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Original Article

Ginger (zingiber officinale) might improve female fertility: A rat model

Yιlmaz, Nafiyea; Seven, Banua,*; Timur, Hakana; Yorgancι, Ayçağa; İnal, Hasan Alib; Kalem, Müberra Namlιc; Kalem, Ziyad; Han, Özgee; Bilezikçi, Banue

Author Information

aUniversity of Health Sciences Ankara Dr. Zekai Tahir Burak Women's Health, Health Application and Research Hospital, Ankara, Turkey

bKonya Education and Research Hospital, Reproductive Endocrinology, Konya, Turkey

cLiv Hospital, Obstetrics and Gynecology Clinic, Ankara, Turkey

dGürgan Clinic, Ankara, Turkey

eGüven Hospital, Pathology Department, Ankara, Turkey

*Corresponding author. author. Dr. Banu Seven, University of Health Sciences Ankara Dr. Zekai Tahir Burak Women's Health, Health Application and Research Hospital, Talatpaşa Bulvarι, Hamamönü, Ankara, Turkey.

E-mail: [email protected]

Submitted October 15, 2017; accepted December 8, 2017.

Conflicts of interest: The authors declare that they have no conflicts of interest related to the subject matter or materials discussed in this article.

Journal of the Chinese Medical Association: October 2018 - Volume 81 - Issue 10 - p 905-911
doi: 10.1016/j.jcma.2017.12.009

    Abstract

    1. Introduction

    Herbal medicine is very popular and gains much attention nowadays. It has been believed that it is much more safer than synthetic drugs. Ginger (Zingiber officinale) has a long historical medicine use dating back 2500 years in China and India.1 Its pharmacological properties are varied including antioxidant, anti-inflammatory, anticancer and antimicrobial activities.2–5

    More than 60 active constituents are known to be present in ginger, which have been broadly divided into volatile and nonvolatile compounds. Hydrocarbons mostly monoterpenoid hydrocarbons and sesquiterpene include the volatile component of ginger and impart distinct aroma and taste to ginger. On the other hand, nonvolatile compounds include gingerols, shogaols, paradols, and also zingerone. The active ingredients like gingerols, shogaols, zingerone, and so forth present in ginger exhibit antioxidant activity. It inhibits an enzyme xanthine oxidase, which is mainly involved in the generation of reactive oxygen species.6

    Antioxidant applications are important for protecting the human body from various sources of oxidative damage and are used extensively for prevention of a variety of diseases. In order to protect the human body from various forms of oxidative damage, recently there has been a noticeable increase in the search and identification of natural and safe antioxidants.

    Oxidative stress can significantly negatively impact cellular survival and longevity and lead to programmed cell death.7 The generations of reactive oxygen species (ROS) that result in oxidative stress include nitrogen based free radical species such as nitric oxide and peroxynitrite as well as superoxide free radicals, hydrogen peroxide, and singlet oxygen.8 Physiological levels of ROS are required for proper functioning of different biological pathways and in maintaining homeostasis within the human body. Low levels of free radicals act as modulators in female reproductive pathways such as oocyte maturation, physiological follicular atresia, ovulation, fertilization, luteal regression, and corpus luteum formation during pregnancy.9 ROS is also believed to play a role in the different phases of the endometrial cycle. Disruption in physiological levels of ROS leads to female reproductive dysfunction.10

    Nitric oxide (NO) is known to mediate physiological functions, such as vasodilation, regulation of angiogenesis, and blood flow in many tissues, including the ovary.11 Endothelial NO synthase (eNOS) was detected in ovarian follicles and in the corpus luteum during the estrous cycle in several species. It has been demonstrated that NO plays a role in the regulation of angiogenesis, steroidogenesis, apoptosis, and luteolysis.12

