Identification of genes showing altered DNA methylation and gene expression in the renal proximal tubular cells of rats treated with ochratoxin A for 13 weeks

Ochratoxin A (OTA) is a mycotoxin that causes renal carcinogenicity following the induction of karyomegaly in proximal tubular cells after repeated administration to rats. Here, we performed gene profiling regarding altered DNA methylation and gene expression in the renal tubules focusing on the mechanism of OTA-induced carcinogenesis. For this purpose, OTA or 3-chloro-1,2-propanediol (3-MCPD), a renal carcinogen not inducing karyomegaly, was administered to rats for 13 weeks, and DNA methylation array and RNA sequencing analyses were performed on proximal tubular cells. Genes for which OTA altered the methylation status and gene expression level, after excluding genes showing similar expression changes by 3-MCPD, were subjected to confirmation analysis of the transcript level by real-time reverse-transcription PCR. Gene Ontology (GO)-based functional annotation analysis of validated genes revealed a cluster of hypermethylated and downregulated genes enriched under the GO term "mitochondrion," such as those associated with metabolic reprogramming in carcinogenic process (Clpx, Mrpl54, Mrps34, and Slc25a23). GO terms enriched for hypomethylated and upregulated genes included "response to arsenic-containing substance," represented by Cdkn1a involved in cell cycle arrest, and "positive regulation of IL-17 production," represented by Osm potentiating cell proliferation promotion. Other genes that did not cluster under any GO term included Lrrc14 involved in NF-κB-mediated inflammation, Gen1 linked to DNA repair, Has1 related to chromosomal aberration, and Anxa3 involved in tumor development and progression. In conclusion, a variety of genes engaged in carcinogenic processes were obtained by epigenetic gene profiling in rat renal tubular cells specific to OTA treatment for 13 weeks.

Activating autophagy and ferroptosis of 3‑Chloropropane‑1,2‑diol induces injury of human umbilical vein endothelial cells via AMPK/mTOR/ULK1

3‑Chloropropane‑1,2‑diol (3‑MCPD) is an internationally recognized food pollutant. 3‑MCPD has reproductive, renal and neurotoxic properties. However, whether 3‑MCPD induces human umbilical vein endothelial cell (HUVEC) injury has not been previously reported. In the present study, HUVECs were treated using 2 µg/ml 3‑MCPD for 24 h at 37˚C. The effects of 3‑MCPD on HUVEC proliferation and cell cycle arrest, death and senescence were then assessed using Cell Counting Kit‑8 (CCK‑8), flow cytometry and β‑galactosidase staining, respectively. Whether 3‑MCPD induced ferroptosis was evaluated using JC‑1 and FerroOrange staining and transmission electron microscopy. A small interfering RNA targeting AMPK was used to assess whether 3‑MCPD promoted ferroptosis via AMPK signaling. The results demonstrated that 3‑MCPD inhibited HUVEC proliferation in a dose‑dependent manner and induced cell cycle arrest. Furthermore, 3‑MCPD promoted senescence in HUVECs with elevated DNA damage and cell death. The CCK‑8 results demonstrated that ferroptosis and autophagy inhibitors significantly reversed cell death caused by 3‑MCPD. Moreover, 3‑MCPD increased mitochondrial membrane potential, which indicated that 3‑MCPD contributed to mitochondrial dysfunction. 3‑MCPD also markedly increased intracellular Fe2+ levels and lipid peroxidation in HUVECs. The present study assessed the underlying mechanism by which 3‑MCPD activated autophagy and ferroptosis in HUVECs. The data demonstrated that 3‑MCPD significantly increased phosphorylation levels of AMPK and unc‑51 like autophagy activating kinase (ULK1) but significantly decreased phosphorylation of mTOR in HUVECs. Furthermore, silencing of AMPK significantly reversed the increase in autophagy, lipid peroxidation and Fe2+ induced by 3‑MCPD. In conclusion, 3‑MCPD demonstrated a significant damaging effect on HUVECs via induction of autophagy and ferroptosis; such effects may be mediated by AMPK/mTOR/ULK1 signaling. To the best of our knowledge, the present study was the first to demonstrate the mechanism of 3‑MCPD‑induced vascular endothelial cell injury and lays a molecular foundation for the prevention of 3‑MCPD‑related vascular diseases.

3-Chloro-1, 2-propanediol inhibits autophagic flux by impairment of lysosomal function in HepG2 cells

3-chloro-1, 2-propanediol (3-MCPD) is a well-known contaminant that was produced in the thermal processing of food. Dietary intake represents the greatest source of exposure to 3-MCPD. Autophagy is an important catabolic pathway that plays an important role in liver physiological function. Evidence suggests that 3-MCPD exposure causes toxicity in liver, but the mechanism remains unknown. Here, we explored the effects of 3-MCPD on autophagic flux and traced the molecular mechanism in HepG2 cells. The data showed 3-MCPD exposure promoted the accumulation of autophagosomes in HepG2 cells. Subsequently, by detected te expression of LC3-Ⅱ and P62 and transfection of mRFP-GFP-LC3 adenovirus, we found that the accumulation of autophagosomes was caused by inhibition of autophagic flux. After that, we investigate lysosomal function and found that 3-MCPD induced lysosomal alkalinization. Further, we detected the expression of TFEB, which is a key nuclear transcription factor in control of lysosome biogenesis and function. We found that 3-MCPD inhibited the nuclear expression of TFEB and mRNA levels of some target genes of TFEB. In order to further verify the role of TFEB in autophagic flux blockage in HepG2 cells induced by 3-MCPD, we overexpressed TFEB by transfection with adenovirus and found that both autophagy inhibition and lysosomal alkalization induced by 3-MCPD were alleviated. These results suggested that 3-MCPD could induce the autophagic flux blockage in HepG2 cells. The possible mechanism was due to the destruction of lysosomal function.

A 4-week study of four 3-monochloropropane-1,2-diol diesters on lipid metabolism in C57BL/6J mice

3-Monochloropropane-1,2-diol (3-MCPD) esters have been detected in many foods, which have become a new safety issue worldwide. In the study, we investigated the effect of four 3-MCPD diesters (palmitate diester: CDP; stearate diester: CDS; oleate diester: CDO; linoleate diester: CDL) on lipid metabolism in C57BL/6J mice. The results showed that CDP, CDS, CDO and CDL significantly increased the serum TC, LDL-C levels and liver TG, TC levels at dose of 16.5μmol/kg/day. These results indicated that 3-MCPD diesters could potentially cause hyperlipidemia in C57BL/6J mice. Moreover, oil red O staining confirmed fat accumulation in liver induced by 3-MCPD diesters. Our work will provide more information for safety evaluation of 3-MCPD diesters. However, whether free 3-MCPD or free fatty acids or combined action compensates for the hyperlipidemia effects should be elucidated in the future.

(S)-α-chlorohydrin inhibits protein tyrosine phosphorylation through blocking cyclic AMP - protein kinase A pathway in spermatozoa

α-Chlorohydrin is a common contaminant in food. Its (S)-isomer, (S)-α-chlorohydrin (SACH), is known for causing infertility in animals by inhibiting glycolysis of spermatozoa. The aim of present work was to examine the relationship between SACH and protein tyrosine phosphorylation (PTP), which plays a critical role in regulating mammalian sperm capacitation. In vitro exposure of SACH 50 µM to isolated rat epididymal sperm inhibited PTP. Sperm-specific glyceraldehyde 3-phosphate dehydrogenase (GAPDS) activities, the intracellular adenosine 5'-triphosphate (ATP) levels, 3'-5'-cyclic adenosine monophosphate (cAMP) levels and phosphorylation of protein kinase A (PKA) substrates in rat sperm were diminished dramatically, indicating that both glycolysis and the cAMP/PKA signaling pathway were impaired by SACH. The inhibition of both PTP and phosphorylation of PKA substrates by SACH could be restored by addition of cAMP analog dibutyryl-cAMP (dbcAMP) and phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). Moreover, addition of glycerol protected glycolysis, ATP levels, phosphorylation of PKA substrates and PTP against the influence of SACH. These results suggested SACH inhibited PTP through blocking cAMP/PKA pathway in sperm, and PTP inhibition may play a role in infertility associated with SACH.

