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Induction of Pseudopregnancy in Adult Rats with Trilafon, a Highly Potent Tranquilizer of Low Toxicity
Induction of Pseudopregnancy in Adult Rats with Trilafon, a Highly Potent Tranquilizer of Low Toxicity Joseph T. Velardo
previous reports have demonstrated that the reproductive function in the female rat and monkey can be modified by reserpine!' 3, 4, 6 and chlorpromazine. 2 ,3 The recent availability of a more potent and less toxic tranquilizer, an amino derivative of chlorphenothiazine, * gave impetus to the present investigation. Furthermore, the wide-scale use of tranquilizing drugs in the clinician's armamentarium, and the possible role of these pharmacologic agents on the subcortex5 make it necessary that greater attention be given to the over-all effects of the ataractics. Of particular concern is the action of these tranquilizing agents on the hypothalamus and its role in the regulation of adenohypophyseal gonadotrophins on the reproductive tract. The present report is directly concerned with an investigation of an amino derivative of chlorphenothiazine (Trilafon3 ) on the reproductive tract of regularly cycling animals of known reproductive history. More specifically, this initial study is concerned with ascertaining the effects of this compound on the estrous cycles of adult albino rats. CERTAIN
From the Department of Anatomy, Yale University School of Medicine, New Haven, Conn. These studies were carried out during the tenure of a Lederle Medical Faculty Award. Supported in part by a research grant (RG-4577) from the United States Public Health Service, National Institutes of Health. Grateful acknowledgment is here recorded to the Schering Corporation, Bloomfield, N. J., for the generous amount of Trilafon used in these experiments. Received for publication June 24, 1957. • Trilafon: 1- (2-hydroxyethyl) -4 [3-chloro-1O- (phenothiazinyl) -propyll-piperazine. 60
Vol. 9, No. I, 1958
TRILAFON·INDUCED PSEUDOPREGNANCY
61
MATERIALS AND METHODS
Adult albino rats, 110--120 days of age weighing 220--235 Gm., of the Charles River strain were used for all the studies here reported. The animals were housed 3 to a 9- x 9- x 18-inch cage, were fed Purina Lab Chow and drinking water ad libitum, and were handled two or three times daily, for no more than a total of 5 minutes, for the purpose of obtaining vaginal smears and giving injections. All injections were given subcutaneously. Animals were begun on the experiments when they had fully cornified vaginal smears (estrus). The animals were divided into two main groups: ( 1) for vaginal smears, and (2) for the possible induction of decidual tissue. Vaginal Smears
Group 1. Saline Controls These animals received the placebo treatment, l.0 cc. saline on the day of estrus and another l.0 cc. saline 36 hours after the first injection. These animals were smeared throughout the duration of the experiment. Group II. Pseudopregnant Controls Since it had been demonstrated that other tranquilizing agents induced pseudopregnancy, it was necessary to induce pseudopregnancy in this group by electrical stimulation7 and determine the mean length of pseudopregnancy. The animals in this group were stimulated by a strong faradic current during the stage of estrus. Groups III, IV, and V. Trilafon-treated Groups Three dose regimens were employed: Group III. Animals in this group were given 10.0 mg. of Trilafon on the day of estrus and 5.0 mg. 36 hours after the first injection. Group IV. The rats in this group received 10.0 mg. Trilafon on the day of estrus, and 2.5 mg. 36 hours later. Group V. These animals received 5.0 mg. Trilafon on the day of estrus, and 2.5 mg. 36 hours later. Vaginal smears were taken daily, and when proestrus smears became evident the animals exhibiting them were smeared 10 hours later to obtain the earliest date of their return to full estrus. Induction of Decidual Tissue
When it became apparent that the animals reCelYlllg Trilafon had a delayed appearance of their estrous cycles, the thought that they might
62
VELARDO
Fertility & Sterility
be pseudopregnant and thus have functioning corpora lutea was entertained. Therefore, five additional groups with the same treatments as described above (I to V) were incorporated into the present study. All animals in these groups were examined for the possibility of being pseudopregnant. The standard positive test for pseudopregnancy in this laboratory was the appearance of a decidual reaction after uterine traumatization. Therefore, in those animals displaying a diestrous vaginal smear 96 hours after the appearance of a fully cornified vaginal smear (estrus) one cornu of the uterus was traumatized throughout its entire length on the antimesometrial surface, from the uterotubal junction down to the cervix, with a burred needle. Seventy-two hours later, necropsies were performed, the uteri were dissected out of the animal and each uterus was bisected at the cervix and weighed to the nearest 0.2 mg. on a Roller-Smith torsion balance. The nontraumatized cornu of each animal served as a control in each animal. These procedures were described in extenso in earlier reports. 8 , 9 Normally, such a procedure in pseudopregnant rats produces a maximal decidual reaction in the antimesometrial aspect and an initial development of decidual tissue in the mesometrial aspect of the uterus.
