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Rapid decline in the behavioral response of paradise fish (Macropodus opercularis) to prostaglandin F2α treatment
GENERAL
AND
COMPARATIVE
ENDOCRINOLOGY
63, 157- 161 (1986)
Rapid Decline in the Behavioral Response of Paradise Fish (Macropodus opercu/aris) to Prostagiandin F,, Treatment’ TRUDY ANN VILLARSANDMARTHABURDICK Wheaton College, Norton, Massachusetts 02766 Accepted September 13, 1985 Prostaglandins (PGs) can affect sexual behavior in a range of vertebrates including goldfish, paradise fish, lizards, frogs, hamsters, and rats. Behavioral responsiveness to PG treatment has not previously been reported to correlate with reproductive condition. Earlier work (Villars et al., 198.5) has suggested that in paradise fish, response to PG treatment may be limited to the period immediately following spawning. In the present experiment, prespawned females were tested for their response to intraperitoneal injection of PGF,, (300 rig/g body wt) at 1 (n = IO), 3 (n = 8), or 5 (n = 8) days postspawning. Only pairs tested 1 day postspawning responded to PG treatment of the female with spawning acts (curving or inverting). Moreover, 1 day PG-treated females showed significantly increased sexual motivation, as measured by the time the female spent under the nest with a nest-building mate and by the frequency of female sexual solicitation, while the 3-day and the 5-day postspawning’ females showed no discernible response to PG treatment. Though differential behavioral experience had been suspected to account for female unresponsiveness seen in earlier work, it now seems possible that physiological changes post spawning may render the females unresponsive to PG treatment. 0 1986 Academic PESS, IIIC.
Prostaglandins influence female sexual behavior in several groups of tetrapod vertebrates including frogs (Diakow and Nemiroff, 1981), lizards (Tokarz and Crews, 1981), and rodents (cf. Hall et aE., 1975; Rodriguez-Sierra and Komisaruk, 1977; Buntin and Lisk, 1979). Prostaglandins have also been shown to stimulate sexual responsiveness in several species of teleost vertebrates (Stacey, 1981; Stacey and Goetz, 1982; Cole and Stacey, 1984). In paradise fish (Macropodus opercularis), treatment with PGF,, (500 rig/fish) produces a dramatic reinstatement of spawning activity in subjects which had recently completed spawning (Villars et al., 1985). Studies with rats and goldfish suggest that the effects of PGs on sexual behavior may occur independently of the gonadal state of the female. Rodriguez-Sierra and
tion
r Funded in part by a grant from the GTE corporathrough Wheaton College.
Komisaruk (1978) found that ovariectomized, hormonally untreated females are behaviorally responsive to PGE,, treatment. In goldfish, males as well as females respond to PGF,, with female sex acts (Stacey, 1981). In contrast, the effects of PGs on the behavior of female paradise fish appear unexpectedly restricted. Though females tested 1 day postspawning show a dramatic response to PG treatment, unspawned females placed with actively nestbuilding males are unresponsive to PGF,, treatment and are behaviorally indistinguishable from vehicle-treated controls (Villars et al., 1985). This unresponsiveness is not due to immature reproductive condition, since both control and PGtreated subjects spawned the day following testing. Ivforeover, unresponsiveness is not due to behavioral inexperience of the unspawned females, since females which had spawned several weeks earlier are also unresponsive to PGFzc, treatment (shrublished observations). The experiment re157 0016-6480186 $1.50 Copyright 0 1986 by Academic Press. Inc. AU rights of reproduction in any form reserved.
