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Reproductive hormones associated with the ovarian cyst response to GnRH
THERIOGENOLOGY REPRODUCTIVE HORMONES ASSOCIATED WITH THE OVARIAN CYST RESPONSE TO GnRHa*b
D. J. Keslerc,
H. A. Garverick, R. G. Elmore, R. S. Youngquist and C. J. Bierschwal Departments of Dairy Husbandry and Veterinary Medicine and Surgery University of Missouri Columbia, Missouri 65201
Received
for Publication:
June 8, 1979
Abstract
Eighteen cows with ovarian cysts were administered 100 ug of GnRH and bled prior to treatment, at half hour intervals for 4 hours posttreatment and on days 1, 5 and 9 posttteatment. Blood plasma was anaRelyzed for estradiol-178, progesterone and LH by radioimmunoassay. sponse to treatment was recorded as positive if ovulation was detected within 30 days posttreatment. Fourteen cows (78%) initiated ovarian cycles by 30 days posttreatMean pretreatment concentrations of estradiol-175, progesterone ment. and LH and the GnRH induced LH release were not different for positive or no response cows. However, all seven cows that had pretreatment progesterone concentrations greater than 1.0 ng/ml had a positive response to treatment. Eight of the remaining eleven cows had a progesterone response (mean progesterone concentrations on days 5 and 9 posttreatment) greater than 1.0 ng/ml; seven had a positive response to treatment. In summary, most cows with ovarian cysts administered GnRH will initiate ovarian cycles within 30 days if: 1) pretreatment progesterone concentrations are greater than 1.0 ng/ml or 2) if progesterone response is greater than 1.0 ng/ml.
a b c
Journal Paper No. 8370, Missouri Agriculture Experiment Approved by the Director. University of Missouri. The authors express appreciation oratories for supplying GnRH.
to Dr. M. D. Brown, Abbott Lab-
Animal Genetics Laboratory, Department Present address: Science, University of Illinois, Urbana 61801.
AUGUST 1979 VOL. 12 NO. 2
Station,
of Animal
109
rHERIOGENOLOGY
Introduction Approximately 80% of the cows with ovarian cysts will reestablish ovarian cycles within a 30 day period following gonadotropin releasing hormone (GnRH) (1, 5, 15). Exogenous GnRH stimulates a luteinizing hormone (LH) release in cows with ovarian cysts (2, 7, 8, 12, 15). In most cows that respond to treatment, progesterone concentratiamin plasma are elevated five to nine days following GnRH (2, 7, 8, 15) due to luteinization of the cysts (11). Progesterone concentrations then decline prior to estrus which occurs about 18 to 23 days posttreatment (2, 7, 8, 15) Reproductive hormone concentrations in cows establishing ovarian cycles following GnRH as compared to those not establishing ovarian cycles have not been studied in detail. Therefore, the objective of this study was to evaluate pituitary and ovarian hormone secretions prior and following GnRH treatment for cows that established ovarian cycles as compared to those that did not.
Methods
and Materials
Fifteen Guernsey and 3 Holstein cows from the University of Missouri dairy herds were in the experiment. All cows were housed and managed as part of the milking herd which was milked twice daily. The cows were fed free-choice a balanced ration of silage and concentrate in outdoor bunks Diagnosis of ovarian cysts was made durand housed in free-stall barns. Clinical ing regular bi-weekly reproductive herd health examinations. diagnosis was based upon the finding of a single or multiple follicular structures on one or both ovaries of at least 2.5 cm in diamater in the absence of a corpus luteum (1, 14). All cows were administered a single 100 ug intramuscular injection of GnRH. Blood samples were collected via jugular venipuncture into heparinized vacutainers prior to treatment, at half hour intervals for 4 hours following treatment and 1, 5 and 9 days posttreatment. Ovaries were examined by rectal palpation the day following treatment and every 4 days thereafter until ovulation. Response to treatment was recorded cows as positive if ovulation was detected within 30 days posttreatment. not ovulating by 30 days posttreatment were classified as not responding. Following collection the blood was chilled in ice water until centrifugation at 10,000 x & for 10 minutes at 4 C. The plasma was stored in LH in plasma was quantified duplicate aliquots at -20 C until assayed. by double antibody radioimmunoassay as described by Niswender et al. (13). Procedures and validation for radioimmunoassay of progesterone and estradial-17B in plasma are described by Cantley et al. (2) and Kesler et al. Statistics included analysis of variance (16), cor(lo), respectively. relation (16) and chi square analysis (6).