RESULTS Vaginal Smear Data Since the main objective of these experiments was to ascertain the influence of a highly potent and less toxic tranquilizing agent on the estrous cycles of adult albino rats of known cyclic history, it was necessary to quantitate the mean length of the estrous cycle of placebo-treated (physiologic saline) rats, and the length of pseudopregnancy induced by electrical stimulation. Examination of Table 1 reveals that the average length of the estrous cycles of placebo-treated animals is 4.5 -+- 0.6 days. Most of these animals had estrous cycles that were either 4 or 5 days in duration. The induction of pseudopregnancy by electrical stimulation of the uterine cervix effected a period of 13.1 ± 1.1 days' delay until the appearance of the next fully cornified vaginal smear, the range occupying a period of 12 to 16 days (Table 1). That Trilafon is capable of effecting a pause in the cycle typical of that of electrical stimulation during estrus (resulting in pseudopregnancy) is borne out by the data in Table 1. The estrous cycle was interrupted from the control mean of 4.5 to 12.3, 12.2, and lO.l for the groups receiving a total of 15.0 mg., 12.5 mg., and 7.5 mg. Trilafon, respectively.
TRILAFON·INDUCED PSEUDOPREGNANCY
Vol. 9, No.1, 1958
TABLE 1.
Influence of Trilafon on Estrous Cycles of the Rat
Treatment
Group I, saline controls: 1.0 cc. during estrus, 1.0 cc. 36 hours later Group II, cervical stimulation during estrus Group III, Trilafon: 10.0 mg. during estrus, 5.0 mg. 36 hours later Group IV, Trilafon: 10.0 mg. during estrus, 2.5 mg. 36 hours later Group V, Trilafon: 5.0 mg. during estrus, 2.5 mg. 36 hours later a
No. rats
36
Length of cycle
Range
(days)
(days)
4-6
4.5 ± 0.6 a
25
13.1 ± 1.1
12-16
11
12.3 ± 1.9
7-16
25
12.2 ± 2.1
8-15
20
10.1 ± 2.6
7-14
Average ± standard error of the mean.
TABLE 2.
Nature of Estrous Cycle After Period of Trilafon-Induced Pseudopregnancy
Treatment
Group I, saline controls Group II, electrically induced pseudopregnancy Group III, Trilafon: 10 mg. followed by 5.0 mg. Group IV, Trilafon: 10 mg. followed by 2.5 mg. Group V, Trilafon: 5.0 mg. followed by 2.5 mg. a
63
Length of pseudopregnancy
Length of subsequent estrous cycles
(days)
(days)
4.5 ± 0.6 a (not pseudopregnant)
4.5
13.1 ± 1.1
4.7
12.3 ± 1.9
4.8
12.2 ± 2.1
4.4
10.1 ± 2.6
4.3
Average ± standard error of the mean.
Of further interest was the determination of the nature of the estrous cycles after the so-called "interruption" of the cyclic, estrous periods. These data reveal that in every animal the cycle is restored to its regularly observed pattern, an arithmetical mean of 4.3 to 4.8 days, and a range of 4 to 6 days (Table 2). Induction of Decidual Tissue Since an «interruption" of the estrous cycle was observed as a result of the administration of a total of 7.5 to 15.0 mg. of Trilafon on the day of
64
Ferti I ity & Sterility
VELARDO
estrus and 36 hours thereafter, the thought that the animals might be pseudopregnant was investigated. In duplicate series (I to V) in which the treatments were identical, one cornu of each uterus was traumatized throughout its entire length 96 hours after the appearance of a fully corni. fied vaginal smear. Seventy-two hours later necropsies were performed and the uteri were quickly removed. Each uterus was bisected at the cervix, and the separated cornua were weighed and examined. Such treatment and procedures evokes the development of decidual tissue in all groups treated with Trilafon or cervical stimulation during estrus (Table 3). It is interesting to point out here that while the placebo-treated animals did not develop decidual tissue, those groups of animals given 12.5 to 15.0 mg. Trilafon formed decidual tissue comparable to those of the pseudopregnant controls (Group II). Of special interest is the fact that the group of animals receiving 7.5 mg. Trilafon (Group V) not only had the smallest amount of decidual tissue, but likewise experienced the shortest period of pseudopregnancy. Other Effects Noted It should be emphasized that the maximal effective dose of Trilafon was used throughout the majority of these initial studies. On the 12.5and 15.0-mg. doses, the rats were so thoroughly tranquilized that they would not exert themselves to bite the food out of its wire-mesh receptacle. Consequently, 4 rats in each group died as a result of starvation. All the remaining animals developed chromodacryorrhea, diarrhea, and a state of lethargy. Furthermore, all animals on these two high dosages lost on the average of 10 to 30 Gm. of body weight, but when the food was TABLE 3.