158
VILLARS
AND BURDICK
ported here was designed to determine the postspawning duration of responsiveness to PGF,,. METHODS
AND PROCEDURES
Subjects. Subjects were obtained through a regional distributor (C.R.A.W.fish Tropical Fish, Worcester, Mass.) and maintained in filtered 120 liter, mixed-sex community tanks. The room in which holding and testing took place has a stablilized temperature (23 t 2”) and a constant photoperiod (16L 8D; lights on at 0600 hr). Fish were fed, in holding aquaria and during testing, twice daily with Tetramin flakes supplemented with frozen brine shrimp. Spawning procedure and hormone treatment. Subjects were paired and allowed to spawn naturally according to the procedures used in previous work (Villars and Davis, 1977; Villars et al., 1985). One, three or five days following spawning, pairs were observed for a lo-min preinjection (baseline) period, following which females were removed, injected ip with 300 rig/g body wt of PGF,, Tris salt (Sigma), and returned to the tank for observations 15,45, and 75 min later. Behavioral observations. Observation periods were 10 min in duration, during which time behavior was recorded according to the procedures used in earlier studies (Villars et al., 1985). The occurrences of behavioral acts were recorded on a microprocessoroperated event recorder (“MORE,” Observational Systems, Seattle, Wash.): Curve was recorded when the female positioned herself nose-up on the male’s flank and the male wrapped his body around her. Invert was recorded when the pair inverted under the nest. Curve and invert are the two primary sex acts of the spawning sequence and involve close cooperation between the male and the female. Female approach was recorded when the female moved within a body’s length of a male who was under the nest. Female time under the nest was the total duration of time the female spent under the nest, in seconds, during the lomin observation period. Female proceptivity was scored as the number of female tailwags and flank bites/butts, both female courtship/solicitation acts. Male nest building was scored using a time-sampling procedure; the percentage of time samples in which the male was observed releasing bubbles into the bubble nest structure was calculated. Statistical analysis. The significance of PC-induced changes in female time under the nest was estimated using a oneway analysis of variance. The significance of differences between pre- and post-treatment percentage responding was estimated using a t test adapted for use with frequency data (Sokol and Rohlf, 1969).
RESULTS Prostaglandin F,, produced a 20-fold increase in the amount of time females spent under the nest in females tested 1 day following spawning [F(3,36) = 4.151 P < 0.005; see Fig. 1). In contrast, there was no effect of PC treatment on females tested 3 [F(3,28) = 0.81, NS] or 5 [F(3,28) = 0.58, NS] days following spawning. During the preinjection (baseline) observation, Day 1 females spent slightly more time under the nest (mdn = 6.5 set) than did Day 3 (mdn = 0) or Day 5 (mdn = 0.5) females; however, those differences were not statistically significant [F = (2,23) = 0.83, NS].
CURVE
OR
INVERT
c
I
PROCEPTIVE
I
MALE
FEMALES
NESTBUILD
I NO
ti 60 FW k
40
‘rp
28 0
-10 MINUTES
15 POST
45
75
INJECTION
FIG. 1. Behavioral effects of time since spawning. The bargraphs indicate median female time under the nest (in seconds), percentage of pairs curving or inverting, percentage of females which showed proceptive acts, and percentage of time males were nest building. Black bars are pairs which spawned 1 day previously (n = lo), shaded bars spawned 3 days previously (n = 8), and open bars spawned 5 days previously (n = 8). All pairs were observed for 10 min prior to prostaglandin injection (baseline), then observed at 1.5, 4.5, and 75 min following prostaglandin injection.
RAPID
DECLINE
IN PROSTAGLANDIN
In contrast to earlier observations (Villars et al., 1985), the PG effect on female approaches and on sex acts peaked not at 45 min but at 7.5 min postinjection. At that time, Day 1 females spent, on the average, 22.6% of the observation period under the nest. Other indicators of female sexual motivation were stimulated by PGF,, in Day 1 but not Day 3 or 5 subjects. Following PC treatment, the percentage of females showing proceptive acts (tailwagging or flank biting/butting) increased over preinjection baseline levels in Day 1 subjects [t(18) = 3.12, P < 0.011 but not in Day 3 or Day 5 subjects. Sex acts of curving or inverting only occurred in PG-treated, Day 1 pairs; while none of the Day 1 pairs performed any sex acts prior to PC treatment of the female, 30% of the pairs did so following treatment. Over all times, Day 1 males showed more nest building than Day 3 or 5 males; however, there was no effect of PGF2, on male nest building in any of the groups. Thus, these observations do not confirm earlier suggestions that nest building might be stimulated in males exposed to PGtreated females (Villars et al., 1985).