Results and Discussion Similar to other reports (1, 5), fourteen of 18 cows (78%) administered GnRH ovulated and initiated ovarian cycles before 30 days
110
AUGUST
1979 VOL. 12 NO. 2
THERIOGENOLOGY posttreatment. There was no difference (P>.lO) in mean pretreatment concentrations of LH, progesterone and estradiol-17B in plasma between cows with a positive response and cows that did not respond to GnRH treatment (Table I). Cantley et al. (2) however, reported higher mean pretreatment concentrations of progesterone and estradiol in cows that responded to GnRH treatment as compared to the cows that did not respond. In this study, although mean concentrations were not different (P>.lO), all seven cows that had pretreatment progesterone concentrations greater than 1.0 ng/ml had a positive response to treatment.
TABLE I.
SUMMARY OF AVERAGE CONCENTRATIONS OF PRETREATMENT HORMONES, PEAK LH, CHANGE IN ESTRADIOL-17B AND PROGESTERONE RESPONSE FOR GnRH TREATED COWS WITH OVARIAN CYSTS BY RESPONSE (NO RESPONSE OR POSITIVE RESPONSE). Positive
Item No. of cows Pretreatment Progesterone Estradiol-17B LH Peak LH Change in estradiol-17Bb Progesterone response cyd a b
' d
Mean + standard
Response
No Response
14 (78%) 1.0 4.3 1.2 9.1 -1.3 1.8
* ? f f & &
4 (22%)
0.2a 0.7 0.2 1.7 0.7 0.2
0.4 4.4 1.1 10.0 -1.2 0.7
+_ 0.2 i: 1.8 i- 0.4 j: 4.8 ir 0.8 + 0.5
error.
Pretreatment concentrations 24 hours posttreatment. Mean concentrations
of estradiol-17B
of progesterone
The two means are significantly
minus concentrations
on days 5 and 9 posttreatment.
different
at .05 level.
The GnRH induced LH peak was not different for cows that responded to treatment as compared to those that did not respond (Table I). Although the mean GnRH induced LH release was 9 to 10 ng/ml, releases of The magnitude of the GnRH 3 to 5 ng/ml were observed in both groups. induced release of LH was correlated (r = .62; p' .Ol) with time to peak Howresponse as reported by Zolman et al. (19) in diestrous heifers. ever, there was no relationship between systemic concentrations of progesterone prior to treatment and the GnRH induced release of LH (r = .13; X,.10). Furthermore, the GnRH induced release of LH did not increase with increasing pretreatment concentrations of endogenous estradiol-17B in plasma (r= -.44; P>.O5) as was reported by Zolman et al. (18) and Kesler et al. (10) in heifers and early postpartum cows, respectively. Systemic concentrations of estradiol-17B tended to decline (PC .lO) by 24 hours following treatment for cows responding or not responding to Mean pretreatment concentrations of estradiol-17B were 4.3 f treatment. .6 pg/ml and at 24 hours following treatment concentrations were 3.0 + .4
AUGUST 1979 VOL. 12 NO. 2
111
THERIOGENOLOGY Estradiol-170 concentrations in plasma declined more within 24 pghl. hours posttreatment in cows with lower systemic progesterone concentrations than cows with higher progesterone concentrations in plasma (r = .36; pc.05). This decline was also reported by other investigators (2, 4 ) for cows that had a positive or no response to GnRH treatment. However, in the study by Kesler et al. (8), there was no decline in estradiol-17B concentrations for untreated cows. This decline in estradiol concentrations may be due to luteinization of ovarian cysts and the conversion of steroidogenic activity of granulosa and theca cells from estradiol to progesterone synthesis (17). Progesterone response (mean progesterone concentrations on days 5 and 9 posttreatment) was higher (PC .05) for cows that had a positive response to treatment as compared-to cows that did not respond (Table I). Furthermore, all positive response cows with pretreatment concentrations of progesterone less than 1.0 ng/ml had a progesterone response greater than 1.0 ng/ml. However, only 1 of 4 (25%) cows that did not respond to treatment with pretreatment concentrations of progesterone less than 1.0 ng/ml had a progesterone response greater than 1.0 ng/ml. Cows with pretreatment progesterone concentrations greater than 1.0 ng/ml tended (2~ .lO) to have fewer days from treatment to estrus than cows with pretreatment progesterone concentrations less than 1.0 ng/ml (15.6 * 2.3 vs. 21.0 f 1.3 days). Pretreatment concentrations of progesterone in plasma were correlated (r = -.68; p< .Ol) with the interval from treatment to estrus.