Microvascular P-glycoprotein expression at the blood-brain barrier following focal astrocyte loss and at the fenestrated vasculature of the area postrema

The multidrug transporter, P-glycoprotein, expressed at the blood-brain barrier is thought to be important for limiting access of toxic agents to the brain, but its relationship to astrocyte expression is unclear. We have studied P-glycoprotein expression in the inferior colliculus after a temporary loss of blood-brain barrier integrity following chemically induced astrocyte loss and at the fenestrated vascular endothelium of the area postrema. Male Fisher F344 rats given 3-chloropropanediol showed astrocyte loss from 12 to 24 h until the lesion was repopulated 8-28 days later. In non-dosed tissue, P-glycoprotein expression was seen the entire length of platelet endothelial cell adhesion molecule immunoreactive vessels. Within 6 h of dosing, a significant (p<0.05) reduction in the total length of P-glycoprotein immunoreactive vasculature was evident. By 48 h, P-glycoprotein immunoreactivity was heavily fragmented. The total length of P-glycoprotein immunoreactive vessels became minimal at 4 days (p<0.001) but was still present in many vessels. From 6 to 28 days, P-glycoprotein immunoreactivity returned across the inferior colliculus, in parallel with astrocytic repopulation of the lesion, and by 28 days resembled that seen in control tissue. The area postrema showed GFAP immunoreactive astrocytes but which made limited contact with the vasculature, while the platelet endothelial cell adhesion molecule immunoreactive vasculature showed no expression of P-glycoprotein. These findings provide evidence supporting a link between GFAP-astrocyte and P-glycoprotein expression in the mature brain vasculature in vivo.

Effect of an inactivator of glyceraldehyde-3-phosphate dehydrogenase, a fortuitous arsenate reductase, on disposition of arsenate in rats

The environmentally prevalent arsenate (AsV) is reduced in the body to the much more toxic arsenite (AsIII). Recently, we have demonstrated that the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) catalyzes the reduction of AsV in the presence of glutathione, yet the role of GAPDH in AsV reduction in vivo is unknown. Therefore, we examined the effect of (S)-alpha-cholorhydrin (ACH), which forms a GAPDH-inhibitory metabolite, on the reduction of AsV in rats. These studies confirmed the in vitro role of GAPDH as an AsV reductase, inasmuch as 3 h after administration of ACH (100 or 200 mg/kg, ip) to rats both the cytosolic GAPDH activity and the AsV-reducing activity dramatically fell in the liver, moderately decreased in the kidneys, and remained unchanged in the muscle. Moreover, the AsV-reducing activity closely correlated with the GAPDH activity in the hepatic cytosols of control and ACH-treated rats. Two confounding effects of ACH (i.e., a slight fall in hepatic glutathione levels and a rise in urinary AsV excretion) prompted us to examine its influence on the disposition of injected AsV (50 micromol/kg, iv) in rats with ligated bile duct as well as in rats with ligated bile duct and renal pedicles. These experiments demonstrated that the hepatic retention of AsV significantly increased, and the combined levels of AsV metabolites (i.e., AsIII plus methylated arsenicals) in the liver decreased in response to ACH; however, ACH failed to delay the disappearance of AsV from the blood of rats with blocked excretory routes. Thus, the GAPDH inactivator ACH inhibits AsV reduction by the liver, but not by the whole body, probably because the impaired hepatic reduction is compensated for by hepatic and extrahepatic AsV-reducing mechanisms spared by ACH. It is most likely that ACH inhibits hepatic AsV reduction predominantly by inactivating GAPDH in the liver; however, a slight ACH-induced glutathione depletion may also contribute. While this study seems to support the conclusion that GAPDH in the liver is involved in AsV reduction in rats, confirmation of the in vivo role of GAPDH as an AsV reductase is desirable.

Ketone bodies could support the motility but not the acrosome reaction of mouse sperm

Ketone bodies, D-beta-hydroxybutyrate and acetoacetate, produced by the metabolism of fatty acids, are an important energy source for many organs, especially the heart, kidney and brain. They are utilized by the body with the help of succinyl CoA transferase (SCOT), which is ubiquitously expressed in various organs. Previously, we identified a novel SCOT-t specifically expressed in testicular germ cells and sperm, substituting somatic cell-type SCOT, however the physiological role of SCOT-t had not then been clarified. In the present study, we investigated the effects of ketone bodies, the substrate of SCOT-t, on the motility and acrosome reaction of mouse sperm. D-beta-hydroxybutyrate and acetoacetate both stimulated the motility of sperm as glucose or pyruvate. The glycolysis inhibitor stopped the motility of sperm mediated by glucose but not by D-beta-hydroxybutyrate. In contrast, ketone bodies did not stimulate the activation of the acrosome reaction of sperm, different from the effect of glucose. These results indicate that ketone bodies could be involved in sperm movement but not the acrosome reaction and the SCOT-t enzyme we have identified in sperm mitochondria may have important roles in the activity of sperm, resulting in male infertility when its function is disabled.

Lack of antifertility properties of novel halogenated glycolytic inhibitors and the urinary excretion and metabolism of 1,6-dichloro-1,6-dideoxy-D-fructofuranose in the male rat

The antifertility action of (R,S)-alpha-chlorohydrin administered orally to male rats was compared with that of several novel chlorinated compounds known to inhibit glycolysis and the kinematics of rat sperm in vitro. Oral gavage of 1,6-dichloro-1,6-dideoxy-D-fructofuranose (dichlorodideoxyfructose, DCF), 1-chloro-3-hydroxypropanone, its dimethylketal and bromopyruvate did not reduce the fertility of male rats below that of controls at the equivalent antifertility dose of (R,S)-alpha-chlorohydrin (5 mg/kg/day) or higher. As anticipated for a compound cleaved to products of (S)-chirality even high doses of DCF (200 mg/kg) showed no effect on renal function. 36Cl-Labelled DCF administered orally to male rats was eliminated only slowly in the urine (16% of the ingested dose excreted in 96 h). In the first 8 h, approximately 50% of DCF was excreted unchanged, 30% was excreted as 3-chlorolactate (BCLA), the oxidation product 3-chlorolactaldehyde and 25% as Cl-. By 24 h little DCF remained and the major metabolite (70%) was BCLA and 20% Cl-. The high rate of dechlorination is most likely responsible for the low antifertility action of DCF.

Differences in sperm motion between high- and low-shuttlebox avoidance rats (Hatano strains)

Sperm from the caudal epididymis of 2 inbred strains of Sprague-Dawley (SD) rats, selected on the basis of their high- or low-shuttlebox avoidance responses, were analyzed for motion characteristics by a computer-assisted sperm motion analysis (CASA) system. Sperm motion in high-avoidance animals (HAA) was characterized by high velocities, high amplitude of lateral head displacement (ALH), and low beat cross frequency (BCF). Conversely, sperm from low-avoidance animals (LAA) displayed low velocities, low ALH, and high BCF. These characteristics in sperm motion were not changed by washing. Furthermore, after treatment with alpha-chlorohydrin (aCH) as a male antifertility agent affecting rat epididymal sperm motion, sperm velocities in HAA rats were significantly reduced to levels similar to those in untreated LAA rats. However, ALH and BCF in HAA rats treated with aCH were different from those in untreated LAA rats. Sperm adenosine triphosphate (ATP) content was higher in HAA than in LAA rats, correlating with values of their sperm velocities. These data suggest there are apparent strain differences in sperm motion between HAA and LAA rats and that these differences are dependent on factors, including sperm energy production.

