Extract of Azadirachta indica (neem) leaf induces apoptosis in rat oocytes cultured in vitro

Reactive oxygen species signalling in the deterioration of quality of mammalian oocytes cultured in vitro: Protective effect of antioxidants

The in vitro fertilization (IVF) is the first choice of infertile couples worldwide to plan for conception. Besides having a significant advancement in IVF procedure, the success rate is still poor. Although several approaches have been tested to improve IVF protocol, minor changes in culture conditions, physical factors and/or drug treatment generate reactive oxygen species (ROS) in oocytes. Due to large size and huge number of mitochondria, oocyte is more susceptible towards ROS-mediated signalling under in vitro culture conditions. Elevation of ROS levels destabilize maturation promoting factor (MPF) that results in meiotic exit from diplotene as well as metaphase-II (M-II) arrest in vitro. Once meiotic exit occurs, these oocytes get further arrested at metaphase-I (M-I) stage or metaphase-III (M-III)-like stage under in vitro culture conditions. The M-I as well as M-III arrested oocytes are not fit for fertilization and limits IVF outcome. Further, the generation of excess levels of ROS cause oxidative stress (OS) that initiate downstream signalling to initiate various death pathways such as apoptosis, autophagy, necroptosis and deteriorates oocyte quality under in vitro culture conditions. The increase of cellular enzymatic antioxidants and/or supplementation of exogenous antioxidants in culture medium protect ROS-induced deterioration of oocyte quality in vitro. Although a growing body of evidence suggests the ROS and OS-mediated deterioration of oocyte quality in vitro, their downstream signalling and related mechanisms remain poorly understood. Hence, this review article summarizes the existing evidences concerning ROS and OS-mediated downstream signalling during deterioration of oocyte quality in vitro. The use of various antioxidants against ROS and OS-mediated impairment of oocyte quality in vitro has also been explored in order to increase the success rate of IVF during assisted reproductive health management.

Azadirachta indica A. Juss (neem) as a contraceptive: An evidence-based review on its pharmacological efficiency

BACKGROUND

Azadirachta indica A. Juss. is an Indian medicinal plant with innumerable pharmacological properties. Studies have proven that the phytochemicals from neem possess remarkable contraceptive abilities with limited knowledge on its mechanism of action.

PURPOSE

The present review aims to summarize the efficiency of A. indica treatment as a contraceptive.

METHODS

The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines were used. Published scientific articles on antifertility, antispermatogenic, antiovulation, hormone altering, contraceptive, and abortifacient activities of A. indica were collected from reputed Journals from 1980 to 2020 using electronic databases. Specific keywords search was completed to collect numerous articles with unique experiment design and significant results. This was followed by the selection of the requisite articles based on the criteria designed by the authors. Data extraction was based on the common research elements included in the articles.

RESULTS

A total of 27 studies were considered for reviewing, which included key pharmacological investigations. In the beginning, authors evaluated a number of publications on the contraceptive properties of A. indica, in which it was revealed that most of the publications were made between 2005 and 2009. All the collected articles were categorised and reviewed as antifertility, antispermatogenic, antiovulation, hormone altering, contraceptive, and abortifacient. Authors also assessed studies based on the plant parts used for pharmacological evaluations including leaves, seeds, stem-bark, and flowers. The article was primarily divided into different sections based on the previous works of authors on phytochemistry and pharmacological review articles.

CONCLUSION

Although A. indica is not reported with the complete alleviation of reproductive system in both male and female animal models, studies have proven its efficacy as a contraceptive. Extracts and phytochemicals from neem neither reduced the libido nor retarded the growth of secondary sexual characters, thus indicating only a temporary and reversible contraceptive activity. However, there is a dearth for clinical studies to prove the efficacy of A. indica as a herbal contraceptive.