General Discussion Exogenous GnRH has been demonstrated to stimulate an LH release in cows with ovarian cysts by several investigators (2, 7, 8, 12, 15). Although physiological concentrations of progesterone do not appear to influence the GnRH induced release of LH (3), the GnRH induced LH release is enhanced by elevated concentrations of estradiol (10, 18). In this study, however, estradiol concentrations were not positively correlated with the GnRH induced LH release. Therefore, the hypothalamus and/or pituitary of cows with ovarian cysts may not be responsive in releasing pituitary LH to elevated concentration of estradiol. Approximately 20% of the cows do not reestablish ovarian cycles following GnRH treatment (1, 5). Since the GnRH induced LH release is not different between cows with a positive or no response, cystic structures in cows not establishing ovarian cycles following treatment probably are not responsive to the GnRH induced LH release due to degeneration of theta interna and granulosa cell layers (17). In cows that respond to treatment, the exogenous GnRH induced LH release stimulates luteinization of ovarian cysts (11). Estradiol-17S Five to 9 days posttreatment, concentrations decline within 24 hours. progesterone concentrations are elevated to concentrations similar to Prior to the subsequent estrus, which is about 18 to an estrous cycle. Therefore, 23 days posttreatment, progesterone concentrations decline. ovarian cycles were reestablished when cows regained reproductive hormone
112
AUGUST
1979 VOL. 12 NO. 2
THERIOGENOLOGY concentrations
similar
to an estrous
cycle.
Although luteinization of ovarian cysts occurs in untreated cows (9) and in some cows not responding to GnRH treatment (one cow in the present study), ovarian cycles were not reestablished unless cows fully regained reproductive hormone concentrations similar to an estrous cycle. In cows with elevated concentrations of progesterone, some luteinization has apparently occurred (11). The GnRH induced release of LH in cows with elevated concentrations of progesterone, therefore, probably stimulates further luteinization rather than initiating luteinization and hence the interval from treatment to estrus is reduced.
References (1)
Bierschwal, C. J., H. A. Garverick, T. C. Cantley and M. D. Brown. with ovarian cysts to GnRH.
(2)
Cantley, T. C., H. A. Garverick, C. J. Bierschwal, C. E. Martin and Hormonal response of dairy cows with ovarian R. S. Youngquist. cysts to GnRH. J. Anim. Sci. -41:1666 (1975).
(3)
Cumming, I. A., J. M. Buckmaster, J. C. Cerini, M. E. Cerini, W. A. Effect of progesterone Charnley, J. K. Findlay ad J. R. Goding. on the release of luteinizing hormone induced by a synthetic gonadotropin-releasing factor in the ewe. Neuroendocrinol. -10: 338 (1972).
