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The effect of Escherichia coli endotoxin on luteal function in Holstein heifers
THERIOGENOLOGY
THE EFFECT OF ESCHERICHIA u ENDOTOXIN ON LUTEAL FUNCTION IN HOLSTEIN HEIFERS R.O. Gilbert,' W.T.K.
Bosu and A.T. Peter
Department of Medical Sciences, School of Veterinary Medicine University of Wisconsin-Madison, Madison, WI 53706 Received
for publication: ~~~~ 30, 1989 Accepted: December 17, 1989 ABSTRACT
This study was undertaken to elucidate the possible role of endotcxin in mediating premature luteolysis in the well- documented phenomenon of short estrous cycles in postpartum dairy cows. Four groups of Holstein heifers (n = 4 to 6 each) received either intrau.terine infusion of sterile culture medium (Group I); intrauterine infusion of Escherichia coli (E_ &) endotoxin (5 pg/kg) in sterile culture medium (Group II): intrauterine administration of 10 ml of a 24-h culture of a strain of E_ coli isolated from the uterus of a cow with metritis (approximatelycolony forming units/ml; Group III): or intravenous administration of E. coli endotoxin (5 pg/kg; Group IV) on Day 7-9 of the estrous cycle. Blood samples were collected every 48 h during the pretreatment estrous cycle and up to the administration of the experi.mental treatment, thereafter 4-h samples were collected for 5 d. Sample collection was then performed every 48 h for the remainder of the treatment cycle and the post treatment cycle. Serum concentrations of progesterone and plasma concentrations of 15-keto-13,14-dihydroprostaglandin F?, (PGFM) were determined by radiolmmunoassay. Intrauterine infusion of endotoxin had no effect on the cycle length or on hormone concentrations, while infusion of viable E_ coli organisms tended to shorten the estrous cycle. Intravenous administration of endotoxin produced a sharp increase in both progesterone and PGFM concentrations, followed by a transient decrease in progesterone concentrations. Cycle length remained unchanged.. It was concluded that the intact endometrium prevents the uptake of endotoxin although pathogenic E_ coli organisms may disrupt the endometrial integrity sufficiently to It is shorten the estrous cycle by premature luteolysis. postulated that intravenous administration of endotoxin influences luteaIL function by the activation of the arachidonic acid cascade, by a direct effect on the corpus luteum, or via other mediators. Key words:
corpus
luteum, endotoxin,
progesterone
This project was supported in part by funds from Acknowledgments: and Life the IJniversity of Wisconsin, College of Agriculture Sciences Project No. 2927, and in part by funds from the University of Wisconsin Graduate School. NYS College of 'Present address: University, Ithaca NY 14853-6401.
MARCH
1990 VOL.
33 NO. 3
Veterinary
Medicine,
Cornell
645
THERIOGENOLOGY
INTRODUCTION This experiment was conducted to clarify the possible role of endotoxin in mediating premature luteolysis in the well-documented phenomenon of short estrous cycles in postpartum dairy cows (1). infection of the uterus by gram negative Persistent puerperal organisms, resulting in endotoxin release, might be expected to result in PGF,, release as reflected by elevated concentrations of PGFM (2,3). Release of PGF,,, it was hypothesized, could result in the premature demise of the corpus luteum, with a shortening of the The aim diestrous period and therefore the interestrous interval. intrauterine the effect of trial was to monitor of this administration of Escherichia coli organisms or E. coli endotoxin, endotoxin on clinical administration of intravenous or of parameters such as cycle length and endocrine profiles in Holstein heifers. MATERIALS
AND METHODS
