Effects of a Non-Steroidal Antiandrogen on Sexual Behavior and Pituitary-Gonadal Function in the Male Rat PER SODERSTEN, GARY GRAY, DAVID A. DAMASSA, ERLA R. SMITH, AND JULIAN M. DAVIDSON1 Department of Physiology, Stanford University School of Medicine, Stanford, California 94305 ABSTRACT. An investigation was conducted on the effects of the non-steroidal antiandrogen flu tarn ide (F; a-a-a-tri-fluoro-2-methyl-4-nitro-m-propionotoluidide) on two neuroendocrine mechanisms in the male rat, androgen-dependent sexual behavior, and LH regulation. F was administered in the dose of 50 ing/kg/day SC. In intact, sexually experienced adult males, no quantitative or qualitative behavioral effects were noted. In long-term castrates, F completely suppressed the effects of 100/xg testosterone prop ion ate (TP) per day on accessory sexual glands and penes, but only partially inhibited the marked stimulatory effects of this moderate TP dose on mating. Although the incidence of testosterone (T)activated ejaculatory behavior was markedly diminished, there was no statistically significant effect on occurrence of mount and intromission behavior. The rapid and profound elevations of circulating LH and T in intact males indicate an
effective antagonism of the negative feedback effect of endogenous androgen, and suggest the usefulness of F as a provocative test of pituitary-testicular function. Pituitary LH response to exogenous LHRH was markedly enhanced, as previously found in castrated rats. The administration of F did not affect circulating T levels in T-treated or untreated castrates, indicating lack of interference of circulating F in the T assay. It was concluded that, like the steroidal antiandrogen cyproterone, non-steroidal F shows a divergence between its effects on peripheral androgen-dependent and central feedback mechanisms on the one hand, and sexual behavior on the other. It was not determined whether the inhibition of ejaculatory behavior following F treatment is centrally mediated or results from failure of the peripheral, androgen-dependent structural or functional elements. (Endocrinology 97: 1468, 1975)
A
POWERFUL steroidal antiandrogen, cyproterone (l,2a-methylene-6chloropregna-4,6-dien-17a-ol-3,20-dione), has been shown to stimulate gonadotropin secretion (1-3), but neither the free nor the acetylated form inhibits spontaneous or androgen-induced male sex behavior in rats (3-5). This divergence of effects suggested a functional difference between the putative androgen-sensitive receptors of the central nervous system which subserve gonadotropin feedback and those related to behavioral mechanisms. It is not, however, known whether this phenomenon is related to the specific structure of cyproterone or is a more general function of antiandrogenicity. More recently, Neri et at. (6) found that a newer, equally potent but non-steroidal Received June 18, 1975. Supported by NIH Grants HD 00778 and MH 21178. 1 Visiting Fellow, Battelle Seattle Research Center, 1974/75. Address correspondence to: Dr. Julian M. Davidson, Department of Physiology, Stanford University, Stanford, California 94305.