(4)
The Edquist, L. E., L. Ekman, B. Gustafsson and 3. 0. Lindell. clinical and hormonal effect of luteinizing hormone-releasing hormone (LH-RH) in cows with cystic ovaries. Nord. Vet. Med. -26:556 (1974).
(5)
Elmore, R. G., C. J. Bierschwal, R. S. Youngquist, T. C. Cantley, D. J. Kesler and H. A. Garverick. Clinical responses of dairy cows with ovarian cysts following treatment with 10,000 IU HCG or 100 mcg GnRH. Vet. Med./Sm. Anim. Clinician. -70:1346 (1975).
(6)
Fisher, R. A. and F. Yates. agricultural and medical ing Co., NY (1963).
(7)
Garverick, H. A., D. J. Kesler, T. C. Cantley, R. G. Elmore, R. S. Youngquist and C. J. Bierschwal. Hormone response of dairy cows with ovarian cysts after treatment with HCG or GnRH. Theriogenology 6:413 (1976).
(8)
Kesler, D. J., H. A. Garverick, A. B. Caudle, C. J. Bierschwal, Clinical and endocrine reR. G. Elmore and R. S. Youngquist. sponses of dairy cows with ovarian cysts to GnRH and PGF2cl. J. Anim. Sci. -46:719 (1978).
(9)
Kesler, D. J., H. A. Garverick, A. B. Caudle, R. G. Elmore, R. S. Reproductive hormone and Youngquist and C. J. Bierschwal.
AUGUST
1979 VOL. 12 NO. 2
C. E. Martin, R. S. Youngquist, Clinical response of dairy cows J. Anim. Sci. 41:1660 (1975).
Statistical tables for biological, Hafner Publishresearch. (6th ed.).
113
THERIOGENOLOCY ovarian changes in cows with ovarian mitted). (1979).
cysts.
J. Dairy Sci. (Sub-
(10)
Kesler, D. J., H. A. Garverick, R. S. Youngquist, R. G. Elmore and C. J. Bierschwal. Effect of days postpartum and endogenous reproductive hormones on GnRH-induced LH release in dairy cows. J. Anim. Sci. -45~797 (1977).
(11)
Kesler, D. J., R. G. Elmore, R. S. Youngquist, E. M. Brown, H. A. Garverick and C. J. Bierschwal. Ovarian morphology in dairy J. Anim. cows with ovarian cysts following treatment with GnRH. Sci. -45 (Suppl. I):176 (Abstr.) (1977).
(12)
Kittok, R. J., J. H. Britt and E. M. Convey. Endocrine response after GnRH in luteal phase cows and cows with ovarian follicular cysts. J. Anim. Sci. x:985 (1973).
(13)
Niswender, G. O., L. E. Reichert, A. B. Midgley and A. V. Nalbandov. Radioimmunoassay of bovine and ovine luteinizing hormone. Endocrinol. -84:1166 (1969).
(14)
Roberts, S. J. Veterinary Obstetrics and Genital Diseases Published by the author, Ithaca, NY (1971).
(15)
Seguin, B. E., E. M. Convey and W. D. Oxender. Effect of gonadotropin-releasing hormone and human chorionic gonadotropin on cows with ovarian follicular cysts, Am. J. Vet. Res. -37:153 (1976).
(16)
Statistical Snedecor, G. W. and W. G. Cochran. The Iowa State Univ. Press, Ames (1967).
(17)
Yamaueki, M. and S. Inui. Studies on ovarian cyst in the cow. II. Endocrinological and histological studies on the correlation between the ovarian cyst and the symptom. Jpn. J. Vet. Sci. -16: 27 (1954).
(18)
Relationship between the Zolman, J., E. M. Convey and J. H. Britt. luteinizing hormone response to gonadotropin releasing hormone and endogenous steroids. 3. Anim. Sci. -39:355 (1974).
(19)
Release of Zolman, J., E. M. Convey, J. H. Britt and H. D. Hafs. bovine luteinizing hormone by purified porcine and synthetic Proc. Sot. Biol. Med. -142:189 gonadotropin releasing hormone. (1973).
