Full Text - Journal of Animal Science
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Full Text - Journal of Animal Science
A L P H A C H L O R O H Y D R I N : S T U D I E S ON T H E M E C H A N I S M OF ACTION IN M A L E SWINE L. A. Johnson and V. G. Pursel U. S. Department o f Agriculture 1 2 3, Beltsville, Maryland 20705 Summary A study was made of the possible causes of infertility which results from feeding a-chlorohydrin to boars. When gilts were inseminated via the oviducts, 37 of 54 ova recovered 2 days later from control gilts were classed as fertilized. However, none of 49 ova were fertilized after gilts were inseminated in the oviducts with semen from boars treated with a-chlorohydrin (5 mg/kg/day). When gilts were inseminated via the oviducts with neat semen containing 1 or 10 mM a-chlorohydrin added in vitro, only two of 111 ova were fertilized. The antifertility action of a-chlorohydrin was very rapid, since pregnancy did not result in any of 13 gilts inseminated with semen collected either 7 or 31 hr. after boars were fed a-chlorohydrin. Of eight gilts inseminated with epididymal semen collected from boars previously treated with a-chlorohydrin, none were pregnant. These studies indicated that failure of sperm cell transport in the gilt was not the primary causative factor in a-chlorohydrin induced infertility of boar spermatozoa. Further, it was determined that the epididymis is the site of action of a-chlorohydrin. A probable mechanism for a-chlorohydrin induced infertility of boar spermatozoa is discussed. Introduction The male antifertility agent 3-chloro 1,2 propanediol (a-chlorohydrin) caused infertility when administered to the boar (Johnson and Pursel, 1972). Its activity was reversible and free from observable side effects. Alpha chlorohydrin also causes infertility in rams (Kreider and Dutt, 1970) and in rats (Coppola, 1969; Ericsson and Baker, 1970). When either the boar or boar semen was treated with a-chlorohydrin, sperm cell motility was depressed through an inhibition of progressive movemefit (Johnson and Pursel, 1972). Oxygen uptake was decreased in spermatozoa from a-chlorohydrin treated rams (Krieder and Dutt, 1972) and rats (Samojlik and Chang, 1970). However, a-chlorohydrin treated monkey sperm showed an increased oxygen uptake Setty et al., 1970). The mechanism of action has not been determined, although the epididymis has been shown to be the major site of action in rats (Ericsson and Connor, 1969; Turner, 1971; Crabo and Appelgren, 1972). Among the mechanisms which have been suggested for a-chlorohydrin induced infertility in the past is the failure of sperm cell transport in the female (Erickson and Bennett, 1971). This study was done to determine if the treatment of boars or boar semen with a-chlorohydrin results in the failure of sperm cell transport in the female, and to determine the approximate time span required for infertility to occur after feeding a-chlorohydrin to the boar. Experimental Procedure 1Animal Physiology and Genetics Institute, Agricultural Research Center-East, ARS. 2 The authors gratefuUy acknowledge the technical assistance of E. M. Dirnen and L. L. Schulman, and thank Ayerst Laboratories Inc., 685 Third Street, New York, N. Y., for the AIMAX, PMS and HCG used in the study. 