BTEX), is a major concern because of their induction of adverse effects in organisms, including reproductive abnormalities. In the present study, we investigated impacts of chronic exposure to BTEX at 25 µg L⁻¹ on the ovaries of the freshwater leech Erpobd...
The aim of the present study was to examine the role of nutritional status, the metabolic hormone ghrelin and their interrelationships in the control of chicken hormones involved in the regulation of reproduction. For this purpose, we identified the effect of food deprivation, administration of ghrelin 1-18 and their combination on plasma levels of...
The aim of the present in-vitro study was to examine the role of obestatin in the direct control of basic avian ovarian granulosa cell functions proliferation, apoptosis and secretory activity. In addition, the effects of obestatin on hormone release by cultured ovarian granulosa cells and follicular fragments (containing both granulosa and theca c...
The aim of this study was to demonstrate the histochemical and histopathological alterations in the livers of cows with a tendency to become emaciated (body condition score - BCS1 and 2) and a tendency to become fattened (BCS4 and 5) in comparison to the cows of average body condition (BCS3) presented as a control. The histochemical analysis (PAS r...
The key biological active molecule of soya is the isoflavone daidzein, which possesses phytoestrogenic activity. The direct effect of soya and daidzein on ovarian cell functions is not known. This study examined the effect of daidzein on basic porcine ovarian granulosa cell functions and the response to follicle-stimulating hormone (FSH). We studie...
The aim of present studies was to examine the interrelationships between reproductive events, age, body mass and steroid hormones in roe deer females (Capreolus capreolus). For this purpose we compared seasonal changes in body mass, blood levels of progesterone and estradiol (1) in young (1 year) and adult (2-4 years old) does and (2) in pregnant a...
The aim of the present study was to determine the activity of superoxide dismutase (SOD), total antioxidant status (TAS) of the hen granulosa cells, and selected biochemical parameters, including calcium, phosphorus, sodium, potassium, glucose, cholesterol, proteins, in the culture medium of granulosa cells after exposing them to ascorbic acid in v...
Protein kinases, transcription factors and other apoptosis- and proliferation-related proteins can regulate reproduction, but their involvement in sexual maturation remains to be elucidated. The general aim of the in-vivo and in-vitro experiments with porcine ovarian granulosa cells was to identify possible intracellular regulators of female sexual...
The aim of this in vitro study was to examine the secretion activity (progesterone, 17 beta-estradiol and insulin-like growth factor-I) of rat ovarian fragments after molybdenum (Mo) addition. Rat ovarian fragments were incubated with ammonium molybdate at the doses 90, 170, 330 and 500 microg.ml(-1) for 24 h and compared with control group without...
The aim of the present study was to examine the possible role of steroid hormones and insulin-like growth factor 1 (IGF-I) in the control of human growth and obesity. We measured plasma level of progesterone, testosterone, estradiol and IGF-I in 301 young women at different stages of their ovarian cycle, and compared them to the standard morphometr...
Oxytocin (OT) and protein kinase A (PKA), a possible intracellular mediator of hormone action in the ovary, can be potent activators of ovarian functions and fertility. Nevertheless, action of OT on ovarian follicle atresia has not been studied yet. Only single administration of PKA activators [3-isobutyl-1-methyl-xanthine (IBMX) and dibutyryl cycl...
The aim of present study was to evaluate the effect of the plant additive “Yucca” on rabbit spermatozoa characteristics. Rabbit males of New Zealand White line were used in the experiments. Males in control group were fed with commercially available normal granular feed. In experimental group (E1) 5 g of plant Yucca shidigera was added to the 100 k...
Body condition can influence bovine fertility, but the morphologi-cal, biochemical and endocrine mechanisms of this influence are not fully un-derstood. The aim of the study was to examine the interrelationships between cow body condition, morphological and endocrine state of the ovary, and blood metabolic indexes. Czech Fleckvieh dairy cows at the...
T-2 mycotoxin, a natural contaminant of cereals and agricultural products, is known to exhibit the severest toxicity and the lowest LD50 value among trichothecenes. Since quercetin has been reported to have strong antioxidant properties, the effect of quercetin and T-2 toxin on rabbit ovarian cell proliferation and apoptosis was assessed. In the ov...
