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.