Susceptibility of glycolytic enzyme activity and motility of spermatozoa from rat, mouse, and human to inhibition by proven and putative chlorinated antifertility compounds in vitro

Nonhormonal contraceptives that act by blocking energy metabolism within sperm have the advantage over spermatogenic inhibitors by their fast onset of infertility and their almost immediate restoration of fertility after withdrawal of the contraceptive agent. This study was done to test new chlorinated compounds for their contraceptive potency on rodent and human sperm in vitro. Cells were incubated in a medium containing glucose as the sole energy source with 1-chloro-3-hydroxypropanone (CHOP) and 1,6-dichloro-1,6-dideoxy-D-fructose (DCDF), chlorinated analogues of glycolytic substrates, as well as racemic (R,S)-alpha-chlorohydrin (ACH). After incubation, enzymatic activity and kinematic parameters were estimated. A dose-dependent inhibition of the glycolytic enzyme, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), of rat and mouse distal cauda epididymidal and human ejaculated sperm by ACH, CHOP, and DCDF was demonstrated. Triosephosphate isomerase (TPI) was inhibited by ACH, but not by CHOP and DCDF, irrespective of species. All compounds inhibited sperm motility and kinematic parameters with increasing concentration. The results confirm that inhibition of glycolytic enzymes of sperm, including those of human, can be effectively brought about by a variety of chloro-compounds that can be converted to (S)-3-chlorolactaldehyde, the stereospecific chloro-derivative of the enzyme's natural substrate, (R)-glyceraldehyde 3-phosphate, and could be developed into contraceptive agents for men.

alpha-chlorohydrin induced changes in sperm fertilizing ability in the rat: association with diminished sperm ATP levels and motility

In the present study, alpha-chlorohydrin (ACH) (5, 10, 25, 50 and 75 mg/kg, po) was administered to rats and the effects on sperm ATP levels, sperm motility, and the ability of sperm to bind and penetrate rat oocytes were determined. Groups of rats were killed 5 days and 3 h following treatment. At both time points, sperm from ACH-treated rats (>/=10 mg/kg) had significantly lower levels of ATP when diluted in media containing glucose. No diminution of ATP was seen in sperm diluted in phosphate-buffered saline (PBS). Computer analysis of sperm motility indicated that straight-line velocity (VSL) was the most sensitive parameter to ACH treatment and was significantly decreased in rat sperm three hours after ACH exposure (25 mg/kg). A clear drop in percent penetration (35% vs. 85% in control) of zona-free rat oocytes by rat sperm of both ACH groups was observed at 10 mg/kg. Higher dose levels produced no significant further decrease in percent penetration. Overall, the fertilizing ability of sperm was highly sensitive to ACH doses that caused minor but significant changes in sperm ATP levels and no significant changes in motility. These data are consistent with the spermatozoan's need for an uncompromised energy supply to maintain its ability to bind and penetrate the oocyte.

In vitro inhibition of rat cauda epididymal sperm glycolytic enzymes by ornidazole, alpha-chlorohydrin and 1-chloro-3-hydroxypropanone

Chlorinated antifertility compounds are known to inhibit glycolysis of spermatozoa as they reside in the epididymis but new compounds need to be evaluated that retain antifertility action but do not exhibit side-effects. In this study, two known antifertility agents and a related compound were compared for their inhibition of rat sperm metabolism and motility in vitro. The dose-dependent inhibition in vitro of the glycolytic enzymes glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and triosephosphate isomerase (TPI) of distal cauda epididymal rat spermatozoa by (R)-, (S)- and (R,S)-ornidazole (ORN), (R,S)-alpha-chlorohydrin (ACH) and 1-chloro-3-hydroxypropanone (CHOP) was compared. The direct inhibition of GAPDH by ORN suggests that it inhibits without prior conversion outside the cell but inhibition was not stereo-specific. The GAPDH, but not TPI, activity of spermatozoa incubated with ACH and CHOP was highly correlated with kinematic parameters of spermatozoa incubated in pyruvate- and lactate-free medium. ACH only inhibited the activity of intact spermatozoa and the inhibition was not reversed by washing the particulate sperm fraction after sonication. High concentrations of ACH (100 mmol/L) killed intact rat spermatozoa and decreased the extent of GAPDH inhibition. CHOP, unlike ACH, was an effective inhibitor of both intact and sonicated cells. Pre-CHOP, the dimethylketal precursor of CHOP, and its other hydrolysis product MeOH, were both ineffective in vitro. CHOP and related ketals may be more effective inhibitors of sperm glycolysis than ACH and may prove useful for investigating sperm-specific glycolytic inhibition, a prerequisite for the development of antiglycolytic, post-testicular acting contraceptives.

Chemical interference with sperm metabolic pathways

During the 1960s, the quest for a simple non-steroidal chemical possessing male antifertility activity culminated with the discovery of the activity of alpha-chlorohydrin in 1970. Investigations into the mechanism of action of this compound revealed that it was affecting the glycolytic pathway within mature spermatozoa through its conversion to an inhibitory metabolite. Use of these and other simple chemical inhibitors has subsequently led to a clearer understanding of the metabolic pathways involved in the generation of ATP, which is necessary for sperm motility. Mature boar spermatozoa from the cauda epididymidis are almost totally reliant on the glycolytic pathway, not necessarily for the immediate generation of ATP, but for the ultimate production of lactate, which appears to be the sole substrate used for the mitochondrial production of ATP. The only exogenous substrates that support lactate production in vitro are fructose, glucose, glycerol and glycerol 3-phosphate and when these substrates are plentiful, there is evidence that compounds can be retained as such or as intermediates of the glycolytic pathway. When exogenous substrates are limited, the cells have the capability to mobilize endogenous compounds and to maintain the continuous synthesis of ATP.

Effects of alpha-chlorohydrin on rat sperm motions in relation to male reproductive functions

alpha-chlorohydrin (ACH) is a known male reproductive toxicant and produces antifertility in rats. The present experiments were performed to determine the relationship between sperm motions and reproductive function, and to further examine the possible mechanism for antifertility. ACH was administered to male rats for 9 days at 1, 3 and 10 mg/kg/day. The males were mated with untreated females and their reproductive status was determined. All mated males failed to impregnate females at 10 mg/kg/day. Low pregnancy rate associated with a decreased implant number was seen at 3 mg/kg/day. When sperm motions were analyzed using the CellSoft computer-assisted sperm analyzer, percentage of motile sperm, curvilinear velocity (VCL) and amplitude of lateral head displacement (ALH) were reduced at 10 mg/kg/day. At 3 mg/kg/day, VCL and ALH were reduced but the percentage of motile sperm was comparable to that of controls. In order to examine a possible mechanism for the effect of ACH on fertility, the number of sperm reaching the oviducts of mated females and the number of fertilized eggs was evaluated. Half of the females mated with ACH-treated males at 3 mg/kg/day had very low sperm numbers in the oviducts. At 10 mg/kg/day, all the mated females had a very low sperm number. The percent of fertilized eggs in the oviducts of mated females was decreased in a dose-dependent manner. These findings suggest that the effect of ACH on fertility was directly related to decreased VCL and ALH as well as percentage of motile sperm, and by the mechanism in which the sperm number reaching the oviducts after mating was reduced, so the reduction resulted in only a rare chance to fertilize.

