scholarly journals Evidence that oestrogen exerts an equivalent negative feedback action on LH secretion in male and female ferrets

Reproduction ◽  
1989 ◽  
Vol 86 (1) ◽  
pp. 235-245 ◽  
Author(s):  
R. S. Carroll ◽  
M. J. Baum
Keyword(s):  
Negative Feedback ◽  
Male And Female ◽  
Lh Secretion

STUDIES OF SEXUAL DIFFERENTIATION OF SHEEP

1978 ◽  
Vol 89 (1) ◽  
pp. 190-195 ◽  
Author(s):  
P. R. Wilson ◽  
M. F. Tarttelin
Keyword(s):  
Negative Feedback ◽  
Sexual Differentiation ◽  
Plasma Samples ◽  
Control Male ◽  
Male And Female ◽  
Ewe Lambs ◽  
Gonadotrophin Releasing Hormone ◽  
Gland Function ◽  
And Control ◽  
Lh Secretion

ABSTRACT Gonadotrophin releasing hormone (GnRH) (1 μg/kg was injected intravenously into pre-natally androgenised and untreated control ram and ewe lambs and castrated pre-natally androgenised rams on each of the 6th, 14th, 22nd and 30th week of post-natal life, and plasma samples collected at −20, −10, 0, 15, 30, 60, 90, 120 and 240 min from injection for LH estimation. No difference in pre-injection LH levels or responses to GnRH were observed between pre-natally androgenised and control male and female lambs. Castration resulted in significantly elevated pre-injection LH levels (P < 0.001) and responses to GnRH (P < 0.05). Forty-five week old control and pre-natally androgenised ewes were subjected to a GnRH injection and plasma sampling routine identical to that described above both before and 2 weeks after ovariectomy. Significantly elevated pre-injection LH levels and LH responses to GnRH (P < 0.001) resulted from ovariectomy but there were no differences in either parameter between control and androgenised ewes either before or after ovariectomy. It is concluded that since pre-natal androgenisation altered neither pituitary gonadotrophic activity nor pituitary or hypothalamic steroid negative feedback activity, the depressed basal LH secretion reported earlier in pre-natally androgenised lambs (Wilson & Tarttelin 1978) was probably due to impairment of hypothalamic production and/or release of endogenous GnRH rather than to modification of pituitary gland function.

scholarly journals Age disrupts androgen receptor-modulated negative feedback in the gonadal axis in healthy men

2010 ◽  
Vol 299 (4) ◽  
pp. E675-E682 ◽  
Author(s):  
Johannes D. Veldhuis ◽  
Paul Y. Takahashi ◽  
Daniel M. Keenan ◽  
Peter Y. Liu ◽  
Kristi L. Mielke ◽  
...  
Keyword(s):  
Androgen Receptor ◽  
Negative Feedback ◽  
Pulse Frequency ◽  
Analysis Of Covariance ◽  
Double Blind ◽  
Healthy Men ◽  
Age Related ◽  
Lh Release ◽  
Lh Secretion ◽  
Double Blind Crossover Study

Testosterone (T) exerts negative feedback on the hypothalamo-pituitary (GnRH-LH) unit, but the relative roles of the CNS and pituitary are not established. We postulated that relatively greater LH responses to flutamide (brain-permeant antiandrogen) than bicalutamide (brain-impermeant antiandrogen) should reflect greater feedback via CNS than pituitary/peripheral androgen receptor-dependent pathways. To this end, 24 healthy men ages 20–73 yr, BMI 21–32 kg/m2, participated in a prospective, placebo-controlled, randomized, double-blind crossover study of the effects of antiandrogen control of pulsatile, basal, and entropic (pattern regularity) measurements of LH secretion. Analysis of covariance revealed that flutamide but not bicalutamide 1) increased pulsatile LH secretion ( P = 0.003), 2) potentiated the age-related abbreviation of LH secretory bursts ( P = 0.025), 3) suppressed incremental GnRH-induced LH release ( P = 0.015), and 4) decreased the regularity of GnRH-stimulated LH release ( P = 0.012). Furthermore, the effect of flutamide exceeded that of bicalutamide in 1) raising mean LH ( P = 0.002) and T ( P = 0.017) concentrations, 2) accelerating LH pulse frequency ( P = 0.013), 3) amplifying total (basal plus pulsatile) LH ( P = 0.002) and T ( P < 0.001) secretion, 4) shortening LH secretory bursts ( P = 0.032), and 5) reducing LH secretory regularity ( P < 0.001). Both flutamide and bicalutamide elevated basal (nonpulsatile) LH secretion ( P < 0.001). These data suggest the hypothesis that topographically selective androgen receptor pathways mediate brain-predominant and pituitary-dependent feedback mechanisms in healthy men.

