Towards a pill for men

This review outlines the prospects for the development of an oral contraceptive for men. Male fertility may be temporarily interrupted by interference with the hormonal control of the testis, a direct action of agents on spermatogenesis or by interference with the acquisition of fertilizing ability once sperm leave the testis. Spermatogenesis can be suppressed successfully by the antigonadotrophic action of androgens, progestagens or oestrogens used alone or in combination and the results of these studies provide the basis for the future development of an oral contraceptive. Achievement of this goal will require the adjustment of doses to provide adequate spermatogenic suppression without loss of libido. Preliminary studies indicate that compounds which are capable of selectively suppressing FSH levels do exist and may enable spermatogenic suppression without alteration of androgenic function. The majority of substances that act directly on the testis appear to be too toxic to suppress spermatogenesis reversibly. However, recent studies with 5-thio-D-glucose have demonstrated inhibition of spermatogenesis which is reversible on ceasing to take the agent. This material appears non-toxic in the doses required and does not alter libido and potency. Interference with the epididymal maturation of sperm is feasible using α -chlorohydrin but toxic effects have prevented its use in primates. Analogues with similar actions have been identified which cause infertility but toxicity data have not been fully evaluated.

Disruption of the metabolism, motility and morphology of spermatozoa by injection of alpha-chlorohydrin into rams

Ejaculated spermatozoa from rams given intramuscular injections of alpha-chlorohydrin (25 mg/kg, daily for 5 days) were studied. Respiratory and glycolytic activity of the spermatozoa was almost entirely suppressed within 1 day and motility had decreased within 4 days of the first injection. Morphologically abnormal spermatozoa appeared in ejaculates after 2 weeks. The most common abnormality was an increase in the number of spermatozoa with looped or bent tails. There was little change in the fructose or amino acid concentration of the seminal plasma. All effects of alpha-chlorohydrin were fully reversible. It is suggested that the initial primary mode of action of alpha-chlorohydrin is to disrupt the metabolism of spermatozoa in the cauda epididymis.

Effects of alpha-chlorohydrin on the metabolism of testicular and epididymal spermatozoa of rams

Spermatozoa were collected from the rete testis and vas deferens of conscious rams. The endogenous oxygen uptake of the spermatozoa was unaffected by alpha-chlorohydrin added in vitro, although this compound abolished the stimulation of oxygen uptake caused by the addition of glycerol. The metabolism of [14C]glycerol by testicular and epididymal spermatozoa was markedly reduced by alpha-chlorohydrin, CO2 production and lactate accumulation being almost totally inhibited. These effects were dependent upon a period of preincubation of the spermatozoa with alpha-chlorohydrin alone, since the presence of glycerol protected the spermatozoa from its action. Longer exposure and a higher concentration of alpha-chlorohydrin were needed with testicular than with epididymal spermatozoa to achieve a maximal effect. The metabolism of [14C]glucose by both sperm types was also inhibited by alpha-chlorohyrin. Spermatozoa of the ram are therefore susceptible to the action of alpha-chlorohydrin throughout the epididymis, although more mature spermatozoa are more affected. It is suggested that alpha-chlorohydrin is converted to an intermediate which is the agent responsible for the inhibition of glycolysis in spermatozoa.

Purification and properties of arylsulphatase A from rabbit testis

Rabbit testis arylsulphatase A was purified 140-fold with a recovery of 20% from detergent extracts of an acetone-dried powder by using DE-52 cellulose column chromatography, gel filtration on Sephadex G-200 and preparative isoelectric focusing. The purified enzyme showed one major band with one minor contaminant on electrophoresis in a 7.5% (w/v) polyacrylamide gel at pH8.3. On sodiumdodecyl sulphate/polyacrylamidegel electrophoresis, a single major band was observed with minor contaminants. The final preparation of enzyme was free from general proteolytic, esterase, hyaluronidase, beta-glucuronidase and beta-galactosidase activities. Rabbit testicular arylsulphatase A exists as a dimer of mol.wt. 110000 at pH7.1. At pH5.0 the enzyme is a tetramer of mol.wt. 220000. Arylsulphatase A appears to consist of two identical subunits of mol.wt. 55000 each. The highly purified enzyme has pI4.6. The enzyme hydrolyses p-nitrocatechol sulphate with Km and Vmax, of 4.1 mM and 80nmol/min respectively, but has no activity toward p-nitrophenyl sulphate. The pH optimum of the enzyme varies with the incubation time. By applying Sephacex G-200 chromatography and preparative isoelectric focusing, one form of enzyme was obtained. The enzyme has properites common to arylsulphatase A of other sources with respect to the anomalous time-activity relationship, pI, inhibition by PO42-, SO32- and Ag+ ions and substrate affinity to p-nitrocatechol sulphate. However, the enzyme shows the temperature optimum of arylsulphatase B of other species.