Demonstration of Induction of Pseudopregnancy in Rats by Trilafon
No. rats
Traumatized comu
Contralateral comu
Increase G
12
125 ± 16 b
126 ± 21
0
20
528 ± 62
120 ± 16
340 ± 39
+
12
509 ± 47
II7 ± 20
335 ± 28
+
II
523 ± 39
II4 ± 25
359 ± 40
+
8 400 ± 68 106 ± 16 277 ± 49 (Ut. weight traumatized cornu) - (Weight control cornu) X 100 = %increase (Weight control cornu) b Average ± standard error of the mean.
+
Treatment
Group I, saliNe controls Group II, electrically induced pseudopregnancy Group III, Trilafon: 10.0 mg. followed by 5.0 mg. Group IV, Trilafon: 10.0 mg. followed by 2.5 mg. Group V, Trilafon: 5.0 mg. followed by 2.5 mg. a
(%)
Decidual reaction
Vol. 9, No. I, 1958
TRILAFON-INDUCED PSEUDOPREGNANCY
65
directly presented to them 5 days after the administration of Trilafon the symptoms mentioned above disappeared and the animals regained almost 50 per cent of their weight loss in the next 8 to 10 days. None of these effects were noted in the animals on the 7.5-mg. treatment. DISCUSSION These data conclusively demonstrate that the amino derivative of chlorphenothiazine (Trilafon) under the conditions of these experiments induces pseudopregnancy in adult albino rats. The fact that this compound is one half as toxic as chlorpromazine, a chemical relative of Trilafon, and is seven times more potent on a behavior basis, lends added strength to the thought that the behavioristic potency is responsible for the induction of pseudopregnancy. Furthermore, these data argue in favor of dissuading the thought that the results obtained are due to the possible toxic effects of the compound under investigation. It is difficult to arrive at a satisfactory explanation concerning the mode of action, but the possibility is suggestive that this tranquilizer acts upon the hypothalamus, thus initiating the sequence of events responsible for the release of luteotropic gonadotrophin, which maintains the functional capacity of the corpus luteum. Witness the data on the development of deciduomas. It is well known that a progestational compound must be secreted by the corpus luteum in the intact animal before a decidual reaction can be formed. 10 This fact certainly supports the contention that Trilafon might in some way be responsible for the release of luteotropic hormone. Of course it is much easier to postulate than it is to prove an endocrine mechanism. It is absolutely essential to devise a series of experiments which can elucidate the modus operandi of Trilafon on the subcortex, or more specifically the hypothalamus. For the present, and with the limited amount of information concerning the pathway of action of Trilafon, it can only be suggested that this compound acts centrally somewhere in the nervous s y s t e m . · Of additional interest is the fact that this tranquilizer may be of tremendous importance as a useful agent in elucidating the release of adenohypophyseal hormones, particularly the luteotropic hormone in rodents and possibly other species. It is recognized that the corpora lutea are not truly functional during the 4- to 5-day estrous cycle in the rat and mouse and that mating, cervical stimulation, or the mechanical induction of pseudopregnancy initiates the release of adenohypophyseal luteotropin. The latter is a requirement for the corpora lutea to secrete both estrogenic
66
VELARDO.
Fertility & Sterility
and progestational hormones. Therefore, it may prove useful to employ this compound in a series of experiments designed to shed light on the release as well as control of the physiologic link between the subcortex and the adenohypophysis. In the final analysis, these data indicate that Trilafon allows the corpora lutea to become functional, and then after the cessation of pseudopregnancy, the animals return to their normal estrous cycles. The reports by DeFeo and Reynolds 4 and the preliminary observations by Barraclough2 are extended and confirmed.