159
iorally responsive to PGF,, 1 day prior to normal spawning (Villars et at., 1985), nor are they responsive 3 or 5 days postspawning, there appears to be a narrow window of behavioral sensitivity to PGF,. This is in marked contrast to reports on rats (Rodriguez-Sierra and Komisaruk, 1978) and on goldfish (Stacey, 1981). Rats show lordosis facilitation to PG treatment even in the absence of their ovaries. (I-Iowever, it should be noted that the magnitude of the behavioral response to PG treatment has not been directly compared in ovariectomized and intact rats.) In goldfish, response to PG treatment occurs in pa~i~ly ovariectomized females and even in males. These results replicate earlier work which showed that PG treatment of fern&e M. opercularis 1 day postspawning reinstates the full pattern of spawning behavior; however, a smaller percentage of PG-treated pairs (30%) showed complete sex acts than in earlier work (87%, Villars et al., 1985). Though the variable responsiveness of female MA opercularis to PGF,, might be modulated by behavioral factors, it seems more likely that such rapid shifts in responsiveness are due to physiological changes surrounding spawning. In this study, the females remained with their mating partners, DISCUSSION and so’ were adequately adapted to the enThese results demonstrate that in M. vironment. Moreover, their recent operculavis, behavioral responsiveness to spawning experience rules out inexperithe effects of PGFzo, declines rapidly. Pros- ence as a source of unresponsiveness It is taglandin-treated females which had unlikely th,at the unresponsiveness is due to spawned 1 day previously showed a 20-fold changes in male motivation, since parentincrease in the time the females spent ing males readily mate with newly introunder the nest over preinjection levels of duced females and may mate ag~n’~ith the time under the nest; time under the nest is a same female within 5 or 6 days (Pollak let sensitive measure of female sexual motivaal., 1981; personal observations). tion, In contrast, prostaglandins did not inThese observations are consistent with crease time under the nest in those females the notion that female reproduc,tive readitested either 3 or 5 days postspawning. ness determines onset of mating b,~havior Moreover, in females tested 3 or 5 days in anabantoid fishes (Cheal and Davis, postspawning, there was no other detect1974). Males readily responded to the feable female response to PG treatment. male courting, unlike m’ale ~ic~iaso~a Since female paradise fish are not behav- (Cole and Stacey, 1984) where male
160
VILLARS
AND BURDICK
partners of treated females showed variable responsiveness to their partner’s behavior. In Macvopodus, the spawning act requires such close coordination between the male and the female that it is not possible to distinguish by observation whether males, females, or both are directly responsible for inversions necessary for egg release. However, since males will readily mate with PG-treated females, it appears that female readiness is of greater importance in the initiation of mating behavior including spawning acts. While the endocrine changes surrounding spawning are not known for the paradise fish or for any tropical teleost species, work in temperate zone species provides indirect indications of endocrine shifts surrounding spawning which might influence responsiveness to PGs: androgens and estrogens (McKenzie et al., 1982; Scott and Baynes, 1982), progestational steroids (Fostier, et al., 1981; McKenzie et al., 1982; Scott and Baynes, 1982; Scott et al., 1983), gonadotropins (Stacey, 1976), or other pituitary factors (cf. Moore, 1979; Diakow and Nemiroff, 1981). Future work will explore both endocrine and behavioral factors possibly modulating behavioral response to prostaglandins. In summary, these observations indicate that changing behavioral responsiveness to prostaglandins is a robust phenomenon which may have physiological significance in paradise fish. In earlier work we had speculated (Villars et al., 1985) that the unresponsiveness of gravid, unspawned females to PGF,, injection might be due to experiential factors or other technical/procedural aspects of the testing situation. The observations reported here suggest that the rapid shifts in responsiveness are physiological rather than procedural effects. Thus, this phenomenon may have wider significance for understanding the physiological regulation and cycling of sexual behavior.
