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Effect of gonadectomy and gonadal hormones on singly established Hymenolepis diminuta in rats
Effect of Gonadectomy and Gonadal Hormones on Singly Established Hymenolepis diminuta in Rats J. Walter Beck1 The Biological
Laboratory,
Rice ~nnstitute, Houston,
Tezas
Previous work on the influence of dietary factors on the pattern of egg elimination of the tapeworm, Hymenolepis diminuta, in rats has demonstrated the usefulness of singly-established worms as a more accurate tool in the study of biological relationships of this parasite. The present report embodies the use of singly-established parasites in a more precise study of the biological effects of gonadectomy and gonadal hormones on H. diminuta in the laboratory rat than has heretofore been possible (Addis, 1946). MATERIALS
AND METHODS
Sexually mature laboratory-bred albino rats, 5 to 8 months of age and free of infection with H. diminuta, were used in this investigation. Laboratory-infected grain beetles, Tenebrio molitor, served as a source of cysticercoids. Egg-counting technic& as well as the “complete” and “deficient” diets used, were identical with those described in connection with previous studies (Beck, 1951). All rats maintained their weights or showed weight gains on both diets. All hosts subjected to castration or spaying showed rapid return to apparently normal activity after recovery from the anesthesia. The normal fecal output did not appear altered at any time and no immediate effect on egg production of the worms was noted. Testosterone (as testosterone propionate) and progesterone were administered subcutaneously in sesame oil. Chorionic gonadotropin was obtained as a dry powder under the trade name of Antuitrin-S (Parke, Davis and Co., 1950). This is a highly purified standardized preparation derived from human pregnancy urine. It was dissolved in physiological saline at the concentration desired and administered subcutaneously as 1 The author wishes to express his guidance in this investigation assistance.
his appreciation to Dr. Asa C. Chandler for and to Mrs. Evelyn Hake for her technical 109
110
J. WALTER BECK
specified. Antuitrin-S differs from the gonadotropins of the pituitary in that it is predominantly luteinizing in action, whereas the anterior pituitary factor has a strong follicle-stimulating effect. All hormone injections were given at approximately noon on designated days. RESULTS
Effect of Host Castration on Egg Output of H. diminuta in Male Rats on “Complete” and “Dejkient’~ Die&
Eight previously infected male rats, after establishment of the normal level of egg production of their single worms, were castrated and continued on “complete” diet until termination of the experiment. There was a gradual decline in egg output to a low level of about 50,000 eggs/24 hrs over a period of approximately 102 days after castration, when the experiment was terminated, although the trend of egg production was still downward. The decline in the level of eggs in feces and the time interval in which this pattern occurred were practically identical with those observed &th a “deficient” diet reported for normal male hosts (Beck, 1951). In an additional experiment 17 previously infected male rats were castrated and placed immediately upon a “deficient” diet. Some of these animals were subsequently used in hormone tests. In all cases,the combination of castration and “deficient” diet caused a much more rapid drop in egg production than either factor alone, so that the worms reached a comparable low in egg production in 40 days instead of over 100 days. Addis (1946) reported the stunting effect of castration on growth of H. diminutu in male rats on “complete” diet and adduced evidence that this phenomenon was due to the absence of the male sex hormone, testosterone. It is not clear from the preceding experiments whether the decline in egg output was due to a direct or indirect effect of lack of testosterone on worm growth, or to the necessity of this hormone in the worm’s reproductive processes. Effects of Hormones on the Pa&w
of Elimh.tion
of H. diminuta
Eggs
a. Testosterone and Progesterone in Castrated Male Rats 012“Dejkient” Diet. To study the effect of testosterone on the production of eggs by H. diminuh, castrated male rats were placed on “deficient” diet and,
after establishment of a low level of egg production by their worms, were divided into two groups of 4. Ten micrograms of testosterone were injected daily into rats of one group and 1 mg into the other group until termination of the experiment 48 days later.