heifers (n = 4 to 6 each) Four groups of Holstein approximately 18 mo old and weighing 400 to 500 kg were used in They were housed in stanchions in a barn at the this trial. of the School of Veterinary Instructional Facility Charmany Medicine in Madison, Wisconsin, where the experiment was completed within a 2-mo period during winter, and fed alfalfa hay and clean Their estrous cycles were monitored by careful water ad libitum. vaginal inspection for vulvar swelling or flaccidity, daily vocalization or behavior, and discharges or changes in retrospectively confirmed by comparison with progesterone profiles. Rectal examination was avoided since this procedure has been associated with increased plasma concentrations of PGFM (4). At least one complete estrous cycle was observed prior to treatment. During the pretreatment cycle, blood samples were collected every 48 h into plain and heparin-containing evacuated tubes. The samples were stored on ice, separated by centrifugation within 30 min of collection and the serum and plasma samples were frozen at 20°C until assayed. During the treatment cycle, on Day 7, 8 or 9 of the estrous to cycle, when the corpus luteum is known to be susceptible prostaglandin-induced luteolysis (5), the heifers received one of the following treatments: intrauterine infusion of 10 ml of sterile peptone water (Group I); intrauterine infusion of E. coli endotoxin (088:B5, Difco Laboratories, Detroit, MI) at 5 pg/kg in 10 ml sterile peptone water (Group II): intrauterine infusion of 10 ml of a 24 h culture in peptone water of a strain of E. coli isolated from the uterus of a cow with purulent endometritis (approximately 109 colony forming units/ml (Group III): or intravenous administration of 5 pg/kg of &_ coli endotoxin in 5 ml sterile saline. During the treatment cycle, blood was collected as above every 48 h until the day of treatment, thereafter samples were collected every 4 h for 5 d. During this period the heifers were carefully observed for clinical symptoms, and temperature, pulse rate and respiratory rate were recorded every 4 h. For the rest
MARCH 1990 VOL. 33 NO. 3
THERIOGENOLOGY
of the treatment cycle and the post-treatment again collected every 48 h.
cycle,
samples were
Serum progesterone and plasma PGFM concentrations determined by radioimmunoassays elsewhere as described Differences in cycle lengths or hormone concentrations determined within heifers by means of a paired t-test.
were (3). were
RESULTS Heifers in Group I showed a scant, transient, clear mucoid vaginal discharge which commenced 20 to 30 min after treatment and disappeared within 4 h. Group II heifers showed similar signs, with a slightly more copious discharge persisting for 4 to 6 h. Group III heifers had a mucopurulent discharge which cleared up within 4 to 8 h. None of the heifers in Group I, II or III showed any signs of systemic illness. Heifers in Group IV, on the other hand, showed an immediate febrile response, with peak temperatures (39.4 to 4O.l'C) being recorded 8 to 16 h after the administration of endotoxin. By 32 h following endotoxin administration, all animals were afebrile. Tachycardia and tachypnea persisted for at least 3 d, and for 5 d in two heifers that became recumbent. All of the heifers in this group showed severe ptyalism, cyanosis and diarrhea, and had cold extremities for the first 12 to 24 h after treatment. In spite of the intravenous route of endotoxin administration, all the animals in this group developed a clear to amber-colored mucoid vaginal discharge. No fatalities occurred. The length of the estrous cycle was altered only in Group III (intrauterine E. coli), where 3 of 4 heifers had shortened cycles (P < 0.10). No alterations were observed in the length of the posttreatment cycle.
Table
I.. Estrous
cycle length in days Group I
n
5
(Mean + SEM)
Group II
5
Group III
4
Group
IV
6
Pretreatment cycle
21.2kO.74
21.040.63
21.5rfr0.63
22.022.51
Treatment cycle
21.2&l-17
20.2+I.a3
I7.o_ti.a3
22.8+2.60
alterations in profiles of NO concentration were noted in Group I or
MARCH 1990 VOL. 33 NO. 3
progesterone In Group II.
or PGFM III, the
647
THERIOGENOLOGY
16
Progesterone hg/ml) ,O7
Progesterone hg/ml)
25
6
0
,I
Day of Cycle
Day of Cycle
Fig 1. Mean serum progesterone concentrations for six heifers injected intravenously with endotoxin on Day 9 of the estrous cycle.
10
Progesterone (ng/ml)
Fig 2. Serum progesterone concentrations for each heifers the six of injected intravenously with endotoxin on Day 9 of the estrous cycle.
PGFM (pg/ml) ,OOU
6-
6-
rlnoot
2-A-. 0
0
5
10
15
20
25
30
Day of Cycle for Fig 3. Progesteroneprofile Heifer 162 during treatmentcycle, showing baseline progesterone after endotoxin administration, followed by ovulation on Day 21.