3 Reference to commercial products or commercial producers in this report does not constitute endorsement by the U.S. Department of Agriculture to the exclusion of others that may also be suitable. TrialI. Ten gilts were used, each of which had expressed estrus at least twice. They were fed a diet containing 1-(a-methylallylthiocarbam o y l ) - 2 - m e t h y l t h i o c a r b amoyl hydrazine (AIMAX, ICI 33, 828, methallibure) at the rate of 100 mg per gilt per day for 18 to 21 consecutive days. On the day after AIMAX was withdrawn, each gilt was given a subcutaneous injection of 1,000 IU Pregnant Mare's Serum 1207 JOURNAL OF ANIMAL SCIENCE,vol. 37, no. 5, 1973 1208 JOHNSON AND PURSEL hr. after ovulation. The ova were flushed from the oviducts and uteri with physiological saline and examined as whole mount preparations by phase-contrast microscopy. The ova were then fixed and cleared for 48 hr. in 25% acetic alcohol and stained with 1% orcein in 45% acetic acid. Ova were examined for the presence of a nucleus in each blastomere and for numbers of accessory spermatozoa in the zona pellucida using phase-contrast microscopy. Trial 11. Eleven gilts were used in this trial. The trial was conducted as trial I, with the following differences. Semen was deposited in the isthmus of the oviduct 4 hr. after expected ovulation. Gilts were inseminated with semen types 1, 2 and 3 as described in trial I; however, some samples of type 3 semen contained a-chlorohydrin at a final concentration of 1 mM rather than 10 raM. Gilts were slaughtered between 46 and 52 hr. after ovulation and eggs recovered and examined as in trial I. Trial IlL Two boars were fed a-chlorohydfin at the rate of 5 mg/kg of body weight/day. Nineteen gilts were treated with AIMAX, PMS and HCG as in trial I. Six of the 19 grits were artifically inseminated with semen collected from the boars before a-chlorohydrin was fed. Seven of the gilts were inseminated with semen collected 7 hr. (day 1) after initiation of a-chlorohydrin treatment. The remaining six gilts were inseminated with semen collected 31 hr. (day 2) after initial treatment, or 7 hr. after the second dose of a-chlorohydrin was fed. Semen was extended in Beltsville L1 extender (BL1; Pursel, Johnson and Schulman, 1973). A total of 6 x 109 spermatozoa in an 80 ml volume were deposited intra-cervically in each gilt using a spiral tip catheter (Melrose and O'Hagan, 1961). The results of insemination were determined by return of the gilts to estms, or by slaughter at 25 days post-insemination. Trial IV. To determine the fertility of epididymal semen, boars were fed a-chlorohydrin (5 mg/kg body wt/day) for 5 days, then slauglttered; caudal epididymal semen was recovered by slicing the tubules with a scapel. The semen was extended and used for insemination (4 x 109 sperm in 80 ml BL1 per gilt) of gilts previously treated with ALMA)(, PMS and HCG as described in trial I. Epididymal semen was obtained and used in the same manner from two other boars not fed ot-chlorohydrin. In addition, one boar in which a vas deferens cannula had been surgically inserted (Johnson, Pursel and Kraeling, 1971) was fed a-chlorohydrin (5 mg/kg wt/day). Both ejaculated and Figure 1. Deposition of semen in the isthmus of the epididymal semen were collected from this boar oviduct. at the same time, both before and after (PMS); 500 IU of Human Chorionic Gonadotrophin (HCG) was given intramuscularly 88 to 96 hr. later. Ovulation was calculated to occur at 40 hr. after HCG injection. Six hours before expected ovulation the gilts were anesthesized with pentothal via the anterior vena cava. Closed circuit fluothane-oxygen-nitrous oxide anesthesia was used thereafter. Mid-ventral laparotomies were performed and both oviducts were exposed. A blunt-tip 20-gauge needle, 4 cm long, was inserted into the uterine lumen approximately 1 cm posterior to the utero-tubal junction and passed into the isthmus of the oviduct (figure 1). Twenty million motile sperm cells in a volume ofO.1 ml were deposited in each oviduct. Semen was collected as the sperm rich fraction. Motility was estimated at 100X using the light microscope. Gilts were inseminated with the following types of semen: (1) neat semen (+ extender) collected from boars demonstrating normal fertility; (2) semen + extender from a boar that had previously demonstrated normal fertility and had been treated for at least 5 consecutive