Luteinizing Hormone Releasing Hormone (LHRH) Neuronal Function in Middle-Aged Female Rats

2000 ◽  
pp. 11-23
Author(s):  
Beverly S. Rubin ◽  
Mercedes Jimenez-Linan
Keyword(s):  
Luteinizing Hormone ◽  
Female Rats ◽  
Neuronal Function ◽  
Middle Aged ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone

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.

scholarly journals Hypothalamic Luteinizing Hormone-Releasing Hormone(LHRH) and LH Secretion in Aging Female Rats.

1990 ◽  
Vol 37 (2) ◽  
pp. 213-221 ◽  
Author(s):  
SUMIO TAKAHASHI ◽  
KOUJI NOMURA ◽  
SEIICHIRO KAWASHIMA
Keyword(s):  
Luteinizing Hormone ◽  
Female Rats ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Lh Secretion

Relation of attenuated proestrous luteinizing hormone surges in middle-aged female rats to in vitro pituitary gonadotropin-releasing hormone responsiveness

1994 ◽  
Vol 130 (5) ◽  
pp. 540-544 ◽  
Author(s):  
Aurelia N Brito ◽  
Timothy E Sayles ◽  
Richard J Krieg ◽  
Dennis W Matt
Keyword(s):  
Luteinizing Hormone ◽  
Gonadotropin Releasing Hormone ◽  
Female Rats ◽  
Aged Rats ◽  
Middle Aged ◽  
Releasing Hormone ◽  
Young Females ◽  
Pituitary Gonadotropin ◽  
Hormone Responsiveness

Brito AN, Sayles TE, Krieg Jr RJ, Matt DW. Relation of attenuated proestrous luteinizing hormone surges in middle-aged female rats to in vitro pituitary gonadotropin-releasing hormone responsiveness. Eur J Endocrinol 1994;130:540–4. ISSN 0804–4643 Prior to the cessation of regular cyclicity, middle-aged rats display pre-ovulatory luteinizing hormone (LH) surges of reduced magnitude. The present study was designed to identify whether middle-aged female rats with attenuated proestrous LH surges have alterations in pituitary responsiveness to gonadotropin-releasing hormone (GnRH). Young (4 months old) and middle-aged (10–12 months old) regularly cycling females were catheterized and sampled on proestrus to characterize their LH surge profiles. On the next proestrus (12.00 h), pituitaries were perifused individually and exposed to three pulses of GnRH (30 nmol/l). The patterns of the proestrous LH surges revealed that 12 of 22 middle-aged rats had attenuated surges (< 7 μg/l) while the remaining 10 middle-aged females had surges that were similar to those of young rats. Pituitaries perifused on the next proestrus showed similar basal LH release among the middle-aged and young females. However, the LH secretory rates following the second and third administration of GnRH, as well as the overall GnRH-stimulated LH secretory rates, were significantly decreased in middle-aged females with previously attenuated LH surges as compared to those from the young proestrous rats. In contrast, middle-aged rats with normal LH surges had pituitary LH responses that were no different from those of young females. These results indicate that a decrease in pituitary LH responsiveness to GnRH is only apparent in middle-aged rats that display attenuated proestrous LH surges. Dennis W Matt. Department of Obstetrics and Gynecology, Medical College of Virginia, Box 980034, Richmond, VA 23298, USA

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