GONADAL
HORMONES
AND
HYMENOLEPIS
DIMINUTA
IN
RATS
111
The injections of 10 pg of testosterone failed completely to stimulate egg production, for the daily output of eggs remained unchanged at a level of 50,000 to 75,000 for the duration of the experiment. On the other hand the group receiving 1 mg of this hormone (see Graph 1) showed a marked increase in egg output, with the trend still moving upward at termination of the experiment. Since castrated male rats on a vitamindeficient diet have stunted worms (Addis, 1946) while normal male rats on “deficient” diet have worms of nearly normal size but which are AVCRAOC OF 4 OAOTRATED MALL RATI
Graph 1. Effect of testosterone male rata on deficient diet.
(1 mg/day)
on egg production
in castrated
deficient in egg output (Beck, 1951), it seemsplausible that testosterone, in sufficient quantity in castrated males, not only stimulates worm growth but also stimulates the reproductive processesof the worm as well. To test the effect of progesterone, 4 castrated male rats were given daily injections of 1 mg of progesterone for 26 days after the elimination of the eggs of their single worms had reached a level of 60,000/24 hrs. An increase in the number of eggs eliminated occurred which was simiIar to that which resuhed from administration of testosterone, i.e. 170,000/24 hrs. The comparable response to these two hormones is not surprising in
112
J. WALTER
BECK
view of their chemical and physiological similarities (Turner, 1948). It is not known, however, whether progesterone as such is androgenic, or whether the host animal is capable of converting progesterone into testosterone or some similar compound. b. Testosterone and Progesterone in Normal Femule Rats on “DeJicient” Diet. The failure of the injection of testosterone or progesterone to prevent a stunting effect on growth of H. diminuta in normal female rats on a vitamin-deficient diet reported by Addis (1946), prompted the study of the effects of these hormones on egg production of this tapeworm under similar conditions. Four female rats which were previously infected with single worms were placed on “deficient” diet’until termination of the experiment. Egg counts were begun at the end of 30 days. On the 44th day, when a low level in the elimination of H. diminuta eggs had been reached, daily injections of 1 mg of testosterone were‘started and continued for 26 days. As in castrated males on “deficient” diet, this hormone raised the output of H. diminuta eggs within the interval studied to a level almost equal to that obtained in normal female rats on “complete” diet (Beck, 1951). The failure to restore growth of H. diminuta to normal in female rats on “deficient” diet with testosterone, reported by Addis (1946)) is difficult to explain for a large increase in egg production would not be expected without some concomitant trend towards normal size. The failure of Addis to supplement the diet with members of the B complex in the absence of yeast may have had some effect, but there is no other evidence that the known members of the B complex in the diet are necessary for growth of this tapeworm. Five female rats which were previously infected with single H. diminuta were given daily injections of 1 mg of progesterone for 26 days after the elimination of H. diminuta eggs had reached a level of 20,000/24 hrs.‘In contrast to testosterone this hormone completely failed to raise the egg output. The ability of progesterone to raise the level of egg production of this tapeworm in castrated males but not in normal female rats, observed in the present studies, confirms the findings of Addis (1946) who demonstrated that progesterone prevented the stunting of H. diminuta in castrated males, but not in normal females on a vitamin-deficient diet. c. Antuitrin-S in Normal and Gonadectomized Male and Female Rats on “Defiient” Diet. Ten male rats, previously infected with H. diminuta, were placed on a “deficient” diet after establishment of the normal pattern in the elimination of eggs of their worms. They were divided into
GONADAL
HORMONES
AND
HYMENOLEPIS
DIMINUTA
IN
RATS
113
two groups, one of which was castrated. Egg counts were continued ‘on both groups until termination of the experiment. The castrated rats were injected daily for 30 days with 25 International Units (I.U.) of Antuitrin-S in 0.25 ml. of solution, beginning on the 54th day of “deficient” diet. The normal rats were given similar injections beginning on the 70th day of “deficient” diet. It is evident from study of the patterns of elimination of H. diminukz eggs in these animals (see Graphs 2 and 3) that Antuitrin-S was effective in raising the level of the elimination of
4-
I
I
I
I
I
I
I
I
I
+
Graph 2. Effect of Antuitrin-S deficient diet.