SUMMARY These experiments reveal that an amino derivative of chlorphenothiazine (Trilafon), a tranquilizing agent which is one half as toxic and seven times more potent than its chemical relative, chlorpromazine, is quite effective in inducing pseudopregnancy in adult rats of known, regular estrous history. All animals so treated and whose uteri were unilaterally traumatized developed maximal decidual reactions, thus adding credence to the thought that the corpora lutea truly become functional as a result of the administration of Trilafon. REFERENCES 1. BARRACLOUGH, C. Blockade of the release of pituitary gonadotrophin by reserpine. Fed. Proc. 14:9, 1955. 2. BARRACLOUGH, C. Induction of pseudopregnancy in the rat by reserpine and chlorpromazine. Anat. Rec. 127:262, 1957. 3. DE FEO, V. J. Effect of large doses of reserpine on the deciduoma response. Anat. Rec. 127:409, 1957. 4. DE FEO, V. J" and REYNOLDS, S. R. M. Modification of the menstrual cycle in rhesus monkeys by reserpine. Science 124:726, 1956. 5. FAZEKAS, J. F., SHEA, J. G., and SULLIVAN, P. D. Ataractics in general practice. General Practitioner 14:74, 1946. 6. GAUNT, R., et al. Endocrine aspects of the pharmacology of reserpine. Ann. N. Y. Acad. Sc. 59:22, 1954. 7. GREEP, R. 0., and HISAW, F. L. Pseudopregnancies from electrical stimulation in the diestrum. Proc. Soc. Exper. Biol. & Med. 39:359, 1938. 8. VELARDO, J. T., and HISAW, F. L. Quantitative inhibition of progesterone by estrogens in the development of deciduomata. Endocrinology 49:530, 1951. 9. VELARDO, J. T. Steroidal aspects of pregnane inhibition of progesterone in decidual development. Am.]. Physiol. 188:317, 1957. 10. VELARDO, J. T., et al. Sequence of histological changes in the uterus and vagina of the rat during prolongation of pseudopregnancy associated with the presence of deciduomata. Am.]. Anat. 93:273, 1953.
previous reports have demonstrated that the reproductive function in the female rat and monkey can be modified by reserpine!' 3, 4, 6 and chlorpromazine. 2 ,3 The recent availability of a more potent and less toxic tranquilizer, an amino derivative of chlorphenothiazine, * gave impetus to the present investigation. Furthermore, the wide-scale use of tranquilizing drugs in the clinician's armamentarium, and the possible role of these pharmacologic agents on the subcortex5 make it necessary that greater attention be given to the over-all effects of the ataractics. Of particular concern is the action of these tranquilizing agents on the hypothalamus and its role in the regulation of adenohypophyseal gonadotrophins on the reproductive tract. The present report is directly concerned with an investigation of an amino derivative of chlorphenothiazine (Trilafon3 ) on the reproductive tract of regularly cycling animals of known reproductive history. More specifically, this initial study is concerned with ascertaining the effects of this compound on the estrous cycles of adult albino rats. CERTAIN
From the Department of Anatomy, Yale University School of Medicine, New Haven, Conn. These studies were carried out during the tenure of a Lederle Medical Faculty Award. Supported in part by a research grant (RG-4577) from the United States Public Health Service, National Institutes of Health. Grateful acknowledgment is here recorded to the Schering Corporation, Bloomfield, N. J., for the generous amount of Trilafon used in these experiments. Received for publication June 24, 1957. • Trilafon: 1- (2-hydroxyethyl) -4 [3-chloro-1O- (phenothiazinyl) -propyll-piperazine. 60
Vol. 9, No. I, 1958
TRILAFON·INDUCED PSEUDOPREGNANCY
61
MATERIALS AND METHODS
Adult albino rats, 110--120 days of age weighing 220--235 Gm., of the Charles River strain were used for all the studies here reported. The animals were housed 3 to a 9- x 9- x 18-inch cage, were fed Purina Lab Chow and drinking water ad libitum, and were handled two or three times daily, for no more than a total of 5 minutes, for the purpose of obtaining vaginal smears and giving injections. All injections were given subcutaneously. Animals were begun on the experiments when they had fully cornified vaginal smears (estrus). The animals were divided into two main groups: ( 1) for vaginal smears, and (2) for the possible induction of decidual tissue. Vaginal Smears