REFERENCES Buntin, J. D., and Lisk, R. D. (1979). Prostaglandin E,-induced Iordosis in estrogen primed female hamsters: Relationship to progesterone action. Physiol. Behav. 23(3), X9-575. Cheal, M., and Davis, R. E. (1974). Sexual behavior: Social and ecological influences in the Anabantoid fish, Trichogaster trichopterus. Behav. Biol. 10, 435-445.
Cole, K. S., and Stacey, N. E. (1984). Prostaglandin induction of spawning behavior in Cichfasoma bimaculatum (Pisces cichlidae). Horm. Behav. 18, 235-248.
Diakow, C., and Nemiroff, A. (1981). Vasotocin, prostaglandin, and female reproductive behavior in the frog, Rana pipiens. Horm. Behav. 15, 86-93. Fostier, A., Jalabert, B., Campbell, C., Terqui, M., and Breton, B. (1981). Cinetique de liberation in vitro de 17a hydroxy-208 dihydroprogesterone par des folicles de truite arc-en-ciel, Salmo gairdneri.
C.R.
Acad.
Sci. Paris
292, 777-780.
Hall, N. R., Luttge, W. G., and Berry, R. B. (1975). Intracerebral prostaglandin E,: Effects upon sexual behavior, open field activity, and body temperature in ovariectomized female rats. Prostagl.
10, 878-887.
McKenzie, D. S., Scott A. P., Stacey, N. E., and Kyle, A. L. (1982). Gonadotropin and sex steroid changes during spawning in the white sucker (Catostomus commersoni). Amer. Zool. (Abstr. No. 585) 22(4),
955.
Moore, E L. (1979). Endocrine control of amphibian sexual behavior: Evidence for a neurohormoneandrogen interaction. Horm. Behav. 13,207-213. Pollak, E. I., Thompson, T., Stabler, A. L., and Keener, D. (1981). Multiple matings in the Blue Gourami, Trichogaster trichopterus (Pisces, Belontiidae). Anim. Behav. 29, 55-63. Rodriguez-Sierra, J. F., and Komisaruk, B. R. (1977). Effects of prostaglandin E, and indomethacin on sexual behavior in the female rat. Horm. Behav. 9, 281-289.
Rodriguez-Sierra, J. F., and Komisaruk, B. R. (1978). Lordosis induction in the rat by prostaglandin E, systemically or intracranially in the absence of ovarian. hormones. Prostaglandins 15, 513-525. Scott, A. I?, and Baynes, S. M. (1982). Plasma levels of sex steroids in relation to ovulation and spermiation in rainbow trout (Salmo Gairdneri). “Proceedings
Int.
Symp.
Reprod.
Physiol.
Fish
(C. J. J. Richter and H. J. Th. Goos, eds.) PUDOC, Wageningen, Netherlands. Scott, A. P., Sumpter, J. P., and Hardiman, P. A. (1983). Hormone changes during ovulation in the rainbow trout (Salmo gairdneri, Richardson). Gen.
Comp.
Endocrinol.
49, 128-134.
RAPID DECLINE
IN PROSTAGLANDIN
Sokol, R. R., and Rohlf, F. J. (1969). “Biometry” Freeman, San Francisco. Stacey, N. E. (1976). Effects of indomethacin and prostaglandins on the spawning behavior of female goldfish. Prostaglandins 12, 113-126. Stacey, N. E. (1981). Hormonal regulation of female reproductive behavior in fish. Amer. Zool. 21, 305-316. Stacey, N. E., and Goetz, F. W. (1982). Role of prostaglandins in fish reproduction. Can. .I. Fish. Aquat. Sci. 39, 92-98. Stacey, N. E., and Liley, N. R. (1974). Regulation of spawning behavior in the female goldfish. Nature (London) 247, 71-72.
