PROSTAGLANDINS
EFFECTS OF PROSTAGLANDIN
E 2 AND DL204
IT, AN INHIBITOR OF
PROSTAGLANDIN DEGRADATION, ON OVULATION AND OVUM TP~NSPORT IN THE HAMSTER.
Leonard J. Lerner*, Claudia Oldani and Adriana Vitale Lepetit Research Laboratories Via Durando, 38, Milan 20158 (Italy)
ABSTRACT The effects of 2(3-ethoxyphenyl)-5,6-dihydro-s-triazole-[5, l-a] isoquinoline (L-I1204 or DL 204 IT) and PGE 2 on ovulation and ova transport were studied. DI 204 IT was administered in doses of 0.2-25 mg/Kg s.c. on the day of estrus. A small reduction in ovulatTng follicles was observed 96 hours later, but only at the 5 mg/Kg dose level. At all dose levels, however, DL 204 IT caused a dose-related reduction in the number of ova in the oviducts. PGE 2 at a total dose of 2 mg/animal s.c., administered in 4 divided doses over the second and third day of the cycle did not affect ovulation or ova transport. PGE 2 plus DL 204 IT (5 mg/Kg), however, completely blocked ovulation in all but one animal. That animal had one ovulated follicle and a single ova was recovered from its oviduct.
*Present address where reprint requests should be sent: Dr'. L. J. Lerner, Department of Obstetrics and Gynecology, Jefferson Medical College, Room 300, Thomas Jefferson University Hospital, 1025 Walnut Street, Philadelphia, Pennsylvania 19107.
MARCH 1978 VOL. 15 NO. 3
525
PROSTAGLANDINS
INTRODUCTION Estrogens (i, 2), antiestrogens (3) and progestogens (4) alter ova transport in laboratory animals. In addition to these hormonal and antihormonal agents many other classes of therapeutic compounds have been studies for their effect on ovum transport but few have been active (5). Prostaglandins, however, have been shown to affect egg transport (6-9). Control of endogenous levels of prostaglandins in the oviduct or preventing the rapid degradation of administered prostaglandins, therefore, might be useful in changing ova transport and thereby affect fertility. Reports from our laboratory have described the effects of a novel series of non-hormonal non-prostaglandin compounds on reproduction. These compounds terminate pregnancy in all species studied including primates (10-13) and inhibit degradation of endogenous and exogenous prostaglandins in a number of tissues (I0, 14, 15). The availability of compounds that could elevate the tissue levels of administered or endogenous prostaglandins stimulated us to study them for their effects on ovulation and on ova transport in the hamster. The compound used in the following study is 2(3-ethoxyphenyl)-5,6-dihydro-s-triazole [5,l-a] isoquinoline (L-I1204 or DL 204 IT).
MATERIALS AND METHODS Golden Syrian hamsters weighing 130-150 g and having consistant regular four-day estrus cycles were employed in this study. These animals were maintained in an animal room that had a temperature of 23 ÷ l°C, a humidity of 50-60% and were illuminated for 14 hours per day.Water and commercial hamster food was provided ad libitum. The hamsters were randomly selected and placed into dose groups of II-22 animals. The compound DL 204 IT was dissolved in sesame oil containing 20% benzyl benzoate and administered subcutaneously in a single dose of 0.2, 1.0, 5.0, or 25 mg/Kg on the day of ovulation, as characterized by a thick vaginal secretion. PGE 2 dissolved in an ethanol-saline vehicle was injected subcutaneously aT a dose of 0.5 mg twice daily on the second and third days of the four-day estrus cycle for a total dose of 2 mg per animal. One group received a treatment of DL 204 IT plus PGE 2 and one group was given the saline vehicle subcutaneously for control purposes. All animals were killed by cervical dislocation 96 hours after administration of DL 204 IT or 40 hours after the last dose of PGE 2. The ovaries were dissected, weighed and ovulation points recorded. The oviducts were flushed with saline solution and the recovered ova were counted.
526
MARCH 1978 VOL. 15 NO. 3
PROSTAGLANDINS
The results are expressed as means + standard errors and the signiflcance of the data was determined by the ~tudent "t'___itest.