Neuronal death in cultured murine cortical cells is induced by inhibition of GAPDH and triosephosphate isomerase

Polyglutamine-containing proteins expressed in the CAG repeat diseases Huntington's disease and dentatorubralpallidoluyisian atrophy have recently been suggested to inhibit the key glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). To examine the consequences of GAPDH inhibition upon neuronal survival, we exposed murine neocortical cell cultures to the inhibitor of GAPDH and triosephosphate isomerase, alpha-monochlorohydrin. Cultures exposed to 6-15 mM alpha-monochlorohydrin for 48 h exhibited an increase in dihydroxyacetone phosphate and a decrease in neuronal ATP that was followed by progressive neuronal death; some glial death occurred at high drug concentrations. The neuronal death was characterized by cell body shrinkage and chromatin condensation and was sensitive to cycloheximide and to the caspase inhibitors Z-Val-Ala-Asp fluoromethylketone and tert-butoxycarbonyl-Asp fluoromethylketone. Neurons in striatal cell cultures were more vulnerable to death induced by exposure to alpha-monochlorohydrin, except that NADPH-diaphorase(+) neurons were selectively spared. Repeated addition of the glycolytic endpoint metabolite pyruvate to the bathing medium attenuated both the drop in neuronal ATP and the neuronal cell death.

Shedding of a rat epididymal sperm protein associated with infertility induced by ornidazole and alpha-chlorohydrin

The protein composition of epididymal fluid and sperm extracts of rats treated with the nitroimidazole compound ornidazole was investigated by two-dimensional gel electrophoresis. Epididymal luminal fluid from the corpus and cauda regions of male animals rendered infertile by ornidazole treatment contained a prominent protein (contraception-associated protein 1, CAP1) with a molecular mass of approximately 25 kDa and an isoelectric point (pI) of 5.8; it was not found in fluids, but was present in sperm, from fertile vehicle-fed rats. Infrared matrix-assisted laser desorption/ionization mass spectrometry indicated that the molecular mass of CAP1 was 20420+/-120 daltons. Analysis of 17 amino acids demonstrated 49% homology to a diuretic hormone from an insect (Acheta domesticus). Densitometric quantitation of CAP1 on silver-stained gels indicated its presence in greater amounts in cauda than in corpus fluid from treated animals, whereas fluid from the rete testis lacked CAP1. In vitro incubations of tissue from the caput, corpus, and cauda epididymidal regions with [35S]methionine gave no hint that CAP1 was a secretion product of the epididymal epithelium. The absence of CAP1 from luminal fluid obtained from the sperm-depleted corpus epididymidis of efferent duct-ligated ornidazole-fed rats suggested a spermatozoal origin. CAP1 was present in spermatozoa from the caput epididymidis but not from the rete testis in control animals. Less CAP1 was present in detergent extracts of cauda sperm from ornidazole-treated rats than in sperm from control animals, suggesting a contraceptive-related displacement of protein from sperm to fluid. The association of ornidazole- and alpha-chlorohydrin-induced infertility with the presence of CAP1 in epididymal fluid, probably originating from spermatozoa, suggests a critical role for this protein in fertilization.

Sperm motion predicts fertility in male hamsters treated with alpha-chlorohydrin

An understanding of the relationship between altered sperm motion and sperm function (fertility) is important when interpreting the biological significance of toxicant-induced changes in sperm velocity in rodent test species. Previous studies showed that a brief (4-day) exposure of male hamsters to the model chemical alpha-chlorohydrin (ACH) results in significant deficits in epididymal and uterine sperm velocity, which are associated with both a delay and a failure of fertilization in vivo. To characterize this effect in terms of fertility, similarly treated male hamsters were bred to untreated females and pups were counted the day before parturition. ACH treatment resulted in a dose-dependent decline in the percentage of sperm-positive females that were pregnant at the end of gestation (100, 78, 67, 22, and 0 where males were treated with 0, 33, 49, 66, and 83 mg ACH/kg/day, respectively). Cauda epididymal sperm from the same males were assayed for motion characteristics using computer-assisted sperm analysis (CASA), and for fertilizing ability in vitro. While the percentage of motile sperm was unaffected by ACH treatment, sperm velocity declined in a dose-dependent manner at all ACH treatment levels. Furthermore, the velocity of sperm from infertile males was shifted downward consistently across the entire velocity distribution. Since treated males tended to either be infertile (no pups) or have near normal litter size, the correlation between sperm velocity and litter size was nonlinear. Therefore, logistic regression models using velocity cut-off values were the most useful models for predicting fertility. These results support the contention that fertility relies on there being a sufficient number of sperm that exceed a velocity threshold. Sperm from treated males were also less likely to support in vitro fertilization (IVF), providing further evidence of impaired sperm function associated with acute exposure to ACH.

alpha-Glucosidase activity in the rat epididymis under different physiological conditions

The estimation of alpha-glucosidase activity in semen is widely used as a marker of epididymal function. In the present studies, glucosidase activity was evaluated in the different segments of the rat epididymis under various physiological conditions. In addition, the effect of two known male antifertility agents, gossypol and alpha-chlorohydrin, on enzyme activity was evaluated. Enzyme activity was absent from the epididymis of rats aged 10 and 20 days but became detectable at 30 days of age when the adult pattern of distribution (highest activity in the caput epididymis) was established. Enzyme activity was reduced significantly in all segments of the epididymis at 7 days after castration and a significant decrease in activity was also observed following the administration of either gossypol or alpha-chlorohydrin. These findings are consistent with a role for alpha-glucosidase in sperm maturation in the epididymis.

Synchronous assessment of sperm motility and fertilizing ability in the hamster following treatment with alpha-chlorohydrin

To investigate the relationship between sperm motion parameters and fertilizing ability, a model was developed to assess both of these endpoints synchronously using a toxicant that inhibits sperm motion. alpha-Chlorohydrin (ACH) was administered daily for 4 days to male hamsters at 0, 33, 49, 66, and 83 mg/kg body weight. These males were then allowed a 45-minute breeding period with untreated estrus females on the morning of day 5. One hour after breeding, sperm samples were surgically recovered from the uteri of the females for motility analysis. Six hours later, eggs were flushed from the oviducts and evaluated for fertilization. Cauda epididymal sperm were also collected from the males shortly after breeding. Proportions of motile and progressively motile sperm were manually quantified, and overall sperm velocity and the velocity of representative vigorously swimming sperm in both the uterine and epididymal samples were measured by computer-aided sperm analysis. Significant decreases in in vivo fertilization rates and epididymal sperm motion parameters were observed at 66 and 83 mg/kg ACH, whereas uterine sperm motion was adversely affected at all ACH dosages used. All sperm motion parameters except the percentage of motile sperm in the epididymis were significantly correlated with fertilization rates by both linear and logistic regression. Overall, uterine and epididymal sperm endpoints predicted fertilizing ability comparably well. Stepwise multiple linear regression gave a model containing epididymal sperm velocity (EVCL) and uterine sperm percent motility (UMOT) with an R2 value of 0.649. Stepwise multiple logistic regression gave models containing EVCL alone and EVCL and UMOT in binary (fertile/infertile) and quantal models, respectively.

Isolation of rat sperm from the vas deferens for sperm motion analysis

A technique for isolation of viable spermatozoa from the rat vas deferens is presented. A single vas deferens from a mature Sprague-Dawley rat contains 35.4 +/- 3.3 million spermatozoa, and a 0.5-cm segment from the distal end of the vas will spontaneously expel 8.96 +/- 1.39 million sperm relatively free of cellular debris when placed into a balanced salt solution. Treatment of rats (n = 5) with alpha-chlorohydrin (100 mg/kg, single dose) significantly reduced, relative to controls (n = 5, water 10 mL/kg), sperm motility by 72%, swimming velocity by 44%, and head displacement motion by 50%, but did not affect the number of sperm in the vas deferens nor sperm recovery. In summary, the isolation of rat sperm from the vas deferens can be achieved with minimum handling in a manner that is not confounded by sperm toxicity.

Inhibition of glycolysis in boar spermatozoa by alpha-chlorohydrin phosphate appears to be mediated by phosphatase activity

(R,S)-alpha-chlorohydrin-1-phosphate, previously shown to have no anti-glycolytic activity on mature boar sperm in vitro, is a substrate for acid and/or neutral phosphatase(s) that are associated with washed sperm. The high phosphatase activity hydrolyses the ester to alpha-chlorohydrin which undergoes oxidation to (S)-3-chlorolactaldehyde, a specific inhibitor of sperm glyceraldehyde-3-phosphate dehydrogenase and triosephosphate isomerase, thereby exhibiting an anti-glycolytic action.