151
Tokarz, R. R., and Crews, D. (1981). Effects of prostaglandins on sexual receptivity in the female lizard, Anolis carolinensis. Endocrinology 159, 451-457. Villars, T. A., and Davis, R. E. (1977). Castration and reproductive behavior in the Paradise Fish, Mucropodus opercularis (L.) (Osteichthyes: Belontiidae). Physiol. Behav. 19, 371-375. Villars, T. A., Hale, N., and Chapnick, D. (1985). Prostaglandm FZa stimulates reproductive behavior of female paradise fish. Harm. Behav. 19, 21-35.
AND
COMPARATIVE
ENDOCRINOLOGY
63, 157- 161 (1986)
Rapid Decline in the Behavioral Response of Paradise Fish (Macropodus opercu/aris) to Prostagiandin F,, Treatment’ TRUDY ANN VILLARSANDMARTHABURDICK Wheaton College, Norton, Massachusetts 02766 Accepted September 13, 1985 Prostaglandins (PGs) can affect sexual behavior in a range of vertebrates including goldfish, paradise fish, lizards, frogs, hamsters, and rats. Behavioral responsiveness to PG treatment has not previously been reported to correlate with reproductive condition. Earlier work (Villars et al., 198.5) has suggested that in paradise fish, response to PG treatment may be limited to the period immediately following spawning. In the present experiment, prespawned females were tested for their response to intraperitoneal injection of PGF,, (300 rig/g body wt) at 1 (n = IO), 3 (n = 8), or 5 (n = 8) days postspawning. Only pairs tested 1 day postspawning responded to PG treatment of the female with spawning acts (curving or inverting). Moreover, 1 day PG-treated females showed significantly increased sexual motivation, as measured by the time the female spent under the nest with a nest-building mate and by the frequency of female sexual solicitation, while the 3-day and the 5-day postspawning’ females showed no discernible response to PG treatment. Though differential behavioral experience had been suspected to account for female unresponsiveness seen in earlier work, it now seems possible that physiological changes post spawning may render the females unresponsive to PG treatment. 0 1986 Academic PESS, IIIC.
Prostaglandins influence female sexual behavior in several groups of tetrapod vertebrates including frogs (Diakow and Nemiroff, 1981), lizards (Tokarz and Crews, 1981), and rodents (cf. Hall et aE., 1975; Rodriguez-Sierra and Komisaruk, 1977; Buntin and Lisk, 1979). Prostaglandins have also been shown to stimulate sexual responsiveness in several species of teleost vertebrates (Stacey, 1981; Stacey and Goetz, 1982; Cole and Stacey, 1984). In paradise fish (Macropodus opercularis), treatment with PGF,, (500 rig/fish) produces a dramatic reinstatement of spawning activity in subjects which had recently completed spawning (Villars et al., 1985). Studies with rats and goldfish suggest that the effects of PGs on sexual behavior may occur independently of the gonadal state of the female. Rodriguez-Sierra and
tion
r Funded in part by a grant from the GTE corporathrough Wheaton College.
Komisaruk (1978) found that ovariectomized, hormonally untreated females are behaviorally responsive to PGE,, treatment. In goldfish, males as well as females respond to PGF,, with female sex acts (Stacey, 1981). In contrast, the effects of PGs on the behavior of female paradise fish appear unexpectedly restricted. Though females tested 1 day postspawning show a dramatic response to PG treatment, unspawned females placed with actively nestbuilding males are unresponsive to PGF,, treatment and are behaviorally indistinguishable from vehicle-treated controls (Villars et al., 1985). This unresponsiveness is not due to immature reproductive condition, since both control and PGtreated subjects spawned the day following testing. Ivforeover, unresponsiveness is not due to behavioral inexperience of the unspawned females, since females which had spawned several weeks earlier are also unresponsive to PGFzc, treatment (shrublished observations). The experiment re157 0016-6480186 $1.50 Copyright 0 1986 by Academic Press. Inc. AU rights of reproduction in any form reserved.