648
I
‘j , 0
I
/
14
2 l-louts
afkr IV ‘endo~oxin l2
PGFM Fig 4. Plasma concentrations in the receiving six heifers endotoxin intravenous injection.
MARCH
1990 VOL.
33 NO. 3
THERIOGENOLOGY
luteal phase (defined here as the period during which the serum progesterone concentration exceeded 1 ng/ml) was shortened from 14.5 + 0.86 days to 10.25 + 1.92 days (P < 0.10). In Group IV, the plasma progesterone concentration increased markedly 4 h after intravenous administration of endotoxin in all six heifers (P < 0.01; Figures 1 and 2). This was followed by a significant decrease 12 to 28 h after endotoxin administration. In five heifers luteal function was regained after this time and In the remaining heifer (Figure the cycle length was unaffected. 3) serum progesterone concentrations remained near basal levels (CO.5 ng/ml), followed by estrus and ovulation at the expected time. The cycle was thus not shortened. A PGFM peak was recorded in Group IV heifers at 4 h after intravenous administration of endotoxin (P < 0.0025; Figure 4). DISCUSSION A failure to evoke endocrinological changes or to affect the cycle length of heifers receiving intrauterine endotoxin probably reflects a failure to absorb endotoxin from the uterus by the Failure to absorb endotoxin has also been normal, cyclic cow. reportled in mares (6) and ewes (7). In sows (8), but not in ewes (7), endotoxin is absorbed from the uterus during the puerperium. Puerperal absorption of endotoxin from the bovine uterus has not been r'eported. given Tne shortening of the estrous cycle in heifers intrauterine E. coli (Group III) is compatible with endometrial irritation (9). The timing of luteolysis indicates that PGF,, release occurs during the stage of endometrial regeneration, as This conclusion is speculative suggested by Seguin et al. (9) * since we have no direct evidence of endometrial damage by this treatment. The acute peak in serum progesterone concentration occurring 4 h after intravenous administration of endotoxin corresponded temporarily to the peak in PGFM concentration, but may reflect a concurrent or prior peak in the luteotrophic PGE, (lo), which was it may be the result of a direct not as,sayed. Alternatively, effect of the endotoxin on the corpus luteum, or it may be mediated in another, yet unknown fashion. concentration 12 to 28 h after The trough in progesterone endotoxin administration is ascribed to the luteolytic effect of the PGF,,. Except in one case (Heifer 162, Figure 3) this effect Prolonged or repeated exposure to endotoxin was only transient. in mediating abortion during early bovine may be significant Its source could be an extragenital infection (11). pregnancy. Abortion has been induced by experimental administration of E. coli endotoxin to swine (12) and Salmonella tvohimurium endotoxin to goats (13). Whether this effect worked directly on the fetus(es)
MARCH 1990VOL.
33 NO. 3
THERIOGENOLOGY
Endotoxinor was mediated by luteolysis was not investigated. induced abortion in mice can be prevented with indomethacin (14). Progesterone supplementation prevented abortion but not fetal death, suggesting effects of endotoxemia both on the corpus luteum and on the fetuses (14). Although it appears that endotoxemia may result in at absorption of endotoxin from the least transient luteolysis, involuting bovine uterus will have to be investigated to clarify its role in inducing premature luteolysis in the postpartum dairy cow. Such studies are in progress in our laboratory. REFERENCES 1.
Morrow, D.A., Roberts, S.J. and McEntee, K. Postpartum ovarian activity and involution of the uterus and cervix in dairy cattle. I. Ovarian activity. Cornell Vet =:173-190 (1969).
2.
Fredricksson, G., Kindahl, H. and Sandstedt, K. Intrauterine bacterial findings and release of PGFzU in the postpartum dairy cow. Zbl. Vet. Med. A. x:368-380 (1985).
3.
Peter, A.T. and Bosu, W.T.K. Effects of intrauterine infection on the function of the corpora lutea formed after the first postpartum ovulations in dairy cows. Theriogenology =:593-609 (1987).
4.
Alam, M.G.S. and Dobson,H. Effect of various veterinary procedures on plasma concentrations of cortisol, luteinising hormone and prostaglandin Fza metabolite in the cow. Veterinary Record m:7-10 (1986).
5.