days before semen collection with a-chlorohydrin (Aldrich Chemical Co., Milwaukee, Wisconsin) at the rate of 5 mg/kg of body weight per day; (3) neat semen as in (1), except that a-chlorohydrin was added to the semen to give a final concentration of I0 mM. All semen was extended in Ringer-fructose prior to insemination (Mann, 1964). Gilts were slaughtered between 40 and 44 1209 ACTION OF ALPHA CHLOROHYDRIN IN BOARS treatment, and used for insemination. A total of 23 gilts were inseminated. Pregnancy was determined as in trial III. Results ~V r,r Trial I. Of 21 normal ova recovered from Group 1 gilts, 12 were fertilized (table 1). Seventeen ova were recovered from gilts slaughtered after insemination with semen from ~-chlorohydrin treated boars (Group 2). None of the 17 ova were fertilized. A similar response was obtained when ~-chlorohydrin was added to semen (Group 3). Of 23 normal ova recovered, only two were fertilized, both from the same gilt. Five abnormal ova were recovered, all from one gilt and all were fertilized. The abnormal ova contained four or five pronuclei or had irregular blastomeres. In the two gilts, in which fertilization occurred, the semen used had approximately 5 ruin. of exposure to the a-chlorohydrin prior to deposition in the oviduct. In subsequent inseminations, a 20-min. exposure time was allowed. It was quite possible that fertilization occurred because of the lack of sufficient exposure time. The number of accessory sperm cells were estimated on each ovum. The ova from Group 1 had a greater number of spermatozoa per ovum than the ova from other groups (table 1). Recovery rates of ova in trial I were not satisfactory. The unavoidable manipulation o f the oviduct before ovulation may have interfered with the pickup of ova by the infundibulum, Trial II. Of the 34 normal ova recovered in Group 1, 25 were fertilized (table 1). Seven of the unfertilized ova were from one gilt which had no fertilized ova. Of the 110 normal ova recovered fr0~ gilts inseminated with semen from a-chlorohydrin treated boars or with ~-chlorohydrin treated semen (Groups 2 and 3), none were fertilized. Two different a-chlorohydrin concentrations were added to semen (10 mM or 1 raM; Group 3), but fertilization was not obtained in either case. Ova recovery rates were much higher in this trial than in trial I, probably due to the fact that inseminations were performed after ovulation. Trial 111. N o n e of 13 gilts were pregnant after insemination with semen collected either 7 hr. after initial treatment with a-chlorohydrin or 7 hr. after the second dose of a-chlorohydrin (table 2). Inseminations were made within 1 hr. o f collection semen. Four of six control gilts were pregnant (4 of 6 vs. 0 of 13, P < .005 by chi-square). Of the total of 19 gilts in this trial, z _~ ,~ z O,lU~ z V 00 u-'Xl~ r,-t C~ ~lt'-- u'~ e.D < u'Xl~ ~lC,1 ~> o z o ~z e~ ~, "r. ~o o 0 ~ o o ~ o~ E ~o~ 0 1210 JOHNSON AND PURSEL TABLE 2. PROPORTION OF GILTS PREGNANT AFTER INSEMINATION WITH SEMEN COLLECTED FROM BOARS BEFORE AND AFTER TREATMENT WITH o-CHLOROHYDRIN Time of semen collection No. gilts No. gilts inseminated pregnant Before feeding 7 hr. after f e e d i n g 31 hr. after feedinga 6 7 6 4 0 0 aSemen collected 7 hr. after second a-chlorohydrin feeding and 31 hr. after initial feeding 12 returned to estms and seven were slaughtered 25 days post-insemination. Trial IV. None of eight gilts inseminated with epididymal semen from boars treated with ol-chlorohydrin were pregnant (table 3). Four of the seven gilts inseminated with epididymal semen from an untreated boar were pregnant, based on recovery of 25-day-old embryos at slaughter (4 of 7 vs. 0 of 8, P < .025 chi-square). Discussion The results of these experiments indicate (a) that failure of sperm cell transport in the gilt was not responsible for the antifertility