antiandrogen, flutamide (a-a-a-tri-fluoro-2methyl-4-nitro-m-propionotoluidide) (F), did not prevent sexually experienced male rats from impregnating estrous females despite the suppression of peripheral androgen-dependent tissues. That report did not, however, include any direct behavioral observations, and it was therefore not clear whether this non-steroidal antiandrogen produced qualitative or quantitative disturbances in the sexual behavior of the males. The purpose of the present study was to determine whether the non-steroidal antiandrogen, F, showed the divergence of effects on reproductive neuroendocrine mechanisms previously demonstrated for the steroidal antiandrogen, cyproterone. In addition, the effects of F treatment on circulating testosterone (T) levels and pituitary sensitivity to LHRH are described. Materials and Methods Long-Evans male rats were used in all experiments. They were housed in air-conditioned, temperature-controlled rooms with food and
1468
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EFFECTS OF FLUTAMIDE ON LH AND BEHAVIOR water providedflrflibitum. The lighting schedule was 14:10 with lights on at 2100 h (experiments 1 and 2) or at 0500 h (experiment 3). For antiandrogen treatment, F was dissolved in methanol, diluted in sesame oil to a concentration of 50 mg/ml, and injected SC in a dose of approximately 50 nig/kg. Assays of LH were carried out on triplicate samples of plasma using the double antibody radioimmunoassay of Nisvvender et al. (7). Testosterone was measured in triplicate plasma samples according to the method of Frankel et al. (8). All samples from a given experiment were measured in the same LH or T assay. The precision of the assays, as measured by the coefficient of variation between 20% and 80% on the inhibition curve, was as follows: T, within assays, 8.3%; between assays, 9.9%; LH, within assays, 9.0% between assays, 9.5%. For behavioral tests, each rat was first allowed to adapt briefly to a semicircular observation cage. A receptive female, brought into heat by a single injection of 100 /xg estradiol benzoate (EB) 2 days previously (experiment 1), or 20 /xg EB 48 h, and 1 mg progesterone 6 h before testing (experiment 2), was introduced through a trap door. All subsequent mounts, intromissions, and ejaculations were recorded on a constant-speed kymograph. The following behavioral indices were measured or calculated for all tests. Intromission latency: time from the onset of the test (introduction of female) to the first intromission. Ejaculation latency: time from the first intromission to the first ejaculation (ejaculatory pattern in the case of castrates). Mount frequency: number of mounts with pelvic thrusts but without intromission, before ejaculation. Intromission frequency: number of intromissions before ejaculation. Post-ejaculatory interval: time from the occurrence of ejaculation to the first intromission of the next series. The test was terminated if a) the intromission latency was >15 min, b) the ejaculation latency was >30 min, or c) the post-ejaculatory interval
1469
was >15 min. If no intromission occurred within the first 7.5 min a new stimulus female was introduced. Experiment 1 was an initial investigation of the effects of F on sexual behavior and feedback. Fourteen sexually experienced adult intact males were pre-tested for behavior, injected daily with F beginning when they were 106 days old, and then tested twice weekly for 4 weeks. They were autopsied 2 days after the last test, following rapid etherization and jugular blood sampling for measurement of plasma LH and T. Seminal vesicles and prostates were removed and weighed. Autopsy and behavioral data from a large number of comparable intact control animals of the same age (used in another experiment) are included as normative data for comparison. Experiment 2 was primarily directed at examining the antiandrogenic effects of F on Tinduced mating behavior. Behavioral testing on 33 males began when the rats were 163 days old. To establish behavioral adequacy, each rat was tested preoperatively until it had ejaculated in three consecutive tests. The rats were then castrated by a trans-scrotal approach under ether anesthesia. Weekly behavioral tests began six weeks postoperatively, and rats were used only after failure to intromit on three consecutive tests (6 weeks for 29 rats, 8 for 3 rats, one excluded). The rats were then randomly assigned to 4 groups and injected SC daily for 14 days with: a) 100 /xg testosterone propionate (TP) in oil (no. = 9), b) 100 /xg TP + 25 mg F (no. = 9), c) 25 mg F + oil, or d) oil only (no. = 7). The total volume injected was 0.6 ml/rat. Autopsy was performed the morning after the final test, as in experiment 1, but penes were also removed, weighed, sectioned 1 mm from the tip of the glans, and stained for the subsequent study of cornified papillae. The short-term effects of F on plasma LH and T, and the response to synthetic LHRH were measured in Experiment 3. Twenty 61-63-dayold males weighing 364 ± 12 g (SE) were used. On day 0, they were rapidly bled under ether anesthesia (1000-1100 h) for measurement of plasma LH and T and then divided into three treatment groups: a) F injections, 17.5 nig/rat/day, b) vehicle injections, or c) castration and F in-
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SODERSTEN ET AL.
1470
jections. All animals were again bled rapidly under ether anesthesia (1000-1100 h) on days 1, 3,5, and 7. Immediately after the final bleeding on day 7, 10 ng synthetic LHRH was injected iv into groups (a) and (b) and another blood sample was taken 10-min post LHRH. The LHRH response was expressed as delta LH (the plasma LH 10 min after LHRH minus plasma LH just prior to LHRH administration).
