Comparison of the effects of tercleucine and tryptophan superanalogs of LH-RH on gonadotropin secretion in heifers |
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| Authors: | J Lidicky B Sevcík J Pícha D Píchová M Flegel |
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| Institution: | Vyzkumny ústav pro biofaktory a veterinární léciva, Spofa. |
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| Abstract: | In six heifers without sexual organs the effects were compared of the superanalogues LH-RH (D-Tle6) and (D-Trp6)] on the secretion of luteinizing hormone (LH) and follicles of stimulating hormone (FSH). The superanalogues were given i. m. at dosages of 10, 50 and 100 micrograms pro toto. Dosages of 50 and 100 micrograms of both superanalogues had a greater effect on the secretion of LH than the dosage of 100 micrograms. The highest average concentration of LH during the time of application (D-Tle6) was recorded in the dosage of 10 micrograms (7.84 ng.ml-1). The average concentrations of LH after application (D-Trp6) were within the range of 5.46 to 9.29 ng.ml-1. Because of the great variability of the concentrations of LH no significant differences were ascertained due to the influence of dosage. From a comparison of the concentrations of LH with the same dosage it emerged that (D-Trp6) after an application of 50 micrograms significantly increased the concentration of LH from the 60th to the 240th minute and thus had a more protracted effect. With dosages of 10 and 100 micrograms of the superanalogues no statistically significant differences were recorded after two hours from application. With (D-Trp6) the higher stimulative effect on the secretion of LH was statistically confirmed. The highest concentrations of follicles of stimulation hormone (FSH) (204.6 and 228.6 ng.ml-1) were found from the 40th to the 100th minute after the application of dosages of 50 and 100 micrograms (D-Tle6). The protracted effect was greatest with a dosage of 100 micrograms (270 mins). (D-Trp6) at a dosage of 100 micrograms caused the greatest effect on the secretion of FSH (226.8 ng.ml-1 for a period of 180 mins). The lower dosages of analogues scarcely differed in response. The dosage of superanalogues has an influence on the concentration of FSH in peripheral blood and on the duration of the protracted effect. |
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