on egg production
I
II
25J4. Auwun~~ - S , DN
in normal male rats on
eggs to a practically normal level in those animals that had not been castrated, but failed completely in the castrated ones. Ten female rats with this tapeworm were treated similarly with injections of Antuitrin-S beginning on the 54th day of “deficient” diet in both the normal and spayed groups, and continuing for 30 days. The effects were almost identical with those on male rats. There was an increase in the number of H. diminuta eggs eliminated in normal females to a level approximat,ing the control period. No increase was observed in the spayed females. During the course of these experiments 5 hosts were found to be infected with 1 to 4 specimens of the acanthocephalan, Mowiliformis
114
J. WALTER
BECK
&&us, accidently acquired by the eating of infected cockroaches. In one host with 4 worms the infection persisted until termination of the experiment. In all other hosts the worms were passed prior to the beginning of hormone injections. Study of the patterns of the elimination of eggs of H. &W&&X in rats with M. cl&us revealed no discernible influence on the trend in egg production of the tapeworms. AVLMOC
ot
5 G*aTMTcD
MALI
RN*
388-
Graph 3. Effect of Antuitrin-S deficient diet.
dn egg production
in castrated male rate on
DISCUSSION
In view of the fact that the nutrition of H. diminuta has been shown (Chandler, 1943) not to be dependent entirely upon unassimilated substances in the intestinal lumen, it is not surprising that hormones exert an influence on worm growth. Addis (1946) demonstrated that testosterone in the male host is necessary for normal growth of H. diminutu; it has been shown here that egg production of this tapeworm depends upon it as well. The ability of progesterone to produce a responsein castrated male rats similar to that
GONADAL
HORMONES
AND
FiYMENOLEPIS
DIMINUTA
IN
RATS
115
produced by testosterone, may be due to the androgenic properties of this hormone. Addis (1946) observed that only pregnant rats were able to produce normal-sized H. diminuta while on a “deficient” diet. He postulated that the gonadotropic hormone found in the urine of pregnant animals might account for this. It is of interest to note that the chorionic gonadotropin used in this investigation stimulated egg production only in normal male and female rats but, not in gonadectomized ones. Chorionic gonadotropin which is rich in lutemizing properties, has been shown to act on the testes and ovaries of the rat resulting in increased size and weight of these organs followed by an enlargement of the accessory sex organs (Burrows, 1945). This probably indicates an enhanced output of androgens and estrogens by the respective gonads. Since testosterone in sufficient quantity raises the egg output of H. diminuta in castrated males on “deficient” diet, and maintains normal worm size in castrated males on complete diet (Addis, 1946), it may be postulated that in normal male rats chorionic gonadotropin raises the egg output of this cestode by stimulating the production of testosterone. This is supported by the fact that this hormone is ineffective in castrated hosts. Further studies with estrogen may show that this hormone has an analogous effect in female hosts, though perhaps in less degree, since chorionic gonadotropin stimulates egg production in normal female hosts also, though not in spayed ones. Addis (1946)) using a vitamin-deficient diet without yeast, observed that theelin partially prevented the stunting effect on worm growth in normal female hosts. Progesterone in these experiments failed to raise egg production of H. diminuta in normal female rats on “deficient” diet while in castrated males its action was comparable with that of testosterone. No explanation for this behavior can be’put forth at this time. Whether these sex hormones are utilized as such by the worms, perhaps to aid in protein synthesis, & are utilized in some indirect manner, remains to be determined. The inability of H. diminutu to grow normally when yeast is omitted from the diet has been construed by several authors as due to a lack of some member of the B complex. Marrian and Parkes (1929)) using a diet free of yeast, produced a state of anestrus in the female rat and attributed this to a vitamin B deficiency. The complexity of yeast scarcely warrants such a conclusion. Hisaw et al., (1936)) for example, demonstrated a gonadotropic principle in brewer’s yeast. Moore and Samuels
116
J. WALTER
BECK
