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Biomedical subjects

D K Saxena

Publications and source records attributed to D K Saxena.

At least 37 records · Page 2Linked to original sources
PubMed2000

Effect of lead on Sertoli-germ cell coculture of rat.

Mixed cultures of Sertoli and germ cells were prepared from rat testes and their response to lead (Pb) was studied. Cultures consisted of a monolayer of Sertoli cells to which clusters of germ cells were attached. The effect of Pb added as lead acetate was tested at 0.0, 0.4, 4.0 and 40.0 microM for 24 and 48 h intervals. Addition of Pb to the culture medium caused germ cells to progressively detach from the Sertoli cell monolayer into the medium in a concentration and duration dependent manner Viability of the detached cells as judged by trypan blue exclusion test showed a decrease with increase in time and concentration of Pb. Significant leakage of lactate dehydrogenase (LDH) was recorded in the culture media only at the higher concentrations of 4.0 and 40.0 microM. Thus Pb at the doses tested induced cytotoxicity in rat Sertoli-germ cell coculture.

Animals↗
PubMed2000

Behaviour and role of an intra-acrosomal antigenic molecule, acrin 3, during mouse fertilisation in vitro.

In this study we examined the behaviour and role of an intra-acrosomal antigenic molecule, acrin 3, during mouse fertilisation in vitro by assessing the effect of its pertinent monoclonal antibody mMC101. Experiments were designed to assess the effect of mMC101 on sperm-zona pellucida binding, the acrosome reaction, zona pellucida penetration, sperm-egg fusion, and fertilisation in vitro. mMC101 did not affect sperm motility or primary and secondary binding to the zona pellucida, but significantly inhibited fertilisation of zona-pellucida-intact oocytes in a dose-dependent manner. In the presence of mMC101 at 100 microg/ml concentration in TYH medium, none of the oocytes developed to pronuclear stage by 5 h after co-incubation of the gametes, but the pronucleus formation rate recovered to some extent (45.3%) after 8 h, indicating a delay of early embryonic development. mMC101 also delayed and significantly suppressed zona pellucida penetration by sperm. Acrin 3 dispersed and did not remain on completely acrosome-reacted sperm. Although mMC101 did not influence the zona-pellucida-induced acrosome reaction, it significantly inhibited fertilisation when acrosome-reacted sperm in the presence of mMC101 inseminated zona-pellucida-free oocytes. However, fertilisation remained unaffected when acrosome-reacted sperm in the absence of mMC101 inseminated zona-pellucida-free oocytes even in its presence. Thus, acrin 3 appears to facilitate zona pellucida penetration and is also likely to be involved in sperm-oocyte fusion by modifying the sperm plasma membrane during the acrosome reaction.

Acrosome↗
PubMed2000

Toxicity of aflatoxin: effects on spermatozoa, oocytes, and in vitro fertilization.

Aflatoxin B1 has been reported to have a deleterious effect on the reproductive capacity of laboratory and domestic animals. We wanted to elucidate the mechanistic aspect of this phenomenon by determining the toxic potential of aflatoxin B1 on the in vitro fertilizing ability of oocytes and epididymal sperm in albino rats. In vitro fertilization medium (IVFM) containing aflatoxin B1 at concentrations of 2.0, 4.0, 8.0, and 16.0 ppb was cultured with oocytes obtained from superovulated healthy fertile female rats and exposed to sperm cells. Epididymal sperm capacitated in IVFM, with or without aflatoxin B1, were exposed to oocytes, and the rates of fertilization in the two experiments were assessed. Aflatoxin B1 significantly reduced the mean number of ova fertilized, even at the lowest concentration. Exposure to aflatoxin caused a significant reduction in the motility of sperm cells. These results demonstrate the adverse effects of aflatoxin B1 on oocytes, spermatozoa, and in vitro fertilization.

Aflatoxin B1↗
PubMed1999

Male reproductive effect of nickel sulphate in mice.