    Defects in ovarian angiogenesis may contribute to a variety of disorders including anovulation and infertility, pregnancy loss, ovarian hyperstimulation syndrome, and ovarian neoplasms.13 Vascular endothelial growth factor (VEGF), during gonadotropin surge, controls the crucial follicles transition from preovulatory to periovulatory stage that precedes ovulation.13 Besides, VEGF is known to play an essential role in the regulation of angiogenesis in the endometrium. Its expression increases during the proliferative phase and has a second expression peak later during the mid-secretory phase, being responsible for maturation of spiral arteries during the “implantation window”.14

    The effects of ginger on male infertility and sperm parameters were investigated in a few studies.15–19 The results showed favorable outcomes on sperm indices.15–18 However, the effects of ginger on ovarian functions have not been studied so far. In this study, we aimed to investigate the effects of ginger powder on ovarian folliculogenesis and implantation in rats. We evaluate the effects of ginger in the ovaries and in the endometrium by VEGF and eNOS levels. This is the first study in the literature that investigates this topic.

    2. Methods

    The experiments were approved by the Experimental Animal Ethics Committee of Ankara Training and Research Hospital (protocol no: 0019/23.10.2014). There were 42 female albino rats in estrous cycle, each weighing approximately 200 gr (28 in the study groups and 14 in the control groups). The animals were housed in standard propylene cages in the same animal facility under conventional conditions (12:12-h light:dark; room temperature: 22 ± 2 °C). Specific pelleted food and filtered bottled tap water were supplied ad libitum. The animals were allowed to acclimatize for 2 weeks. Three days before the beginning of the experiments, the female rats were exposed to soiled bedding of a mature male rat to synchronize their estrous cycles.20 Estrous phase was confirmed by vaginal smear examinations. Organic ginger roots were rinsed with distilled water. After drying, the roots were grated into small pieces and dried again using a dehydrator. Then, a mixer was used to grind the small ginger pieces until a powder was obtained. There were two study groups, each with a different length of treatment.

    Group 1 (5-day treatment group): 100 mg ginger powder, 200 mg ginger powder or 2 cc distilled water (control group) was given to three subgroups, each containing seven rats, daily for 5 days (one estrous cycle). Ginger powder was mixed with 2 cc distilled water and administered by gavage. The control group also received 2 cc distilled water by gavage.

    Group 2 (10-day treatment group): 100 mg ginger powder, 200 mg ginger powder or 2 cc distilled water (control group) were given to three subgroups, each containing seven rats, daily for 10 days (two estrous cycle). Like the 5-day treatment group, the ginger powder was mixed with 2 cc distilled water and administered by gavage. The control group also received 2 cc distilled water by gavage.

    At the end of the 5th and 10th days, the rats were sacrificed and the inner genital organs were removed. All surgeries were performed under sodium pentobarbital anesthesia and all efforts were made to minimize suffering. The ovarian volumes and ovarian weights were measured. The primordial, antral, and atretic follicles and the corpus luteums were counted using histopathological examination stained with hematoxylin eosin in the entire cross-sectional area of both ovaries for each rat. To evaluate the angiogenic effects of ginger, immunohistochemical assessment of ovarian cortical, ovarian stromal, and endometrial VEGF were done by anti-VEGF receptor 2-antibody kit (catalog number ab15292, Abcam, Cambridge, UK). For both groups, eNOS was immunohistochemically examined in the ovaries (cortical and stromal) and in the endometrium by eNOS antibody kit (catalog number ab66127, Abcam, Cambridge, UK). For each rat, the entire cross-sectional area of the ovaries and endometrium were scanned consecutively and the stained cells were counted at ×200 magnification. All pathological and immunohistochemical examinations were done by the same pathologist who was blinded to the codes given to the rats.

    Statistical analyses were performed using the Statistical Package for the Social Sciences version 15.0 (SPSS, Chicago, IL, USA). The variables are expressed as mean ± standard deviation (SD). Shapiro–Wilk tests were used to determine the normality of the distributions of the continuous variables. The normally distributed variables were examined using one-way analyses of variance, followed by Tukey's post-hoc tests. The non-normally distributed variables were analyzed with Kruskal–Wallis tests and Mann–Whitney U tests, with post hoc Bonferroni corrections. p values < 0.05 were considered to be statistically significant.