Results
Effects of flutamide on male sex behavior Experiment 1 was a preliminary attempt to determine whether there were any obvious qualitative or quantitative changes in sex behavior of normal intact males treated with F. The results are presented in Table 1, which also includes data from normal untreated Long-Evans rats of the same age autopsied at approximately the same time as the F-treated intact males. The various measures of sex behavior showed very similar values in both groups. The plasma LH values of the F-treated males resembled those of long-term castrates from our laboratory (9) while the plasma T levels were some 5 times higher than the mean of untreated normal adults. Because of the markedly elevated plasma T levels, it was TABLE 1. Effects of 30 clays of flutamide treatment on behavioral and somatic responses in intact male rats*
No.
% Intromitting % Ejaculating Intromission latency (min) Ejaculation latency (min) Post-ejaculatory interval Intromission frequency Mount frequency LH (ng/ml) Testosterone (ng/ml) Seminal vesicle (mg) Ventral prostate (mg) Body weight (g)
Flutamide
Untreated
14 100 100
19 100 100 0.7 dt 0.2 5.9; t 0.4 4.7 dt 1.9 9.2: t 0.9 2.5:t 0.6 58.1:t 8.7 5.0; t 0.7 414.8 d: 15.2 454.4 d: 23.4 420 dt 8
0 . 3 : O.lt 5.2: 0.6 5.1 : 0.3 7.4: 0.8 2.5: 0.5 384.0 i 38.7 27.1 : 3.2 302.6 d 13.7 262.2 d 14.3 388 ± 7
* 106-day-old males were injected with 50 nig/kg flutamide and data were collected from the last test prior to autopsy, f Mean ± SE.
Knclo • 1975 \'ol 97 • No 6
possible that the antiandrogen did not adequately compete for "behavioral receptor sites" in the brain, especially since sex behavior is more sensitive to androgen than LH feedback mechanisms or sex accessory gland weights (10,11). Experiment 2 was designed in part to eliminate the problem of elevated endogenous T levels by injecting castrates with F together with a dose of TP which is effective in restoring male sex behavior in longterm castrates but has marginal effects on plasma LH. Fig. 1 shows that most rats in all groups displayed mounts, and that F inhibited androgenic restoration of ejaculatory but not intromission behavior. A Kruskal-Wallis one-way analysis of variance revealed no group differences in the number of tests in which mounts were observed. However, the number of tests in which intromissions were displayed differed significantly between the groups (P < 0.02, Mann-Whitney U test), but there was no difference between the TP- and TP + Ftreated groups or between the oil - and the oil + F-treated groups in the number of tests with intromissions. There was also a statistically significant group difference in the number of tests in which ejaculation was displayed (P < 0.01, Kurskal-Wallis). TPtreated rats ejaculated in significantly more tests than those in all other treatment groups (P < 0.02, Mann-Whitney). No other group differences were statistically significant. Table 2 shows behavioral details from tests with ejaculation. No statistical comparisons have been included due to the low ejaculation frequency in all but the TP-treated group. Data on effects of F on peripheral tissues are shown in Table 3. There were no statistically significant overall group differences in body weight. TP treatment stimulated the growth of the seminal vesicles, the ventral prostate, the glans penis, and the development of cornified papillae on the glans penis to levels significantly above those ofall other treatment groups (P < 0.01,
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EFFECTS OF FLUTAMIDE ON LH AND BEHAVIOR t tests after analysis of variance). F treatment completely antagonized this stimulatory effect of TP. Rats treated with TP + F did not differ significantly from oil- or Ftreated rats in any of these indices of peripheral androgenicity. Table 3 also shows that there was no difference in the plasma T levels of TPor TP + F-treated rats, and that the amount of T in the plasma of oil- or F-treated rats was undetectable at the volume of plasma assayed. In addition there was no significant effect of any treatment on plasma LH (analysis of variance: F = 2.21, df 3,28).