The aim of this study was to examine possible effects of bee pollen added to the feed mixture (FM) on rat ovarian functions (secretion activity and apoptosis). We evaluated the bee pollen effect on the release of insulin-like growth factor I (IGF-I) and steroid hormones (progesterone and estradiol), as well as on the expression of markers of apopto...
General objective of this in vitro study was to examine combined effect of Ricinus communis extract and resveratrol on the release of steroid hormone progesterone and testosterone, and expression of markers of proliferation (Cyclin B1) and apoptosis (Caspase-3) in porcine ovarian granulosa cells. Concentrations of progesterone and testosterone were...
RNA interference, a recently discovered new mechanism controlling gene expression via small RNAs, was shown to be involved in the characterization and control of basic ovarian cell functions. The main classes of small RNAs, as well as their expression in ovaries have been described. Furthermore, the successful application of RNA interference for th...
The aim of our in vitro experiments was to examine the role of transcription factor p53 and the metabolic hormone leptin, in controlling basic functions (proliferation, apoptosis and secretory activity) of ovarian cells, as well as involvement of p53 in mediating or modulating actions of leptin, on ovarian cells. Porcine ovarian granulosa cells, tr...
Leptin, a product of adipose and some other tissues, which production is promoted by food intake and other stimuli, can be an important hormone through which different external factors affect reproductive processes. Leptin can affect reproduction through the hypothalamo-hypophysial system and by direct action on gonads. Regarding the effects of lep...
The castor plant (Ricinus communis L.) is a robust perennial shrub of Euphorbiaceae family and different parts of the plant are widely used by various communities and forest dwellers in many regions of the world for treating a variety of ailments. About 80% of world population is still dependent on traditional herbal medicines. The plant is documen...
The general aim of our in vitro experiments was to study the role of the metabolic hormones leptin, ghrelin, obestatin and IGF-I and mitogen-activated protein kinase (MAPK)-dependent intracellular mechanisms in the control of nuclear maturation of porcine oocytes. For this purpose, porcine oocytes were isolated from the ovary and cultured in the pr...
This book represents an attempt to review the most recent knowledge concerning basic processes occurring in the most important female reproductive organ - ovary and their regulators. The most important processes (ovarian cyclic changes and oogenesis), as well as their extracellular (hormones and growth factors) and intracellular (protein kinases, t...
The goal of this study was to examine the effect of epidermal growth factor (EGF) on sperm viability using two fluorescent techniques and to analyze the obtained results in relation to sperm motility, determined by subjective estimation. Fresh ram semen diluted in a Biladyl commercial extender was cooling stored (at 4 °C in a fridge) for four days...
The aim of our study was to examine the influence of 3-isobutyl-1-methyl-xanthine (IBMX), an inhibitor of cyclic adenosine monophosphate and cyclic guanosine monophosphate phosphodiesterases, on the reproductive efficiency of gonadotropin-stimulated rabbits (Oryctolagus cuniculus, Leporidae, Lagomorpha). The ovarian cycle and ovulation of control r...
The aim of the present study was to define the role of protein kinase A (PKA)-, mitogen-activated protein kinase (MAPK)-, and cyclin-dependent kinase (CDK)-dependent pathways in the control of ovarian cell functions. The effects of PKA, MAPK, and CDK blockers (KT 5720, PD 98059, and olomoucine, respectively), given at doses of 0.001-10.0 μg/ml medi...
The aim of our study is to examine the influence of administration of 3-isobutyl-1-methyl-xanthine (IBMX), inhibitor of cAMP and cGMP phosphodiesterases on ovarian functions (folliculogenesis, atresia and luteogenesis), as well as on some reproductive parameters in rabbits whose ovarian cycle and ovulation was induced by gonadotropins. Ovarian cycl...
The aim of the present study was to understand the hormonal mechanisms behind the effect of high temperatures on reproductive function. It was proposed that high temperatures can directly alter production of ovarian hormones and/or the response of ovarian cells to hormonal stimulators. To examine this hypothesis, in the 1st series of experiments, w...