Exploring the role of Azadirachta indica (neem) and its active compounds in the regulation of biological pathways: an update on molecular approach

In ethnomedicine, plant parts and compounds are used traditionally to treat different diseases. Neem (Azadirachta indica A. Juss) is the most versatile and useful medicinal plant ever found. Its every part is rich in bioactive compounds, which have traditionally been used to treat different ailments including infectious diseases. Bioactive compounds such as nimbolide, azarirachtin, and gedunin of neem are reported to have a tremendous ability to regulate numerous biological processes in vitro and in vivo. The present review article aims to explore the importance of neem extracts and bioactive compounds in the regulation of different biological pathways. We have reviewed research articles up to March 2020 on the role of neem in antioxidant, anti-inflammatory, antiangiogenic, immunomodulatory, and apoptotic activities. Studies on the concerned fields demonstrate that the bioactive compounds and extracts of neem have a regulatory effect on several biological mechanisms. It has been unveiled that extensive research is carried out on limonoids such as nimbolide and azarirachtin. It is evidenced by different studies that neem extracts are the potential to scavenge free radicals and reduce ROS-mediated damage to cells. Neem can be used to normalize lipid peroxidation and minimize ROS-mediated cell death. Besides, neem extracts can significantly reduce the release of proinflammatory cytokines and elevate the count of CD4 + and CD8 + T-cells. This review indicates the pivotal roles of A. indica in the regulation of different biological pathways. However, future investigations on other bioactive compounds of neem may reveal different therapeutic potentials.

Necrosis and necroptosis in germ cell depletion from mammalian ovary

The maximum number of germ cells is present during the fetal life in mammals. Follicular atresia results in rapid depletion of germ cells from the cohort of the ovary. At the time of puberty, only a few hundred (<1%) germ cells are either culminated into oocytes or further get eliminated during the reproductive life. Although apoptosis plays a major role, necrosis as well as necroptosis, might also be involved in germ cell elimination from the mammalian ovary. Both necrosis and necroptosis show similar morphological features and are characterized by an increase in cell volume, cell membrane permeabilization, and rupture that lead to cellular demise. Necroptosis is initiated by tumor necrosis factor and operated through receptor interacting protein kinase as well as mixed lineage kinase domain-like protein. The acetylcholinesterase, cytokines, starvation, and oxidative stress play important roles in necroptosis-mediated granulosa cell death. The granulosa cell necroptosis directly or indirectly induces susceptibility toward necroptotic or apoptotic cell death in oocytes. Indeed, prevention of necrosis and necroptosis pathways using their specific inhibitors could enhance growth/differentiation factor-9 expression, improve survivability as well as the meiotic competency of oocytes, and prevent decline of reproductive potential in several mammalian species and early onset of menopause in women. This study updates the information and focuses on the possible involvement of necrosis and necroptosis in germ cell depletion from the mammalian ovary.

Morphological, cellular and molecular changes during postovulatory egg aging in mammals

Postovulatory aging is associated with several morphological, cellular and molecular changes that deteriorate egg quality either by inducing abortive spontaneous egg activation (SEA) or by egg apoptosis. The reduced egg quality results in poor fertilization rate, embryo quality and reproductive outcome. Although postovulatory aging-induced abortive SEA has been reported in several mammalian species, the molecular mechanism(s) underlying this process remains to be elucidated. The postovulatory aging-induced morphological and cellular changes are characterized by partial cortical granules exocytosis, zona pellucida hardening, exit from metaphase-II (M-II)arrest and initiation of extrusion of second polar body in aged eggs. The molecular changes include reduction of adenosine 3',5'- cyclic monophosphate (cAMP) level, increase of reactive oxygen species (ROS) and thereby cytosolic free calcium (Ca²⁺) level. Increased levels of cAMP and/or ROS trigger accumulation of Thr-14/Tyr-15 phosphorylated cyclin-dependent kinase 1 (Cdk1) on one hand and degradation of cyclin B1 through ubiquitin-mediated proteolysis on the other hand to destabilize maturation promoting factor (MPF). The destabilized MPF triggers postovulatory aging-induced abortive SEA and limits various assisted reproductive technologies (ARTs) outcome in several mammalian species. Use of certain drugs that can either increase cAMP or reduce ROS level would prevent postovulatory aging-induced deterioration in egg quality so that more number of good quality eggs can be made available to improve ART outcome in mammals including human.