The neurotoxicity of alpha-chlorohydrin in rats and mice: II. Lesion topography and factors in selective vulnerability in acute energy deprivation syndromes

Mice and rats have been found almost equally susceptible to (R, S)-alpha-chlorohydrin neurotoxicity, but in rats the distribution of lesions in the neuraxis is less widespread. The topography of the brain lesions shows an incomplete relationship to the regional hierarchy of local glucose utilization in rats and local cerebral blood flow in mice, suggesting that other, unknown, factors also play roles in determining this. Evidence suggesting progressive tonotopic selective vulnerability was found in inferior colliculi in rats given five doses of 50 mg/kg/day. Distinct differences in the patterns of damage to brain stem centres found with chlorohydrin by comparison with other acute energy deprivation syndromes, despite the proximity of the metabolic lesions along the energy generation pathway, suggests there are other unrecognized factors that play a role in determining whether a neuronal centre is at risk or not.

Glucose regulation of guinea-pig sperm motility

Washed guinea-pig spermatozoa from the vas deferens re-acquired progressive motility within 1-2 min of incubation in minimal culture medium containing pyruvate and lactate. When glucose was added, either at the beginning or after 15 min of incubation, the cells showed stimulated motility (increased straight-line velocity, linearity and beat-cross frequency, P less than 0.01). Re-acquisition of progressive motility was preceded by a significant (P less than 0.005) transient increase in sperm concentration of cyclic adenosine 5'-phosphate (cAMP) with or without glucose in the medium. Papaverine caused another large significant (P less than 0.001) increase in cAMP concentration; and 5.56mM glucose with papaverine caused a further stimulation in cAMP beyond that with papaverine alone (P less than 0.005). Although 0.05 or 5.56mM glucose plus alpha-chlorohydrin stimulated sperm motility, they did not further stimulate the increase in cAMP after 30 s of incubation. Thus, there was no apparent correlation between the glucose-stimulating effect on sperm motility and the enhancement of cAMP at 30 s. However, there was a close correlation between glucose-stimulated motility and enhancement of ATP (P less than 0.05) by glucose even under incubation conditions in which glucose caused the Crabtree effect (decrease in respiration rate).

Genotoxicity of 1,3-dichloro-2-propanol in the SOS chromotest and in the Ames test. Elucidation of the genotoxic mechanism

1,3-Dichloro-2-propanol (1,3-DCP-OH, glycerol dichlorohydrin) is of great importance in many industrial processes and has been detected in foodstuffs, in particular in soup spices and instant soups. It has been shown to be carcinogenic, genotoxic and mutagenic. Its genotoxic mechanisms are, however, not yet entirely understood. We have investigated whether alcohol dehydrogenase (ADH) catalysed activation to the highly mutagenic and carcinogenic 1,3-dichloroacetone or formation of epichlorohydrin or other genotoxic compounds play a role for mutagenicity and genotoxicity. In our studies, no indications of ADH catalysed formation of 1,3-dichloropropane could be found, although we could demonstrate a clear activation by ADH in the case of 2-chloropropenol. Formation of allyl chloride could also be excluded. We found, however, clear evidence that epichlorohydrin formed chemically in the buffer and medium used in the test is responsible for genotoxicity. No indication was found that enzymatic formation of epichlorohydrin plays a role. Additional mutagenicity and genotoxicity studies with epichlorohydrin also confirmed the hypothesis that genotoxic effects of 1,3-DCP-OH depend on the chemical formation of epichlorohydrin.

Metabolism of fructose-1,6-bisphosphate by mature boar spermatozoa

Mature epididymal boar spermatozoa converted glucose and fructose to carbon dioxide and lactate and maintained high concentrations of ATP. In the presence of (S)-alpha-chlorohydrin these processes were inhibited and there was an accumulation of fructose-1,6-bisphosphate and dihydroxyacetone phosphate. With fructose-1,6-bisphosphate as the substrate, the concentration of ATP was maintained, carbon dioxide was evolved and dihydroxyacetone phosphate accumulated. Cells pre-incubated with (S)-alpha-chlorohydrin did not maintain ATP levels, evolved less carbon dioxide and produced dihydroxyacetone phosphate. Assays of incubates in which fructose-1,6-bisphosphate was used as the substrate showed the presence of equilibrium quantities of fructose-6-phosphate and glucose-6-phosphate which were not detected when either fructose or glucose were used as substrates. [14C]Fructose and [14C]glucose were not produced from [14C]fructose-1,6-bisphosphate in spermatozoal incubates which had or had not been pre-incubated with (S)-alpha-chlorohydrin. Evidence is presented that a high concentration of fructose-1,6-bisphosphate leads to the formation of fructose-6-phosphate and glucose-6-phosphate but not of fructose and/or glucose.

Effect of alpha-chlorohydrin on in situ pH in rat testis and epididymis

The effect of the male contraceptive, alpha-chlorohydrin, on in situ pH in seminiferous tubules and epididymal duct of the rat has been studied employing in vivo microelectrode techniques. After eight days of low-dose alpha-chlorohydrin administration (15mg/kg/day), a significant increase in acidity of luminal fluid in seminiferous tubules, proximal caput, middle caput, and proximal cauda epididymidis was observed. Increased acidity in the testis and epididymis may play an important role in the antifertility effect of alpha-chlorohydrin.

Oxidative metabolic activity of boar spermatozoa: a system for assessing anti-glycolytic activity of potential inhibitors in vitro

The oxidative metabolic capability of mature boar spermatozoa has been determined in vitro. The high rate of oxidation of fructose, glucose, glycerol, glycerol-3-phosphate and lactate to CO2 and the optimization of incubation conditions indicates that these cells could constitute a model system for investigating the anti-glycolytic activity of potential male anti-fertility agents. The effects of several chemical agents on the oxidative metabolism of boar spermatozoa are reported.

Inhibitory effects of (S)-3-chlorolactaldehyde on the metabolic activity of boar spermatozoa in vitro

(S)-alpha-Chlorohydrin and 3-chloro-1-hydroxyacetone inhibited the oxidative metabolism of fructose by boar spermatozoa only after a period of incubation in which they presumably underwent conversion to (S)-3-chlorolactaldehyde, an inhibitor of sperm glyceraldehyde 3-phosphate dehydrogenase. With glycerol as substrate, 3-chloro-1-hydroxyacetone had a similar effect, (S)-alpha-chlorohydrin was ineffective while (R,S)-3-chlorolactaldehyde was immediately effective with either substrate. All three compounds caused the accumulation of fructose 1,6-bisphosphate and dihydroxyacetone phosphate from fructose but not from glycerol which led to the conclusion that inhibition of triosephosphate isomerase was also associated with the anti-glycolytic action of (S)-3-chlorolactaldehyde. (S)-3-Chlorolactaldehyde caused the depletion of ATP in incubates of boar spermatozoa metabolizing fructose but not glycerol. This suggests that futile substrate cycling may play an important function in the anti-glycolytic action of (S)-3-chlorolactaldehyde and/or that boar spermatozoa can synthesize ATP from glycerol by a mechanism not involving the glycolytic pathway.

