scholarly journals Aromatase Knockout Mice Show Normal Steroid-Induced Activation of Gonadotrophin-Releasing Hormone Neurones and Luteinising Hormone Surges With a Reduced Population of Kisspeptin Neurones in the Rostral Hypothalamus

2012 ◽  
Vol 24 (9) ◽  
pp. 1222-1233 ◽  
Author(s):  
L. Szymanski ◽  
J. Bakker
Keyword(s):  
Knockout Mice ◽  
Luteinising Hormone ◽  
Releasing Hormone ◽  
Rostral Hypothalamus ◽  
Gonadotrophin Releasing Hormone

Temporal Migration of Gonadotrophin-Releasing Hormone-1 Neurones is Modified in GAD67 Knockout Mice

2007 ◽  
Vol 20 (1) ◽  
pp. 93-103 ◽  
Author(s):  
J. M. Lee ◽  
J. Tiong ◽  
D. M. Maddox ◽  
B. G. Condie ◽  
S. Wray
Keyword(s):  
Knockout Mice ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone

THE EFFECT OF CYPROTERONE ACETATE ON THE PLASMA GONADOTROPHIN RESPONSE TO GONADOTROPHIN RELEASING HORMONE

1976 ◽  
Vol 81 (3) ◽  
pp. 680-684 ◽  
Author(s):  
Richard A. Donald ◽  
Eric A. Espiner ◽  
R. John Cowles ◽  
Joy E. Fazackerley
Keyword(s):  
Testosterone Level ◽  
Cyproterone Acetate ◽  
Luteinising Hormone ◽  
Follicle Stimulating Hormone ◽  
Plasma Testosterone ◽  
Plasma Testosterone Level ◽  
Releasing Hormone ◽  
Lh Release ◽  
Gonadotrophin Releasing Hormone ◽  
Male Patients

ABSTRACT Cyproterone acetate (100–150 mg daily) was administered to 8 male patients with excessive libido. Within 3 months a significant fall (P < 0.02) in plasma testosterone was demonstrated. The plasma luteinising hormone (LH) and follicle stimulating hormone (FSH) responses to gonadotrophin releasing hormone (LH/FSH-RH) were also significantly impaired (P < 0.05). A direct correlation between the resting plasma testosterone level and the LH response to LH/FSH-RH was demonstrated (r = 0.743). It is concluded that the fall in plasma testosterone levels in patients receiving cyproterone acetate may be attributed to suppression of LH release, rather than an antiandrogen effect on the testis or hypothalamus.

Ovine serum and pituitary isoforms of luteinising hormone during the luteal phase

2006 ◽  
Vol 18 (4) ◽  
pp. 485 ◽  
Author(s):  
E. Arrieta ◽  
A. Porras ◽  
E. González-Padilla ◽  
C. Murcia ◽  
S. Rojas ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Relative Abundance ◽  
Luteal Phase ◽  
Luteinising Hormone ◽  
Saline Solution ◽  
Control Group ◽  
Acidic Ph ◽  
Releasing Hormone ◽  
Relative Composition ◽  
Gonadotrophin Releasing Hormone

The relative abundance of the different isoforms of pituitary and circulating luteinising hormone (LH) in ewes, at different times after the administration of gonadotrophin-releasing hormone (GnRH), during the luteal phase of the oestrous cycle was investigated. Sixteen ewes on Day 9 of their cycle were divided into four groups (n = 4). The control group (T0) received saline solution; the remaining animals received 100 μg GnRH (i.m.) 30, 90 or 180 min (T30, T90 and T180, respectively) before serum and pituitary gland collection. Luteinising hormone polymorphism was analysed by chromatofocusing (pH 10.5–3.5). The LH eluted from each chromatofocusing was grouped on the basis of the following three criteria: (1) according to the pH of elution (pH ≥ 10–3.5); (2) as either a basic (pH ≥ 7.5), neutral (pH 7.4–6.5) and acidic (pH ≤ 6.4) elution of LH of serum and hypophyseal origin; and (3) on the basis of distinct isoforms, of which 10 (A–J) were identifiable in hypophyseal extracts and four (A–D) were found in the serum. In general, the most abundant forms of LH in both the pituitary and serum, at all times, were basic. However, that proportion was greater in hypophyseal extracts (84 ± 3%, 81 ± 4%, 82 ± 3% and 83 ± 2% at T0, T30, T90 and T180, respectively) than in serum (51 ± 5%, 48 ± 10% and 54 ± 6% at T30, T90 and T180, respectively). Neutral and acidic LH made up a larger proportion of the total LH in sera (neutral: 17 ± 4%, 20 ± 6% and 23 ± 3% at T30, T90 and T180, respectively; acidic: 32 ± 8%, 32 ± 11% and 23 ± 6% at T30, T90 and T180, respectively) than in the pituitary extracts (neutral: 4.0 ± 0.7%, 10 ± 4%, 7 ± 2% and 5.0 ± 0.5% at T0, T30, T90 and T180, respectively; acidic: 12 ± 3%, 11 ± 2%, 12 ± 2% and 12 ± 2% at T0, T30, T90 and T180, respectively) at all times. These data reveal that the relative composition of the LH present in the pituitary gland and the LH secreted into the circulation is different, with more neutral and acidic isoforms being secreted. The pattern of circulating LH isoforms changes between 30 and 180 min after GnRH peak induction, with a greater proportion of isoform C (eluting between pH 7.0 and 6.5) at T180 compared with T30 and T90.

