Peptide hormones. 137. Structural requirements in positions 1, 2, 3, and 6 of the luteinizing hormone-releasing hormone (LH-RH) for antiovulatory activity

1979 ◽  
Vol 22 (7) ◽  
pp. 774-777 ◽  
Author(s):  
John Humphries ◽  
Yieh-Ping Wan ◽  
Tadeusz Wasiak ◽  
Karl Folkers ◽  
Cyril Y. Bowers
Keyword(s):  
Luteinizing Hormone ◽  
Peptide Hormones ◽  
Structural Requirements ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Lh Rh ◽  
Antiovulatory Activity

STUDIES WITH FRAGMENTS OF A HIGHLY ACTIVE ANALOGUE OF LUTEINIZING HORMONE RELEASING HORMONE

1979 ◽  
Vol 81 (2) ◽  
pp. 175-182 ◽  
Author(s):  
J. SANDOW ◽  
W. KÖNIG
Keyword(s):  
Luteinizing Hormone ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Enzyme Stability ◽  
Organ Distribution ◽  
Structural Requirements ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Highly Active ◽  
Lh Rh

The minimal structural requirements for gonadotrophin releasing activity were studied with fragments of a highly active analogue of luteinizing hormone releasing hormone (LH-RH), [d-Ser(But)6]LH-RH(1–9)nonapeptide-ethylamide (Hoe 766). All fragments are related to the C-terminal structure of LH-RH and have increased enzyme stability. Ovulation in phenobarbitone-blocked rats was induced with a median effective dose/rat, of 1·9 μg of the (3–9)-heptapeptide, Trp-Ser-Tyr-d-Ser(But)-Leu-Arg-Pro-ethylamide and 6·8, 18·0 and 38·3 μg for the (4–9), (5–9) and (6–9) fragments respectively. The (3–9)-heptapeptide and (4–9)-hexapeptide induced release of LH and FSH in phenobarbitone-blocked rats with a ratio similar to that of LH-RH. Degradation of LH-RH by enzyme preparations of liver, kidney and hypothalamic or anterior pituitary tissue was not modified by addition of the (3–9)-heptapeptide fragment. The organ distribution of the 125I-labelled (3–9)-heptapeptide fragments was similar to LH-RH, but not to Hoe 766. The peptide accumulated in liver and kidney, but was eliminated from the anterior pituitary gland 15 min after i.v. injection, whereas Hoe 766 showed progressive accumulation in the pituitary gland (tissue: plasma ratio = 6·6 after 60 min). In contrast to C-terminal fragments of LH-RH, the corresponding fragments of nonapeptide analogues retained significant biological activity, and the minimal structural requirements for LH release may be related to the C-terminal sequence of LH-RH.

EFFECT OF CORTISOL OR ADRENOCORTICOTROPHIN ON RELEASE OF LUTEINIZING HORMONE INDUCED BY LUTEINIZING HORMONE RELEASING HORMONE IN THE DAIRY HEIFER

1982 ◽  
Vol 92 (1) ◽  
pp. 141-146 ◽  
Author(s):  
R. L. MATTERI ◽  
G. P. MOBERG
Keyword(s):  
Luteinizing Hormone ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Dairy Heifers ◽  
Significant Difference ◽  
Significant Depression ◽  
Lh Rh ◽  
Lh Releasing Hormone ◽  
And Control ◽  
Slight Depression

During treatment with cortisol or ACTH, dairy heifers were given two doses of LH releasing hormone (LH-RH) spaced 1·5 h apart. Serum concentrations of cortisol and LH were monitored during each treatment. Treatment with both ACTH and cortisol raised plasma cortisol levels above the respective saline controls (P<0·001). Neither treatment affected basal LH concentrations. A slight depression in LH response was seen in the cortisol-treated animals after the first LH-RH injection, as shown by a statistically significant depression at three of the sample times. There was no significant difference between treated and control LH values after the second LH-RH administration. Treatment with ACTH resulted in significantly reduced LH values at all sample times after both injections of LH-RH.

