scholarly journals Effects of high doses of a series of new luteinizing hormone-releasing hormone analogues in intact female rats

1979 ◽  
Vol 39 (3) ◽  
pp. 274-279 ◽  
Author(s):  
P V Maynard ◽  
R I Nicholson
Keyword(s):  
Luteinizing Hormone ◽  
Female Rats ◽  
Intact Female ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
High Doses

SERUM LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE CONCENTRATIONS IN IMMATURE FEMALE RATS TREATED WITH MULTIPLE INJECTIONS AND VARIOUS AMOUNTS OF LUTEINIZING HORMONE RELEASING HORMONE

1975 ◽  
Vol 66 (1) ◽  
pp. 13-20 ◽  
Author(s):  
D. C. JOHNSON ◽  
R. S. MALLAMPATI
Keyword(s):  
Luteinizing Hormone ◽  
Constant Stimulus ◽  
Female Rats ◽  
Intact Female ◽  
Immature Female ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Serum Luteinizing Hormone ◽  
Serum Lh ◽  
Lh Rh

SUMMARY Release of immunoreactive LH and FSH was induced in immature intact female rats by repeated injections of synthetic luteinizing hormone releasing hormone (LH-RH). Altering the dose of LH-RH (5, 10, 20, 50 ng) and the frequency of administration (every 10, 20, 30 or 60 min) over a period of 2 h produced a variety of serum LH and FSH concentrations and ratios. When the dose was a constant 20 ng but the frequency of injections was either 20 or 30 min, a steady state in serum gonadotrophin concentrations was reached within 1 h and the level remained the same during the second hour. When given every 10 min, 20 ng LH-RH produced a much higher concentration of both LH and FSH during the second hour of stimulation. Examination of the gonadotrophin levels after each injection of LH-RH showed that the pituitary response was variable in spite of a constant stimulus.

Modulation of pituitary responsiveness to LHRH by androgens in ovariectomized female rats

1977 ◽  
Vol 55 (2) ◽  
pp. 188-192
Author(s):  
Padmaja N. Kulkarni ◽  
Alan A. Simpson ◽  
William H. Moger
Keyword(s):  
Luteinizing Hormone ◽  
Follicle Stimulating Hormone ◽  
Estradiol Benzoate ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Luteinizing Hormone Releasing Hormone ◽  
Daily Dose ◽  
17Β Estradiol ◽  
High Doses ◽  
Pronounced Inhibition

The effect of androgens on pituitary response to luteinizing-hormone-releasing hormone (LHRH) and their ability to modify effects of 17β-estradiol (E2) on pituitary responsiveness to LHRH were tested in ovariectomized rats maintained on a daily dose of 0.25 μg estradiol benzoate per rat for 6 d before androgen administration.Testosterone propionate (TP) (4, 40, 400, or 4000 μg per rat), administered 24 h before LHRH (500 ng per rat), had no significant effect on luteinizing hormone (LH) or follicle-stimulating hormone (FSH) response. Similar doses of dihydrotestosterone (DHT) did not significantly alter the LH response but significantly suppressed the FSH response. Even the lowest dose completely blocked the FSH response to LHRH. TP in combination with 4 or 400 μg of E2 suppressed the stimulatory effect of E2 on both LH and FSH response to LHRH in a dose-related manner. DHT and E2 in combination affected LH response inconsistently, whereas their ratio determined FSH response; there was pronounced inhibition of FSH response in rats given high doses of DHT combined with low doses of E2; DHT inhibition of FSH response in animals receiving 4 μg of DHT with 400 μg E2 was partially overcome by the stimulatory effect of E2. Our results indicate that TP and DHT affect LH and FSH response to LHRH differently. The ratio of androgen to estrogen is important in determining the response to LHRH.

Sign in / Sign up

Export Citation Format

Share Document