    3. Results

    First, we analyzed Group 1 (5-day treatment group), which was divided into three subgroups and given 100 mg ginger, 200 mg ginger, or 2 cc distilled water for 5 days (Table 1). In the 100 mg subgroup, the ovarian volume, ovarian weight, primordial follicle count, atretic follicle count, corpus luteum count, ovarian cortical VEGF, endometrial VEGF, ovarian cortical eNOS, ovarian stromal eNOS, and endometrial eNOS were not statistically different in comparison to the control group (p > 0.05). The antral follicle count and ovarian stromal VEGF were significantly high in the 100 mg group (p < 0.05) (Fig. 1-A, B). The comparison of the 200 mg subgroup and the control group revealed no statistically significant differences between the variables.

    T1-10
    Table 1:
    Comparison of the variables between the Group 1 subgroups with ± standard deviations.
    F1-10
    Fig. 1.:
    AHistopathological image of the increased antral follicle count in the 100 mg/5-day treatment subgroup; B Immunohistochemical staining of the ovarian stromal VEGF in the 100 mg/5-day treatment subgroup; C Immunohistochemical staining of the endometrial VEGF in 100 mg/10-day treatment subgroup; D Immunohistochemical staining of the ovarian stromal eNOS in 100 mg/10-day treatment subgroup.

    We then analyzed Group 2 (10-day treatment group), which was divided into three subgroups and given 100 mg ginger, 200 mg ginger or 2 cc distilled water for ten days (Table 2). Ovarian volume, ovarian weight, primordial follicle count, antral follicle count, atretic follicle count, corpus luteum count, ovarian cortical and stromal VEGF, ovarian cortical eNOS, and endometrial eNOS were not statistically different between the three subgroups (p > 0.05). Endometrial VEGF and ovarian stromal eNOS were significantly high in the 100 mg ginger subgroup in comparison to the control group (p < 0.05) (Fig. 1C and D). No statistically significant differences in the variables were found between the 200 mg subgroup and the control group.

    T2-10
    Table 2:
    Comparison of the variables between the Group 2 subgroups with ± standard deviations.

    Figs. 2 and 3 show the immunohistochemical staining images of two proteins in the three subgroups for the 5-day and 10-day treatment groups, respectively.

    F2-10
    Fig. 2.:
    a Immunohistochemical staining of the endometrial stromal VEGFx400 in the 5-day control group; b Immunohistochemical staining of the endometrial stromal VEGFx400 in the 100 mg/5-day treatment subgroup; c Immunohistochemical staining of the ovarian antral follicle wall VEGF ×400 in the 200 mg/5-day treatment subgroup; d Immunohistochemical staining of the endometrial stromal eNOS ×200 in 5-day control group; e Immunohistochemical staining of the endometrial stromal eNOS ×400 in the 100 mg/5-day treatment subgroup; f Immunohistochemical staining of the ovarian antral follicle wall eNOS ×400 in the 200 mg/5-day treatment subgroup.
    F3-10
    Fig. 3.:
    a Immunohistochemical staining of the endometrial stromal VEGF ×400 in the 10-day control group; b Immunohistochemical staining of the endometrial stromal VEGF ×400 in the 100 mg/10-day treatment subgroup; c Immunohistochemical staining of the ovarian antral follicle wall VEGF ×400 in the 200 mg/10-day treatment subgroup; d Immunohistochemical staining of the endometrial stromal eNOS ×200 in the 10-day control group; e Immunohistochemical staining of the endometrial stromal eNOS ×400 in the 100 mg/10-day treatment subgroup; f Immunohistochemical staining of the ovarian antral follicle wall eNOS ×400 in 200 mg/5-day treatment subgroup.