Acidic Aqueous Extraction of Hypothalamic Luteinizing Hormone Releasing Hormone to Study Biological Effects

1974 ◽  
Vol 52 (3) ◽  
pp. 754-758 ◽  
Author(s):  
S. H. Shin ◽  
C. J. Howitt
Keyword(s):  
Luteinizing Hormone ◽  
Biological Effects ◽  
Extraction Procedure ◽  
Extraction Methods ◽  
Water Soluble ◽  
Acid Extraction ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Aqueous Solvent ◽  
Lh Rh

Several aqueous solvent systems were tested for their efficiency in extracting luteinizing hormone releasing hormone (LH-RH) from rat hypothalamus. Although LH-RH is a water-soluble decapeptide, neutral distilled water extracted only 10% of the LH-RH obtained using acid extraction methods. The efficiency of the acid extraction procedure suggests that in the hypothalamus the releasing hormone is bound to a relatively large molecular weight compound. Using the acidic extraction procedure, we found that hypothalamic LH-RH content is significantly lower in the castrated animal than in the normal rat.

PROLONGED RELEASE BY DIOESTROUS RATS OF FOLLICLE-STIMULATING HORMONE DURING THE PERIOD OF OVULATION INDUCED BY LUTEINIZING HORMONE RELEASING HORMONE

1979 ◽  
Vol 81 (1) ◽  
pp. 109-118 ◽  
Author(s):  
SHUJI SASAMOTO ◽  
SHIGEO HARADA ◽  
KAZUYOSHI TAYA
Keyword(s):  
Luteinizing Hormone ◽  
Plasma Concentrations ◽  
High Plasma ◽  
Oestrous Cycle ◽  
Prolonged Release ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Follicular Maturation ◽  
Lh Rh ◽  
Premature Ovulation

When 1·0 μg luteinizing hormone releasing hormone (LH-RH) was given i.v. three times at 1 h intervals from 17.00 to 19.00 h on the day of dioestrus (day 0) to regular 4 day cyclic rats, premature ovulation was induced the next morning (day 1) with the number of ova present comparable to normal spontaneous ovulation. The next spontaneous ovulation occurred on the morning of day 5, 4 days after premature ovulation induced by LH-RH. Plasma concentrations of FSH and LH showed transient rises and falls within 1 h of administration of LH-RH; concentrations of FSH in the plasma decreased from 20.00 h on day 0 but markedly increased again from 23.00 h on day 0 to 02.00 h on day 1 and these high levels persisted until 14.00 h on day 1, with only a small increase of plasma LH during this period. The duration of increased FSH release during premature ovulation induced by LH-RH treatment was 6 h longer than the FSH surge occurring after administration of HCG on day 0. Surges of gonadotrophin were absent on the afternoon of day 1 (the expected day of pro-oestrus) and the surges characteristic of pro-oestrus occurred on the afternoon of day 4 and ovulation followed the next morning. The pituitary content of FSH did not decrease despite persisting high plasma levels of FSH during premature ovulation induced by either LH-RH or HCG on day 0. The changes in uterine weight indicated that the pattern of oestrogen secretion from the day of premature ovulation induced by LH-RH to the day of the next spontaneous ovulation was similar to that of the normal 4 day oestrous cycle. When 10 i.u. HCG were given on day 0, an increase in oestrogen secretion occurred on day 2, 1 day earlier than in the group given LH-RH on day 0. This advancement of oestrogen secretion was assumed to be responsible for the gonadotrophin surges on day 3. Similar numbers of fully developed follicles were found by 17.00 h on day 2 after premature ovulation induced by either LH-RH or HCG, suggesting that the shorter surge of FSH during premature ovulation induced by HCG had no serious consequences on the initiation of follicular maturation for the succeeding oestrous cycle in these rats. Administration of LH-RH on day 0 had no direct effect on the FSH surge during premature ovulation. Secretory changes in the ovary during ovulation may be responsible for this prolonged selective release of FSH.

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