Group 1. Saline Controls These animals received the placebo treatment, l.0 cc. saline on the day of estrus and another l.0 cc. saline 36 hours after the first injection. These animals were smeared throughout the duration of the experiment. Group II. Pseudopregnant Controls Since it had been demonstrated that other tranquilizing agents induced pseudopregnancy, it was necessary to induce pseudopregnancy in this group by electrical stimulation7 and determine the mean length of pseudopregnancy. The animals in this group were stimulated by a strong faradic current during the stage of estrus. Groups III, IV, and V. Trilafon-treated Groups Three dose regimens were employed: Group III. Animals in this group were given 10.0 mg. of Trilafon on the day of estrus and 5.0 mg. 36 hours after the first injection. Group IV. The rats in this group received 10.0 mg. Trilafon on the day of estrus, and 2.5 mg. 36 hours later. Group V. These animals received 5.0 mg. Trilafon on the day of estrus, and 2.5 mg. 36 hours later. Vaginal smears were taken daily, and when proestrus smears became evident the animals exhibiting them were smeared 10 hours later to obtain the earliest date of their return to full estrus. Induction of Decidual Tissue
When it became apparent that the animals reCelYlllg Trilafon had a delayed appearance of their estrous cycles, the thought that they might
62
VELARDO
Fertility & Sterility
be pseudopregnant and thus have functioning corpora lutea was entertained. Therefore, five additional groups with the same treatments as described above (I to V) were incorporated into the present study. All animals in these groups were examined for the possibility of being pseudopregnant. The standard positive test for pseudopregnancy in this laboratory was the appearance of a decidual reaction after uterine traumatization. Therefore, in those animals displaying a diestrous vaginal smear 96 hours after the appearance of a fully cornified vaginal smear (estrus) one cornu of the uterus was traumatized throughout its entire length on the antimesometrial surface, from the uterotubal junction down to the cervix, with a burred needle. Seventy-two hours later, necropsies were performed, the uteri were dissected out of the animal and each uterus was bisected at the cervix and weighed to the nearest 0.2 mg. on a Roller-Smith torsion balance. The nontraumatized cornu of each animal served as a control in each animal. These procedures were described in extenso in earlier reports. 8 , 9 Normally, such a procedure in pseudopregnant rats produces a maximal decidual reaction in the antimesometrial aspect and an initial development of decidual tissue in the mesometrial aspect of the uterus.
RESULTS Vaginal Smear Data Since the main objective of these experiments was to ascertain the influence of a highly potent and less toxic tranquilizing agent on the estrous cycles of adult albino rats of known cyclic history, it was necessary to quantitate the mean length of the estrous cycle of placebo-treated (physiologic saline) rats, and the length of pseudopregnancy induced by electrical stimulation. Examination of Table 1 reveals that the average length of the estrous cycles of placebo-treated animals is 4.5 -+- 0.6 days. Most of these animals had estrous cycles that were either 4 or 5 days in duration. The induction of pseudopregnancy by electrical stimulation of the uterine cervix effected a period of 13.1 ± 1.1 days' delay until the appearance of the next fully cornified vaginal smear, the range occupying a period of 12 to 16 days (Table 1). That Trilafon is capable of effecting a pause in the cycle typical of that of electrical stimulation during estrus (resulting in pseudopregnancy) is borne out by the data in Table 1. The estrous cycle was interrupted from the control mean of 4.5 to 12.3, 12.2, and lO.l for the groups receiving a total of 15.0 mg., 12.5 mg., and 7.5 mg. Trilafon, respectively.
TRILAFON·INDUCED PSEUDOPREGNANCY
Vol. 9, No.1, 1958
TABLE 1.
Influence of Trilafon on Estrous Cycles of the Rat
Treatment
Group I, saline controls: 1.0 cc. during estrus, 1.0 cc. 36 hours later Group II, cervical stimulation during estrus Group III, Trilafon: 10.0 mg. during estrus, 5.0 mg. 36 hours later Group IV, Trilafon: 10.0 mg. during estrus, 2.5 mg. 36 hours later Group V, Trilafon: 5.0 mg. during estrus, 2.5 mg. 36 hours later a
No. rats
36
Length of cycle
Range
(days)
(days)
4-6
4.5 ± 0.6 a
25
13.1 ± 1.1
12-16
11
12.3 ± 1.9
7-16
25
12.2 ± 2.1
8-15
20
10.1 ± 2.6
7-14
Average ± standard error of the mean.