Nickel sulphate was administered orally to adult male mice at dose level of 5 and 10 mg/kg body weight (5 days per week) for 35 days. There was no change in body weight. However a significant decrease in absolute and organ-to-body weight ratios of testes, epididymides, seminal vesicles and prostate gland was observed. The sperm abnormality, associated with decrease in sperm motility and sperm count was also observed. Significant alterations in the activities of marker testicular enzymes, viz. sorbitol dehydrogenase (decreases), lactate dehydrogenase (increases) and gamma-glutamyl transpeptidase (increases) associated with histopathological changes in testes, epididymides and seminal vesicles, were also observed. Accumulation of nickel in testes, epididymides and seminal vesicles was also observed. The study reveals that the oral exposure to nickel may affect the histology of testes, epididymides, seminal vesicles and sperms morphology. These testicular and spermatotoxic changes may be responsible for observed male mediated developmental toxic effects.

Animals↗
PubMed1999

Role of intra-acrosomal antigenic molecules acrin 1 (MN7) and acrin 2 (MC41) in penetration of the zona pellucida in fertilization in mice.

In this study the role of two intra-acrosomal molecules, acrin 1 (MN7) and acrin 2 (MC41), during in vitro fertilization (IVF) was examined. The pertinent monoclonal antibodies mMN7 and mMC41 specifically recognize a 90 kDa protein (acrin 1) localized to the entire acrosome and a 200 kDa protein (acrin 2) localized to the cortex region of the anterior acrosome, respectively. Experiments were designed to assess the effects of mMN7 and mMC41 on fertilization in mice using TYH medium containing mMN7 or mMC41 at 0.0, 0.025, 0.05 and 0.1 mg ml-1. Under these conditions, capacitated spermatozoa inseminated the cumulus-invested oocytes. Acrosome-reacted spermatozoa inseminated the zona pellucida-free oocytes. The antibodies had no effect on sperm motility and primary binding to the zona pellucida, but significantly inhibited the rate of fertilization of zona pellucida-intact oocytes in a dose-dependent manner. A significantly small number of spermatozoa remained attached to the zona pellucida at 5 h after insemination in the presence of mMC41. mMC41 and mMN7 antibodies did not affect the fertilization rate of zona pellucida-free oocytes. Confocal laser scanning microscopy with indirect immunofluorescence traced the effect of the monoclonal antibodies on the zona pellucida-induced acrosome reaction, and revealed that mMN7 prevented completion of acrosomal matrix dispersal, whereas mMC41 did not affect the acrosome reaction. mMC41 appeared to inhibit secondary binding or some biochemical steps on the zona pellucida after the acrosome reaction but before penetration of the zona pellucida. Thus, the intra-acrosomal antigenic molecules acrin 1 and acrin 2 are essential for distinct events before sperm penetration of the zona pellucida in mice.

Acrosome↗
PubMed1999

Effect of cadmium on the hatching of Metaphire posthuma cocoons.

Earthworms are considered ideal soil organisms for use in terrestrial ecotoxicology. Due to their susceptibility of heavy metals, the effect of cadmium on the hatching of M. posthuma cocoons was studied. The hatching was observed by the water incubation method and the doses of Cd were 0, 1.25, 2.5, 5.0, 10.0 and 40.0 ppm. The 0 and 1.25 ppm treated cocoons hatched within 45-60 days at 20 degrees C with 80% hatching rate and one juvenile per cocoon; no hatching was observed at higher concentrations. Furthermore, there was a linear increase in Cd residue in the treated cocoons. These results are apparently ill effects of Cd on embryonic development of the earthworms.

Animals↗
PubMed1998

Immunocytochemical alterations in the intra-acrosomal antigen MN7 during epididymal maturation of guinea pig spermatozoa.

We have previously shown that a 90-kDa intra-acrosomal antigen, MN7, is restricted to the anterior acrosomal region of mouse, rat, and hamster spermatozoa. The present study has examined the localization and the behavior of MN7 during sperm maturation in the epididymis of the guinea pig by immunoelectron microscopy. MN7 showed not only a specific localization in the apical segment of the guinea pig sperm acrosome, but also a distinct alteration during maturation, as follows. MN7 was exclusively found both at the dorsal matrix and on the outer acrosome membrane (OAM)/matrix-associated materials in the apical segment. MN7 was initially distributed throughout the electron-lucent dorsal matrix in immature sperm but, during maturation, became more restricted to the spherical bodies within the electron-lucent area. MN7 on OAM/matrix-associated materials was first distributed along the ventral margin and the small area posterior to the dorsal matrix but, during maturation, disappeared from the ventral margin and became restricted to the dorsal region. These results indicate that MN7 is a good tool for studying the stepwise maturation of epididymal spermatozoa.