Oestradiol increases the extracellular levels of amine metabolites in the ewe hypothalamus during anoestrus: a microdialysis study

1992 ◽  
Vol 135 (3) ◽  
pp. 421-NP ◽  
Author(s):  
V. Gayrard ◽  
B. Malpaux ◽  
J. C. Thiéry
Keyword(s):  
Negative Feedback ◽  
Homovanillic Acid ◽  
Regulatory Mechanism ◽  
The Other ◽  
Mediobasal Hypothalamus ◽  
Extracellular Medium ◽  
Oestradiol Treatment ◽  
Microdialysis Study ◽  
Lh Secretion ◽  
Retrochiasmatic Area

ABSTRACT Giving a subcutaneous oestradiol implant during anoestrus to ovariectomized ewes inhibits pulsatile LH secretion. This effect results from an increased negative feedback of oestradiol and depends on the synthesis of biogenic amines, mainly from the mediobasal hypothalamus. In the present study, we examined the effect of oestradiol on the extracellular levels of amines and their metabolites. Eight ewes were sampled by microdialysis from the lateral retrochiasmatic area, including the dopaminergic A15 nucleus, during inhibition of LH secretion by long days. Two dialysis sessions were carried out on each ewe; one after a 10-day oestradiol treatment and the other one after 10 days without oestradiol treatment. Half of the ewes were first oestradiol-treated then untreated, the other half received the treatment in the reverse order. Oestradiol caused a decline in pulsatile LH secretion without affecting the secretion of prolactin. This steroid also led to a significant increase in the levels of amine metabolites: 3,4-dihydroxyphenylacetic acid, homovanillic acid and 5-hydroxyindolacetic acid in the extracellular medium. These results demonstrate the effect of oestradiol on aminergic activity as related to changes in hormonal secretions during long days (16 h of light per 24 h). Thus our data support the hypothesis that amines inhibit gonadotrophic secretion during anoestrus in the ewe and suggest that there is an activation of the aminergic neurones from the retrochiasmatic area in this regulatory mechanism. Journal of Endocrinology (1992) 135, 421–430

scholarly journals Probabilistic reversal learning under acute tryptophan depletion in healthy humans: a conventional analysis

2020 ◽  
Vol 34 (5) ◽  
pp. 580-583
Author(s):  
Jonathan W Kanen ◽  
Frederique E Arntz ◽  
Robyn Yellowlees ◽  
Rudolf N Cardinal ◽  
Annabel Price ◽  
...  
Keyword(s):  
Reversal Learning ◽  
Negative Feedback ◽  
Acute Tryptophan Depletion ◽  
Tryptophan Depletion ◽  
Serotonin Synthesis ◽  
Male And Female ◽  
Healthy Humans ◽  
Enhanced Sensitivity ◽  
Conventional Analysis ◽  
Probabilistic Reversal Learning

The involvement of serotonin in responses to negative feedback is well established. Acute serotonin reuptake inhibition has enhanced sensitivity to negative feedback (SNF), modelled by behaviour in probabilistic reversal learning (PRL) paradigms. Whilst experiments employing acute tryptophan depletion (ATD) in humans, to reduce serotonin synthesis, have shown no clear effect on SNF, sample sizes have been small. We studied a large sample of healthy volunteers, male and female, and found ATD had no effect on core behavioural measures in PRL. These results indicate that ATD effects can differ from other manipulations of serotonin expected to have a parallel or opposing action.

scholarly journals 5-HT1 and 5-HT2 receptor activation reduces N-methyl-D-aspartate (NMDA)-stimulated LH secretion in prepubertal male and female rats

2003 ◽  
pp. 121-127 ◽  
Author(s):  
L Pinilla ◽  
LC Gonzalez ◽  
M Tena-Sempere ◽  
E Aguilar
Keyword(s):  
Methyl Ester ◽  
Receptor Activation ◽  
Female Rats ◽  
Receptor Subtypes ◽  
Serotoninergic System ◽  
Gonadotropin Secretion ◽  
Male And Female ◽  
Receptor Agonists ◽  
Male And Female Rats ◽  
Lh Secretion

OBJECTIVE: Excitatory amino acids and serotonin are involved in the control of gonadotropin secretion. The actions of these neurotransmitters are interconnected and recently we have reported that 5-HT(1) and 5-HT(2) receptor agonists blunted (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-stimulated GH secretion in prepubertal rats. The present experiments were carried out to analyze the effects of activation of different 5-hydroxytryptamine (5-HT) receptor subtypes on gonadotropin secretion and their role in the N-methyl-d-aspartate (NMDA)-stimulated LH release. DESIGN AND METHODS: We analyzed the gonadotropin secretion after manipulation of serotoninergic and aminoacidergic systems and their interactions in 5-, 16- and 23-day-old male and female rats. To this end, serum LH and FSH concentrations were measured in rats treated with 5-hydroxytryptophan methyl ester (5-HTP) (a precursor of 5-HT synthesis) plus Fluoxetine (Fx, a blocker of 5-HT reuptake), d,l-p-chlorophenyl-alanine methyl ester (PCPA, a blocker of 5-HT synthesis), R-(+)-8-hydroxydipropylaminotetralin hydrobromide (8-OH-DPAT, an agonist of 5-HT(1A) receptors), (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI) and alpha-methyl-5-hydroxytryptamine (alpha-Me-5-HT, agonists of 5-HT(2) receptors), and 1-Phenylbiguanide (1-PHE an agonist of 5-HT(3) receptors). In addition, the effects of 8-OH-DPAT and DOI on NMDA-stimulated LH secretion were analyzed. RESULTS: Neither the activation nor blockade of the serotoninergic system modified LH secretion. Basal gonadotropin secretion remained unchanged in 23-day-old male and female rats after activation of 5-HT(1A), 5-HT(2) and 5-HT(3) receptors. The stimulatory effect of NMDA on LH secretion was blocked in both sexes after activation of the serotoninergic system, through specific 5-HT(1) and 5-HT(2) receptor agonists. CONCLUSIONS: Activation of serotoninergic receptors decreased the stimulatory effect of NMDA on LH secretion in prepubertal male and female rats.