Futile substrate cycles in the glycolytic pathway of boar and rat spermatozoa and the effect of alpha-chlorohydrin

In boar spermatozoa incubated with 0.1 mM-glucose about 20 nmol glucose were converted to lactate and CO2 and the rate of futile substrate cycling between glucose and glucose 6-phosphate was about 6 nmol/10(8) spermatozoa/30 min. Futile cycling was increased in the presence of 0.05 or 1 mM-alpha-chlorohydrin but not to an extent sufficient to account for the rapid decline in ATP concentration observed under these conditions. These estimates include a substantial rate of fructose formation from fructose phosphates. The addition of 10 mM-L-lactate plus 1 mM-pyruvate protected the spermatozoa against the effect of alpha-chlorohydrin and glucose on the ATP concentration but increased futile substrate cycling. Substrate cycling between fructose 6-phosphate and fructose 1,6-bisphosphate could not be measured in boar spermatozoa but in rat spermatozoa its rate (nmol/10(8) spermatozoa/30 min) was about 10 under control condition and about 25 in the presence of 1 mM-alpha-chlorohydrin. This increase was insufficient to account for the decline in ATP concentration. In both species futile substrate cycling consumed a significant proportion of the ATP synthesis during lactate production but only about 5% of that produced in the oxidation of glucose to acetyl carnitine and CO2.

Qualitative and quantitative changes of acid and alkaline phosphatases in the testis and epididymis of mice in relation to single high dose of alpha-chlorohydrin

The present study is designed to know whether the enzymes related to permeability and general metabolism of the cells of testis and epididymis are affected by alpha-chlorohydrin. For this purpose two enzymes, viz., acid and alkaline phosphatases are studied thoroughly by qualitative and quantitative parameters during single high dose (90 mg/kg body weight) treatment after 24 and 48 hours of drug administration. Along with this, the changes in the behaviour of the animals and histological structure of testis and epididymis of mice are also recorded.

Mechanism of inhibition of fructolysis in ram spermatozoa by chlorinated antifertility agents

When ejaculated ram spermatozoa were incubated with (S)-alpha-chlorohydrin (up to 0.25 mM) the oxidative metabolism of fructose to carbon dioxide was inhibited in a concentration-dependent manner. This appears to be due to inhibition of glyceraldehyde-3-phosphate dehydrogenase which leads to the accumulation of fructose-1,6-bisphosphate, dihydroxyacetone phosphate and, to a lesser extent, glyceraldehyde-3-phosphate. (R)-alpha-Chlorohydrin (10 mM) had no significant effect on the oxidative metabolism of fructose. The inhibition of the oxidative metabolism of fructose by (S)-alpha-chlorohydrin (0.1 mM) was not immediate but was detected after incubation for 15 min. By contrast, (R,S)-3-chlorolactaldehyde (5 mM) caused an immediate inhibition of this metabolic pathway. 1-Chloro-3-hydroxyacetone (0.5 mM) immediately decreased the oxidative metabolism of fructose which resulted in the accumulation of key fructolytic intermediates in a manner comparable to that produced by (S)-alpha-chlorohydrin. At a concentration of 20 mM, 6-chloro-6-deoxyglucose had no significant effect on the metabolic activity of ram spermatozoa. We suggest that the anti-fructolytic actions of (S)-alpha-chlorohydrin and 1-chloro-3-hydroxyacetone are mediated via a common metabolite, (S)-3-chlorolactaldehyde, and that the inactivity of 6-chloro-6-deoxyglucose is due to the inability of ram spermatozoa to metabolise this chlorinated sugar to (S)-3-chlorolactaldehyde.

The concerted effect of alpha-chlorohydrin and glucose on the ATP concentration in spermatozoa is associated with the accumulation of glycolytic intermediates

In the absence of a glycolysable sugar the effect of 1 mM-RS-alpha-chlorohydrin on the ATP concentration in ram or boar spermatozoa was relatively small but the addition of 0.10 or 0.03 mM-glucose initiated a rapid loss of ATP. When the spermatozoa were incubated with 0.05 mM-RS-alpha-chlorohydrin, the addition of 1.0 mM (ram) or 0.06 mM (boar)-glucose was required to produce ATP dissipation. In ram spermatozoa treated with 0.05 or 1.00 mM-RS-alpha-chlorohydrin, ATP loss was caused by 10 mM-fructose or 10 mM-mannose but not by 10 mM-glycerol or 10 mM-inositol. In boar spermatozoa incubated with 1 mM-RS-alpha-chlorohydrin the addition of 10 mM-L-lactate plus 1.0 mM-pyruvate protected the spermatozoa against the ability of 1.0 mM-glucose to produce a decline in ATP concentration. Every combination of treatments capable of inducing a marked decline in ATP concentration also caused a dramatic (20-100-fold) increase in the concentration of fructose 1,6-bisphosphate. An increase in fructose 1,6-bisphosphate concentration was never observed when the ATP concentration was unaffected. We conclude that it is very probable that the concerted effect of alpha-chlorohydrin and glycolysable sugar is responsible for the contraceptive action of alpha-chlorohydrin in vivo and that fructose 1,6-bisphosphate is implicated in its mechanism of action.

Effects of alpha-chlorohydrin on the reproductive organs of the male bandicoot rat (Bandicota bengalensis)

The present study was undertaken to determine the effects of alpha-chlorohydrin at a dosage of 50, 100 or 150 mg/kg body weight and were killed 2 or 10 days later. alpha-chlorohydrin at employed dose levels induced selective damage to the germinal epithelium which seemed to be confined to one "cycle" only. No permanent epididymal lesions were observed in any of the treated bandicoots even following a toxic dose of the drug. Administration of this compound at a dose level of 50 or 100 mg/kg also had no effect on the weight of the testis or sex accessory organs or fructose levels in coagulating glands when compared to controls. These data indicate that the alpha-chlorohydrin possibly acts directly on the testis without influencing the normal endocrine status of the animal.

Inhibition of fructolytic enzymes in boar spermatozoa by (S)-alpha-chlorohydrin and 1-chloro-3-hydroxypropanone

When boar spermatozoa were incubated with the (S)-isomer of the male antifertility agent alpha-chlorohydrin the activity of glyceraldehyde-3-phosphate dehydrogenase was inhibited. The (R)-isomer had no significant effect on the activity of this enzyme whereas (R,S)-3-chlorolactaldehyde caused an inhibition of its activity and also in that of lactate dehydrogenase. The in vitro production of (S)-3-chlorolactaldehyde, the active metabolite of (S)-alpha-chlorohydrin, was attempted by incubating boar spermatozoa with 1-chloro-3-hydroxypropanone. Preliminary results lead us to propose that this compound is converted into (S)-3-chlorolactaldehyde as well as to another metabolite which is an inhibitor of other enzymes within the fructolytic pathway.

Effect of alpha-chlorohydrin on the epididymis of the Indian palm squirrel (Funambulus pennanti)

The effects of alpha-chlorohydrin administration on the epididymis of the Indian palm squirrel were investigated. The drug induced dose-and duration related regressive histological changes in the three epididymal segments. In spite of the regressive changes in the epididymis, spermatogenesis continued uninterruptedly in alpha-chlorohydrin-treated animals. Treatment with the drug also induced alterations in the levels of epididymal nucleic acids, protein, sialic acid and glycogen. The alterations in the histology and chemical constituents of the epididymis in drug treated animals were completely reversible. Within 21 days after drug withdrawal, epididymal histology and constituents returned to the pre-treatment state.

Antifertility activity and toxicity of alpha-chlorohydrin aromatic ketal analogues in male rats

The antifertility activity and toxicity of alpha-chlorohydrin and seven aromatic ketal derivatives were investigated in male rats. At a dose of 5 mg/kg injected intraperitoneally each day for 14 days, alpha-chlorohydrin and the methoxy benzaldehyde derivative (compound 2) produced complete infertility. The benzaldehyde derivative (compound 1) was 89% effective and the other five compounds 71-25% effective. All compounds except the least effective antifertility agent, the methylbenzaldehyde derivative (compound 3), reduced the motility of sperm recovered from the epididymis. None of the compounds caused a decrease in body or testes weight but some increased adrenal weight.