(1931) demonstrated that a diet supplemented with autoclaved yeast produced changes in the male accessory sex organs characteristic of diminished testosterone output, and that injection of testosterone or chorionic gonadotropin brought the accessory sex organs back to normal. They attributed the diminished testosterone production to a vitamin B1 deficiency, but Hisaw et al., (1936) demonstrated that the gonadotropic principle isolated from brewer’s yeast was also heat labile. To date, there is no conclusive evidence that the factor (or factors) in yeast, necessary for the normal growth and reproduction of H. diminuta, is a member of the B complex, nor is it certain that it is the gonadotropic substance isolated by Hisaw et al. It has been stated (Burrows, 1945) that a yeastless diet reduces the gonadotropic potency of the pituitary by a direct action on the gland, resulting in suppression of ovarian and testicular function. Subsequent injection of either estrogen or pituitary extract into the female and either androgen or pituitary extract into the male, restores normal ovarian and testicular function. It would have been of interest, therefore, to have studied histologically the gonads and the pituitaries of rats on the “deficient” diet herein used, in which many of the known members of the B complex were supplied in synthetic form but brewer’s yeast omitted, and to have compared them with glands from animals on the “complete” diet. In view of the fact that egg production of H. diminuta in normal male rats on “complete” diet (Beck, 1951) exceeded that of worms in normal females, it is of interest to note that the gonadotropic potency of the male pituitary is considered greater than that of the female (Clark, 1935). It is of interest to note also, as was observed by Chandler et al. (1950)) that Monilifarmis dub&s was readily lost from hosts on “deficient” diet, suggesting that this parasite is even more dependent on some factor in brewer’s yeast than is H. diminuta. SUMMARY
The effects of gonadectomy and gonadal hormones on singly-established H. diminuta in rats on “complete” and “deficient” diets have been studied by means of estimations of the number of eggs eliminated by the parasite per 24-hour periods over varying intervals of time. A decline in the number of eggs of H. dimintia eliminated per 24 hours over a period of 3 months was observed in castrated male rats fed a
GONADAL HORMONES ANDHYMENOLEPISDIMINUTAIN
RATS
117
“complete” diet which was comparable to the effects observed in normal male hosts on a “deficient” diet. Castrated males fed a “deficient” diet, however, exhibited a decline in the numbers of eggs of this cestode eliminated which was comparable to that observed in normal female hosts on a “deficient” diet. Testosterone and .progesterone, administered at the rate of 1 mg per day, restored egg output to approximately normal levels in castrated male hosts. Testosterone was also similarly effective in normal female rats on “deficient” diet, but progesterone was ineffective. Chorionic gonadotropin raised the egg output of H. diminuta in normal male and female rats on “deficient” diet but not in gonadectomised hosts. A stimulation of testosterone production is postulated as a possible mechanism in the case of normal male rats and possibly the production of estrogen in the normal female hosts. Accidental concurrent infections with a few Monilijormis dubius had no evident effect on egg production of H. diminutu. These acanthocephalans were lost quickly from hosts on “deficient” diet. REFERENCES
C. J., JR. 1946. Experiments on the relation between sex hormones and the growth of tapeworms (Hymenolepis diminuta) in rats. J. Parasitol. 32,
ADDIS,
574-588.
W. 1951. Effect of diet upon singly established Hymenolepis diminuta in rats. Exptl. Parasitol. 1, 46-59. BURROWS, H. 1945. Biological Actions of Sex Hormones. Cambridge Univ. Press, London. CHANDLER, A. C. 1943. Studies on the nutrition of tapeworms. Am. J. Hyg. 37, 121-130. CHANDLER, A. C., READ, C. P., AND NICHOLAS, H. 0.1959. Observations on certain phases of nutrition and host parasite relations of Hymenolepis diminuta in white rats. J. Parasitol. 36, 523-535. CLARK, H. M. 1935. A prepubertal reversal of the sex difference in the gonadotropic hormone content of the pituitary gland of the rat. Anat. Record 61, 175192. HISAW, F. L., GREEP, R. O., AND FEVOLD, H. L. 1936. Pituitary-like effect of yeast extracts. Anat. Rec. 67, Suppl: 50. MARRIAN, G. F., AND PARHES, A. S. 1929. The effect of anterior pituitary preparations administered during dietary anoestrus. Proc. Roy. Sot. London B106, 248-258. MOORE, C. R., AND SAMUELS, L. T. 1931. The action of testis hormones in correcting changes induced in the rat prostate and seminal vesicles by vitamin B deficiency or partial inanition. Am. J. Physiol. 96, 278-288. PARKE, DAVIS AND Co., 1950. Personal communication. TURNER, C. D. 1948. General Endocrinology. Saunders, Philadelphia. BECK, J.
