LHRH self priming of gonadotrophin secretion: time course of development

1983 ◽  
Vol 244 (5) ◽  
pp. C410-C418 ◽  
Author(s):  
D. W. Waring ◽  
J. L. Turgeon
Keyword(s):  
Luteinizing Hormone ◽  
Time Course ◽  
Interpulse Interval ◽  
Time Curve ◽  
Luteinizing Hormone Releasing Hormone ◽  
First Derivative ◽  
Gonadotrophin Secretion ◽  
Time Required ◽  
Lh Secretion

The luteinizing hormone-releasing hormone (LHRH) self-priming effect, in which the gonadotrophin secretory response to LHRH is augmented by prior exposure to LHRH, was studied in vitro using pituitaries of proestrous rats. Individual, quartered anterior pituitaries were superfused for 6 h at 1 ml/min. Using two or three 10-min LHRH pulses of 0.8 nM in which the interpulse interval was 20-170 min or a single 2-h LHRH pulse of 0.8 nM, LHRH self priming of luteinizing hormone (LH) secretion was demonstrable within 30-40 min of LHRH exposure. LHRH self priming of follicle-stimulating hormone occurred 40-50 min after the start of LHRH exposure. The first derivative of the 2-h LHRH pulse rate of secretion vs. time curve provided a sensitive indicator of the time required for development of the self-priming response. Once initiated by a 10-min LHRH pulse, priming of LH secretion persisted with no decrease, as determined by the area under the secretion rate vs. time curve and by the slope of the rise of this curve, over the longest interpulse interval examined, 170 min. The observed time course of development and persistence of LHRH self priming are consistent with its presumed important role in development of the preovulatory gonadotrophin surges.

EFFECTS OF LUTEINIZING HORMONE RELEASING HORMONE ON PLASMA FOLLICLE-STIMULATING HORMONE AND LUTEINIZING HORMONE LEVELS IN THE FERRET

1977 ◽  
Vol 73 (1) ◽  
pp. 37-52 ◽  
Author(s):  
B. T. DONOVAN ◽  
M. B. TER HAAR
Keyword(s):  
Luteinizing Hormone ◽  
Intravenous Injection ◽  
Follicle Stimulating Hormone ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Hormone Levels ◽  
Oestradiol Treatment ◽  
Gonadotrophin Secretion ◽  
Lh Rh ◽  
Lh Secretion

SUMMARY Heterologous radioimmunoassays for FSH and LH were employed to examine the effect of synthetic LH-RH upon gonadotrophin secretion in the ferret. Intravenous injection of 4 μg LH-RH induced a surge of FSH and of LH secretion in male and in female animals. In intact and in castrated males, the rise of LH was much more marked than that of FSH. The gonadotrophin response to LH-RH was greater in anoestrous than in oestrous females; FSH secretion was not enhanced during oestrus. Ovariectomized females behaved as anoestrous females with respect to LH secretion, while FSH secretion remained unchanged. Treatment of ovariectomized females with progesterone did not alter the pattern of response to LH-RH, but oestradiol treatment depressed the reaction to match that seen in oestrous females. Repetitive injections of LH-RH induced repetitive surges of FSH and LH in anoestrous females, but only of LH during oestrus: slow i.v. infusion of LH-RH induced a sustained elevation of plasma LH levels both in oestrous and in anoestrous females; again FSH levels rose only in anoestrous females. Injection of synthetic TRH did not alter gonadotrophin secretion in corresponding groups of male or female ferrets.

APPLICATION OF AN IN-VITRO PERIFUSION TECHNIQUE TO STUDIES OF LUTEINIZING HORMONE RELEASE BY RAT ANTERIOR HEMI-PITUITARIES: SELF-POTENTIATION BY LUTEINIZING HORMONE RELEASING HORMONE

1976 ◽  
Vol 68 (2) ◽  
pp. 197-207 ◽  
Author(s):  
J. A. EDWARDSON ◽  
D. GILBERT
Keyword(s):  
Luteinizing Hormone ◽  
Priming Effect ◽  
Hormone Release ◽  
Physiological Control ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Hypothalamic Extract ◽  
Lh Rh ◽  
Lh Secretion

SUMMARY A technique is described for the continuous perifusion of rat adenohypophyses. Exposure of the perifused glands to repeated equal 5 min stimuli with hypothalamic extract resulted in a series of equal peaks of corticotrophin secretion, the response was proportional to log dose over the range 0·25–2·0 rat hypothalamic equivalents/ml. Repeated equal stimuli with hypothalamic extract, or with luteinizing hormone releasing hormone (LH-RH) at concentrations of 2 or 10 ng/ml, resulted in a progressively increasing series of peaks of LH secretion, i.e. a self-potentiating or priming effect. The effect took between 30 min and 1 h to develop. A delayed increase in the responsiveness of the glands was also seen with continuous incubation of anterior pituitaries with LH-RH. The relevance of these observations to the physiological control of LH secretion is discussed.