activity of a-chlorohydrin in boar spermatozoa (trials I and II); (b) that a-chlorohydrin was rapidly absorbed and rapidly transported to the site of activity (trial III); (c) that the boar epididymis was the site of ~-chlorohydrin activity (trial IV). In addition, oviductal deposition of semen resulted in a higher ovum recovery rate if conducted after ovulation. The results of these experiments lead us to conclude that ~-ch/orohydrin acts at the level of the cauda epididymis in the boar. This conclusion is based on the evidence that cauda TABLE 3. PROPORTION OF GILTS PREGNANT A_FTER INSEMINATION WITH EJACULATED OR EPIDIDYMAL SE_MEN FROM BOARS FED a-CHLOROHYDRIN a Ejaculated s e m e n E p i d i d y m a l s e m e n T i m e o f se- No. in- No. No. in- No. m e n collec- s e m i n pregseminpregtion ated nant ated nant Before treatment 5 3 7 4 After treatment 3 a5 mg/kg b o d y wt/day. 0 8 0 epididymal spermatozoa recovered from a-cbAorohydrin treated boars do not have the capacity to fertilize ova (trial IV). In addition, the observed antifertility action takes place within 7 hr. of a-chlorohydrin feeding (trial III). Thus, the a-chlorohydrin reaching the cauda epididymis acts upon the already mature spermatozoa. Turner (1971) and Crabo and Appelgren (1972) have reported similar results with the rat, using somewhat different techniques. It also should be pointed out that the boar, unlike many other mammals, has essentially no storage of spermatozoa in the ductus deferens. Thus, it may be possible in some species for cells to be affected in the ductus deferens, but it is not possible in the boar. Since the cauda epididymis is the environment in which the a-chlorohydrin acts, the next question is how is a-chlorohydrin activity mediated? Based on these and other experiments we suggest that a-chlorohydrin acts directly on the sperm cell to cause infertility. Several findings support this suggestion: (a) progressive sperm cell motility is depressed both by treating the boar or by treating ejaculated semen directly. Data on the effect of a-chlorohydrin on motility was reported earlier (Johnson and Pursel, 1972) and the same effect on motility was seen in this study. Alpha-chlorohydrin given to male rabbits does not cause infertility or depress sperm cell motility (Samojlik and Chang, 1970); a similar non-effect response was obtained when rabbit epididymal semen was treated in vitro with ~-chlorohydrin in which the response was based on motility patterns alone (L. A. Johnson, unpublished). Another finding (b) is that accessory gland secretions do not carry sufficient (if any) (x-chlorohydrin to cause infertility. This was shown when neat boar semen was centrifuged, the plasma removed, and seminal plasma was added from a vasectomized boar, which had been fed a-chlorohydrin (25 mg/kg body wt/day) for 20 days. These spermatozoa exhibited both normal motility patterns and normal fertility (L. A. Johnson, unpublished). Kreider and Dutt (1972) reported similar results with the ram. Further (c) failure of sperm transport in the female was not a causative factor in the infertility of ~-chloryhydrin affected semen. The results in trials I and II differ from those reported by Erickson and Bennett (1971) for the rat; they suggested that failure of sperm transport in the female was the factor causing infertility of rat spermatozoa. In their study, spermatozoa were transferred from the uterus of female rats 3 to 4 hours after mating to a-chlorohydrin treated males, into the ovarian ACTION OF ALPHA CHLOROHYDRIN IN BOARS bursa o f unmated females, resulting in fertility. In the present study, spermatozoa were deposited directly into the oviducts without prior exposure to the uterine environment. The differing results would seem to involve one o f two factors. First, it could be that exposure to the uterine environment might