Laboratory,
Rice ~nnstitute, Houston,
Tezas
Previous work on the influence of dietary factors on the pattern of egg elimination of the tapeworm, Hymenolepis diminuta, in rats has demonstrated the usefulness of singly-established worms as a more accurate tool in the study of biological relationships of this parasite. The present report embodies the use of singly-established parasites in a more precise study of the biological effects of gonadectomy and gonadal hormones on H. diminuta in the laboratory rat than has heretofore been possible (Addis, 1946). MATERIALS
AND METHODS
Sexually mature laboratory-bred albino rats, 5 to 8 months of age and free of infection with H. diminuta, were used in this investigation. Laboratory-infected grain beetles, Tenebrio molitor, served as a source of cysticercoids. Egg-counting technic& as well as the “complete” and “deficient” diets used, were identical with those described in connection with previous studies (Beck, 1951). All rats maintained their weights or showed weight gains on both diets. All hosts subjected to castration or spaying showed rapid return to apparently normal activity after recovery from the anesthesia. The normal fecal output did not appear altered at any time and no immediate effect on egg production of the worms was noted. Testosterone (as testosterone propionate) and progesterone were administered subcutaneously in sesame oil. Chorionic gonadotropin was obtained as a dry powder under the trade name of Antuitrin-S (Parke, Davis and Co., 1950). This is a highly purified standardized preparation derived from human pregnancy urine. It was dissolved in physiological saline at the concentration desired and administered subcutaneously as 1 The author wishes to express his guidance in this investigation assistance.
his appreciation to Dr. Asa C. Chandler for and to Mrs. Evelyn Hake for her technical 109
110
J. WALTER BECK
specified. Antuitrin-S differs from the gonadotropins of the pituitary in that it is predominantly luteinizing in action, whereas the anterior pituitary factor has a strong follicle-stimulating effect. All hormone injections were given at approximately noon on designated days. RESULTS
Effect of Host Castration on Egg Output of H. diminuta in Male Rats on “Complete” and “Dejkient’~ Die&
Eight previously infected male rats, after establishment of the normal level of egg production of their single worms, were castrated and continued on “complete” diet until termination of the experiment. There was a gradual decline in egg output to a low level of about 50,000 eggs/24 hrs over a period of approximately 102 days after castration, when the experiment was terminated, although the trend of egg production was still downward. The decline in the level of eggs in feces and the time interval in which this pattern occurred were practically identical with those observed &th a “deficient” diet reported for normal male hosts (Beck, 1951). In an additional experiment 17 previously infected male rats were castrated and placed immediately upon a “deficient” diet. Some of these animals were subsequently used in hormone tests. In all cases,the combination of castration and “deficient” diet caused a much more rapid drop in egg production than either factor alone, so that the worms reached a comparable low in egg production in 40 days instead of over 100 days. Addis (1946) reported the stunting effect of castration on growth of H. diminutu in male rats on “complete” diet and adduced evidence that this phenomenon was due to the absence of the male sex hormone, testosterone. It is not clear from the preceding experiments whether the decline in egg output was due to a direct or indirect effect of lack of testosterone on worm growth, or to the necessity of this hormone in the worm’s reproductive processes. Effects of Hormones on the Pa&w
of Elimh.tion
of H. diminuta
Eggs
a. Testosterone and Progesterone in Castrated Male Rats 012“Dejkient” Diet. To study the effect of testosterone on the production of eggs by H. diminuh, castrated male rats were placed on “deficient” diet and,
after establishment of a low level of egg production by their worms, were divided into two groups of 4. Ten micrograms of testosterone were injected daily into rats of one group and 1 mg into the other group until termination of the experiment 48 days later.
GONADAL
HORMONES
AND
HYMENOLEPIS
DIMINUTA
IN
RATS
111
The injections of 10 pg of testosterone failed completely to stimulate egg production, for the daily output of eggs remained unchanged at a level of 50,000 to 75,000 for the duration of the experiment. On the other hand the group receiving 1 mg of this hormone (see Graph 1) showed a marked increase in egg output, with the trend still moving upward at termination of the experiment. Since castrated male rats on a vitamindeficient diet have stunted worms (Addis, 1946) while normal male rats on “deficient” diet have worms of nearly normal size but which are AVCRAOC OF 4 OAOTRATED MALL RATI
Graph 1. Effect of testosterone male rata on deficient diet.
