Serum LH Levels in Bulls Treated with Synthetic Luteinizing Hormone-Releasing Hormone/Follicle Stimulating Hormone-Releasing Hormone (LH-RH/FSH-RH)2

Golter, Terry D.; Reeves, Jerry J.; O'mary, C. C.; Arimura, Akira

doi:10.2527/jas1973.371123x

Cited by 71 publications

(14 citation statements)

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“…Before implantation in experiment 1, testosterone concentrations averaged 5.09 ng/ml and were similar to concentrations previously reported for bulls of similar age (7,8,11,12). Because testosterone is released episodically, pretreatment concentrations were variable (standard deviation 3.21).…”

Section: Resultssupporting

confidence: 52%

“…Furthermore, this is the first report demonstrating the high sensitivity of the bovine testis in releasing testosterone in response to gonadorelin (6)(7)(8)23). Without norgestomet treatment, most studies have used 40 µg or more of gonadorelin.…”

Section: Discussionmentioning

confidence: 90%

“…Although numerous biological assays have been identified, all are time consuming and expensive. Although it has been well known that the gonadorelin-induced LH surge stimulates a significant release of testosterone (6)(7)(8), it has not been used as a bioassay because the pretreatment episodic variability of testosterone concentrations diminishes efficacy. The objective of these experiments was to determine if the gonadorelin-induced release of testosterone could be developed into a biological assay for quality assurance of gonadorelin after synthesis and/or manufacturing.…”

Section: Introductionmentioning

confidence: 99%

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Gonadorelin-Induced Testosterone Release: A Biological Assay for Quality Assurance of Gonadorelin in Veterinary Medicine

Kesler

Summers

Peterson

et al. 1999

Drug Development and Industrial Pharmacy

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Two experiments were conducted with bulls administered norgestomet and gonadorelin to determine if the gonadorelin-induced release of testosterone could be developed into a biological assay for quality assurance of gonadorelin. Implants containing norgestomet (0 to 36 mg) reduced the episodic release (r = -.81; P < .05) and mean concentrations of testosterone (r = -.82; P < .05). Gonadoreline-induced testosterone release increased (r = .99; P < .05) with increasing dosage of gonadorelin (up to 5 micrograms) in norgestomet-implanted bulls (36 mg). Maximal testosterone was released (> sixfold increase) with 5 to 40 micrograms of gonadorelin. In summary, the gonadorelin-induced testosterone release in bulls administered a synthetic progestin is a sensitive (0.008 microgram per kg body weight for 5 micrograms of gonadorelin) biological assay with a rapid turnaround time for the confirmation of gonadorelin potency. Based on a per-kg-body-weight basis, the norgestomet-treated bull is the most sensitive biological assay model.

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Section: Resultssupporting

confidence: 52%

Section: Discussionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Gonadorelin-Induced Testosterone Release: A Biological Assay for Quality Assurance of Gonadorelin in Veterinary Medicine

Kesler

Summers

Peterson

et al. 1999

Drug Development and Industrial Pharmacy

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“…Variation in the LH response to this treatment results from differences in the steroid hormone environment of various domestic animals including cattle (Convey 1973;Schams 8c Höfer 1973;Kittok et al 1973;Zolman et al 1974;Schams et al 1974). Reports in males are not so numerous but it was shown that injection of Gn-RH produced an increase in circulating LH and indirectly a rise in testosterone peripheral plasma con¬ centration (Zolman et al 1972;Goiter et al 1973;Mongkonpiinya et al 1973). This was also reported in man (Schally et al 1972).…”

mentioning

confidence: 90%

EFFECT OF SYNTHETIC GONADOTROPHINRELEASING HORMONE (Gn-RH) ON CIRCULATING LUTEINIZING HORMONE (LH) AND TESTOSTERONE IN YOUNG POST-PUBERTAL BULLS