Seguin, B., Momont, H. and Baumann, L. dinoprost tromethamine in experimental treating unobserved estrus in dairy cows. 90 (1985).
6.
Mollett, T.A., Elmore, R.G., Blanchard, T.L. and Berg, J.N. Effects of intrauterine infusion of Escherichia & endotoxin in anestrous and steroid treated pony mares. Theriogenology =:597-606 (1985).
7.
Elmore, R.G., Mollett, T.A., Berg, J.N. and Schmidt, D.A. Escherichia coli endotoxin absorption from the ewe's uterus and peritoneal cavity. Theriogenology =:841-847 (1983).
8.
Elmore, R-G., Martin, C.E. and Berg, J.N. Absorption of Escherichia coli endotoxin from the mammary glands and uteri of early postpartum sows and gilts. Theriogenology =:439445 (1978).
660
Cloprostenol and and field trials Bov. Pratt. =:89-
MARCH 1990 VOL. 33 NO. 3
THERIOGENOLOGY
9.
Luteolysis, Seguin, B.E., Morrow, D.A. and Louis, T.M. luteostasis and the effect of prostaglandin F,, in cows after endometrial irritation. Am. J. Vet. Res. %:57-61 (1974).
10.
Giminez, T. and Henricks, D.M. Prolongation of the luteal phase by prostaglandin Ez during the estrous cycle of the cow. A preliminary report. Theriogenology u:693-700 (1983).
11.
Roberts, S.J. Veterinary Obstetrics and Genital Diseases. Published by the author, Ithaca, NY, 1971, p. 116.
12.
Wrathall, A.E., Bailey, J. and Wells, D.E. Experimentally induced bacterial endotoxaemia and absorption in pigs. Br. Vet. J. m:225-230 (1978).
13.
Fredricksson, G., Kindahl, H. and Edqvist, L.-E. Endotoxininduced prostaglandin release and corpus luteum function in goats. Anim. Repr. Sci. 8:109-121.
14.
Harper, M.J.K. and Skarnes, R.C. The role of prostaglandin in endotoxin-induced fetal death. Adv. abortion and Biosciences 9:789-793 (1973).
MARCH 1990 VOL. 33 NO. 3
651
THE EFFECT OF ESCHERICHIA u ENDOTOXIN ON LUTEAL FUNCTION IN HOLSTEIN HEIFERS R.O. Gilbert,' W.T.K.
Bosu and A.T. Peter
Department of Medical Sciences, School of Veterinary Medicine University of Wisconsin-Madison, Madison, WI 53706 Received
for publication: ~~~~ 30, 1989 Accepted: December 17, 1989 ABSTRACT
This study was undertaken to elucidate the possible role of endotcxin in mediating premature luteolysis in the well- documented phenomenon of short estrous cycles in postpartum dairy cows. Four groups of Holstein heifers (n = 4 to 6 each) received either intrau.terine infusion of sterile culture medium (Group I); intrauterine infusion of Escherichia coli (E_ &) endotoxin (5 pg/kg) in sterile culture medium (Group II): intrauterine administration of 10 ml of a 24-h culture of a strain of E_ coli isolated from the uterus of a cow with metritis (approximatelycolony forming units/ml; Group III): or intravenous administration of E. coli endotoxin (5 pg/kg; Group IV) on Day 7-9 of the estrous cycle. Blood samples were collected every 48 h during the pretreatment estrous cycle and up to the administration of the experi.mental treatment, thereafter 4-h samples were collected for 5 d. Sample collection was then performed every 48 h for the remainder of the treatment cycle and the post treatment cycle. Serum concentrations of progesterone and plasma concentrations of 15-keto-13,14-dihydroprostaglandin F?, (PGFM) were determined by radiolmmunoassay. Intrauterine infusion of endotoxin had no effect on the cycle length or on hormone concentrations, while infusion of viable E_ coli organisms tended to shorten the estrous cycle. Intravenous administration of endotoxin produced a sharp increase in both progesterone and PGFM concentrations, followed by a transient decrease in progesterone concentrations. Cycle length remained unchanged.. It was concluded that the intact endometrium prevents the uptake of endotoxin although pathogenic E_ coli organisms may disrupt the endometrial integrity sufficiently to It is shorten the estrous cycle by premature luteolysis. postulated that intravenous administration of endotoxin influences luteaIL function by the activation of the arachidonic acid cascade, by a direct effect on the corpus luteum, or via other mediators. Key words:
corpus
luteum, endotoxin,
progesterone
This project was supported in part by funds from Acknowledgments: and Life the IJniversity of Wisconsin, College of Agriculture Sciences Project No. 2927, and in part by funds from the University of Wisconsin Graduate School. NYS College of 'Present address: University, Ithaca NY 14853-6401.