158
VILLARS
AND BURDICK
ported here was designed to determine the postspawning duration of responsiveness to PGF,,. METHODS
AND PROCEDURES
Subjects. Subjects were obtained through a regional distributor (C.R.A.W.fish Tropical Fish, Worcester, Mass.) and maintained in filtered 120 liter, mixed-sex community tanks. The room in which holding and testing took place has a stablilized temperature (23 t 2”) and a constant photoperiod (16L 8D; lights on at 0600 hr). Fish were fed, in holding aquaria and during testing, twice daily with Tetramin flakes supplemented with frozen brine shrimp. Spawning procedure and hormone treatment. Subjects were paired and allowed to spawn naturally according to the procedures used in previous work (Villars and Davis, 1977; Villars et al., 1985). One, three or five days following spawning, pairs were observed for a lo-min preinjection (baseline) period, following which females were removed, injected ip with 300 rig/g body wt of PGF,, Tris salt (Sigma), and returned to the tank for observations 15,45, and 75 min later. Behavioral observations. Observation periods were 10 min in duration, during which time behavior was recorded according to the procedures used in earlier studies (Villars et al., 1985). The occurrences of behavioral acts were recorded on a microprocessoroperated event recorder (“MORE,” Observational Systems, Seattle, Wash.): Curve was recorded when the female positioned herself nose-up on the male’s flank and the male wrapped his body around her. Invert was recorded when the pair inverted under the nest. Curve and invert are the two primary sex acts of the spawning sequence and involve close cooperation between the male and the female. Female approach was recorded when the female moved within a body’s length of a male who was under the nest. Female time under the nest was the total duration of time the female spent under the nest, in seconds, during the lomin observation period. Female proceptivity was scored as the number of female tailwags and flank bites/butts, both female courtship/solicitation acts. Male nest building was scored using a time-sampling procedure; the percentage of time samples in which the male was observed releasing bubbles into the bubble nest structure was calculated. Statistical analysis. The significance of PC-induced changes in female time under the nest was estimated using a oneway analysis of variance. The significance of differences between pre- and post-treatment percentage responding was estimated using a t test adapted for use with frequency data (Sokol and Rohlf, 1969).
RESULTS Prostaglandin F,, produced a 20-fold increase in the amount of time females spent under the nest in females tested 1 day following spawning [F(3,36) = 4.151 P < 0.005; see Fig. 1). In contrast, there was no effect of PC treatment on females tested 3 [F(3,28) = 0.81, NS] or 5 [F(3,28) = 0.58, NS] days following spawning. During the preinjection (baseline) observation, Day 1 females spent slightly more time under the nest (mdn = 6.5 set) than did Day 3 (mdn = 0) or Day 5 (mdn = 0.5) females; however, those differences were not statistically significant [F = (2,23) = 0.83, NS].
CURVE
OR
INVERT
c
I
PROCEPTIVE
I
MALE
FEMALES
NESTBUILD
I NO
ti 60 FW k
40
‘rp
28 0
-10 MINUTES
15 POST
45
75
INJECTION
FIG. 1. Behavioral effects of time since spawning. The bargraphs indicate median female time under the nest (in seconds), percentage of pairs curving or inverting, percentage of females which showed proceptive acts, and percentage of time males were nest building. Black bars are pairs which spawned 1 day previously (n = lo), shaded bars spawned 3 days previously (n = 8), and open bars spawned 5 days previously (n = 8). All pairs were observed for 10 min prior to prostaglandin injection (baseline), then observed at 1.5, 4.5, and 75 min following prostaglandin injection.