    4. Discussion

    The present study aimed to investigate the effects of ginger powder on ovarian folliculogenesis and implantation in rats. Many studies have described the antioxidant, anti-inflammatory, anticancer, and antimicrobial activities of ginger. But, this is the first study in the literature, which investigates the optimal dose and duration of the ginger powder on the female reproductive system. In our study, we found statistically high antral follicle count and ovarian stromal VEGF in the 100 mg/5-day treatment subgroup. Antral follicle count is one of the most reliable tools that show ovarian reserve. These two findings indicate the favorable effects of ginger in ovarian folliculogenesis.

    The control of ovarian stromal cells and germ cell function is a diverse paradigm and oxidative stress may be one of the modulators of ovarian germ cell and stromal cell physiology. A number of autocrine and paracrine factors affect the modulation of various ovarian functions and steroidogenesis.21 Mammalian ovulation or follicular rupture was proposed to result from the vascular changes and the proteolytic cascade.22 The cross talk between these two cascades is mediated by cytokines, VEGF and reactive nitrogen and oxygen radicals.21 Oxidative stress and cytokines are proposed to be interlinked and act as intercellular and intracellular messengers in the ovary.

    The importance of the follicular vasculature for maintaining follicular health has been emphasized in several studies.23 VEGF is expressed and secreted in the human ovary in a manner that suggests a role for this growth factor in both cyclic angiogenesis and regulation of vascular permeability, both of which are critical for ovarian folliculogenesis and normal reproductive function.13 Follicle selection success is strictly related to the development of a widespread blood vessel network required to sustain the enhanced proliferative and endocrine function of follicles. Blood vessels allow growing follicles to acquire an increasing amount of nutrients, precursors and hormones, as to release steroids and other regulating ovarian hormonal molecules to the systemic circulation. In addition, reduced follicular vascularity is one of the earliest signs of atresia marked by a smaller vascular network and increased apoptosis in thecal capillaries.24

    Angiogenesis is important for cyclical regeneration of endometrium in the menstrual cycle. Any imbalance between the cytokines and angiogenic factors could result in implantation failure and pregnancy loss.25 Estrogens promote angiogenesis in the endometrium by controlling the expression of factors such as VEGF.26 Reactive oxygen species generated from NADP (H) oxidase is critical for VEGF signaling in vitro and angiogenesis in vivo.27 Recent studies suggest that early pregnancy loss and implantation failure may be caused by an impaired VEGF expression, although the data are controversial.28 Luteal phase defect was found to be accompanied by an increased impedance of blood flow in the corpus luteum and spiral arteries in infertile patients.29 It was recently shown that recurrent miscarriage and failed IVF attempts may be associated with an impaired expression of VEGF, the main angiogenic factor in the endometrium.30

    Another our finding was significantly high endometrial VEGF in the subgroup, which was given 100 mg ginger for 10 days. This finding may indicate the positive effects of ginger in implantation. Though we did not observe any changes in endometrial eNOS levels, both iNOS and eNOS proteins are shown to be up-regulated in the implantation sites.31 NOS inhibitors block decidualization and establishment of pregnancy and additionally NOS inhibitors act synergistically with antiprogestins. However, besides progesterone, additional embryonic signals are shown to be involved in NOS regulation.31 As we did not mate the rats and look for pregnancy outcome, perhaps lack of embryonic signals may the reason for unchanged levels of endometrial eNOS.