(1 mg/day)
on egg production
in castrated
deficient in egg output (Beck, 1951), it seemsplausible that testosterone, in sufficient quantity in castrated males, not only stimulates worm growth but also stimulates the reproductive processesof the worm as well. To test the effect of progesterone, 4 castrated male rats were given daily injections of 1 mg of progesterone for 26 days after the elimination of the eggs of their single worms had reached a level of 60,000/24 hrs. An increase in the number of eggs eliminated occurred which was simiIar to that which resuhed from administration of testosterone, i.e. 170,000/24 hrs. The comparable response to these two hormones is not surprising in
112
J. WALTER
BECK
view of their chemical and physiological similarities (Turner, 1948). It is not known, however, whether progesterone as such is androgenic, or whether the host animal is capable of converting progesterone into testosterone or some similar compound. b. Testosterone and Progesterone in Normal Femule Rats on “DeJicient” Diet. The failure of the injection of testosterone or progesterone to prevent a stunting effect on growth of H. diminuta in normal female rats on a vitamin-deficient diet reported by Addis (1946), prompted the study of the effects of these hormones on egg production of this tapeworm under similar conditions. Four female rats which were previously infected with single worms were placed on “deficient” diet’until termination of the experiment. Egg counts were begun at the end of 30 days. On the 44th day, when a low level in the elimination of H. diminuta eggs had been reached, daily injections of 1 mg of testosterone were‘started and continued for 26 days. As in castrated males on “deficient” diet, this hormone raised the output of H. diminuta eggs within the interval studied to a level almost equal to that obtained in normal female rats on “complete” diet (Beck, 1951). The failure to restore growth of H. diminuta to normal in female rats on “deficient” diet with testosterone, reported by Addis (1946)) is difficult to explain for a large increase in egg production would not be expected without some concomitant trend towards normal size. The failure of Addis to supplement the diet with members of the B complex in the absence of yeast may have had some effect, but there is no other evidence that the known members of the B complex in the diet are necessary for growth of this tapeworm. Five female rats which were previously infected with single H. diminuta were given daily injections of 1 mg of progesterone for 26 days after the elimination of H. diminuta eggs had reached a level of 20,000/24 hrs.‘In contrast to testosterone this hormone completely failed to raise the egg output. The ability of progesterone to raise the level of egg production of this tapeworm in castrated males but not in normal female rats, observed in the present studies, confirms the findings of Addis (1946) who demonstrated that progesterone prevented the stunting of H. diminuta in castrated males, but not in normal females on a vitamin-deficient diet. c. Antuitrin-S in Normal and Gonadectomized Male and Female Rats on “Defiient” Diet. Ten male rats, previously infected with H. diminuta, were placed on a “deficient” diet after establishment of the normal pattern in the elimination of eggs of their worms. They were divided into
GONADAL
HORMONES
AND
HYMENOLEPIS
DIMINUTA
IN
RATS
113
two groups, one of which was castrated. Egg counts were continued ‘on both groups until termination of the experiment. The castrated rats were injected daily for 30 days with 25 International Units (I.U.) of Antuitrin-S in 0.25 ml. of solution, beginning on the 54th day of “deficient” diet. The normal rats were given similar injections beginning on the 70th day of “deficient” diet. It is evident from study of the patterns of elimination of H. diminukz eggs in these animals (see Graphs 2 and 3) that Antuitrin-S was effective in raising the level of the elimination of
4-
I
I
I
I
I
I
I
I
I
+
Graph 2. Effect of Antuitrin-S deficient diet.