The aim of our studies was to compare the roles of leptin and ghrelin in the direct control of proliferation, apoptosis, and secretory activity by porcine ovarian cells. In our in vitro experiments, we analyzed the effects of leptin and ghrelin treatments (at 0, 1, 10, or 100ng/mL medium) on the accumulation of proliferation-related peptides (PCNA,...
The aim of this experiment was to evaluate the levels of hormones (progesterone, IGF-I and IGFBP-3) in blood plasma, growth, carcass traits and their interactions of sexually immature (n = 18) and sexually mature (n = 17) gilts. To calculate average daily weight gain (ADG), gilts were individually weighed at the beginning of the trial and at slaugh...
The aim of the present study is to understand the hormonal mechanisms of the effect of malnutri- tion on ovarian follicle functions. For this purpose, we examined the effect of malnutrition/serum deprivation, addition of metabolic hormones and gonadotropin (IGF-I, leptin and FSH) and their combination on the release of progesterone (P 4), testoster...
The general objective of this in vitro study was to examine the secretory activity of ovarian granulosa cells of hens after lead (Pb) and molybdenum (Mo) administrations. In this study the effect of various doses of Pb and Mo on the insulin-like growth factor-I (IGF-I) and progesterone (P<sub>4</sub>) release by ovarian granulosa cells was demonstr...
The aim of these in vivo and in vitro studies was to examine the role of leptin in the control of plasma hormone concentrations, reproduction, and secretory activity of ovarian granulosa cells. In in vivo experiments, 15 female European domestic rabbit (Oryctolagus cuniculus) were treated with leptin (5 microg animal(-1)d(-1) for 1 wk before induct...
The aim of our investigation was to examine the influence of chronic administration of ghrelin on the rat ovarian state. Morphometrical and intracellular changes in the ovary of 35-d female Wistar rats after sc injection of 1 nmol of ghrelin for 10 consecutive days were studied. Control animals (n=10) were injected with normal saline using similar...
The aim of the present study was to evaluate the development and ultrastructure of preimplantation bovine embryos that were exposed to bovine viral diarrhea virus (BVDV) in vitro .
The embryos were recovered from superovulated and fertilized Holstein-Friesian donor cows on day 6 of the estrous cycle. Compact morulae were microinjected with 20 pl of...
The aim of these in vitro experiments was (1) to examine the effects of ghrelin on the basic functions of ovarian cells (proliferation, apoptosis, secretory activity); (2) to determine the possible involvement of the GHS-R1a receptor and PKA- and MAPK-dependent post-receptor intracellular signalling cascades; (3) to identify the active part of the...
The aim of our in vitro studies was to understand the role of leptin in controlling proliferation, apoptosis, and protein kinase A (PKA) in human ovarian cells. We analyzed the in vitro effects of leptin (0, 1, 10 or 100 ng/ml) on the accumulation of proliferation-related peptides (PCNA, cyclin B1), apoptosis-associated peptide (Bax) and the intrac...
The aim of our in-vitro experiments was to examine, whether leptin can directly control functions of avian ovarian cells and to outline potential intracellular mediators of its effects. Granulosa cells or fragments of ovarian follicular wall were cultured with leptin (0, 1, 10 or 100 ng/mL medium). The expression of peptides involved in apoptosis (...
The aim of our in vitro experiments was to investigate the role of obestatin, a newly discovered metabolic hormone produced in the stomach and other tissues, in the direct control of ovarian cell proliferation, apoptosis and secretion. Porcine granulosa cells were cultured in the presence of obestatin (0, 1, 10 and 100ng/ml medium). The expression...
The general aim of these in-vitro experiments was to determine whether ghrelin controls the secretory activity of chicken ovarian cells and whether its action is mediated by TK-, MAPK-, CDK- or PKA-dependent intracellular mechanisms. We postulated that particular protein kinases could be considered as mediators of ghrelin action (a) if they are con...
Ghrelin has recently emerged as pleiotropic regulator of a wide array of endocrine and non-endocrine functions. The former likely includes the control of gonadal function, as expression of ghrelin and its putative receptor, the GH secretagogue receptor type 1a (GHS-R1a), has been described in mammalian gonads, and direct effects of ghrelin in the c...