MARCH
1990 VOL.
33 NO. 3
Veterinary
Medicine,
Cornell
645
THERIOGENOLOGY
INTRODUCTION This experiment was conducted to clarify the possible role of endotoxin in mediating premature luteolysis in the well-documented phenomenon of short estrous cycles in postpartum dairy cows (1). infection of the uterus by gram negative Persistent puerperal organisms, resulting in endotoxin release, might be expected to result in PGF,, release as reflected by elevated concentrations of PGFM (2,3). Release of PGF,,, it was hypothesized, could result in the premature demise of the corpus luteum, with a shortening of the The aim diestrous period and therefore the interestrous interval. intrauterine the effect of trial was to monitor of this administration of Escherichia coli organisms or E. coli endotoxin, endotoxin on clinical administration of intravenous or of parameters such as cycle length and endocrine profiles in Holstein heifers. MATERIALS
AND METHODS
heifers (n = 4 to 6 each) Four groups of Holstein approximately 18 mo old and weighing 400 to 500 kg were used in They were housed in stanchions in a barn at the this trial. of the School of Veterinary Instructional Facility Charmany Medicine in Madison, Wisconsin, where the experiment was completed within a 2-mo period during winter, and fed alfalfa hay and clean Their estrous cycles were monitored by careful water ad libitum. vaginal inspection for vulvar swelling or flaccidity, daily vocalization or behavior, and discharges or changes in retrospectively confirmed by comparison with progesterone profiles. Rectal examination was avoided since this procedure has been associated with increased plasma concentrations of PGFM (4). At least one complete estrous cycle was observed prior to treatment. During the pretreatment cycle, blood samples were collected every 48 h into plain and heparin-containing evacuated tubes. The samples were stored on ice, separated by centrifugation within 30 min of collection and the serum and plasma samples were frozen at 20°C until assayed. During the treatment cycle, on Day 7, 8 or 9 of the estrous to cycle, when the corpus luteum is known to be susceptible prostaglandin-induced luteolysis (5), the heifers received one of the following treatments: intrauterine infusion of 10 ml of sterile peptone water (Group I); intrauterine infusion of E. coli endotoxin (088:B5, Difco Laboratories, Detroit, MI) at 5 pg/kg in 10 ml sterile peptone water (Group II): intrauterine infusion of 10 ml of a 24 h culture in peptone water of a strain of E. coli isolated from the uterus of a cow with purulent endometritis (approximately 109 colony forming units/ml (Group III): or intravenous administration of 5 pg/kg of &_ coli endotoxin in 5 ml sterile saline. During the treatment cycle, blood was collected as above every 48 h until the day of treatment, thereafter samples were collected every 4 h for 5 d. During this period the heifers were carefully observed for clinical symptoms, and temperature, pulse rate and respiratory rate were recorded every 4 h. For the rest
MARCH 1990 VOL. 33 NO. 3
THERIOGENOLOGY
of the treatment cycle and the post-treatment again collected every 48 h.
cycle,
samples were
Serum progesterone and plasma PGFM concentrations determined by radioimmunoassays elsewhere as described Differences in cycle lengths or hormone concentrations determined within heifers by means of a paired t-test.