Production of (S)-3-chlorolactaldehyde from (S)-alpha-chlorohydrin by boar spermatozoa and the inhibition of glyceraldehyde 3-phosphate dehydrogenase in vitro

The (S)-isomer of the male antifertility agent alpha-chlorohydrin was metabolized by mature boar spermatozoa in vitro to (S)-3-chlorolactaldehyde. This oxidative process, which did not occur when (R)-alpha-chlorohydrin was offered as a substrate, was catalysed by an NADP+-dependent dehydrogenase that converts glycerol to glyceraldehyde. (S)-3-chlorolactaldehyde, produced by this metabolic reaction or when added to suspensions of boar spermatozoa, was a specific inhibitor of glyceraldehyde 3-phosphate dehydrogenase as assessed by the accumulation of fructose 1,6-bisphosphate and the triosephosphates. When glycerol and (S)-alpha-chlorohydrin were added concomitantly to boar spermatozoa in vitro, the presence of glycerol decreased the degree of inhibition of glyceraldehyde 3-phosphate dehydrogenase. Extracts of glyceraldehyde 3-phosphate dehydrogenase that were obtained from boar spermatozoa incubated with (S)-alpha-chlorohydrin or (R,S)-3-chlorolactaldehyde showed significant reductions in their enzymic activity.

The anti-glycolytic action of (S)-alpha-chlorohydrin on epididymal bovine spermatozoa in vitro

(S)-alpha-Chlorohydrin interferes with glycolysis in bovine spermatozoa whereas the (R)-isomer is ineffective. The action of the (S)-isomer, which involves inhibition of the reaction catalysed by glyceraldehyde 3-phosphate dehydrogenase, is not immediate but is evident only after a brief period of incubation with the spermatozoa. This inhibitory action is prevented when glycerol is present suggesting that the mechanism of action of (S)-alpha-chlorohydrin requires its oxidation to (S)-3-chlorolactaldehyde which is the active metabolite. Addition of racemic 3-chlorolactaldehyde to bovine spermatozoa caused immediate inhibition of glycolysis. It is proposed that the action of (S)-alpha-chlorohydrin in bovine spermatozoa is similar to that observed in the spermatozoa of other species in being a two-stage process; first, its oxidation to (S)-3-chlorolactaldehyde, and then inhibition of the glycolytic enzyme by this metabolite.

Effect of alpha-chlorohydrin on metabolism and testosterone secretion by rat testicular interstitial cells

The direct effect of alpha-chlorochydrin (alpha-CH) on basic metabolism (glucose utilization and oxygen consumption) and testosterone secretion by isolated rat interstitial cells (I-cells) has been studied. In the range of concentrations between 5 and 100 microliter/ml, only the highest doses of alpha-CH decreased cell vitality and their histochemical stain for 3 beta-HSD. Oxygen consumption of I-cells was depressed at all doses higher than 10 microliter/ml and this effect was reversible only with doses lower than 50 microliter/ml. glucose utilization by I-cells was depressed significantly by alpha-CH and this effect was particularly dramatic with doses higher than 50 microliter/ml. alpha-CH decreased testosterone secretion by I-cells, with maximal effects at 100 microliter/ml. I-cells responded to hCG challenge by increasing testosterone secretion, and hCG prevented the toxic effect of alpha-CH at the lowest dose (10 microliter/ml) of alpha-CH, but failed to overcome the effects of a high dose (100 microliter/ml).

The presence of glucose increases the lethal effect of alpha-chlorohydrin on ram and boar spermatozoa in vitro

Ram cauda epididymal spermatozoa were incubated for 10 min at 34 degrees C with or without 1.0 mM-RS-alpha-chlorohydrin before (1) 5 mM-D-glucose or (2) 10 mM-L-lactate plus 1 mM pyruvate or (3) 5 mM-D-glucose plus 10 mM-L-lactate plus 1 mM-pyruvate or (4) no substrate was added. Without alpha-chlorohydrin, the motility, the ATP concentration and the energy charge of the spermatozoa were maintained for 240 min by substrate combinations 1-3 but with no added substrate (4) the motility declined after 60 min. All the values decreased dramatically after 10 min in spermatozoa exposed to alpha-chlorohydrin in substrate conditions 1 and 3 (glucose present) but alpha-chlorohydrin had no significant effect in conditions 2 and 4 (no glucose) except after prolonged incubation. In a dose-response experiment glucose-dependent ATP dissipation began to occur with 0.025 mM-RS-alpha-chlorohydrin. A similar effect was seen in boar spermatozoa exposed to 0.1-5.0 mM-alpha-chlorohydrin and 5 mM-D-glucose. With boar spermatozoa the presence of 10 mM-L-lactate and 1 mM-pyruvate as well as glucose prevented the loss of ATP. We conclude that this concerted action of alpha-chlorohydrin and glucose is probably responsible for the contraceptive action of alpha-chlorohydrin and propose that it may depend on 'futile substrate cycling' in the glycolytic pathway.

Effect of physiological (in lamb) or drug-induced (in adult) immaturity of ram spermatozoa on seminal plasma alpha-glucosidase activity

We have been able to collect ejaculates from four pre-pubertal Finnish Landrace and Suffolk lambs. Respective seminal plasma alpha-glucosidase specific activity was low (less than 0.3 mU/mg) whatever the season of observation. At puberty, it reached a level higher than 1 mU/mg as observed in adult rams. Administration of alpha-chlorohydrin to 14 adult rams (25 mg/kg/day during 25 days) led to the appearance of immature sperm. Seminal plasma alpha-glucosidase activity dropped from 1.5 to 0.5 mU/mg in both breeds, while fructose was raised from 2 to 6 mg/ml. L-carnitine and blood plasma testosterone remained unchanged during treatment. Semen characteristics appeared normal one month after the end of treatment when fructose concentration decreased simultaneously and enzymatic activity increased during two months to normal levels. The present findings suggest that seminal plasma alpha-glucosidase may be considered as a useful epididymal marker in ram.

The action of (S)-alpha-chlorohydrin and 6-chloro-6-deoxyglucose on the metabolism of guinea pig spermatozoa

(S)-alpha-Chlorohydrin inhibits the conversion of fructose to lactate by mature guinea pig spermatozoa in vitro. At a concentration of 2mM, there is a specific inhibition of glyceraldehyde-phosphate dehydrogenase resulting in the accumulation of fructose-1,6-bisphosphate, dihydroxyacetone phosphate and glyceraldehyde-3-phosphate and a concomitant decrease in the concentration of endogenous lactate. (R,S)-[3-36Cl]-alpha-Chlorohydrin is metabolised by the spermatozoa to 3-chlorolactaldehyde of unknown configuration. Exogenous (R,S)-3-chlorolactaldehyde (2mM) is an inhibitor of glyceraldehyde-phosphate dehydrogenase in guinea pig spermatozoa, whereas (R)-alpha-chlorohydrin (10mM) has no significant effect on the metabolism of fructose. 6-Chloro-6-deoxyglucose (10mM) inhibits glyceraldehyde-phosphate dehydrogenase in guinea pig spermatozoa in vitro and is metabolised to 3-chlorolactaldehyde which is presumably the (S)-isomer. The anti-glycolytic actions of (S)-alpha-chlorohydrin and 6-chloro-6-deoxyglucose in guinea pig spermatozoa are suggested to be due to the action of a common metabolite, (S)-3-chlorolactaldehyde.

The action of (R)- and (S)-alpha-chlorohydrin and their metabolites on the metabolism of boar sperm

The action of (R,S)-alpha-chlorohydrin in inhibiting glycolysis in boar sperm is due to the (S)-isomer. Its effect on the concentrations of glycolytic intermediates suggests that the pathway is inhibited at the glyceraldehyde 3-phosphate dehydrogenase reaction. alpha-Chlorohydrin is oxidized by boar liver homogenates via 3-chlorolactaldehyde to 3-chlorolactate. Racemic mixtures of both compounds, and a proposed metabolite, 3-chloropyruvate, inhibit the oxidative metabolism of fructose, lactate and pyruvate possibly by interfering with processes occurring within the sperm mitochondria. It is proposed that the toxic action of these metabolites account for the effects of (R)-alpha-chlorohydrin on sperm motility, as this compound possesses no antifertility activity of itself.