RAPID
DECLINE
IN PROSTAGLANDIN
In contrast to earlier observations (Villars et al., 1985), the PG effect on female approaches and on sex acts peaked not at 45 min but at 7.5 min postinjection. At that time, Day 1 females spent, on the average, 22.6% of the observation period under the nest. Other indicators of female sexual motivation were stimulated by PGF,, in Day 1 but not Day 3 or 5 subjects. Following PC treatment, the percentage of females showing proceptive acts (tailwagging or flank biting/butting) increased over preinjection baseline levels in Day 1 subjects [t(18) = 3.12, P < 0.011 but not in Day 3 or Day 5 subjects. Sex acts of curving or inverting only occurred in PG-treated, Day 1 pairs; while none of the Day 1 pairs performed any sex acts prior to PC treatment of the female, 30% of the pairs did so following treatment. Over all times, Day 1 males showed more nest building than Day 3 or 5 males; however, there was no effect of PGF2, on male nest building in any of the groups. Thus, these observations do not confirm earlier suggestions that nest building might be stimulated in males exposed to PGtreated females (Villars et al., 1985).
159
iorally responsive to PGF,, 1 day prior to normal spawning (Villars et at., 1985), nor are they responsive 3 or 5 days postspawning, there appears to be a narrow window of behavioral sensitivity to PGF,. This is in marked contrast to reports on rats (Rodriguez-Sierra and Komisaruk, 1978) and on goldfish (Stacey, 1981). Rats show lordosis facilitation to PG treatment even in the absence of their ovaries. (I-Iowever, it should be noted that the magnitude of the behavioral response to PG treatment has not been directly compared in ovariectomized and intact rats.) In goldfish, response to PG treatment occurs in pa~i~ly ovariectomized females and even in males. These results replicate earlier work which showed that PG treatment of fern&e M. opercularis 1 day postspawning reinstates the full pattern of spawning behavior; however, a smaller percentage of PG-treated pairs (30%) showed complete sex acts than in earlier work (87%, Villars et al., 1985). Though the variable responsiveness of female MA opercularis to PGF,, might be modulated by behavioral factors, it seems more likely that such rapid shifts in responsiveness are due to physiological changes surrounding spawning. In this study, the females remained with their mating partners, DISCUSSION and so’ were adequately adapted to the enThese results demonstrate that in M. vironment. Moreover, their recent operculavis, behavioral responsiveness to spawning experience rules out inexperithe effects of PGFzo, declines rapidly. Pros- ence as a source of unresponsiveness It is taglandin-treated females which had unlikely th,at the unresponsiveness is due to spawned 1 day previously showed a 20-fold changes in male motivation, since parentincrease in the time the females spent ing males readily mate with newly introunder the nest over preinjection levels of duced females and may mate ag~n’~ith the time under the nest; time under the nest is a same female within 5 or 6 days (Pollak let sensitive measure of female sexual motivaal., 1981; personal observations). tion, In contrast, prostaglandins did not inThese observations are consistent with crease time under the nest in those females the notion that female reproduc,tive readitested either 3 or 5 days postspawning. ness determines onset of mating b,~havior Moreover, in females tested 3 or 5 days in anabantoid fishes (Cheal and Davis, postspawning, there was no other detect1974). Males readily responded to the feable female response to PG treatment. male courting, unlike m’ale ~ic~iaso~a Since female paradise fish are not behav- (Cole and Stacey, 1984) where male
160
VILLARS
AND BURDICK
partners of treated females showed variable responsiveness to their partner’s behavior. In Macvopodus, the spawning act requires such close coordination between the male and the female that it is not possible to distinguish by observation whether males, females, or both are directly responsible for inversions necessary for egg release. However, since males will readily mate with PG-treated females, it appears that female readiness is of greater importance in the initiation of mating behavior including spawning acts. While the endocrine changes surrounding spawning are not known for the paradise fish or for any tropical teleost species, work in temperate zone species provides indirect indications of endocrine shifts surrounding spawning which might influence responsiveness to PGs: androgens and estrogens (McKenzie et al., 1982; Scott and Baynes, 1982), progestational steroids (Fostier, et al., 1981; McKenzie et al., 1982; Scott and Baynes, 1982; Scott et al., 1983), gonadotropins (Stacey, 1976), or other pituitary factors (cf. Moore, 1979; Diakow and Nemiroff, 1981). Future work will explore both endocrine and behavioral factors possibly modulating behavioral response to prostaglandins. In summary, these observations indicate that changing behavioral responsiveness to prostaglandins is a robust phenomenon which may have physiological significance in paradise fish. In earlier work we had speculated (Villars et al., 1985) that the unresponsiveness of gravid, unspawned females to PGF,, injection might be due to experiential factors or other technical/procedural aspects of the testing situation. The observations reported here suggest that the rapid shifts in responsiveness are physiological rather than procedural effects. Thus, this phenomenon may have wider significance for understanding the physiological regulation and cycling of sexual behavior.