were (3). were
RESULTS Heifers in Group I showed a scant, transient, clear mucoid vaginal discharge which commenced 20 to 30 min after treatment and disappeared within 4 h. Group II heifers showed similar signs, with a slightly more copious discharge persisting for 4 to 6 h. Group III heifers had a mucopurulent discharge which cleared up within 4 to 8 h. None of the heifers in Group I, II or III showed any signs of systemic illness. Heifers in Group IV, on the other hand, showed an immediate febrile response, with peak temperatures (39.4 to 4O.l'C) being recorded 8 to 16 h after the administration of endotoxin. By 32 h following endotoxin administration, all animals were afebrile. Tachycardia and tachypnea persisted for at least 3 d, and for 5 d in two heifers that became recumbent. All of the heifers in this group showed severe ptyalism, cyanosis and diarrhea, and had cold extremities for the first 12 to 24 h after treatment. In spite of the intravenous route of endotoxin administration, all the animals in this group developed a clear to amber-colored mucoid vaginal discharge. No fatalities occurred. The length of the estrous cycle was altered only in Group III (intrauterine E. coli), where 3 of 4 heifers had shortened cycles (P < 0.10). No alterations were observed in the length of the posttreatment cycle.
Table
I.. Estrous
cycle length in days Group I
n
5
(Mean + SEM)
Group II
5
Group III
4
Group
IV
6
Pretreatment cycle
21.2kO.74
21.040.63
21.5rfr0.63
22.022.51
Treatment cycle
21.2&l-17
20.2+I.a3
I7.o_ti.a3
22.8+2.60
alterations in profiles of NO concentration were noted in Group I or
MARCH 1990 VOL. 33 NO. 3
progesterone In Group II.
or PGFM III, the
647
THERIOGENOLOGY
16
Progesterone hg/ml) ,O7
Progesterone hg/ml)
25
6
0
,I
Day of Cycle
Day of Cycle
Fig 1. Mean serum progesterone concentrations for six heifers injected intravenously with endotoxin on Day 9 of the estrous cycle.
10
Progesterone (ng/ml)
Fig 2. Serum progesterone concentrations for each heifers the six of injected intravenously with endotoxin on Day 9 of the estrous cycle.
PGFM (pg/ml) ,OOU
6-
6-
rlnoot
2-A-. 0
0
5
10
15
20
25
30
Day of Cycle for Fig 3. Progesteroneprofile Heifer 162 during treatmentcycle, showing baseline progesterone after endotoxin administration, followed by ovulation on Day 21.
648
I
‘j , 0
I
/
14
2 l-louts
afkr IV ‘endo~oxin l2
PGFM Fig 4. Plasma concentrations in the receiving six heifers endotoxin intravenous injection.
MARCH
1990 VOL.
33 NO. 3
THERIOGENOLOGY
luteal phase (defined here as the period during which the serum progesterone concentration exceeded 1 ng/ml) was shortened from 14.5 + 0.86 days to 10.25 + 1.92 days (P < 0.10). In Group IV, the plasma progesterone concentration increased markedly 4 h after intravenous administration of endotoxin in all six heifers (P < 0.01; Figures 1 and 2). This was followed by a significant decrease 12 to 28 h after endotoxin administration. In five heifers luteal function was regained after this time and In the remaining heifer (Figure the cycle length was unaffected. 3) serum progesterone concentrations remained near basal levels (CO.5 ng/ml), followed by estrus and ovulation at the expected time. The cycle was thus not shortened. A PGFM peak was recorded in Group IV heifers at 4 h after intravenous administration of endotoxin (P < 0.0025; Figure 4). DISCUSSION A failure to evoke endocrinological changes or to affect the cycle length of heifers receiving intrauterine endotoxin probably reflects a failure to absorb endotoxin from the uterus by the Failure to absorb endotoxin has also been normal, cyclic cow. reportled in mares (6) and ewes (7). In sows (8), but not in ewes (7), endotoxin is absorbed from the uterus during the puerperium. Puerperal absorption of endotoxin from the bovine uterus has not been r'eported. given Tne shortening of the estrous cycle in heifers intrauterine E. coli (Group III) is compatible with endometrial irritation (9). The timing of luteolysis indicates that PGF,, release occurs during the stage of endometrial regeneration, as This conclusion is speculative suggested by Seguin et al. (9) * since we have no direct evidence of endometrial damage by this treatment. The acute peak in serum progesterone concentration occurring 4 h after intravenous administration of endotoxin corresponded temporarily to the peak in PGFM concentration, but may reflect a concurrent or prior peak in the luteotrophic PGE, (lo), which was it may be the result of a direct not as,sayed. Alternatively, effect of the endotoxin on the corpus luteum, or it may be mediated in another, yet unknown fashion. concentration 12 to 28 h after The trough in progesterone endotoxin administration is ascribed to the luteolytic effect of the PGF,,. Except in one case (Heifer 162, Figure 3) this effect Prolonged or repeated exposure to endotoxin was only transient. in mediating abortion during early bovine may be significant Its source could be an extragenital infection (11). pregnancy. Abortion has been induced by experimental administration of E. coli endotoxin to swine (12) and Salmonella tvohimurium endotoxin to goats (13). Whether this effect worked directly on the fetus(es)
MARCH 1990VOL.