    Ovarian folliculogenesis not only involves gonadotropins and the steroids, but it also involves local autocrine and paracrine factors. Nitric oxide radical is one of the local factors involved in ovarian folliculogenesis and steroidogenesis.21 The major regulator of NO production is the enzyme, NO synthase (NOS), which appears in three isoforms: neuronal NOS (nNOS), inducible NOS (iNOS), and endothelial NOS (eNOS). Both eNOS and iNOS have been detected in ovarian tissues of several species.32 A regulatory role for NO in ovulation is supported in most species, with sources thought to be both iNOS and eNOS, with iNOS activity increasing with the LH surge.33 eNOS was detected in ovarian follicles and corpus luteum during the estrous cycle in several species. It has been demonstrated that NO plays a role in the regulation of angiogenesis, steroidogenesis, apoptosis, and luteolysis.12

    NO is one of several intraovarian mediators that have been shown to influence ovarian functions, including follicular development and atresia, ovulation, steroidogenesis, oocyte quality, apoptosis, and luteal function.34 In addition, NO may positively regulate the expression of angiogenic factors, including VEGF and the angiogenesis in the ovaries and other tissues.35

    Folliculogenesis involves the participation of both growth and programmed cell death and NO regulates both. We found statistically high ovarian stromal eNOS in the 100mg/10-day subgroup. The interpretation of our result is somewhat difficult but a negative relationship between VEGF and NO levels were observed in porcine granulosa cells.36 Although low concentrations of NO may prevent apoptosis, pathologically high concentrations of NO may promote cell death.37 On the other hand, in the 100 mg/5-day subgroup, we found high levels of antral follicle count and high levels of ovarian stromal VEGF with normal levels of ovarian stromal eNOS. Under these findings, we can only speculate that the optimal duration of ginger powder on folliculogenesis may be for short term. We postulate that with the increase of ovarian stromal eNOS in the long protocol, the positive effects of ginger displayed in the short protocol are lost. Very recently, a study showing similar detrimental effects of increased levels of eNOS and iNOS in rat spermatogenesis has been published.38 In this study, impaired spermatogenesis could not been improved by long usage of antioxidants (12 weeks) and especially overexpression of iNOS was shown to be responsible for destructive effects. In fact, the studies indicating beneficial effects on sperm indices have used ginger for 4–8 weeks, which is the average duration of spermatogenesis in rats.39

    Physiological levels of ROS are required for proper functioning of different biological pathways and in maintaining homeostasis within the human body. Any disruption in the antioxidant/ROS balance leads to a state of oxidative stress in the cell with damaging consequences In our study, positive findings were only observed in 100 mg ginger powder given group, instead of 200 mg ginger powder given group. This shows that high dose antioxidant disturbs physiologic balance in folliculogenesis and implantation. This is in close correlation with the statement that follicle maturation is a classic example of the delicate balance that exists between ROS and antioxidants in the maintenance of the regulated sequence of events that culminate in ovulation as mentioned by Gupta et al.10

    In conclusion, our results showed that ginger powder increases antral follicle count and ovarian stromal VEGF at low dose with short duration and endometrial VEGF at low dose with long duration. Our results suggest positive effects of ginger in folliculogenesis and implantation. Essentially, the results of this study stress the importance of ginger as an antioxidant to suppress ROS buildup and maintain physiological levels of free radicals for proper cell functioning and homeostasis. Newer studies should be designed with different doses, intervals and parameters to show the exact effects of ginger in female reproductive system before routine recommendation for infertile women to achieve pregnancy.