Neem (Azadirachta indica L.) leaf extract deteriorates oocyte quality by inducing ROS-mediated apoptosis in mammals

Neem (Azadirachta indica L.) leaf has been widely used in ayurvedic system of medicine for fertility regulation for a long time. The molecular mechanism by which neem leaf regulates female fertility remains poorly understood. Animal studies suggest that aqueous neem leaf extract (NLE) induces reactive oxygen species (ROS) - mediated granulosa cell apoptosis. Granulosa cell apoptosis deprives oocytes from nutrients, survival factors and cell cycle proteins required for the achievement of meiotic competency of follicular oocytes prior to ovulation. Under this situation, follicular oocyte becomes more susceptible towards apoptosis after ovulation. The increased level of hydrogen peroxide (H₂O₂) inside the follicular fluid results in the transfer of H₂O₂ from follicular fluid to the oocyte. The increased level of H₂O₂ induces p53 activation and over expression of Bax protein that modulates mitochondrial membrane potential and trigger cytochrome c release. The increased cytosolic cytochrome c level induces caspase-9 and caspase-3 activities that trigger destruction of structural and specific proteins leading to DNA fragmentation and thereby oocyte apoptosis. Based on these animal studies, we propose that NLE induces generation of ROS and mitochondria-mediated apoptosis both in granulosa cells as well as in follicular oocyte. The induction of apoptosis deteriorates oocyte quality and thereby limits reproductive outcome in mammals.

An increase of granulosa cell apoptosis mediates aqueous neem (Azadirachta indica) leaf extract-induced oocyte apoptosis in rat

Objective:

Neem plant (Azadirachta indica) has been extensively used in Ayurvedic system of medicine for female fertility regulation for a long time, but its mechanism of action remains poorly understood. Hence, the present study was aimed to determine whether an increase of granulosa cell apoptosis is associated with aqueous neem leaf extract (NLE)-induced oocyte apoptosis.

Materials and Methods:

Sexually immature female rats of 20 days old were fed NLE (50 mg/day) for 10 days and then subjected to superovulation induction protocol. The morphological changes in cumulus oocyte complexes (COCs), rate of oocyte apoptosis, hydrogen peroxide (H₂O₂), total nitrite, and cytochrome c concentrations, inducible nitric oxide synthase (iNOS), cytochrome c, p53, Bcl2 and Bax expressions, deoxyribonucleic acid (DNA) fragmentation, and estradiol 17β level in granulosa cells collected from preovulatory COCs were analyzed.

Results:

Aqueous NLE increased H₂O₂ concentration and decreased catalase activity, increased iNOS expression and total nitrite concentration, increased p53, Bax, and p53 expressions but decreased Bcl2 expression, increased cytochrome c concentration and induced DNA fragmentation in granulosa cells. An increased granulosa cell apoptosis resulted in reduced estradiol 17β concentration and induced apoptosis in ovulated oocytes.

Conclusion:

We conclude that aqueous NLE-induced granulosa cell apoptosis through the mitochondria-mediated pathway, reduced estradiol 17β concentration and induced apoptosis in ovulated oocytes. Thus, granulosa cell apoptosis mediates NLE-induced oocyte apoptosis during female fertility regulation in rat.

Fertility control of rodent pests: a review of the inhibitory effects of plant extracts on ovarian function

BACKGROUND

Plant extracts can inhibit fertility by adversely affecting, directly or indirectly, reproductive processes ranging from gonadal function and development to gestation. This review focuses on plant extracts that disrupt ovarian function in rodents.

RESULTS

Extracts from at least 40 plant species exert some of their disruptive reproductive effects at the ovarian level. Of those, 13 plants induce a reduction in the number and type of ovarian follicles and also cause disruption to the oestrous cycle. Their effects are short term and reversible once treatment ceases.

CONCLUSIONS

Protection of plant extracts to prevent their degradation before uptake in the gastrointestinal tract could enhance short-term efficacy but would not enhance the longevity of their effects. Identification and further testing of the specific chemicals responsible for reproductive effects would be beneficial. The adoption of a standard protocol for treatment and assessment of the inhibitory effects of potential control agents on reproductive function in rodents is essential. Treatment with higher concentrations of extracts in conjunction with other extracts or with other chemosterilants could have potential complementary effects and lead to more rapid and permanent changes in ovarian function. An orally delivered agent(s) that causes major depletion of all follicle types, and particularly of non-regenerating primordial follicles, could be an ideal fertility control product and serve as an additional tool for population control of pest rodents.