Acrosome↗
PubMed1998

Effect of alpha-tocopherol supplementation on the impact of aflatoxin B1 on the testes of rats.

Rats were given aflatoxin B1 (7.5 microg/200 g b.w.) and alpha-tocopherol (0.9 mg/200 g b.w.) for 14 days oral intubation to investigate the effect of alpha-tocopherol on the toxicity of aflatoxin B1 on rat's testes. There were significant alterations in testicular sorbitol dehydrogenase, lactic dehydrogenase, glucose-6-phosphate dehydrogenase, gamma glutamyl transpeptidase; reduced quality of sperm and marked pathological changes in the testis of rats given aflatoxin B1 alone. Alpha-tocopherol supplementation increased the aflatoxin blood level. A reduction in the toxicity of free radicals by alpha-tocopherol in association with a reduction in aflatoxin metabolism seem to be responsible for the protective influence observed.

Aflatoxin B1↗
PubMed1998

An MN9 antigenic molecule, equatorin, is required for successful sperm-oocyte fusion in mice.

The acrosome plays an important role in fertilization. This study was designed to examine the role and behavior of a molecule, equatorin (the antigenic molecule of the monoclonal antibody mMN9), localized at the equatorial segment of the acrosome. In vitro fertilization (IVF) investigation was conducted to examine the role of this molecule, by assessing the effect of mMN9 in TYH medium (a modified Krebs Ringer bicarbonate solution) containing mMN9 at 0 (control), 25, 50, and 100 microg/ml. Under these conditions, the IVF investigation was divided into two experiments: 1) the zona pellucida (zona)-intact experiment, in which capacitated sperm inseminated cumulus- and zona-intact oocytes; and 2) the zona-free experiment, in which acrosome-reacted sperm inseminated zona-free oocytes. It was found that mMN9 did not affect sperm motility, zona binding, or zona penetration, but it significantly inhibited fertilization, reducing the rates of pronucleus and two-cell embryo formation in both the zona-intact and zona-free oocyte experiments. In addition, when judged at 5 h after insemination in the zona-intact experiment, nearly half of the unfertilized oocytes had accumulated sperm in the perivitelline space (perivitelline sperm), and concurrently we confirmed by electron microscopy the presence of many unreleased cortical granules preserved beneath the oolemma, indicating no occurrence of sperm-oocyte fusion. Confocal laser scanning light microscopy with indirect immunofluorescence demonstrated that equatorin was localized at the equatorial segment in both capacitated and perivitelline sperm (acrosome-reacted sperm). These results suggest that equatorin that is preserved at the equatorial segment is involved in the process of sperm-oocyte fusion in mice.

Acrosome↗
PubMed1998

Effect of hexachlorocyclohexane on hsp26 expression in transgenic Drosophila melanogaster.

Hexachlorocyclohexane (HCH) at different concentrations (0.5 to 5.0 ng/ml) mixed with food was fed to third instar larvae of hsp26-lacZ transgenic Drosophila for 2 hr and hsp26 gene expression was examined by beta-galactosidase staining. Puffing in salivary gland polytene chromosomes was also studied. Brain and midgut of larvae showed dark blue staining at 2.0 and 5.0 ng/ml of HCH. Absence of induced puffing at 67B and 84D in the salivary gland polytene chromosomes indicated that these glands are not affected. The study suggests presence of the vulnerable sites in larvae to the higher concentrations of HCH.

Animals↗
PubMed1997

Lead-induced changes in ovarian follicular development and maturation in mice.

Lead, a potent reproductive toxicant in humans and experimental animals, was used to detect the morphological basis of ovarian toxicity in mice by counting the various stages of follicular development using different doses of lead acetate (0, 2, 4 or 8 mg/kg/d) for 60 d (5 d/wk) by oral gavage. Our results revealed that while small and medium follicles were significantly affected even at the lowest dose (2 mg), the large follicles were affected mostly at the highest dose. Atresia even in the medium follicles reflected the extent of damage caused by lead. These findings correlated well with increased blood lead levels. Therefore, lead seems to affect the follicular development and maturation, if mice are, exposed to sufficiently high concentrations of metal through the oral route.

Animals↗
PubMed1997

Aflatoxin B1 and reproduction. I. Reproductive performance in female rats.