114
AUGUST
Methods.
(2nd ed.).
(6th ed.).
1979 VOL.12N0.2
D. J. Keslerc,
H. A. Garverick, R. G. Elmore, R. S. Youngquist and C. J. Bierschwal Departments of Dairy Husbandry and Veterinary Medicine and Surgery University of Missouri Columbia, Missouri 65201
Received
for Publication:
June 8, 1979
Abstract
Eighteen cows with ovarian cysts were administered 100 ug of GnRH and bled prior to treatment, at half hour intervals for 4 hours posttreatment and on days 1, 5 and 9 posttteatment. Blood plasma was anaRelyzed for estradiol-178, progesterone and LH by radioimmunoassay. sponse to treatment was recorded as positive if ovulation was detected within 30 days posttreatment. Fourteen cows (78%) initiated ovarian cycles by 30 days posttreatMean pretreatment concentrations of estradiol-175, progesterone ment. and LH and the GnRH induced LH release were not different for positive or no response cows. However, all seven cows that had pretreatment progesterone concentrations greater than 1.0 ng/ml had a positive response to treatment. Eight of the remaining eleven cows had a progesterone response (mean progesterone concentrations on days 5 and 9 posttreatment) greater than 1.0 ng/ml; seven had a positive response to treatment. In summary, most cows with ovarian cysts administered GnRH will initiate ovarian cycles within 30 days if: 1) pretreatment progesterone concentrations are greater than 1.0 ng/ml or 2) if progesterone response is greater than 1.0 ng/ml.
a b c
Journal Paper No. 8370, Missouri Agriculture Experiment Approved by the Director. University of Missouri. The authors express appreciation oratories for supplying GnRH.
to Dr. M. D. Brown, Abbott Lab-
Animal Genetics Laboratory, Department Present address: Science, University of Illinois, Urbana 61801.
AUGUST 1979 VOL. 12 NO. 2
Station,
of Animal
109
rHERIOGENOLOGY
Introduction Approximately 80% of the cows with ovarian cysts will reestablish ovarian cycles within a 30 day period following gonadotropin releasing hormone (GnRH) (1, 5, 15). Exogenous GnRH stimulates a luteinizing hormone (LH) release in cows with ovarian cysts (2, 7, 8, 12, 15). In most cows that respond to treatment, progesterone concentratiamin plasma are elevated five to nine days following GnRH (2, 7, 8, 15) due to luteinization of the cysts (11). Progesterone concentrations then decline prior to estrus which occurs about 18 to 23 days posttreatment (2, 7, 8, 15) Reproductive hormone concentrations in cows establishing ovarian cycles following GnRH as compared to those not establishing ovarian cycles have not been studied in detail. Therefore, the objective of this study was to evaluate pituitary and ovarian hormone secretions prior and following GnRH treatment for cows that established ovarian cycles as compared to those that did not.
Methods
and Materials
Fifteen Guernsey and 3 Holstein cows from the University of Missouri dairy herds were in the experiment. All cows were housed and managed as part of the milking herd which was milked twice daily. The cows were fed free-choice a balanced ration of silage and concentrate in outdoor bunks Diagnosis of ovarian cysts was made durand housed in free-stall barns. Clinical ing regular bi-weekly reproductive herd health examinations. diagnosis was based upon the finding of a single or multiple follicular structures on one or both ovaries of at least 2.5 cm in diamater in the absence of a corpus luteum (1, 14). All cows were administered a single 100 ug intramuscular injection of GnRH. Blood samples were collected via jugular venipuncture into heparinized vacutainers prior to treatment, at half hour intervals for 4 hours following treatment and 1, 5 and 9 days posttreatment. Ovaries were examined by rectal palpation the day following treatment and every 4 days thereafter until ovulation. Response to treatment was recorded cows as positive if ovulation was detected within 30 days posttreatment. not ovulating by 30 days posttreatment were classified as not responding. Following collection the blood was chilled in ice water until centrifugation at 10,000 x & for 10 minutes at 4 C. The plasma was stored in LH in plasma was quantified duplicate aliquots at -20 C until assayed. by double antibody radioimmunoassay as described by Niswender et al. (13). Procedures and validation for radioimmunoassay of progesterone and estradial-17B in plasma are described by Cantley et al. (2) and Kesler et al. Statistics included analysis of variance (16), cor(lo), respectively. relation (16) and chi square analysis (6).