allow detoxification o f the spermatozoa from the effects of the a-chlorohydrin, or secondly, that the mechanism of a-chlorohydrin antifertility in the rat may be different from that in the boar. The proportion of ova which could be recovered after insemination into the oviducts was somewhat lower than that which would be obtained following intra-cervical insemination techniques. Polge, Salamon and Wilmut (1970) reported a similar problem in pigs inseminated in the oviduct. Semen deposition 4 hr. after ovulation appears to be preferred to 4 hr. before ovulation, since a dramatic improvement in ova recovery was experienced in trial II over trial I. Results o f trial II showed a 77% recovery rate, somewhat higher than the 58% reported by Polge et al. (1970) in gilts inseminated 4 hr. after ovulation. We have suggested that a-chlorohydfin acts directly on the boar sperm cell, causing infertility. In attempting to determine what specific parts or constituents of the sperm cell are affected we have ruled out certain aspects based on the results o f preliminary experiments. There were no significant morphological changes observed in the affected sperm cells when examined under the microscope; spermatozoa phospholipid content was unchanged; pH of semen with a-chlorohydrin added was not changed significantly; zinc content o f the spermatozoa (a possible indication of plasma membrane integrity) was unaffected by treatment (L. A. Johnson, unpublished data). It seems possible that a-chlorohydrin may cause infertility by blocking an enzyme site or sites on the sperm cell. 1211 Literature Cited Coppola, J. A. 1969. An extragonadal male anti-fertility agent. Life Sciences 8: Part I, 43. Crabo, B. and L. E. Appelgren. 1972. Distributions of 14 C ~-chlorohydrin in mice and rats. J. Reprod. Fertil 30:161. Erickson, G. I. and J. P. Bennett. 1971. Mechanism of antifertility activity of minimal effective dose levels of c~-cMorohydrin in the male rat. Biol. Repiod. 5:98 (Abstr.) Ericsson, R. J. and N. D. Connor. 1969. Lesions of the rat epididymis and subsequent sterility produced by U-5897 (3-chloro-l,2-propanediol). Soc. Study Reprod. 2nd Ann. Mtg. Davis, Calif. Sept. 8-10. (Abstr.) Ericsson, R. J. and V. F. Baker. 1970. Male antifertility compounds: Biological properties of U-5897 and U-15,646, I. Reprod. Fertil. 21:267. Johnson, L. A., V. G. Pursel and R. R. Kraeling. 1971. Cannulation of the Boar Vas Deferens. J. Anita. Sci. 33:1159 (Abstr.). Johnson, L. A. and V. G. Pursel. 1972. Reversible Infertility in Male Swine fed c~-chlorohydrin. J. Anim. Sci. 34:241. Kreider, J. L. and R. H. Dutt. 1970. Induction of temporary infertility in rams with an orally administered chlorohydrin. J. Anim. Sci. 31:95. Kreider, J. L. and R. H. Dutt. 1972. Effect of 3-chloro-1, 2-propanedioi (U-5897) on accessory gland secretions of rams. J. Anim. Sci. 35:246 (Abstr.) Mann, T. 1964. "The Biochemistry of Semen and of the Male Reproductive Tract." John Wiley & Co. Melrose, D. R. and C. O'Hagan. 1961. Investigations into the techniques of insemination in the pig. Proc. IVth Inter. Congr. Anita. Reprod. and Art. Insem. The Hague, 4:855. Polge, C., S. Salamon and I. Wilmut. 1970. Fertilizing capacity of frozen boar semen following surgical inseminations. Vet. Rec. 87:424. Pursel, V. G., L. A. Johnson and L. L. Schulman. 1973. Fertilizing Capacity of Boar Semen Stored at 15~ J. Anita. Sci. (In press). Samojlik, E. and M. C. Chang. 1970. Anti.fertility activity of 3-chloro-l,2-propanediol (U-5897) on male rats. Biol. Reprod. 2:299. Setty, B. S., A. B. Kar, S. K. Roy and S. R. Chowdhury. 1970. Studies with sub-toxic doses of a-chlorohydfin in the male monkey (Macaca Mulatta) Contraception 1: 279. Turner, M. A. 1971. Effects of a-chlorohydrin upon the fertility of spermatozoa of the cauda epididymis of the rat. J. Reprod. Fertil. 24: 267.