1471
A T • F
00
80 60
40
20
\ h
y
il X.\ / f i f / V •-'•
. .* Con
//•• v i ^
V
0
Intromission
Effects of flutamide on pituitanj-testicular axis
hypothalamic-
Because of the extremely high plasma T and LH levels obtained in experiment 1, it was of interest to study the development of pituitary-testicular responses as well as to examine pituitary sensitivity to LHRH. The results from experiment 3 are presented in Fig. 2. By day one plasma T levels were markedly elevated over those seen in intact controls, and values remained high for the duration of the experiment. Plasma LH TABLE 2. Sexual behavior displayed by castrated male rats heated with testosterone propionate(TP), flutamide (F), a combination of the two, or oil for two weeks
Ejaculation 100
Treatment Behavior patterns Mounts Intromissions
TP + oil
TP + F
F
oil-
+
Oil + oil"
5.2 ± 1.3
12.1 ±2.1
6
14
9
8
12.3 ± 1.5
10.8 ± 2.6
Intromission latency (min)
1.2 ± 0.3
1.1 ±0.6
0.3
12.4
Ejaculation latency (min)
10.5 ± 1.8
9.7 ± 1.2
11.9
14.9
Post-ejaculatory interval (min)
6.5 ± 0.2
6.1 ±0.4
14.9
Number of animals Per cent ejaculating
Con >15
9
9
7
7
88.9
33.3
14.1
14.1
TP: 100 /is SC/day. F: 25 nig sc/day. The values represent the overall Means ± SE of six tests. Only tests with ejaculation are included. 8 Based on one positive test for one animal only.
FIG. 1. The effects of flutamide on testosteroneinduced sexual behavior in castrated male rats. T, testosterone propionate (100 Mg/d X 14d); F, flutamide (25 mg/d x 14d); CON, vehicle-injected controls. Nine animals per group for the two TP groups and 7 animals per group for the other 2 groups.
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Endo < 1975 Vol 97 « No 6
SODERSTEN ET AL.
1472
TABLE 3. Mean ± SE organ weights, number of cornified papillae on the glans penis, and plasma levels of LH and testosterone of castrated male rats treated with testosterone propionate (TP), flutamide (F), a combination of the two, or oil for two weeks Treatment TP + oil Body weight (g) Seminal vesicles (nig) Ventral prostate (mg) Glans penis (mg) No. cornified papillae LH (ng/ml) Testosterone (ng/ml) No. rats
512.1 ± 11.3 409.1 ± 40.4 243.3 ± 30.5 166.7 ± 4.6 35.7 ± 2.8 243.8 ± 62.1 L.30 ± 0.04 9
TP + F 515.6 116.6 41.1 140.9
d: 22.1 d: 3.4 dt 3.9 dt 5.2
6.7 :t 1.3 217.4 dt 26.1 1.41 :t 0.12 9
F + oil
Oil + oil
pa
472.6 d:23.9 121.9 dt 9.1
482.3 ± 19.9 122.6 ± 5.5 32.0 ± 4.5 137.9 ± 4.7 5.0 ± 1.0 373.1 ± 48.8
effective antagonism of the negative feedback effect of endogenous androgen, and suggest the usefulness of F as a provocative test of pituitary-testicular function. Pituitary LH response to exogenous LHRH was markedly enhanced, as previously found in castrated rats. The administration of F did not affect circulating T levels in T-treated or untreated castrates, indicating lack of interference of circulating F in the T assay. It was concluded that, like the steroidal antiandrogen cyproterone, non-steroidal F shows a divergence between its effects on peripheral androgen-dependent and central feedback mechanisms on the one hand, and sexual behavior on the other. It was not determined whether the inhibition of ejaculatory behavior following F treatment is centrally mediated or results from failure of the peripheral, androgen-dependent structural or functional elements. (Endocrinology 97: 1468, 1975)
A
POWERFUL steroidal antiandrogen, cyproterone (l,2a-methylene-6chloropregna-4,6-dien-17a-ol-3,20-dione), has been shown to stimulate gonadotropin secretion (1-3), but neither the free nor the acetylated form inhibits spontaneous or androgen-induced male sex behavior in rats (3-5). This divergence of effects suggested a functional difference between the putative androgen-sensitive receptors of the central nervous system which subserve gonadotropin feedback and those related to behavioral mechanisms. It is not, however, known whether this phenomenon is related to the specific structure of cyproterone or is a more general function of antiandrogenicity. More recently, Neri et at. (6) found that a newer, equally potent but non-steroidal Received June 18, 1975. Supported by NIH Grants HD 00778 and MH 21178. 1 Visiting Fellow, Battelle Seattle Research Center, 1974/75. Address correspondence to: Dr. Julian M. Davidson, Department of Physiology, Stanford University, Stanford, California 94305.
