The effect of treatment with a gonadotrophin releasing hormone on the fertility of beef cows

1996 ◽  
Vol 1996 ◽  
pp. 67-67
Author(s):  
Duncan Pullar ◽  
Anthony Wrathall

Use of the gonadotrophin releasing hormone (GnRH) analogue, buserelin has been shown to be effective reducing embryo mortality, by a luteoprotective mechanism, in reproductively normal dairy cows. Drew and Peters, (1991) increased mean pregnancy rates to AI from 53.4 to 65.4% in dairy herds by a buserelin treatment, given 10-12 post service. The objective of this experiment was to determine whether buserelin can also have a beneficial effect on pregnancy rate, in normal and known problem suckler cows.Seventy-eight Hereford x Friesian cows (from 0-4 parities) were used. Forty were considered reproductively normal ('normal' cows) having calved each year from their first season and currently with a 10 week old calf at-foot; while 38 had a history of reproductive disorders ('suspect' cows) and had not calved in the previous 15 months (May 1994 to July 1995).

1996 ◽  
Vol 1996 ◽  
pp. 67-67
Author(s):  
Duncan Pullar ◽  
Anthony Wrathall

Use of the gonadotrophin releasing hormone (GnRH) analogue, buserelin has been shown to be effective reducing embryo mortality, by a luteoprotective mechanism, in reproductively normal dairy cows. Drew and Peters, (1991) increased mean pregnancy rates to AI from 53.4 to 65.4% in dairy herds by a buserelin treatment, given 10-12 post service. The objective of this experiment was to determine whether buserelin can also have a beneficial effect on pregnancy rate, in normal and known problem suckler cows.Seventy-eight Hereford x Friesian cows (from 0-4 parities) were used. Forty were considered reproductively normal ('normal' cows) having calved each year from their first season and currently with a 10 week old calf at-foot; while 38 had a history of reproductive disorders ('suspect' cows) and had not calved in the previous 15 months (May 1994 to July 1995).


Author(s):  
S.B. Drew ◽  
A.R. Peters

Work in New Zealand has suggested that treatment of dairy cows with buserelin an analogue of GnRH between days 11 and 13 after insemination can increase pregnancy rate by reducing embryo loss (MacMillan, Taufa and Day, 1986). This effect is probably mediated via a luteoprotective mechanism (MacMillan, Thatcher & Drost 1989; Thatcher, MacMillan, Hansen & Drost, 1989). The present study was carried out to attempt to confirm this effect of buserelin under UK conditions.A total of 660 Holstein/Friesian cows on 10 commercial dairy farms were used. The cows were paired according to date, of previous calving and allocated at random to control or treated group on the day of service. Only cows in the parity range 1-5 with no obvious reproductive disorders were used. Bulls and inseminators were used on the same number of cows in each group. Milk samples were taken on the day of service for progesterone assay. Cows not in oestrus were removed from the study. Cows in treated groups were given an intramuscular injection of 10 ug buserelin [2.5 ml Receptal, Hoechst] 12 days after first insemination. Cows not observed to return to oestrus before Day 24 were re-sampled for progesterone assay. Pregnancy was confirned by palpation or ultrasonic scanning at six weeks.


1995 ◽  
Vol 132 (1) ◽  
pp. 91-96 ◽  
Author(s):  
John AM Mattheij ◽  
Hans JM Swarts

Mattheij JAM, Swarts HJM. Induction of luteinized unruptured follicles in the rat after injection of luteinizing hormone early in pro-oestrus. Eur J Endocrinol 1995;132:91–6. ISSN 0804–4643 The cause of formation of luteinized unruptured follicles (LUF) is unknown. Formation of LUF was studied after injection of a varying small dose of luteinizing hormone (LH) with or without subsequent injection of gonadotrophin-releasing hormone (GnRH); in addition, the effect of suppression of prolactin on LUF formation was studied. Luteinization without ovulation occurred in virtually all graafian follicles, if 0.5–1.0 μg of LH was injected some hours before the presumed endogenous LH surge (suppressed by Nembutal); with increasing doses of LH progressively increasing numbers of ovulations were observed. If in early pro-oestrus 1 μg of GnRH was given 4 h after 1 μg of LH, formation of LUF was partly prevented; if the interval between LH and GnRH was 8 h or more, the great majority of graafian follicles developed into LUF. If early in pro-oestrus 1 μg of LH was given and 8 h later 0.1 μg of a potent GnRH analogue, about 50% of the follicles became LUF; in similarly treated rats, suppression of prolactin by ergocryptine reduced but did not prevent LUF formation. The data support the idea that deficient LH secretion in the period before ovulation may be involved in the formation of LUF. John AM Mattheij, Department of Human and Animal Physiology, Haarweg 10, 6709 PJ Wageningen, The Netherlands


2000 ◽  
Vol 6 (1) ◽  
pp. 19-22
Author(s):  
Andrew Prentice

Endometriosis is an oestrogen sensitive condition, leading to reluctance to prescribe hormone replacement therapy. Treatment of endometriosis either medically with gonadotrophin releasing hormone analogues or with surgery involving bilateral oophorectomy leads to oestrogen deficiency. While this may lead to vasomotor symptoms, the consequence which has been of most concern is a reduction in bone mass. Repeated courses of gonadotrophin releasing hormone analogues may mean that women with endometriosis enter the menopause with a below average bone density. Thus, there is a place for hormone replacement therapy both as add-back therapy in premenopausal women receiving gonadotrophin releasing hormone analogues, and in postmenopausal women with a past history of endometriosis. Addback therapy with continuous combined regimes and tibolone do not prevent disease resolution in the hypogonadal patient. The evidence regarding the use of hormone replacement therapy in patients with a history of endometriosis is poor, but suggests that we could be less conservative than we have been.