scholarly journals Pharmacological Basis of CD101 Efficacy: Exposure Shape Matters

2017 ◽  
Vol 61 (11) ◽  
Author(s):  
Elizabeth A. Lakota ◽  
Justin C. Bader ◽  
Voon Ong ◽  
Ken Bartizal ◽  
Lynn Miesel ◽  
...  
Keyword(s):  
Time Course ◽  
Fungicidal Activity ◽  
Control Group ◽  
Time Curve ◽  
Content Type ◽  
Treatment Groups ◽  
Concentration Time ◽  
Treatment Control Group ◽  
Pharmacological Basis

ABSTRACT CD101 is a novel echinocandin with concentration-dependent fungicidal activity in vitro and a long half-life (∼133 h in humans, ∼70 to 80 h in mice). Given these characteristics, it is likely that the shape of the CD101 exposure (i.e., the time course of CD101 concentrations) influences efficacy. To test this hypothesis, doses which produce the same total area under the concentration-time curve (AUC) were administered to groups of neutropenic ICR mice infected with Candida albicans R303 using three different schedules. A total CD101 dose of 2 mg/kg was administered as a single intravenous (i.v.) dose or in equal divided doses of either 1 mg/kg twice weekly or 0.29 mg/kg/day over 7 days. The studies were performed using a murine disseminated candidiasis model. Animals were euthanized at 168 h following the start of treatment. Fungi grew well in the no-treatment control group and showed variable changes in fungal density in the treatment groups. When the CD101 AUC from 0 to 168 h (AUC0–168) was administered as a single dose, a >2 log10 CFU reduction from the baseline at 168 h was observed. When twice-weekly and daily regimens with similar AUC values were administered, net fungal stasis and a >1 log10 CFU increase from the baseline were observed, respectively. These data support the hypothesis that the shape of the CD101 AUC influences efficacy. Thus, CD101 administered once per week demonstrated a greater degree of fungal killing than the same dose divided into twice-weekly or daily regimens.

Involvement of H1 Histamine Receptor in Basal and Estrogen-Stimulated Luteinizing Hormone-Releasing Hormone Secretion in Rats in vitro

1987 ◽  
Vol 45 (3) ◽  
pp. 191-196 ◽  
Author(s):  
Akira Miyake ◽  
Shirou Ohtsuka ◽  
Takamichi Nishizaki ◽  
Keiichi Tasaka ◽  
Toshihiro Aono ◽  
...  
Keyword(s):  
Luteinizing Hormone ◽  
Hormone Secretion ◽  
Histamine Receptor ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone

PHOTOPERIODIC MODULATION OF GONADOTROPHIN SECRETION IN CASTRATED JAPANESE QUAIL

1982 ◽  
Vol 92 (1) ◽  
pp. 73-83 ◽  
Author(s):  
H. F. URBANSKI ◽  
B. K. FOLLETT
Keyword(s):  
Japanese Quail ◽  
Plasma Levels ◽  
Time Course ◽  
Neural Mechanisms ◽  
Gonadal Steroids ◽  
Photoperiodic Control ◽  
Gonadotrophin Secretion ◽  
Lh Secretion ◽  
Sexually Mature ◽  
Short Days

Male Japanese quail were castrated when sexually immature and immediately exposed to one of the following stimulatory lighting regimes for 52 days: 11 h light: 13 h darkness/day (11L : 13D), 12L : 12D, 13L : 11D, 14L : 10D, 15L : 9D, 16L : 8D, 20L : 4D or 23L : 1D. One group was retained on short days (8L : 16D). Clearcut differences in the plasma levels of LH and FSH emerged between the various groups. Levels remained very low in castrated quail on 8L : 16D but were much greater in those on 14L : 10D, 15L : 9D, 16L : 8D, 20L : 4D and 23L : 1D, eventually becoming 15 to 20 times higher. Less pronounced castration responses developed on 13L : 11D, 12L : 12D or 11L : 13D. Alterations in photoperiod after day 52 caused an appropriate rise or fall in LH secretion. Photoperiodically induced suppressions were rapid, being highly significant within 4 days, but increases usually had a slower time course. When sexually mature quail (on 16L : 8D) were castrated and transferred to 8L : 16D they also exhibited a rapid suppression in LH secretion. Thus in quail, unlike some mammals, the photoperiodic control over gonadotrophin secretion is independent of the reproductive status of the animal at the time of castration. The results confirm the view that changes in sensitivity of the hypothalamo-pituitary axis to gonadal steroids are not a primary factor in the neural mechanisms underlying photoperiodism in quail.

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