    References

    1. Grant KL, Lutz RB. Ginger. Am J Health Syst Pharm. 2000;57:945-947.
    2. Rajan I, Narayanan N, Rabindran R, Jayasree PR, Manish Kumar PR. Zingerone protects against stannous chloride-induced and hydrogen peroxide-induced oxidative DNA damage in vitro. Biol Trace Elem Res. 2013;155:455-459.
    3. Kim MK, Chung SW, Kim DH, Kim JM, Lee EK, Kim JY, et al. Modulation of age-related NF-kappaB activation by dietary zingerone via MAPK pathway. Exp Gerontol. 2010;45:419-426.
    4. Vinothkumar R, Vinothkumar R, Sudha M, Nalini N. Chemopreventive effect of zingerone against colon carcinogenesis induced by 1,2-dimethylhydrazine in rats. Eur J Cancer Prev. 2014;23:361-371.
    5. Kumar L, Chhibber S, Harjai K. Zingerone inhibit biofilm formation and improve antibiofilm efficacy of ciprofloxacin against Pseudomonas aeruginosa PAO1. Fitoterapia. 2013;90:73-78.
    6. Ahmad B, Rehman MU, Amin I, Arif A, Rasool S, Bhat SA, et al. A review on pharmacological properties of zingerone (4-(4-Hydroxy-3-methoxyphenyl)-2-butanone). Sci World J. 2015;2015:816364.
    7. Maiese K. New insights for oxidative stress and diabetes mellitus. Oxid Med Cell Longev. 2015;2015:875961.
    8. Kwon SH, Hong SI, Ma SX, Lee SY, Jang CG. 3′,4′,7-Trihydroxyflavone prevents apoptotic cell death in neuronal cells from hydrogen peroxide-induced oxidative stress. Food Chem Toxicol. 2015;80:41-51.
    9. Riley JC, Behrman HR. Oxygen radicals and reactive oxygen species in reproduction. Proc Soc Exp Biol Med. 1991;198:781-791.
    10. Gupta S, Ghulmiyyah J, Sharma R, Halabi J, Agarwal A. Power of proteomics in linking oxidative stress and female infertility. BioMed Res Int. 2014;2014:916212.
    11. Duda DG, Fukumura D, Jain RK. Role of eNOS in neovascularization: NO for endothelial progenitor cells. Trends Mol Med. 2004;10:143-145.
    12. Al-Gubory KH, Ceballos-Picot I, Nicole A, Bolifraud P, Germain G, Michaud M, et al. Changes in activities of superoxide dismutase, nitric oxide synthase, glutathione-dependent enzymes and the incidence of apoptosis in sheep corpus luteum during the estrous cycle. Biochim Biophys Acta. 2005;1725:348-357.
    13. Geva E, Jaffe RB. Role of vascular endothelial growth factor in ovarian physiology and pathology. Fertil Steril. 2000;74:429-438.
    14. Smith SK. Angiogenesis and reproduction. BJOG. 2001;108:777-783.
    15. Khaki A, Farnam A, Badie AD, Nikniaz H. Effects of onion (Allium cepa) and ginger (Zingiber officinale) on sexual behavior of rat after inducing antiepileptic drug (lamotrigine). Balkan Med J. 2012;29:236-242.
    16. Khaki A, Khaki AA, Hajhosseini L, Golzar FS, Ainehchi N. The anti-oxidant effects of ginger and cinnamon on spermatogenesis dys-function of diabetes rats. Afr J Tradit Complement Altern Med. 2014;11:1-8.
    17. Bordbar H, Esmaeilpour T, Dehghani F, Panjehshahin MR. Stereological study of the effect of ginger's alcoholic extract on the testis in busulfan-induced infertility in rats. Iran J Reprod Med. 2013;11:467-472.
    18. Ghlissi Z, Atheymen R, Boujbiha MA, Sahnoun Z, MakniAyedi F, Zeghal K, et al. Antioxidant and androgenic effects of dietary ginger on reproductive function of male diabetic rats. Int J Food Sci Nutr. 2013;64:974-978.
    19. Bardaweel SK. Alternative and antioxidant therapies used by a sample of infertile males in Jordan: a cross-sectional survey. BMC Compl Altern Med. 2014;14:244.
    20. Dodge JC, Kristal MB, Badura LL. Male-induced estrus synchronization in the female Siberian hamster (Phodopus sungorus sungorus). Physiol Beha. 2002;77:227-231.