An experimental group of female rats was exposed to aflatoxin B1 at a dose of 7.5 mg/kg body weight daily for 14 days through oral intubation. A deleterious effect on the gonads and embryotoxicity in the experimental animals were observed. There were reductions in ovarian and uterine sizes, increases in fetal resorption, implantation loss, and intra-uterine death. The data showed significant disturbances in oestrus cycle, inhibition of lordosis, and reductions in the conception rates and litter sizes, suggesting severe impairment of fertility in the aflatoxin exposed rats. An aflatoxin blood level of 86.2 +/- 1.3 ppb was recovered in the experimental animals.

Aflatoxin B1↗
PubMed1997

Aflatoxin B1 and reproduction. II. Gametoxicity in female rats.

It has been reported that aflatoxin B1 impairs the reproductive performance of female animals. The mechanism of action of this toxin on the reproductive system was investigated. Female Druckery Strain rats were administered aflatoxin B1 at doses of 7.5 and 15.0 mg/kg body weight through oral intubation for 21 days. The ovary was examined by counting superovulated oocytes and the follicles in 6 mm thick sections. Estradiol and progesterone blood levels were determined. The body and sex organ weights of rats were recorded. There were significant reductions in the number of oocytes and large follicles in a dose dependent response. The blood hormone level and body and sex organ weight were significantly disturbed. We propose that aflatoxin B1 is gametotoxic and deranges hormonal balance in affected animals.

Aflatoxin B1↗
PubMed1996

Ovarian dysfunction in mice following chromium (VI) exposure.

Chromium (VI) was given through drinking water in two sets of adult Swiss albino female mice in three doses; 250 ppm, 500 ppm and 750 ppm for 20 days in set 1 and 0.05 ppm, 0.5 ppm and 5.0 ppm in set II for 90 days. At the termination of the treatment, the animals of both the sets were euthanized for histopathology, follicle counting, counting of the superovulated ova, duration of estrus cycle and for ultrastructural studies. Ovaries of the highest dose group (750 ppm) showed large numbers of atretic follicles and congestion in stromal tissue compared to the rest of the treated groups. Also, there was a dose-dependent reduction in the number of follicles at different stages of their maturation. The number of ova recovered from superovulated chromium (VI)-treated animals showed significant decreases in the 500 and 750 ppm dosed groups compared to lower dosed (250 ppm) and control groups. The duration of estrus cycle increased in highest dosed (750 ppm) group. A dose-dependent increase in blood chromium level was also seen in treated mice. Ultrastructural observations revealed disintegrated cell membranes of two layered follicular cells and altered villiform mitochondria in thecal cells of 5 ppm dosed group. From the study it was concluded that ovarian physiology and rate of ovulation might be altered if females are exposed to sufficiently high chromium through oral route.

Administration, Oral↗
PubMed1996

Embryotoxicity of orally administered chromium in mice: exposure during the period of organogenesis.

Administration of chromium (VI)(250, 500 and 750 ppm as potassium dichromate) via drinking water during organogenesis (days 6-14 of gestation) in mice revealed embryo- and fetotoxic effects. Reduced fetal weight, retarded fetal development, number of fetuses (live and dead) per mother and high incidences of dead fetuses and resorptions in treated mothers in the highest dosed group were evident. No significant gross structural abnormalities were observed in any of the fetuses of chromium (VI)-treated mothers. Significant incidences of reduced ossification were found in the highest dosed group. Chromium levels were increased in a dose-dependent manner in maternal blood, placenta and fetuses. The present study suggests a risk to the developing embryo if the mother is exposed to a sufficiently high concentration of chromium (VI) through drinking water during the period of organogenesis.

Abnormalities, Drug-Induced↗
PubMed1995

Effect of hypoxia by intermittent altitude exposure on semen characteristics and testicular morphology of male rhesus monkeys.

Semen characteristics and testicular morphology of rhesus monkeys were studied on exposure to a simulated high altitude of 4411 m for 21 days. There was a partially reversible decrease in the semen volume, sperm count and sperm motility, as well as an elevation of pH and fructose concentration. These changes were associated with degeneration of the germinal epithelium and spermatogenic arrest at the end of third week of exposure which had not recovered even 3 weeks after the exposure.

Altitude Sickness↗