Inhibition of bull and rabbit sperm enzymes by alpha-chlorohydrin

High concentrations of alpha-chlorohydrin were found to inhibit hyaluronidase, beta-glucuronidase, and aryl sulphatases in bull and rabbit spermatozoa, but not acrosin and neuraminidase. Preincubation of the enzyme and alpha-chlorohydrin was essential to achieve the maximum inhibition which was irreversible.

Fertilizing ability in vivo and in vitro of spermatozoa of rats and mice treated with alpha-chlorohydrin

The fertilizing ability of epididymal spermatozoa from rats and mice treated for 3 or 4 or 9 or 10 days with various doses of alpha-chlorohydrin was tested in vitro, and in vivo by intrauterine insemination. The minimum doses (per kg/day) needed to affect fertilization significantly were: rat, in vitro, 8-8 mg for 3 or 4 days, 4-4 mg for 4 days and 2-7 mg for 9 or 10 days; in vivo, 4-4 mg for 3 or 4 days and 2-7 mg for 9 or 10 days: mouse, in vitro, 4-4 mg for 3 days and 13-3 mg for 9 days; in vivo, 44-2 mg for 3 days and 26-5 for 9 days. Rats were infertile for at least 18 days after receiving 44-2 mg alpha-chlorohydrin/kg/day for 3 days, but fertilizing ability, tested in vivo and in vitro, was restored 10-11 days and 15-18 days, respectively, after daily treatment with 11-1 mg alpha-chlorohydrin/kg for 3 days.

Sequential histopathological and biochemical events in rat caput epididymis after alpha monochlorohydrin administration

This paper presents sequential histological, histochemical and biochemical changes in rat caput epididymis after a single 100 mg/kg oral dose of alpha chlorohydrin. Desquamation of caput epithelium occurs as early as two days after drug treatment. The caput epididymis is blocked because of accumulation of testicular fluid containing exfoliated immature testicular cells and caput epithelium. There was no effect of drug on motility and morphology of spermatozoa examined from different segments of epididymis and vas deferens. Marked decrease in acid and alkaline phosphatases, nucleic acids and proteins have been registered after drug treatment. On the contrary increase in SDH, cholesterol and glycogen was observed after drug treatment. Decrease in phospholipids in initial stages has also been observed.

The effects of alpha-chlorohydrin on the composition of rat and rabbit epididymal plasma: a possible explanation of species difference

The relationship between the antifertility effect of alpha-chlorohydrin and changes in composition of luminal plasma from the cauda epididymidis of rats and rabbits has been investigated. At each dose regimen studied, the fertilizing capacity of rats treated with alpha-chlorohydrin was reduced to zero. The levels of sodium, potassium, glycerylphosphorylcholine (GPC), acid phosphatase and alkaline phosphatase in epididymal plasma were not markedly affected by drug treatment. The most noticeable change was a considerable increase in the concentration of lactic dehydrogenase (LDH) at all dose levels and of glutamic-oxaloacetic transaminase (GOT) after 7 days of treatment with 8 and 16 mg/kg. The effect of cold shock on the composition of epididymal plasma showed that LDH and GOT are, at least in part, derived from spermatozoa. In contrast, alpha-chlorohydrin did not have an antifertility action in the rabbit, and the only notable change in the compositon of epididymal plasma was an increase in the level of GPC. These results provide evidence that, in the rat, alpha-chlorohydrin or a metabolite primarily exerts its antifertility effect by a direct action on the spermatozoa, whilst in the rabbit a barrier may exist to the entrance of the drug into the lumen of the epididymal duct.

Effects of alpha-chlorohydrin on the testes and epididymides of dog: a preliminary study

Chronic administration of alpha-chlorohydrin (8 mg/kg for 30 days, caused lesions in the testis of dog. Seminiferous tubules presented marked degenerative changes. Leydig cell hypertrophy was conspicous. Epididymal epithelium was regressed and the lumen was devoid of spermatozoa. Obstruction of the epididymal lumen was not seen. Alpha-Chlorohydrin inhibited the synthesis of RNA and sialic acid in the testis, caput epidiymis, corpus epididymis, and cauda epididymis. The total cholesterol per gram of testis was increased significantly after alpha-chlorohydrin administration. The anti-androgenic nature of alpha-chlorohydrin is suggested.

Phagocytosis of spermatozoa by the epithelial cells of the ductuli efferentes after epididymal obstruction in the rat

The effects of ligation of an isolated loop of the ductus epididymidis in the region of the caput were compared with those of the exfoliative lesion of the epididymis that follows administration of alpha-chlorhydrin to rats. Electron micrographs of the ductuli efferentes in both cases revealed early phagocytosis of apparently normal spermatozoa by the epithelial cells, followed at later intervals by invasion of macrophages and intraluminal phagocytosis. It is concluded that epithelial spermiophagy is a consequence of obstruction, whether mechanically or chemically induced.