antiandrogen, flutamide (a-a-a-tri-fluoro-2methyl-4-nitro-m-propionotoluidide) (F), did not prevent sexually experienced male rats from impregnating estrous females despite the suppression of peripheral androgen-dependent tissues. That report did not, however, include any direct behavioral observations, and it was therefore not clear whether this non-steroidal antiandrogen produced qualitative or quantitative disturbances in the sexual behavior of the males. The purpose of the present study was to determine whether the non-steroidal antiandrogen, F, showed the divergence of effects on reproductive neuroendocrine mechanisms previously demonstrated for the steroidal antiandrogen, cyproterone. In addition, the effects of F treatment on circulating testosterone (T) levels and pituitary sensitivity to LHRH are described. Materials and Methods Long-Evans male rats were used in all experiments. They were housed in air-conditioned, temperature-controlled rooms with food and
1468
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EFFECTS OF FLUTAMIDE ON LH AND BEHAVIOR water providedflrflibitum. The lighting schedule was 14:10 with lights on at 2100 h (experiments 1 and 2) or at 0500 h (experiment 3). For antiandrogen treatment, F was dissolved in methanol, diluted in sesame oil to a concentration of 50 mg/ml, and injected SC in a dose of approximately 50 nig/kg. Assays of LH were carried out on triplicate samples of plasma using the double antibody radioimmunoassay of Nisvvender et al. (7). Testosterone was measured in triplicate plasma samples according to the method of Frankel et al. (8). All samples from a given experiment were measured in the same LH or T assay. The precision of the assays, as measured by the coefficient of variation between 20% and 80% on the inhibition curve, was as follows: T, within assays, 8.3%; between assays, 9.9%; LH, within assays, 9.0% between assays, 9.5%. For behavioral tests, each rat was first allowed to adapt briefly to a semicircular observation cage. A receptive female, brought into heat by a single injection of 100 /xg estradiol benzoate (EB) 2 days previously (experiment 1), or 20 /xg EB 48 h, and 1 mg progesterone 6 h before testing (experiment 2), was introduced through a trap door. All subsequent mounts, intromissions, and ejaculations were recorded on a constant-speed kymograph. The following behavioral indices were measured or calculated for all tests. Intromission latency: time from the onset of the test (introduction of female) to the first intromission. Ejaculation latency: time from the first intromission to the first ejaculation (ejaculatory pattern in the case of castrates). Mount frequency: number of mounts with pelvic thrusts but without intromission, before ejaculation. Intromission frequency: number of intromissions before ejaculation. Post-ejaculatory interval: time from the occurrence of ejaculation to the first intromission of the next series. The test was terminated if a) the intromission latency was >15 min, b) the ejaculation latency was >30 min, or c) the post-ejaculatory interval
1469
was >15 min. If no intromission occurred within the first 7.5 min a new stimulus female was introduced. Experiment 1 was an initial investigation of the effects of F on sexual behavior and feedback. Fourteen sexually experienced adult intact males were pre-tested for behavior, injected daily with F beginning when they were 106 days old, and then tested twice weekly for 4 weeks. They were autopsied 2 days after the last test, following rapid etherization and jugular blood sampling for measurement of plasma LH and T. Seminal vesicles and prostates were removed and weighed. Autopsy and behavioral data from a large number of comparable intact control animals of the same age (used in another experiment) are included as normative data for comparison. Experiment 2 was primarily directed at examining the antiandrogenic effects of F on Tinduced mating behavior. Behavioral testing on 33 males began when the rats were 163 days old. To establish behavioral adequacy, each rat was tested preoperatively until it had ejaculated in three consecutive tests. The rats were then castrated by a trans-scrotal approach under ether anesthesia. Weekly behavioral tests began six weeks postoperatively, and rats were used only after failure to intromit on three consecutive tests (6 weeks for 29 rats, 8 for 3 rats, one excluded). The rats were then randomly assigned to 4 groups and injected SC daily for 14 days with: a) 100 /xg testosterone propionate (TP) in oil (no. = 9), b) 100 /xg TP + 25 mg F (no. = 9), c) 25 mg F + oil, or d) oil only (no. = 7). The total volume injected was 0.6 ml/rat. Autopsy was performed the morning after the final test, as in experiment 1, but penes were also removed, weighed, sectioned 1 mm from the tip of the glans, and stained for the subsequent study of cornified papillae. The short-term effects of F on plasma LH and T, and the response to synthetic LHRH were measured in Experiment 3. Twenty 61-63-dayold males weighing 364 ± 12 g (SE) were used. On day 0, they were rapidly bled under ether anesthesia (1000-1100 h) for measurement of plasma LH and T and then divided into three treatment groups: a) F injections, 17.5 nig/rat/day, b) vehicle injections, or c) castration and F in-
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SODERSTEN ET AL.