The effect of alpha-chlorohydrin on the oxidation of fructose by rabbit spermatozoa in vitro

(R,S)-alpha-Chlorohydrin inhibits the oxidative metabolism of fructose in mature rabbit spermatozoa in vitro. This effect is not noticeable at concentrations of the compound up to 10 mM, is evident at 50 mM but at 100 mM is apparently accompanied by cell damage. At a concentration of 50 mM, (R,S)-alpha-chlorohydrin causes the specific inhibition of the enzyme glyceraldehyde 3-phosphate dehydrogenase and is metabolised by the spermatozoa to 3-chlorolactaldehyde of unknown configuration. Exogenous (R,S)-3-chlorolactaldehyde (5 mM and 10 mM) appears to inhibit glyceraldehyde 3-phosphate dehydrogenase in rabbit spermatozoa as well as affecting other metabolic pathways. The ineffectiveness of (R,S)-alpha-chlorohydrin as an anti-fertility agent in male rabbits may be due to the inability of the spermatozoa to produce a sufficient amount of the inhibitory metabolite (S)-3-chlorolactaldehyde.

Efficacy of alpha-chlorhydrin in sewer rat control

A single application of the male chemosterilant, alpha-chlorhydrin, to a problem sewer rat infestation resulted in reductions of rat numbers and distribution which was comparable to effects of warfarin baiting methods. Rat numbers were reduced by more than 85% by both methods. More rapid mortality and recruitment were evident for warfarin effects; the alpha-chlorhydrin treated population had a longer lag phase of growth so that reinfestation of sewer habitat to pre-treatment numbers, and distribution over a 40 square block area, required approximately 1.5-2 times longer after alpha-chlorhydrin treatment when compared with warfarin treatment. Comparisons of changes in rat densities in infested sewers following the two treatments indicate that recovery of warfarin treated populations is achieved by reproductive recruitment followed by dispersal while alpha-chlorhydrin treated populations recover by slower immigration and later reproductive recruitment. Alpha-chlorohydrin should be a useful addition to a limited arsenal of rat control agents because of its specificity for the Norway rat, its single dose effectiveness as a toxicant-chemosterilant, and its short environmental half-life.

Correlative histochemical and biochemical studies on the adenosine triphosphatase, succinic dehydrogenase and acetylcholinesterase in the epididymis of mice after alpha-chlorohydrin treatment

The present paper deals with the correlative histochemical and biochemical studies of the epididymis following the treatments of alpha-chlorohydrin. This drug was administered in chronic low dose (15 mg/kg body weight/day) for 20 and 30 days and a single high dose (90 mg/kg body weight). Histochemical alterations of ATPase, SDH and AChE were studied in various components of epididymal epithelium and the total enzyme content was measured by biochemical parameters. The study shows progressive decrease of the enzymes in the interstitium and the epithelium of both the caput and cauda epididymes with increasing dose and duration, except for the high dose effect of alpha-chlorohydrin on AChE. Since alpha-chlorohydrin decreases the androgen dependent enzymes (ATPase, SDH, AChE), there is a possibility that the drug may be antiandrogenic in nature. In such case the action of these drugs may not be directly on the spermatozoa, as proposed by earlier workers, but is mediated by changing the physiology of the epididymis, affecting the milieu in which the spermatozoa mature.

The activity of glyceraldehyde 3-phosphate dehydrogenase in spermatozoa from different regions of the epididymis in laboratory rodents treated with alpha-chlorohydrin or 6-chloro-deoxyglucose

The activity of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) (mUnits/10(6) spermatozoa: mean +/- s.e.m., N = 12) in spermatozoa from the rat epididymis declined from 22.0 +/- 1.4 in the caput to 14.1 +/- 1.3 in the corpus region but there was no further decrease in the cauda region. In hamsters (N = 4), GAPDH activity in spermatozoa declined from 24.8 +/- 2.2 in the caput to 15.2 +/- 1.2 in the distal cauda epididymidis with the greatest decrease between the corpus and proximal cauda regions. In guinea-pigs (N = 4) GAPDH activity in spermatozoa increased from 11.4 +/- 0.79 in the caput to 18.0 +/- 0.7 in the corpus and cauda regions of the epididymis. The activity of GAPDH in spermatozoa therefore changes during maturation in a species dependent manner. GAPDH in spermatozoa from the distal cauda epididymidis of rats given alpha-chlorohydrin (4, 8 or 25 mg/kg/day by mouth) or 6-chloro-6-deoxyglucose (24 or 96 mg/kg/day by mouth) for 10 days was inhibited by greater than 80% but was only inhibited by 25-45% in spermatozoa from the caput epididymidis. The enzyme was inhibited to an intermediate and dose-dependent extent in spermatozoa from the corpus region. A similar pattern of inhibition was seen in spermatozoa from hamsters given alpha-chlorohydrin (50 or 100 mg/kg/day) for 10 days. alpha-Chlorohydrin (66 mg/kg/day s.c.) for 10 days inhibited GAPDH in spermatozoa from the caput or corpus epididymidis of the guinea-pig by less than 20% but decreased GAPDH activity by almost 90% in the cauda region. In rats the greater effect of alpha-chlorohydrin on spermatozoa from the cauda region of the epididymis occurred even after short periods of treatment or when the passage of spermatozoa through the duct was interrupted by a ligature around the corpus region, indicating that the effect is not simply a reflection of the length of time the spermatozoa have spent in the epididymis. It is concluded that either spermatozoa undergo a maturational change which increases their sensitivity to alpha-chlorohydrin or that alpha-chlorohydrin (or an active metabolite) is concentrated in the lumen of the cauda epididymidis.

The male antifertility agents alpha chlorohydrin, 5-thio-D-glucose, and 6-chloro-6-deoxy-D-glucose interfere with sugar transport across the epithelium of the rat caput epididymidis

The effects of the male antifertility agents alpha-chlorohydrin, 5-thio-D-glucose, and 6-chloro-6-deoxy-D-glucose on sugar transport (3H-3-O-methyl-D-glucose and 3H-2-deoxy-D-glucose) across the rat caput epithelium was studied in vivo and in vitro. The compound alpha-chlorohydrin reduced sugar transport uptake in vivo but not in vitro, whereas 5-thio-D-glucose and 6-chloro-6-deoxy-D-glucose were both effective in vivo and in vitro. The mechanism of action of these compounds on sugar movement across the caput epithelium is probably complex. Direct competition for the glucose carrier situated on the basolateral membrane and intratubular effects are suggested. Thirty-day injections of 5-thio-D-glucose or alpha-chlorohydrin did not have adverse effects on sugar transport or the permeability of the blood-testis and blood-epididymis barriers as assessed by an in vitro technique.

Antifertility actions of alpha-chlorohydrin in the male

Non-steroidal chemicals that affect male fertility have been known for over 25 years but only one compound, alpha-chlorohydrin, possesses most of the attributes of an ideal male contraceptive. In the male rat, for example, continuous daily oral administration of low doses produces an almost immediate and continuous antifertility response that ceases when treatment is withdrawn. Such a dose regime does not interfere with libido, is apparently not toxic and the action is specific towards mature sperm. Furthermore, the action of the compound is species-specific: it is effective in the rat, ram, boar, guinea pig, hamster, rhesus monkey and upon ejaculated human sperm but it is ineffective in the mouse and the rabbit. High doses of alpha-chlorohydrin can be neurotoxic, nephrotoxic and, in rats, lead to prolonged or permanent infertility. However, the antifertility response and the toxicity of racemic alpha-chlorohydrin may be due, respectively, to the separate enantiomers. No other antifertility chemical has been investigated to such an extent as alpha-chlorohydrin; this article reviews the progress that has been achieved with alpha-chlorohydrin during the past six years.