Results and Discussion Similar to other reports (1, 5), fourteen of 18 cows (78%) administered GnRH ovulated and initiated ovarian cycles before 30 days
110
AUGUST
1979 VOL. 12 NO. 2
THERIOGENOLOGY posttreatment. There was no difference (P>.lO) in mean pretreatment concentrations of LH, progesterone and estradiol-17B in plasma between cows with a positive response and cows that did not respond to GnRH treatment (Table I). Cantley et al. (2) however, reported higher mean pretreatment concentrations of progesterone and estradiol in cows that responded to GnRH treatment as compared to the cows that did not respond. In this study, although mean concentrations were not different (P>.lO), all seven cows that had pretreatment progesterone concentrations greater than 1.0 ng/ml had a positive response to treatment.
TABLE I.
SUMMARY OF AVERAGE CONCENTRATIONS OF PRETREATMENT HORMONES, PEAK LH, CHANGE IN ESTRADIOL-17B AND PROGESTERONE RESPONSE FOR GnRH TREATED COWS WITH OVARIAN CYSTS BY RESPONSE (NO RESPONSE OR POSITIVE RESPONSE). Positive
Item No. of cows Pretreatment Progesterone Estradiol-17B LH Peak LH Change in estradiol-17Bb Progesterone response cyd a b
' d
Mean + standard
Response
No Response
14 (78%) 1.0 4.3 1.2 9.1 -1.3 1.8
* ? f f & &
4 (22%)
0.2a 0.7 0.2 1.7 0.7 0.2
0.4 4.4 1.1 10.0 -1.2 0.7
+_ 0.2 i: 1.8 i- 0.4 j: 4.8 ir 0.8 + 0.5
error.
Pretreatment concentrations 24 hours posttreatment. Mean concentrations
of estradiol-17B
of progesterone
The two means are significantly
minus concentrations
on days 5 and 9 posttreatment.
different
at .05 level.
The GnRH induced LH peak was not different for cows that responded to treatment as compared to those that did not respond (Table I). Although the mean GnRH induced LH release was 9 to 10 ng/ml, releases of The magnitude of the GnRH 3 to 5 ng/ml were observed in both groups. induced release of LH was correlated (r = .62; p' .Ol) with time to peak Howresponse as reported by Zolman et al. (19) in diestrous heifers. ever, there was no relationship between systemic concentrations of progesterone prior to treatment and the GnRH induced release of LH (r = .13; X,.10). Furthermore, the GnRH induced release of LH did not increase with increasing pretreatment concentrations of endogenous estradiol-17B in plasma (r= -.44; P>.O5) as was reported by Zolman et al. (18) and Kesler et al. (10) in heifers and early postpartum cows, respectively. Systemic concentrations of estradiol-17B tended to decline (PC .lO) by 24 hours following treatment for cows responding or not responding to Mean pretreatment concentrations of estradiol-17B were 4.3 f treatment. .6 pg/ml and at 24 hours following treatment concentrations were 3.0 + .4
AUGUST 1979 VOL. 12 NO. 2
111
THERIOGENOLOGY Estradiol-170 concentrations in plasma declined more within 24 pghl. hours posttreatment in cows with lower systemic progesterone concentrations than cows with higher progesterone concentrations in plasma (r = .36; pc.05). This decline was also reported by other investigators (2, 4 ) for cows that had a positive or no response to GnRH treatment. However, in the study by Kesler et al. (8), there was no decline in estradiol-17B concentrations for untreated cows. This decline in estradiol concentrations may be due to luteinization of ovarian cysts and the conversion of steroidogenic activity of granulosa and theca cells from estradiol to progesterone synthesis (17). Progesterone response (mean progesterone concentrations on days 5 and 9 posttreatment) was higher (PC .05) for cows that had a positive response to treatment as compared-to cows that did not respond (Table I). Furthermore, all positive response cows with pretreatment concentrations of progesterone less than 1.0 ng/ml had a progesterone response greater than 1.0 ng/ml. However, only 1 of 4 (25%) cows that did not respond to treatment with pretreatment concentrations of progesterone less than 1.0 ng/ml had a progesterone response greater than 1.0 ng/ml. Cows with pretreatment progesterone concentrations greater than 1.0 ng/ml tended (2~ .lO) to have fewer days from treatment to estrus than cows with pretreatment progesterone concentrations less than 1.0 ng/ml (15.6 * 2.3 vs. 21.0 f 1.3 days). Pretreatment concentrations of progesterone in plasma were correlated (r = -.68; p< .Ol) with the interval from treatment to estrus.