Pituitary and testicular endocrine responses to exogenous gonadotrophin-releasing hormone (GnRH) and luteinising hormone in male dogs treated with GnRH agonist implants

2007 ◽  
Vol 19 (8) ◽  
pp. 891 ◽  
Author(s):  
A. Junaidi ◽  
P. E. Williamson ◽  
G. B. Martin ◽  
P. G. Stanton ◽  
M. A. Blackberry ◽  
...  
Keyword(s):  
Leydig Cells ◽  
Luteinising Hormone ◽  
Plasma Concentrations ◽  
Control Group ◽  
Release Formulation ◽  
Male Adult ◽  
Releasing Hormone ◽  
Slow Release Formulation ◽  
Gonadotrophin Releasing Hormone ◽  
Lh Releasing Hormone

The present study tested whether exogenous gonadotrophin-releasing hormone (GnRH) and luteinising hormone (LH) can stimulate LH and testosterone secretion in dogs chronically treated with a GnRH superagonist. Twenty male adult dogs were assigned to a completely randomised design comprising five groups of four animals. Each dog in the control group received a blank implant (placebo) and each dog in the other four groups received a 6-mg implant containing a slow-release formulation of deslorelin (d-Trp6-Pro9-des-Gly10–LH-releasing hormone ethylamide). The same four control dogs were used for all hormonal challenges, whereas a different deslorelin-implanted group was used for each challenge. Native GnRH (5 μg kg–1 bodyweight, i.v.) was injected on Days 15, 25, 40 and 100 after implantation, whereas bovine LH (0.5 μg kg–1 bodyweight, i.v.) was injected on Days 16, 26, 41 and 101. On all occasions after Day 25–26 postimplantation, exogenous GnRH and LH elicited higher plasma concentrations of LH and testosterone in control than deslorelin-treated animals (P < 0.05). It was concluded that, in male dogs, implantation of a GnRH superagonist desensitised the pituitary gonadotrophs to GnRH and also led to a desensitisation of the Leydig cells to LH. This explains, at least in part, the profound reduction in the production of androgen and spermatozoa in deslorelin-treated male dogs.

Corpus luteum life span and pituitary oestrogen and progesterone receptors in cyclic and gonadotrophin-releasing hormone-treated anoestrous ewes

2005 ◽  
Vol 17 (7) ◽  
pp. 721 ◽  
Author(s):  
C. Tasende ◽  
M. Rodríguez-Piñón ◽  
S. Acuña ◽  
E. G. Garófalo ◽  
M. Forsberg
Keyword(s):  
Luteal Phase ◽  
Luteinising Hormone ◽  
Binding Assay ◽  
Hormone Secretion ◽  
Progesterone Receptors ◽  
Oestrous Cycle ◽  
Inhibitory Effects ◽  
Releasing Hormone ◽  
Expected Time ◽  
Gonadotrophin Releasing Hormone

The present study investigated the pituitary oestrogen (ER) and progesterone (PR) receptor concentrations in ewes during the oestrous cycle in the breeding season (n = 19), and in anoestrous ewes treated with gonadotrophin-releasing hormone (GnRH) (n = 11) and anoestrous ewes treated with progesterone + GnRH (n = 11). The pituitary ER and PR concentrations at the expected time of ovulation and in the early and late luteal phases were measured by binding assay. The pattern of pituitary ER and PR concentrations in the progesterone + GnRH-treated ewes resembled the pattern found during the normal oestrous cycle, with ER and PR concentrations decreasing from the time of ovulation to the early luteal phase. In contrast, in ewes treated with GnRH alone, ER and PR concentrations increased in the early luteal phase, which may increase the inhibitory effects of steroid hormones on luteinising hormone secretion, ultimately leading to the development of subnormal luteal phases.

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