TABLE 2.
Nature of Estrous Cycle After Period of Trilafon-Induced Pseudopregnancy
Treatment
Group I, saline controls Group II, electrically induced pseudopregnancy Group III, Trilafon: 10 mg. followed by 5.0 mg. Group IV, Trilafon: 10 mg. followed by 2.5 mg. Group V, Trilafon: 5.0 mg. followed by 2.5 mg. a
63
Length of pseudopregnancy
Length of subsequent estrous cycles
(days)
(days)
4.5 ± 0.6 a (not pseudopregnant)
4.5
13.1 ± 1.1
4.7
12.3 ± 1.9
4.8
12.2 ± 2.1
4.4
10.1 ± 2.6
4.3
Average ± standard error of the mean.
Of further interest was the determination of the nature of the estrous cycles after the so-called "interruption" of the cyclic, estrous periods. These data reveal that in every animal the cycle is restored to its regularly observed pattern, an arithmetical mean of 4.3 to 4.8 days, and a range of 4 to 6 days (Table 2). Induction of Decidual Tissue Since an «interruption" of the estrous cycle was observed as a result of the administration of a total of 7.5 to 15.0 mg. of Trilafon on the day of
64
Ferti I ity & Sterility
VELARDO
estrus and 36 hours thereafter, the thought that the animals might be pseudopregnant was investigated. In duplicate series (I to V) in which the treatments were identical, one cornu of each uterus was traumatized throughout its entire length 96 hours after the appearance of a fully corni. fied vaginal smear. Seventy-two hours later necropsies were performed and the uteri were quickly removed. Each uterus was bisected at the cervix, and the separated cornua were weighed and examined. Such treatment and procedures evokes the development of decidual tissue in all groups treated with Trilafon or cervical stimulation during estrus (Table 3). It is interesting to point out here that while the placebo-treated animals did not develop decidual tissue, those groups of animals given 12.5 to 15.0 mg. Trilafon formed decidual tissue comparable to those of the pseudopregnant controls (Group II). Of special interest is the fact that the group of animals receiving 7.5 mg. Trilafon (Group V) not only had the smallest amount of decidual tissue, but likewise experienced the shortest period of pseudopregnancy. Other Effects Noted It should be emphasized that the maximal effective dose of Trilafon was used throughout the majority of these initial studies. On the 12.5and 15.0-mg. doses, the rats were so thoroughly tranquilized that they would not exert themselves to bite the food out of its wire-mesh receptacle. Consequently, 4 rats in each group died as a result of starvation. All the remaining animals developed chromodacryorrhea, diarrhea, and a state of lethargy. Furthermore, all animals on these two high dosages lost on the average of 10 to 30 Gm. of body weight, but when the food was TABLE 3.
Demonstration of Induction of Pseudopregnancy in Rats by Trilafon
No. rats
Traumatized comu
Contralateral comu
Increase G
12
125 ± 16 b
126 ± 21
0
20
528 ± 62
120 ± 16
340 ± 39
+
12
509 ± 47
II7 ± 20
335 ± 28
+
II
523 ± 39
II4 ± 25
359 ± 40
+
8 400 ± 68 106 ± 16 277 ± 49 (Ut. weight traumatized cornu) - (Weight control cornu) X 100 = %increase (Weight control cornu) b Average ± standard error of the mean.