RESULTS AND DISCUSSION Hamster ovarian weight was only slightly reduced by DL 204 IT treatment and was unaffected by PGE 2 treatment (Table I). Moreover simultaneous administration of both compounSs did not alter the weight of this organ. Ovulation, however, was slightly reduced by DL 204 IT but only at the 5 mg/Kg dose. This dose is approximately 3 times greater than that required to terminate pregnancy in I00% of hamsters when administered on day 4 post-mating. Prostaglandin E2 when administered according to the protocol described, was ineffective in altering ovulation. The combination of PGE 2 with a dose of DL 204 IT (5 mg/Kg), caused a dramatic and complete inhibition of ovulation. Only one of 13 animals ovulated and that hamster ovulated only one ova. The effect of treatment on ova transport was very different from that on ovulation. Administration of as little as 0.2 mg/Kg of DL 204 IT caused a 26% reduction in the number of oviductal ova but this decrease was not statistically significant. However, I, 5 or 25 mg/Kg caused reductions in oviductal ova and this effect was dose-related and highly significant ( p ~ 0.01). The highest dose employed resulted in a 77% decrease in ova In the oviduct although eva were found in the tubes of every animal at every dose level of the drug. While the number of oviductal ova was reduced with the administration of PGE 2, the values were not significantly different from those of the control-animals. The one animal that ovulated of the 13 that were given the combination of DL 204 IT and PGE2, had a single ova in the oviduct. It is tempting to speculate that the failure to significantly alter ova transport with PGE 2 in the present study as well as in other studies in hamsters C16) may have been due to the rapid metabolism of prostaglandins in the body. The necessary concentration and residence of prostaglandin in oviductal tissue required for the transport mechanism, therefore, being unsatisfied. The effectiveness of DL 204 IT in evacuating the ova from the oviducts might be due to its property of blocking the degradation of endogenous prostaglandins (I0, 14, 15), thereby causing an elevation of the concentration of oviductal prostaglandin. Of course other mechanisms cannot be ruled out since It has been shown that DL 204 IT treatment also can increase histamine and hlstaminase in the reproductive tract (15). The reason for the inhibition of ovulation by DL 204 IT and by this compound plus PGE 7 treatment is unclear. Studies in several laboratories have indicated that prostaglandins may be involved in ovulation. For example, the concentration of prostaglandins in the rat ~raafian follicle increases at the time of the LH peak just before ovulation (17) and similar findings were reported for whole rat ovaries (18) and for swine follicular
MARCH. 1978 VOL. 15 NO. 3
527
PROSTAGLANDINS 0D
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EFFECTS OF PROSTAGLANDIN
E 2 AND DL204
IT, AN INHIBITOR OF
PROSTAGLANDIN DEGRADATION, ON OVULATION AND OVUM TP~NSPORT IN THE HAMSTER.
Leonard J. Lerner*, Claudia Oldani and Adriana Vitale Lepetit Research Laboratories Via Durando, 38, Milan 20158 (Italy)
ABSTRACT The effects of 2(3-ethoxyphenyl)-5,6-dihydro-s-triazole-[5, l-a] isoquinoline (L-I1204 or DL 204 IT) and PGE 2 on ovulation and ova transport were studied. DI 204 IT was administered in doses of 0.2-25 mg/Kg s.c. on the day of estrus. A small reduction in ovulatTng follicles was observed 96 hours later, but only at the 5 mg/Kg dose level. At all dose levels, however, DL 204 IT caused a dose-related reduction in the number of ova in the oviducts. PGE 2 at a total dose of 2 mg/animal s.c., administered in 4 divided doses over the second and third day of the cycle did not affect ovulation or ova transport. PGE 2 plus DL 204 IT (5 mg/Kg), however, completely blocked ovulation in all but one animal. That animal had one ovulated follicle and a single ova was recovered from its oviduct.
*Present address where reprint requests should be sent: Dr'. L. J. Lerner, Department of Obstetrics and Gynecology, Jefferson Medical College, Room 300, Thomas Jefferson University Hospital, 1025 Walnut Street, Philadelphia, Pennsylvania 19107.
MARCH 1978 VOL. 15 NO. 3
525
PROSTAGLANDINS
INTRODUCTION Estrogens (i, 2), antiestrogens (3) and progestogens (4) alter ova transport in laboratory animals. In addition to these hormonal and antihormonal agents many other classes of therapeutic compounds have been studies for their effect on ovum transport but few have been active (5). Prostaglandins, however, have been shown to affect egg transport (6-9). Control of endogenous levels of prostaglandins in the oviduct or preventing the rapid degradation of administered prostaglandins, therefore, might be useful in changing ova transport and thereby affect fertility. Reports from our laboratory have described the effects of a novel series of non-hormonal non-prostaglandin compounds on reproduction. These compounds terminate pregnancy in all species studied including primates (10-13) and inhibit degradation of endogenous and exogenous prostaglandins in a number of tissues (I0, 14, 15). The availability of compounds that could elevate the tissue levels of administered or endogenous prostaglandins stimulated us to study them for their effects on ovulation and on ova transport in the hamster. The compound used in the following study is 2(3-ethoxyphenyl)-5,6-dihydro-s-triazole [5,l-a] isoquinoline (L-I1204 or DL 204 IT).