Thibier

1976

Acta Endocrinologica

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The reproducibility of LH and testosterone responses after Gn-RH treatment in young post-pubertal bulls was tested. Ten bulls were injected im (250 \g=m\g) twice with an interval of 4 weeks. Blood samples were collected every 15 min for 2\ m=1/ 2\ h and then on the second occasion, every hour. LH increases very rapidly and reaches an initial peak by 30 min after Gn-RH injection. This increase over basal level was 25 to 30-fold. After a plateau of high levels lasting 40 to 50 min, a second peak of LH concentration occurs. LH then decreases and returns to basal levels by 6 to 7 h after treatment. The increase of plasma testosterone was more prolonged and of smaller magnitude than that of LH: 3 to 4-fold. There was a large and significant variation between bulls; but with LH, a given individual responded in a consistent manner on the two separate occasions. It is concluded that LH response to Gn-RH treatment might be useful and should be tested as of diagnostic value for clinical or breeding purposes. The testosterone response does not seem to be as valuable and reliable as that of LH.The availability of synthetic gonadotrophin-releasing hormone (Gn-RH) has provided the opportunity to evaluate the pituitary mobilizable reserve of LH gonadotrophin hormone and the indirect response of interstitial tissue to this

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“…Serum LH concentrations were determined by the double antibody radioimmunoassay as described by Goiter et al (1973), in all of the serial samples using rabbit antiserum against bovine LH (JJR-RABLH#5), highly purified iodinated ovine LH (LER-1056-C2) as labelled hormone and NIH-LH-B7 as standard. Serum LH has been determined in 100-, 200-and 300-1xl sample volumes in each of three pools of bovine serum in our laboratory.…”

Section: Experimental Animals and Estradiol Implants Fifteen Nullipamentioning

confidence: 99%

Endocrine Changes during Restoration of Estrous Cycles Following Induction of Anestrus by Restricted Nutrient Intake in Beef Heifers1

Imakawa

Day

Garcia-Winder

et al. 1986

Journal of Animal Science

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The working hypotheses in this experiment were: 1) that ovarian estradiol would inhibit luteinizing hormone (LH) secretion in heifers that were anestrus as a result of restricted dietary energy intake and 2) the responsiveness of LH secretion to estradiol negative feedback would decrease during the period when restoration of estrous cycles occurred following feeding of diets adequate in energy. Fifteen heifers wei~hin~ 341 • 12 (mean • SE) kg were fed a diet containing 50% of the energy required for maintenance until 40 to 50 d following cessation of estrous cycles. Heifers were assigned to intact control (C, n = 5), ovariectomized (OVX, n = 5) or ovariectomized-estradiol-17[3-implanted (OVX + E 2, n = 5) treatments. Heifers were subsequently provided a high-energy (HE) diet until termination of the study. Progesterone concentrations indicating cessation of corpus luteum function were detected after heifers had lost 71 • 8 kg body weight over 186 • 28 d. Control heifers re-initiated estrous cycles as indicated by increased progesterone concentrations in serum at 49 • 9 d after initiation of feeding the HE diet (360 • 18 kg body weight). Initiation of pulsatile LH secretion was observed in heifers by d 12 following OVX. Estradiol suppressed LH secretion in OVX + E 2 heifers during the period of nutritional anestrus in C heifers. Suppressive effects of E2 on LH secretion continued in OVX heifers after C heifers had initiated corpus luteum function. Therefore, the working hypothesis that LH secretion is inhibited by E2 in the nutritionally anestrous heifer is accepted but responsiveness to estradiol does not subside with re-initiation of estrous cycles, thus this working hypothesis is rejected.

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Serum LH Levels in Bulls Treated with Synthetic Luteinizing Hormone-Releasing Hormone/Follicle Stimulating Hormone-Releasing Hormone (LH-RH/FSH-RH)2

Cited by 71 publications

References 0 publications

Gonadorelin-Induced Testosterone Release: A Biological Assay for Quality Assurance of Gonadorelin in Veterinary Medicine

Gonadorelin-Induced Testosterone Release: A Biological Assay for Quality Assurance of Gonadorelin in Veterinary Medicine

EFFECT OF SYNTHETIC GONADOTROPHINRELEASING HORMONE (Gn-RH) ON CIRCULATING LUTEINIZING HORMONE (LH) AND TESTOSTERONE IN YOUNG POST-PUBERTAL BULLS

Endocrine Changes during Restoration of Estrous Cycles Following Induction of Anestrus by Restricted Nutrient Intake in Beef Heifers1

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