33 NO. 3
THERIOGENOLOGY
Endotoxinor was mediated by luteolysis was not investigated. induced abortion in mice can be prevented with indomethacin (14). Progesterone supplementation prevented abortion but not fetal death, suggesting effects of endotoxemia both on the corpus luteum and on the fetuses (14). Although it appears that endotoxemia may result in at absorption of endotoxin from the least transient luteolysis, involuting bovine uterus will have to be investigated to clarify its role in inducing premature luteolysis in the postpartum dairy cow. Such studies are in progress in our laboratory. REFERENCES 1.
Morrow, D.A., Roberts, S.J. and McEntee, K. Postpartum ovarian activity and involution of the uterus and cervix in dairy cattle. I. Ovarian activity. Cornell Vet =:173-190 (1969).
2.
Fredricksson, G., Kindahl, H. and Sandstedt, K. Intrauterine bacterial findings and release of PGFzU in the postpartum dairy cow. Zbl. Vet. Med. A. x:368-380 (1985).
3.
Peter, A.T. and Bosu, W.T.K. Effects of intrauterine infection on the function of the corpora lutea formed after the first postpartum ovulations in dairy cows. Theriogenology =:593-609 (1987).
4.
Alam, M.G.S. and Dobson,H. Effect of various veterinary procedures on plasma concentrations of cortisol, luteinising hormone and prostaglandin Fza metabolite in the cow. Veterinary Record m:7-10 (1986).
5.
Seguin, B., Momont, H. and Baumann, L. dinoprost tromethamine in experimental treating unobserved estrus in dairy cows. 90 (1985).
6.
Mollett, T.A., Elmore, R.G., Blanchard, T.L. and Berg, J.N. Effects of intrauterine infusion of Escherichia & endotoxin in anestrous and steroid treated pony mares. Theriogenology =:597-606 (1985).
7.
Elmore, R.G., Mollett, T.A., Berg, J.N. and Schmidt, D.A. Escherichia coli endotoxin absorption from the ewe's uterus and peritoneal cavity. Theriogenology =:841-847 (1983).
8.
Elmore, R-G., Martin, C.E. and Berg, J.N. Absorption of Escherichia coli endotoxin from the mammary glands and uteri of early postpartum sows and gilts. Theriogenology =:439445 (1978).
660
Cloprostenol and and field trials Bov. Pratt. =:89-
MARCH 1990 VOL. 33 NO. 3
THERIOGENOLOGY
9.
Luteolysis, Seguin, B.E., Morrow, D.A. and Louis, T.M. luteostasis and the effect of prostaglandin F,, in cows after endometrial irritation. Am. J. Vet. Res. %:57-61 (1974).
10.
Giminez, T. and Henricks, D.M. Prolongation of the luteal phase by prostaglandin Ez during the estrous cycle of the cow. A preliminary report. Theriogenology u:693-700 (1983).
11.
Roberts, S.J. Veterinary Obstetrics and Genital Diseases. Published by the author, Ithaca, NY, 1971, p. 116.
12.
Wrathall, A.E., Bailey, J. and Wells, D.E. Experimentally induced bacterial endotoxaemia and absorption in pigs. Br. Vet. J. m:225-230 (1978).
13.
Fredricksson, G., Kindahl, H. and Edqvist, L.-E. Endotoxininduced prostaglandin release and corpus luteum function in goats. Anim. Repr. Sci. 8:109-121.
14.
Harper, M.J.K. and Skarnes, R.C. The role of prostaglandin in endotoxin-induced fetal death. Adv. abortion and Biosciences 9:789-793 (1973).
MARCH 1990 VOL. 33 NO. 3
651