1986 ◽  
Vol 111 (2) ◽  
pp. 228-234 ◽  
Author(s):  
Alessandro Mongioi ◽  
Grazia Maugeri ◽  
Maria Macchi ◽  
Aldo Calogero ◽  
Enzo Vicari ◽  
...  

Abstract. A gonadotrophin-releasing hormone (GnRH) analogue, D-Ser[TBU]LRH-EA10, (GnRH-A), at a dose of 200 μg was given daily for 2 months to 6 women with polycystic ovarian disease (PCO). Prior to therapy the patients presented elevated LH, testosterone (T), oestrone (E1) and dihydrotestosterone (DHT) in the circulation. In response to GnRH-A, these subjects exhibited a marked decrease in circulating T, DHT and androstenedione (A) levels as measured 24 h after GnRH-A injection, by 4 weeks and onwards (P < 0.05). After 2 weeks of daily administration, the serum LH profile, evaluated by sampling at 2, 4. 7 and 24 h after injection of GnRH-A, was not different from baseline, whereas after 4, 6 and 8 weeks the levels were significantly lower (*P < 0.01). The profile of serum T levels was unmodified at the second week, but significantly decreased thereafter (*P <0.01). At the end of treatment, the E1 concentrations, elevated in pre-injection condition, were markedly decreased. These data demonstrate that in PCO subjects, GnRH-A significantly lowered the elevated levels of androgens commonly found in these patients. The close correlation observed between reduced serum LH and androgen concentrations suggests that pituitary desensitization could be responsible for the reduction in androgen levels, and may be evidence for a gonadotrophin dependence of the elevated concentrations of T in these patients.


2003 ◽  
Vol 15 (6) ◽  
pp. 317 ◽  
Author(s):  
A. Junaidi ◽  
P. E. Williamson ◽  
J. M. Cummins ◽  
G. B. Martin ◽  
M. A. Blackberry ◽  
...  

In the present study, we tested the effect of treatment with a slow-release implant containing the gonadotrophin-releasing hormone agonist DeslorelinTM (Peptech Animal Health Australia, North Ryde, NSW, Australia) on pituitary and testicular function in mature male dogs. Four dogs were treated with Deslorelin (6-mg implant) and four were used as controls (blank implant). In control dogs, there were no significant changes over the 12 months of the study in plasma concentrations of luteinising hormone (LH) or testosterone, or in testicular volume, semen output or semen quality. In Deslorelin-treated dogs, plasma concentrations of LH and testosterone were undetectable after 21 and 27 days, testicular volume fell to 35% of pretreatment values after 14 weeks and no ejaculates could be obtained after 6 weeks. Concentrations returned to the detectable range for testosterone after 44 weeks and for LH after 51 weeks and both were within the normal range after 52 weeks. Semen characteristics had recovered completely by 60 weeks after implantation. At this time, the testes and prostate glands were similar histologically to those of control dogs. We conclude that a single slow-release implant containing 6 mg Deslorelin has potential as a long-term, reversible antifertility agent for male dogs.


1992 ◽  
Vol 30 (23) ◽  
pp. 92-92

In our article Gonadotrophin releasing hormone analogues for advanced prostate cancer (17 August, page 65) we warned that testosterone levels might rebound above normal if a dose of a depot preparation of a GnRH analogue missed. In fact if the dose is delayed by 2 weeks, serum testosterone concentrations may rise above the castration range in about 30% of patients but do not rise above normal.1 In the Practice Synopsis included in the article we mentioned that goserelin (Zoladex) was licensed for advanced prostate cancer and endometriosis but omitted to mention that it was also licensed for advanced breast cancer in pre- and peri-menopausal women.


1996 ◽  
Vol 3 (3) ◽  
pp. 203-206 ◽  
Author(s):  
Alun L Edwards ◽  
M Sarah Rose ◽  
Lois E Donovan ◽  
Gordon T Ford

Variability in the severity of asthma during various phases of the menstrual cycle has been frequently suspected. However, the hormonal changes that might affect mediators of bronchospasm have yet to be elucidated. The case of a 41-year-old woman suffering from longstanding asthma with life-threatening exacerbations is reported. The patient was treated with buserelin, a gonadotropin releasing hormone (GnRH) analogue, which created a temporary chemical menopause and thus permitted diagnosis of a premenstrual exacerbation of asthma and offered insight into potential therapy. GnRH analogues may therefore be of value in assessing women with severe asthma suspected to vary with the menstrual cycle. The addition of estrogens and progestins at the same time as treatment with GnRH analogue may be of value in determining the role of these hormones in the pathogenesis of menstrually related exacerbations of asthma.


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