Azadirachta indica acts as a pro-oxidant and modulates cell cycle associated proteins during DMBA/TPA induced skin carcinogenesis in mice

The present study was designed to determine the modulatory effect of aqueous Azadirachta indica leaf extract (AAILE) on cell cycle-associated proteins during two-stage skin carcinogenesis in mice. Considering the dual role of reactive oxygen species in cancer and its chemoprevention, the levels of lipid peroxidation (index of peroxidative damage) were also determined. Skin tumours were induced by topical application of 7,12-dimethylbenz(a)anthracene (DMBA) as a carcinogen followed by the repetitive application of 12-O-tetradecanoylphorbol-13-acetate (TPA) as a promoter. Skin tumours obtained in the DMBA/TPA group exhibited enhanced expression of proliferating cell nuclear antigen (PCNA, index of proliferation), p21 and cyclin D1, with no alterations in p53 expression in comparison to the control group. Tumours in AAILE + DMBA/TPA group exhibited low PCNA and cyclin D1 expression and enhanced expression of p53 and p21 in comparison to the DMBA/TPA group. The skin tumours obtained in the AAILE + DMBA/TPA group exhibited high lipid peroxidation levels in comparison to the tumours obtained in the DMBA/TPA group. The observations of the present study suggest that AAILE behaves as a pro-oxidant in the tumours, thereby rendering them susceptible to damage, which eventually culminates into its anti-neoplastic action. Also, cell cycle regulatory proteins may be modulated by AAILE and could affect the progression of cells through the cell cycle.

High cytosolic free calcium level signals apoptosis through mitochondria-caspase mediated pathway in rat eggs cultured in vitro

The present study was aimed to find out whether an increase of cytosolic free calcium level induces egg apoptosis through mitochondria-caspase mediated pathway. To increase cytosolic free calcium level and morphological apoptotic changes, ovulated eggs were cultured in Ca(2+)/Mg(2+) free media-199 with or without various concentrations of calcium ionophore (0.5, 1, 2, 3, 4 μM) for 3 h in vitro. The morphological apoptotic changes, cytosolic free calcium level, hydrogen peroxide (H(2)O(2)) concentration, catalase activity, cytochrome c concentration, caspase-9 and caspase-3 activities and DNA fragmentation were analyzed. Calcium ionophore induced morphological apoptotic features in a concentration-dependent manner followed by degeneration at higher concentrations (3 and 4 μM). Calcium ionophore increased cytosolic free calcium level, induced generation of hydrogen peroxide (H(2)O(2)) and inhibited catalase activity in treated eggs. The increased H(2)O(2) concentration was associated with increased cytochrome c concentration, caspase-9 and caspase-3 activities that resulted in the induction of morphological features characteristic of egg apoptosis. The increased caspase-3 activity finally induced DNA fragmentation as evidenced by TUNEL positive staining in calcium ionophore-treated eggs. These findings suggest that high cytosolic free calcium level induces generation of H(2)O(2) that leads to egg apoptosis through mitochondria-caspase mediated pathway.

Aqueous extract of Azadirachta indica (neem) leaf induces generation of reactive oxygen species and mitochondria-mediated apoptosis in rat oocytes

OBJECTIVE

Present study was aimed to determine whether aqueous neem leaf extract (NLE) induces generation of reactive oxygen species (ROS) and apoptosis through mitochondria-mediated pathway in rat oocytes.

DESIGN

A controlled prospective study.

SETTING

Laboratory research setting at Department of Zoology of Banaras Hindu University.

ANIMAL(S)

Forty eight sexually immature female rats that were 20-30 days of age.

INTERVENTION(S)

Sexually immature female rats were fed palatable dose of NLE (10 mg/g dry feed palate) for 10 days and then subjected to superovulation induction protocol. Thereafter, rats were euthanized, ovulated cumulus oocyte complexes were collected from oviduct and oocytes were denuded.

MAIN OUTCOME MEASURE(S)

Rate of morphological apoptotic changes, measurement of hydrogen peroxide, nitric oxide and cytochrome c concentrations, caspase-9, caspases-3 activities and DNA fragmentation in oocytes.

RESULTS

In vivo NLE treatment induced morphological apoptotic changes were associated with increased hydrogen peroxide, nitric oxide and cytochrome c concentrations, caspase-9, caspase-3 activities and DNA fragmentation in oocyte.

CONCLUSION

NLE induces generation of ROS that leads to oocytes apoptosis through mitochondria-mediated pathway.