1470
jections. All animals were again bled rapidly under ether anesthesia (1000-1100 h) on days 1, 3,5, and 7. Immediately after the final bleeding on day 7, 10 ng synthetic LHRH was injected iv into groups (a) and (b) and another blood sample was taken 10-min post LHRH. The LHRH response was expressed as delta LH (the plasma LH 10 min after LHRH minus plasma LH just prior to LHRH administration).
Results
Effects of flutamide on male sex behavior Experiment 1 was a preliminary attempt to determine whether there were any obvious qualitative or quantitative changes in sex behavior of normal intact males treated with F. The results are presented in Table 1, which also includes data from normal untreated Long-Evans rats of the same age autopsied at approximately the same time as the F-treated intact males. The various measures of sex behavior showed very similar values in both groups. The plasma LH values of the F-treated males resembled those of long-term castrates from our laboratory (9) while the plasma T levels were some 5 times higher than the mean of untreated normal adults. Because of the markedly elevated plasma T levels, it was TABLE 1. Effects of 30 clays of flutamide treatment on behavioral and somatic responses in intact male rats*
No.
% Intromitting % Ejaculating Intromission latency (min) Ejaculation latency (min) Post-ejaculatory interval Intromission frequency Mount frequency LH (ng/ml) Testosterone (ng/ml) Seminal vesicle (mg) Ventral prostate (mg) Body weight (g)
Flutamide
Untreated
14 100 100
19 100 100 0.7 dt 0.2 5.9; t 0.4 4.7 dt 1.9 9.2: t 0.9 2.5:t 0.6 58.1:t 8.7 5.0; t 0.7 414.8 d: 15.2 454.4 d: 23.4 420 dt 8
0 . 3 : O.lt 5.2: 0.6 5.1 : 0.3 7.4: 0.8 2.5: 0.5 384.0 i 38.7 27.1 : 3.2 302.6 d 13.7 262.2 d 14.3 388 ± 7
* 106-day-old males were injected with 50 nig/kg flutamide and data were collected from the last test prior to autopsy, f Mean ± SE.
Knclo • 1975 \'ol 97 • No 6
possible that the antiandrogen did not adequately compete for "behavioral receptor sites" in the brain, especially since sex behavior is more sensitive to androgen than LH feedback mechanisms or sex accessory gland weights (10,11). Experiment 2 was designed in part to eliminate the problem of elevated endogenous T levels by injecting castrates with F together with a dose of TP which is effective in restoring male sex behavior in longterm castrates but has marginal effects on plasma LH. Fig. 1 shows that most rats in all groups displayed mounts, and that F inhibited androgenic restoration of ejaculatory but not intromission behavior. A Kruskal-Wallis one-way analysis of variance revealed no group differences in the number of tests in which mounts were observed. However, the number of tests in which intromissions were displayed differed significantly between the groups (P < 0.02, Mann-Whitney U test), but there was no difference between the TP- and TP + Ftreated groups or between the oil - and the oil + F-treated groups in the number of tests with intromissions. There was also a statistically significant group difference in the number of tests in which ejaculation was displayed (P < 0.01, Kurskal-Wallis). TPtreated rats ejaculated in significantly more tests than those in all other treatment groups (P < 0.02, Mann-Whitney). No other group differences were statistically significant. Table 2 shows behavioral details from tests with ejaculation. No statistical comparisons have been included due to the low ejaculation frequency in all but the TP-treated group. Data on effects of F on peripheral tissues are shown in Table 3. There were no statistically significant overall group differences in body weight. TP treatment stimulated the growth of the seminal vesicles, the ventral prostate, the glans penis, and the development of cornified papillae on the glans penis to levels significantly above those ofall other treatment groups (P < 0.01,
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EFFECTS OF FLUTAMIDE ON LH AND BEHAVIOR t tests after analysis of variance). F treatment completely antagonized this stimulatory effect of TP. Rats treated with TP + F did not differ significantly from oil- or Ftreated rats in any of these indices of peripheral androgenicity. Table 3 also shows that there was no difference in the plasma T levels of TPor TP + F-treated rats, and that the amount of T in the plasma of oil- or F-treated rats was undetectable at the volume of plasma assayed. In addition there was no significant effect of any treatment on plasma LH (analysis of variance: F = 2.21, df 3,28).