REFERENCES Buntin, J. D., and Lisk, R. D. (1979). Prostaglandin E,-induced Iordosis in estrogen primed female hamsters: Relationship to progesterone action. Physiol. Behav. 23(3), X9-575. Cheal, M., and Davis, R. E. (1974). Sexual behavior: Social and ecological influences in the Anabantoid fish, Trichogaster trichopterus. Behav. Biol. 10, 435-445.
Cole, K. S., and Stacey, N. E. (1984). Prostaglandin induction of spawning behavior in Cichfasoma bimaculatum (Pisces cichlidae). Horm. Behav. 18, 235-248.
Diakow, C., and Nemiroff, A. (1981). Vasotocin, prostaglandin, and female reproductive behavior in the frog, Rana pipiens. Horm. Behav. 15, 86-93. Fostier, A., Jalabert, B., Campbell, C., Terqui, M., and Breton, B. (1981). Cinetique de liberation in vitro de 17a hydroxy-208 dihydroprogesterone par des folicles de truite arc-en-ciel, Salmo gairdneri.
C.R.
Acad.
Sci. Paris
292, 777-780.
Hall, N. R., Luttge, W. G., and Berry, R. B. (1975). Intracerebral prostaglandin E,: Effects upon sexual behavior, open field activity, and body temperature in ovariectomized female rats. Prostagl.
10, 878-887.
McKenzie, D. S., Scott A. P., Stacey, N. E., and Kyle, A. L. (1982). Gonadotropin and sex steroid changes during spawning in the white sucker (Catostomus commersoni). Amer. Zool. (Abstr. No. 585) 22(4),
955.
Moore, E L. (1979). Endocrine control of amphibian sexual behavior: Evidence for a neurohormoneandrogen interaction. Horm. Behav. 13,207-213. Pollak, E. I., Thompson, T., Stabler, A. L., and Keener, D. (1981). Multiple matings in the Blue Gourami, Trichogaster trichopterus (Pisces, Belontiidae). Anim. Behav. 29, 55-63. Rodriguez-Sierra, J. F., and Komisaruk, B. R. (1977). Effects of prostaglandin E, and indomethacin on sexual behavior in the female rat. Horm. Behav. 9, 281-289.
Rodriguez-Sierra, J. F., and Komisaruk, B. R. (1978). Lordosis induction in the rat by prostaglandin E, systemically or intracranially in the absence of ovarian. hormones. Prostaglandins 15, 513-525. Scott, A. I?, and Baynes, S. M. (1982). Plasma levels of sex steroids in relation to ovulation and spermiation in rainbow trout (Salmo Gairdneri). “Proceedings
Int.
Symp.
Reprod.
Physiol.
Fish
(C. J. J. Richter and H. J. Th. Goos, eds.) PUDOC, Wageningen, Netherlands. Scott, A. P., Sumpter, J. P., and Hardiman, P. A. (1983). Hormone changes during ovulation in the rainbow trout (Salmo gairdneri, Richardson). Gen.
Comp.
Endocrinol.
49, 128-134.
RAPID DECLINE
IN PROSTAGLANDIN
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