on egg production
I
II
25J4. Auwun~~ - S , DN
in normal male rats on
eggs to a practically normal level in those animals that had not been castrated, but failed completely in the castrated ones. Ten female rats with this tapeworm were treated similarly with injections of Antuitrin-S beginning on the 54th day of “deficient” diet in both the normal and spayed groups, and continuing for 30 days. The effects were almost identical with those on male rats. There was an increase in the number of H. diminuta eggs eliminated in normal females to a level approximat,ing the control period. No increase was observed in the spayed females. During the course of these experiments 5 hosts were found to be infected with 1 to 4 specimens of the acanthocephalan, Mowiliformis
114
J. WALTER
BECK
&&us, accidently acquired by the eating of infected cockroaches. In one host with 4 worms the infection persisted until termination of the experiment. In all other hosts the worms were passed prior to the beginning of hormone injections. Study of the patterns of the elimination of eggs of H. &W&&X in rats with M. cl&us revealed no discernible influence on the trend in egg production of the tapeworms. AVLMOC
ot
5 G*aTMTcD
MALI
RN*
388-
Graph 3. Effect of Antuitrin-S deficient diet.
dn egg production
in castrated male rate on
DISCUSSION
In view of the fact that the nutrition of H. diminuta has been shown (Chandler, 1943) not to be dependent entirely upon unassimilated substances in the intestinal lumen, it is not surprising that hormones exert an influence on worm growth. Addis (1946) demonstrated that testosterone in the male host is necessary for normal growth of H. diminutu; it has been shown here that egg production of this tapeworm depends upon it as well. The ability of progesterone to produce a responsein castrated male rats similar to that
GONADAL
HORMONES
AND
FiYMENOLEPIS
DIMINUTA
IN
RATS
115
produced by testosterone, may be due to the androgenic properties of this hormone. Addis (1946) observed that only pregnant rats were able to produce normal-sized H. diminuta while on a “deficient” diet. He postulated that the gonadotropic hormone found in the urine of pregnant animals might account for this. It is of interest to note that the chorionic gonadotropin used in this investigation stimulated egg production only in normal male and female rats but, not in gonadectomized ones. Chorionic gonadotropin which is rich in lutemizing properties, has been shown to act on the testes and ovaries of the rat resulting in increased size and weight of these organs followed by an enlargement of the accessory sex organs (Burrows, 1945). This probably indicates an enhanced output of androgens and estrogens by the respective gonads. Since testosterone in sufficient quantity raises the egg output of H. diminuta in castrated males on “deficient” diet, and maintains normal worm size in castrated males on complete diet (Addis, 1946), it may be postulated that in normal male rats chorionic gonadotropin raises the egg output of this cestode by stimulating the production of testosterone. This is supported by the fact that this hormone is ineffective in castrated hosts. Further studies with estrogen may show that this hormone has an analogous effect in female hosts, though perhaps in less degree, since chorionic gonadotropin stimulates egg production in normal female hosts also, though not in spayed ones. Addis (1946)) using a vitamin-deficient diet without yeast, observed that theelin partially prevented the stunting effect on worm growth in normal female hosts. Progesterone in these experiments failed to raise egg production of H. diminuta in normal female rats on “deficient” diet while in castrated males its action was comparable with that of testosterone. No explanation for this behavior can be’put forth at this time. Whether these sex hormones are utilized as such by the worms, perhaps to aid in protein synthesis, & are utilized in some indirect manner, remains to be determined. The inability of H. diminutu to grow normally when yeast is omitted from the diet has been construed by several authors as due to a lack of some member of the B complex. Marrian and Parkes (1929)) using a diet free of yeast, produced a state of anestrus in the female rat and attributed this to a vitamin B deficiency. The complexity of yeast scarcely warrants such a conclusion. Hisaw et al., (1936)) for example, demonstrated a gonadotropic principle in brewer’s yeast. Moore and Samuels
116
J. WALTER
BECK