MATERIALS AND METHODS Golden Syrian hamsters weighing 130-150 g and having consistant regular four-day estrus cycles were employed in this study. These animals were maintained in an animal room that had a temperature of 23 ÷ l°C, a humidity of 50-60% and were illuminated for 14 hours per day.Water and commercial hamster food was provided ad libitum. The hamsters were randomly selected and placed into dose groups of II-22 animals. The compound DL 204 IT was dissolved in sesame oil containing 20% benzyl benzoate and administered subcutaneously in a single dose of 0.2, 1.0, 5.0, or 25 mg/Kg on the day of ovulation, as characterized by a thick vaginal secretion. PGE 2 dissolved in an ethanol-saline vehicle was injected subcutaneously aT a dose of 0.5 mg twice daily on the second and third days of the four-day estrus cycle for a total dose of 2 mg per animal. One group received a treatment of DL 204 IT plus PGE 2 and one group was given the saline vehicle subcutaneously for control purposes. All animals were killed by cervical dislocation 96 hours after administration of DL 204 IT or 40 hours after the last dose of PGE 2. The ovaries were dissected, weighed and ovulation points recorded. The oviducts were flushed with saline solution and the recovered ova were counted.
526
MARCH 1978 VOL. 15 NO. 3
PROSTAGLANDINS
The results are expressed as means + standard errors and the signiflcance of the data was determined by the ~tudent "t'___itest.
RESULTS AND DISCUSSION Hamster ovarian weight was only slightly reduced by DL 204 IT treatment and was unaffected by PGE 2 treatment (Table I). Moreover simultaneous administration of both compounSs did not alter the weight of this organ. Ovulation, however, was slightly reduced by DL 204 IT but only at the 5 mg/Kg dose. This dose is approximately 3 times greater than that required to terminate pregnancy in I00% of hamsters when administered on day 4 post-mating. Prostaglandin E2 when administered according to the protocol described, was ineffective in altering ovulation. The combination of PGE 2 with a dose of DL 204 IT (5 mg/Kg), caused a dramatic and complete inhibition of ovulation. Only one of 13 animals ovulated and that hamster ovulated only one ova. The effect of treatment on ova transport was very different from that on ovulation. Administration of as little as 0.2 mg/Kg of DL 204 IT caused a 26% reduction in the number of oviductal ova but this decrease was not statistically significant. However, I, 5 or 25 mg/Kg caused reductions in oviductal ova and this effect was dose-related and highly significant ( p ~ 0.01). The highest dose employed resulted in a 77% decrease in ova In the oviduct although eva were found in the tubes of every animal at every dose level of the drug. While the number of oviductal ova was reduced with the administration of PGE 2, the values were not significantly different from those of the control-animals. The one animal that ovulated of the 13 that were given the combination of DL 204 IT and PGE2, had a single ova in the oviduct. It is tempting to speculate that the failure to significantly alter ova transport with PGE 2 in the present study as well as in other studies in hamsters C16) may have been due to the rapid metabolism of prostaglandins in the body. The necessary concentration and residence of prostaglandin in oviductal tissue required for the transport mechanism, therefore, being unsatisfied. The effectiveness of DL 204 IT in evacuating the ova from the oviducts might be due to its property of blocking the degradation of endogenous prostaglandins (I0, 14, 15), thereby causing an elevation of the concentration of oviductal prostaglandin. Of course other mechanisms cannot be ruled out since It has been shown that DL 204 IT treatment also can increase histamine and hlstaminase in the reproductive tract (15). The reason for the inhibition of ovulation by DL 204 IT and by this compound plus PGE 7 treatment is unclear. Studies in several laboratories have indicated that prostaglandins may be involved in ovulation. For example, the concentration of prostaglandins in the rat ~raafian follicle increases at the time of the LH peak just before ovulation (17) and similar findings were reported for whole rat ovaries (18) and for swine follicular
MARCH. 1978 VOL. 15 NO. 3
527
PROSTAGLANDINS 0D
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I
-c
O
o) ©
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z~ (D >
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