1471
A T • F
00
80 60
40
20
\ h
y
il X.\ / f i f / V •-'•
. .* Con
//•• v i ^
V
0
Intromission
Effects of flutamide on pituitanj-testicular axis
hypothalamic-
Because of the extremely high plasma T and LH levels obtained in experiment 1, it was of interest to study the development of pituitary-testicular responses as well as to examine pituitary sensitivity to LHRH. The results from experiment 3 are presented in Fig. 2. By day one plasma T levels were markedly elevated over those seen in intact controls, and values remained high for the duration of the experiment. Plasma LH TABLE 2. Sexual behavior displayed by castrated male rats heated with testosterone propionate(TP), flutamide (F), a combination of the two, or oil for two weeks
Ejaculation 100
Treatment Behavior patterns Mounts Intromissions
TP + oil
TP + F
F
oil-
+
Oil + oil"
5.2 ± 1.3
12.1 ±2.1
6
14
9
8
12.3 ± 1.5
10.8 ± 2.6
Intromission latency (min)
1.2 ± 0.3
1.1 ±0.6
0.3
12.4
Ejaculation latency (min)
10.5 ± 1.8
9.7 ± 1.2
11.9
14.9
Post-ejaculatory interval (min)
6.5 ± 0.2
6.1 ±0.4
14.9
Number of animals Per cent ejaculating
Con >15
9
9
7
7
88.9
33.3
14.1
14.1
TP: 100 /is SC/day. F: 25 nig sc/day. The values represent the overall Means ± SE of six tests. Only tests with ejaculation are included. 8 Based on one positive test for one animal only.
FIG. 1. The effects of flutamide on testosteroneinduced sexual behavior in castrated male rats. T, testosterone propionate (100 Mg/d X 14d); F, flutamide (25 mg/d x 14d); CON, vehicle-injected controls. Nine animals per group for the two TP groups and 7 animals per group for the other 2 groups.
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Endo < 1975 Vol 97 « No 6
SODERSTEN ET AL.
1472
TABLE 3. Mean ± SE organ weights, number of cornified papillae on the glans penis, and plasma levels of LH and testosterone of castrated male rats treated with testosterone propionate (TP), flutamide (F), a combination of the two, or oil for two weeks Treatment TP + oil Body weight (g) Seminal vesicles (nig) Ventral prostate (mg) Glans penis (mg) No. cornified papillae LH (ng/ml) Testosterone (ng/ml) No. rats
512.1 ± 11.3 409.1 ± 40.4 243.3 ± 30.5 166.7 ± 4.6 35.7 ± 2.8 243.8 ± 62.1 L.30 ± 0.04 9
TP + F 515.6 116.6 41.1 140.9
d: 22.1 d: 3.4 dt 3.9 dt 5.2
6.7 :t 1.3 217.4 dt 26.1 1.41 :t 0.12 9
F + oil
Oil + oil
pa
472.6 d:23.9 121.9 dt 9.1
482.3 ± 19.9 122.6 ± 5.5 32.0 ± 4.5 137.9 ± 4.7 5.0 ± 1.0 373.1 ± 48.8