General Discussion Exogenous GnRH has been demonstrated to stimulate an LH release in cows with ovarian cysts by several investigators (2, 7, 8, 12, 15). Although physiological concentrations of progesterone do not appear to influence the GnRH induced release of LH (3), the GnRH induced LH release is enhanced by elevated concentrations of estradiol (10, 18). In this study, however, estradiol concentrations were not positively correlated with the GnRH induced LH release. Therefore, the hypothalamus and/or pituitary of cows with ovarian cysts may not be responsive in releasing pituitary LH to elevated concentration of estradiol. Approximately 20% of the cows do not reestablish ovarian cycles following GnRH treatment (1, 5). Since the GnRH induced LH release is not different between cows with a positive or no response, cystic structures in cows not establishing ovarian cycles following treatment probably are not responsive to the GnRH induced LH release due to degeneration of theta interna and granulosa cell layers (17). In cows that respond to treatment, the exogenous GnRH induced LH release stimulates luteinization of ovarian cysts (11). Estradiol-17S Five to 9 days posttreatment, concentrations decline within 24 hours. progesterone concentrations are elevated to concentrations similar to Prior to the subsequent estrus, which is about 18 to an estrous cycle. Therefore, 23 days posttreatment, progesterone concentrations decline. ovarian cycles were reestablished when cows regained reproductive hormone
112
AUGUST
1979 VOL. 12 NO. 2
THERIOGENOLOGY concentrations
similar
to an estrous
cycle.
Although luteinization of ovarian cysts occurs in untreated cows (9) and in some cows not responding to GnRH treatment (one cow in the present study), ovarian cycles were not reestablished unless cows fully regained reproductive hormone concentrations similar to an estrous cycle. In cows with elevated concentrations of progesterone, some luteinization has apparently occurred (11). The GnRH induced release of LH in cows with elevated concentrations of progesterone, therefore, probably stimulates further luteinization rather than initiating luteinization and hence the interval from treatment to estrus is reduced.
References (1)
Bierschwal, C. J., H. A. Garverick, T. C. Cantley and M. D. Brown. with ovarian cysts to GnRH.
(2)
Cantley, T. C., H. A. Garverick, C. J. Bierschwal, C. E. Martin and Hormonal response of dairy cows with ovarian R. S. Youngquist. cysts to GnRH. J. Anim. Sci. -41:1666 (1975).
(3)
Cumming, I. A., J. M. Buckmaster, J. C. Cerini, M. E. Cerini, W. A. Effect of progesterone Charnley, J. K. Findlay ad J. R. Goding. on the release of luteinizing hormone induced by a synthetic gonadotropin-releasing factor in the ewe. Neuroendocrinol. -10: 338 (1972).
(4)
The Edquist, L. E., L. Ekman, B. Gustafsson and 3. 0. Lindell. clinical and hormonal effect of luteinizing hormone-releasing hormone (LH-RH) in cows with cystic ovaries. Nord. Vet. Med. -26:556 (1974).