    21. Agarwal A, Gupta S, Sharma RK. Role of oxidative stress in female reproduction. Reprod Biol Endocrinol. 2005;3:28.
    22. Tsafriri A, Reich R. Molecular aspects of mammalian ovulation. Exp Clin Endocrinol Diabetes. 1999;107:1-11.
    23. Jiang JY, Macchiarelli G, Tsang BK, Sato E. Capillary angiogenesis and degeneration in bovine ovarian antral follicles. Reproduction. 2003;125:211-223.
    24. Mattioli M, Barboni B, Turriani M, Galeati G, Zannoni A, Castellani G, et al. Follicle activation involves vascular endothelial growth factor production and increased blood vessel extension. Biol Reprod. 2001;65:1014-1019.
    25. Choi HK, Choi BC, Lee SH, Kim JW, Cha KY, Baek KH. Expression of angiogenesis-and apoptosis-related genes in chorionic villi derived from recurrent pregnancy loss patients. Mol Reprod Dev. 2003;66:24-31.
    26. Albrecht ED, Babischkin JS, Lidor Y, Anderson LD, Udoff LC, Pepe GJ. Effect of estrogen on angiogenesis in co-cultures of human endometrial cells and microvascular endothelial cells. Hum Reprod. 2003;18:2039-2047.
    27. Ushio-Fukai M, Alexander RW. Reactive oxygen species as mediators of angiogenesis signaling: role of NAD(P)H oxidase. Mol Cell Biochem. 2004;264:85-97.
    28. Sadekova ON, Nikitina LA, Rashidov TN, Voloschuk IN, Samokhodskaya LM, Demidova EM, et al. Luteal phase defect is associated with impaired VEGF mRNA expression in the secretory phase endometrium. Reprod Biol. 2015;15:65-68.
    29. Kupesic S, Kurjak A, Vujisic S, Petrovic Z. Luteal phase defect: comparison between Doppler velocitometry, histological and hormonal markers. Ultrasound Obstet Gynecol. 1997;9:105-112.
    30. Seo WS, Jee BC, Moon SY. Expression of endometrial protein markers in infertile women and the association with subsequent in vitro fertilization outcome. Fertil Steril. 2011;95:2707-2710.
    31. Chwalisz K, Garfield RE. Role of nitric oxide in implantation and menstruation. Hum Reprod. 2000;15(Suppl. 3):96-111.
    32. Olson LM, Jones-Burton CM, Jablonka-Shariff A. Nitric oxide decreases estradiol synthesis of rat luteinized ovarian cells: possible role for nitric oxide in functional luteal regression. Endocrinology. 1996;137:3531-3539.
    33. Zamberlam G, Sahmi F, Price CA. Nitric oxide synthase activity is critical for the preovulatory epidermal growth factor-like cascade induced by luteinizing hormone in bovine granulosa cells. Free Radic Biol Med. 2014;74:237-244.
    34. Grazul-Bilska AT, Navanukraw C, Johnson ML, Arnold DA, Reynolds LP, Redmer DA. Expression of endothelial nitric oxide synthase in the ovine ovary throughout the estrous cycle. Reproduction. 2006;132:579-587.
    35. Reynolds LP, Grazul-Bilska AT, Redmer DA. Angiogenesis in the corpus luteum. Endocrine. 2000;12:1-9.
    36. Grasselli F, Basini G, Bussolati S, Tamanini C. Effects of VEGF and bFGF on proliferation and production of steroids and nitric oxide synthase in the pocrine granulosa cells. Reprod Domest Anim. 2002;37:362-368.
    37. Rosselli M, Keller PJ, Dubey RK. Role of nitric oxide in the biology, physiology and pathophysiology of reproduction. Hum Reprod Update. 1998;4:3-24.
    38. Sohrabi M, Hosseini M, Inan S, Alizadeh Z, Vahabian M, Vahidinia AA, et al. Effect of antioxidants on testicular iNOS and eNOS after high-fat diet in rat. Pak J Biol Sci. 2017;20:289-297.
    39. Creasy DM. Evaluation of testicular toxicity in safety evaluation studies: the appropriate use of spermatogenic staging. Toxicol Pathol. 1997;25:119-131.
    Keywords:

    eNOS; Folliculogenesis; Ginger; Implantation; Oxidative stress; VEGF

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