+
Treatment
Group I, saliNe controls Group II, electrically induced pseudopregnancy Group III, Trilafon: 10.0 mg. followed by 5.0 mg. Group IV, Trilafon: 10.0 mg. followed by 2.5 mg. Group V, Trilafon: 5.0 mg. followed by 2.5 mg. a
(%)
Decidual reaction
Vol. 9, No. I, 1958
TRILAFON-INDUCED PSEUDOPREGNANCY
65
directly presented to them 5 days after the administration of Trilafon the symptoms mentioned above disappeared and the animals regained almost 50 per cent of their weight loss in the next 8 to 10 days. None of these effects were noted in the animals on the 7.5-mg. treatment. DISCUSSION These data conclusively demonstrate that the amino derivative of chlorphenothiazine (Trilafon) under the conditions of these experiments induces pseudopregnancy in adult albino rats. The fact that this compound is one half as toxic as chlorpromazine, a chemical relative of Trilafon, and is seven times more potent on a behavior basis, lends added strength to the thought that the behavioristic potency is responsible for the induction of pseudopregnancy. Furthermore, these data argue in favor of dissuading the thought that the results obtained are due to the possible toxic effects of the compound under investigation. It is difficult to arrive at a satisfactory explanation concerning the mode of action, but the possibility is suggestive that this tranquilizer acts upon the hypothalamus, thus initiating the sequence of events responsible for the release of luteotropic gonadotrophin, which maintains the functional capacity of the corpus luteum. Witness the data on the development of deciduomas. It is well known that a progestational compound must be secreted by the corpus luteum in the intact animal before a decidual reaction can be formed. 10 This fact certainly supports the contention that Trilafon might in some way be responsible for the release of luteotropic hormone. Of course it is much easier to postulate than it is to prove an endocrine mechanism. It is absolutely essential to devise a series of experiments which can elucidate the modus operandi of Trilafon on the subcortex, or more specifically the hypothalamus. For the present, and with the limited amount of information concerning the pathway of action of Trilafon, it can only be suggested that this compound acts centrally somewhere in the nervous s y s t e m . · Of additional interest is the fact that this tranquilizer may be of tremendous importance as a useful agent in elucidating the release of adenohypophyseal hormones, particularly the luteotropic hormone in rodents and possibly other species. It is recognized that the corpora lutea are not truly functional during the 4- to 5-day estrous cycle in the rat and mouse and that mating, cervical stimulation, or the mechanical induction of pseudopregnancy initiates the release of adenohypophyseal luteotropin. The latter is a requirement for the corpora lutea to secrete both estrogenic
66
VELARDO.
Fertility & Sterility
and progestational hormones. Therefore, it may prove useful to employ this compound in a series of experiments designed to shed light on the release as well as control of the physiologic link between the subcortex and the adenohypophysis. In the final analysis, these data indicate that Trilafon allows the corpora lutea to become functional, and then after the cessation of pseudopregnancy, the animals return to their normal estrous cycles. The reports by DeFeo and Reynolds 4 and the preliminary observations by Barraclough2 are extended and confirmed.
SUMMARY These experiments reveal that an amino derivative of chlorphenothiazine (Trilafon), a tranquilizing agent which is one half as toxic and seven times more potent than its chemical relative, chlorpromazine, is quite effective in inducing pseudopregnancy in adult rats of known, regular estrous history. All animals so treated and whose uteri were unilaterally traumatized developed maximal decidual reactions, thus adding credence to the thought that the corpora lutea truly become functional as a result of the administration of Trilafon. REFERENCES 1. BARRACLOUGH, C. Blockade of the release of pituitary gonadotrophin by reserpine. Fed. Proc. 14:9, 1955. 2. BARRACLOUGH, C. Induction of pseudopregnancy in the rat by reserpine and chlorpromazine. Anat. Rec. 127:262, 1957. 3. DE FEO, V. J. Effect of large doses of reserpine on the deciduoma response. Anat. Rec. 127:409, 1957. 4. DE FEO, V. J" and REYNOLDS, S. R. M. Modification of the menstrual cycle in rhesus monkeys by reserpine. Science 124:726, 1956. 5. FAZEKAS, J. F., SHEA, J. G., and SULLIVAN, P. D. Ataractics in general practice. General Practitioner 14:74, 1946. 6. GAUNT, R., et al. Endocrine aspects of the pharmacology of reserpine. Ann. N. Y. Acad. Sc. 59:22, 1954. 7. GREEP, R. 0., and HISAW, F. L. Pseudopregnancies from electrical stimulation in the diestrum. Proc. Soc. Exper. Biol. & Med. 39:359, 1938. 8. VELARDO, J. T., and HISAW, F. L. Quantitative inhibition of progesterone by estrogens in the development of deciduomata. Endocrinology 49:530, 1951. 9. VELARDO, J. T. Steroidal aspects of pregnane inhibition of progesterone in decidual development. Am.]. Physiol. 188:317, 1957. 10. VELARDO, J. T., et al. Sequence of histological changes in the uterus and vagina of the rat during prolongation of pseudopregnancy associated with the presence of deciduomata. Am.]. Anat. 93:273, 1953.