(5)
Elmore, R. G., C. J. Bierschwal, R. S. Youngquist, T. C. Cantley, D. J. Kesler and H. A. Garverick. Clinical responses of dairy cows with ovarian cysts following treatment with 10,000 IU HCG or 100 mcg GnRH. Vet. Med./Sm. Anim. Clinician. -70:1346 (1975).
(6)
Fisher, R. A. and F. Yates. agricultural and medical ing Co., NY (1963).
(7)
Garverick, H. A., D. J. Kesler, T. C. Cantley, R. G. Elmore, R. S. Youngquist and C. J. Bierschwal. Hormone response of dairy cows with ovarian cysts after treatment with HCG or GnRH. Theriogenology 6:413 (1976).
(8)
Kesler, D. J., H. A. Garverick, A. B. Caudle, C. J. Bierschwal, Clinical and endocrine reR. G. Elmore and R. S. Youngquist. sponses of dairy cows with ovarian cysts to GnRH and PGF2cl. J. Anim. Sci. -46:719 (1978).
(9)
Kesler, D. J., H. A. Garverick, A. B. Caudle, R. G. Elmore, R. S. Reproductive hormone and Youngquist and C. J. Bierschwal.
AUGUST
1979 VOL. 12 NO. 2
C. E. Martin, R. S. Youngquist, Clinical response of dairy cows J. Anim. Sci. 41:1660 (1975).
Statistical tables for biological, Hafner Publishresearch. (6th ed.).
113
THERIOGENOLOCY ovarian changes in cows with ovarian mitted). (1979).
cysts.
J. Dairy Sci. (Sub-
(10)
Kesler, D. J., H. A. Garverick, R. S. Youngquist, R. G. Elmore and C. J. Bierschwal. Effect of days postpartum and endogenous reproductive hormones on GnRH-induced LH release in dairy cows. J. Anim. Sci. -45~797 (1977).
(11)
Kesler, D. J., R. G. Elmore, R. S. Youngquist, E. M. Brown, H. A. Garverick and C. J. Bierschwal. Ovarian morphology in dairy J. Anim. cows with ovarian cysts following treatment with GnRH. Sci. -45 (Suppl. I):176 (Abstr.) (1977).
(12)
Kittok, R. J., J. H. Britt and E. M. Convey. Endocrine response after GnRH in luteal phase cows and cows with ovarian follicular cysts. J. Anim. Sci. x:985 (1973).
(13)
Niswender, G. O., L. E. Reichert, A. B. Midgley and A. V. Nalbandov. Radioimmunoassay of bovine and ovine luteinizing hormone. Endocrinol. -84:1166 (1969).
(14)
Roberts, S. J. Veterinary Obstetrics and Genital Diseases Published by the author, Ithaca, NY (1971).
(15)
Seguin, B. E., E. M. Convey and W. D. Oxender. Effect of gonadotropin-releasing hormone and human chorionic gonadotropin on cows with ovarian follicular cysts, Am. J. Vet. Res. -37:153 (1976).
(16)
Statistical Snedecor, G. W. and W. G. Cochran. The Iowa State Univ. Press, Ames (1967).
(17)
Yamaueki, M. and S. Inui. Studies on ovarian cyst in the cow. II. Endocrinological and histological studies on the correlation between the ovarian cyst and the symptom. Jpn. J. Vet. Sci. -16: 27 (1954).
(18)
Relationship between the Zolman, J., E. M. Convey and J. H. Britt. luteinizing hormone response to gonadotropin releasing hormone and endogenous steroids. 3. Anim. Sci. -39:355 (1974).
(19)
Release of Zolman, J., E. M. Convey, J. H. Britt and H. D. Hafs. bovine luteinizing hormone by purified porcine and synthetic Proc. Sot. Biol. Med. -142:189 gonadotropin releasing hormone. (1973).
114
AUGUST
Methods.
(2nd ed.).
(6th ed.).
1979 VOL.12N0.2