Chemopreventive activity of Azadirachta indica on two-stage skin carcinogenesis in murine model

The present study reports the chemopreventive activity of aqueous Azadirachta indica leaf extract (AAILE) in a murine two-stage skin carcinogenesis model. Skin tumors were induced by topical application of 7,12-dimethylbenz(a)anthracene (DMBA) (500 nmol/100 µL for 2 weeks) followed by 12-O-tetradecanoylphorbol-13-acetate (TPA) (1.7 nmol/100 µL of acetone, twice weekly) as a promoter. Male LACA mice were divided into four groups: control, DMBA/TPA, AAILE and AAILE + DMBA/TPA. AAILE was administered orally at a dose level of 300 mg/kg body weight thrice a week for 20 weeks. 100% tumor incidence was observed in the DMBA/TPA treated animals, whereas the AAILE + DMBA treated animals exhibited a tumor incidence of 58.3% only. A significant reduction in the mean tumor burden (54.5%) and mean tumor volume (45.6%) was observed in the mice that received AAILE along with DMBA/TPA. Topical application of DMBA/TPA to the skin resulted in well-developed carcinomas associated with decreased expression of pro-apoptotic protein such as caspase 3 and enhanced expression of antiapoptotic protein such as bcl-2 when compared with the control counterparts. However, adminstration of AAILE inhibited skin carcinogenesis with induction of pro-apoptotic proteins such as bax, caspase 3, caspase 9 and inhibition of antiapoptotic proteins such as bcl-2. These results suggest that the induction of apoptosis may be one of the mechanisms underlying the chemopreventive effects of A. indica.

Calcium ionophore-induced egg activation and apoptosis are associated with the generation of intracellular hydrogen peroxide

The present study was designed to investigate whether calcium ionophore-induced activation and apoptosis are associated with the generation of hydrogen peroxide (H(2)O(2)) in rat eggs cultured in vitro. Culture of metaphase-II (M-II) arrested eggs in Ca(2+)/Mg(2+)-deficient medium did not induce egg activation, while a second polar body was observed in 20% of eggs when cultured in Ca(2+)/Mg(2+)-supplemented medium. In Ca(2+)/Mg(2+)-deficient medium, lower concentrations of calcium ionophore (0.2,0.4 and 0.8 microm) not only induced egg activation in a dose-dependent manner but also generation of intracellular H(2)O(2) (84.40+/-0.50 ng/egg) when compared to control eggs (80.46+/-1.34 ng/egg). The higher concentration of calcium ionophore (1.6 microm) induced apoptosis and pronounced generation of intracellular H(2)O(2) (92.43+/-0.93 ng/egg) in treated eggs. Conversely, cell-permeant antioxidant such as 2(3)-tert-butyl-4-hydroxyanisole (BHA) reduced intracellular H(2)O(2) level (81.20+/-1.42 ng/egg) and protected against calcium ionophore-induced morphological changes characteristics of egg activation and apoptosis. These results clearly suggest that calcium ionophore-induced activation and apoptosis are associated with the generation of intracellular H(2)O(2) in rat eggs.

Verapamil reversibly inhibits spontaneous parthenogenetic activation in aged rat eggs cultured in vitro

The present study was designed to investigate whether verapamil could inhibit spontaneous parthenogenetic activation in aged rat eggs cultured in vitro. Eggs collected from oviduct after 19 h post human chorionic gonadotropin (hCG) were arrested at the metaphase-II (M-II) stage and exhibited a first polar body. Culture of these aged eggs in calcium/magnesium (Ca(2+)/Mg(2+))-deficient and serum-free medium for 3 h induced exit from M-II, a morphological sign of spontaneous parthenogenetic activation in all eggs. However, verapamil reversibly inhibited spontaneous parthenogenetic activation in a dose-dependent manner. Further, lower doses (6.25, 12.5, and 25 muM) of verapamil induced egg survival, while higher doses (50 and 100 muM) were associated with the appearance of morphological apoptotic features such as shrinkage, membrane blebbing and cytoplasmic granulation prior to degeneration. The DNA fragmentation was induced [as evidenced by terminal deoxynucleotidyl transferase (TdT) nick-end labeling (TUNEL) positive staining] in eggs undergoing morphological apoptotic changes. On the other hand, caspase-3 inhibitor (1 muM) partially inhibited morphological apoptotic changes (44.34+/-3.53%) suggesting the involvement of both Ca(2+)and caspase-3-mediated apoptotic pathways. These findings suggest that verapamil reversibly inhibits spontaneous parthenogenetic activation and induces egg survival at lower doses, while higher doses induce cell death via apoptosis.