(1931) demonstrated that a diet supplemented with autoclaved yeast produced changes in the male accessory sex organs characteristic of diminished testosterone output, and that injection of testosterone or chorionic gonadotropin brought the accessory sex organs back to normal. They attributed the diminished testosterone production to a vitamin B1 deficiency, but Hisaw et al., (1936) demonstrated that the gonadotropic principle isolated from brewer’s yeast was also heat labile. To date, there is no conclusive evidence that the factor (or factors) in yeast, necessary for the normal growth and reproduction of H. diminuta, is a member of the B complex, nor is it certain that it is the gonadotropic substance isolated by Hisaw et al. It has been stated (Burrows, 1945) that a yeastless diet reduces the gonadotropic potency of the pituitary by a direct action on the gland, resulting in suppression of ovarian and testicular function. Subsequent injection of either estrogen or pituitary extract into the female and either androgen or pituitary extract into the male, restores normal ovarian and testicular function. It would have been of interest, therefore, to have studied histologically the gonads and the pituitaries of rats on the “deficient” diet herein used, in which many of the known members of the B complex were supplied in synthetic form but brewer’s yeast omitted, and to have compared them with glands from animals on the “complete” diet. In view of the fact that egg production of H. diminuta in normal male rats on “complete” diet (Beck, 1951) exceeded that of worms in normal females, it is of interest to note that the gonadotropic potency of the male pituitary is considered greater than that of the female (Clark, 1935). It is of interest to note also, as was observed by Chandler et al. (1950)) that Monilifarmis dub&s was readily lost from hosts on “deficient” diet, suggesting that this parasite is even more dependent on some factor in brewer’s yeast than is H. diminuta. SUMMARY
The effects of gonadectomy and gonadal hormones on singly-established H. diminuta in rats on “complete” and “deficient” diets have been studied by means of estimations of the number of eggs eliminated by the parasite per 24-hour periods over varying intervals of time. A decline in the number of eggs of H. dimintia eliminated per 24 hours over a period of 3 months was observed in castrated male rats fed a
GONADAL HORMONES ANDHYMENOLEPISDIMINUTAIN
RATS
117
“complete” diet which was comparable to the effects observed in normal male hosts on a “deficient” diet. Castrated males fed a “deficient” diet, however, exhibited a decline in the numbers of eggs of this cestode eliminated which was comparable to that observed in normal female hosts on a “deficient” diet. Testosterone and .progesterone, administered at the rate of 1 mg per day, restored egg output to approximately normal levels in castrated male hosts. Testosterone was also similarly effective in normal female rats on “deficient” diet, but progesterone was ineffective. Chorionic gonadotropin raised the egg output of H. diminuta in normal male and female rats on “deficient” diet but not in gonadectomised hosts. A stimulation of testosterone production is postulated as a possible mechanism in the case of normal male rats and possibly the production of estrogen in the normal female hosts. Accidental concurrent infections with a few Monilijormis dubius had no evident effect on egg production of H. diminutu. These acanthocephalans were lost quickly from hosts on “deficient” diet. REFERENCES
C. J., JR. 1946. Experiments on the relation between sex hormones and the growth of tapeworms (Hymenolepis diminuta) in rats. J. Parasitol. 32,
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W. 1951. Effect of diet upon singly established Hymenolepis diminuta in rats. Exptl. Parasitol. 1, 46-59. BURROWS, H. 1945. Biological Actions of Sex Hormones. Cambridge Univ. Press, London. CHANDLER, A. C. 1943. Studies on the nutrition of tapeworms. Am. J. Hyg. 37, 121-130. CHANDLER, A. C., READ, C. P., AND NICHOLAS, H. 0.1959. Observations on certain phases of nutrition and host parasite relations of Hymenolepis diminuta in white rats. J. Parasitol. 36, 523-535. CLARK, H. M. 1935. A prepubertal reversal of the sex difference in the gonadotropic hormone content of the pituitary gland of the rat. Anat. Record 61, 175192. HISAW, F. L., GREEP, R. O., AND FEVOLD, H. L. 1936. Pituitary-like effect of yeast extracts. Anat. Rec. 67, Suppl: 50. MARRIAN, G. F., AND PARHES, A. S. 1929. The effect of anterior pituitary preparations administered during dietary anoestrus. Proc. Roy. Sot. London B106, 248-258. MOORE, C. R., AND SAMUELS, L. T. 1931. The action of testis hormones in correcting changes induced in the rat prostate and seminal vesicles by vitamin B deficiency or partial inanition. Am. J. Physiol. 96, 278-288. PARKE, DAVIS AND Co., 1950. Personal communication. TURNER, C. D. 1948. General Endocrinology. Saunders, Philadelphia. BECK, J.