scholarly journals Evidence that Orphanin FQ Mediates Progesterone Negative Feedback in the Ewe

Endocrinology ◽  
2013 ◽  
Vol 154 (11) ◽  
pp. 4249-4258 ◽  
Author(s):  
Casey C Nestor ◽  
Lique M. Coolen ◽  
Gail L. Nesselrod ◽  
Miro Valent ◽  
John M. Connors ◽  
...  
Keyword(s):  
Estrogen Receptor ◽  
Negative Feedback ◽  
Luteal Phase ◽  
Arcuate Nucleus ◽  
Pulse Amplitude ◽  
Estrogen Receptor Α ◽  
Pulse Frequency ◽  
Orphanin Fq ◽  
High Degree ◽  
Lh Secretion

Orphanin FQ (OFQ), a member of the opioid family, is found in many areas of the hypothalamus and, when given centrally OFQ inhibits episodic LH secretion in rodents and sheep. Because GnRH neurons are devoid of the appropriate receptors to mediate steroid negative feedback directly, neurons that release OFQ may be involved. Using immunocytochemistry, we first determined that most OFQ neurons in the arcuate nucleus (ARC) and other hypothalamic regions of luteal phase ewes contained both estrogen receptor α and progesterone (P) receptor. Given a similar high degree of steroid receptor colocalization in other ARC subpopulations, we examined whether OFQ neurons of the ARC contained those other neuropeptides and neurotransmitters. OFQ did not colocalize with kisspeptin, tyrosine hydroxylase, or agouti-related peptide, but all ARC OFQ neurons coexpressed proopiomelanocortin. To test for a role for endogenous OFQ, we examined the effects of an OFQ receptor antagonist, [Nphe1,Arg14,Lys15]Nociceptin-NH2 (UFP-101) (30 nmol intracerebroventricular/h), on LH secretion in steroid-treated ewes in the breeding season and ovary-intact ewes in anestrus. Ovariectomized ewes with luteal phase concentrations of P and estradiol showed a significant increase in LH pulse frequency during infusion of UFP-101 (4.5 ± 0.5 pulses/6 h) compared with saline infusion (2.6 ± 0.4 pulses/6 h), whereas ewes implanted with only estradiol did not. Ovary-intact anestrous ewes displayed no significant differences in LH pulse amplitude or frequency during infusion of UFP-101. Therefore, we conclude that OFQ mediates, at least in part, the negative feedback action of P on GnRH/LH pulse frequency in sheep.

EFFECTS OF GONADECTOMY AND OESTRADIOL TREATMENT ON PLASMA LUTEINIZING HORMONE CONCENTRATIONS IN THE MARMOSET MONKEY, CALLITHRIX JACCHUS

1978 ◽  
Vol 76 (2) ◽  
pp. 271-281 ◽  
Author(s):  
J. K. HODGES
Keyword(s):  
Luteinizing Hormone ◽  
Negative Feedback ◽  
Positive Feedback ◽  
Pituitary Hormones ◽  
Male And Female ◽  
Oestradiol Treatment ◽  
Marmoset Monkey ◽  
Biphasic Effect ◽  
Clear Increase

A heterologous double-antibody radioimmunoassay for marmoset LH is described in detail. The system uses NIAMDD rat LH-I-1 for iodination, NIAMDD rat LH-RP-1 as standard and anti-ovine rabbit LH 610V serum. The assay measures the level of marmoset LH in plasma and shows a maximum cross-reaction (B/Bo = 50%) of < 0·3% with other rat, human or bovine pituitary hormones. The heterologous assay has been applied to the measurement of the level of LH in the marmoset after gonadectomy and after the subsequent implantation of oestradiol-17β capsules. A clear increase in the concentration of LH in the plasma was observed by day 3 after gonadectomy and in most animals the level reached a plateau by day 9. The rates of increase in the concentration of LH and the maximum levels attained after gonadectomy were similar in male and female marmosets. The secretion of LH in long-term gonadectomized marmosets was episodic. In four of the marmosets studied, the frequency of the pulsatile discharges of LH was circhoral, whereas in the remaining five animals the frequency could not be determined. Subcutaneous implants containing oestradiol-17β were seen to have a biphasic effect on the secretion of LH in all gonadectomized marmosets. After a transient increase in the concentration of LH (positive feedback) on day 1, levels fell markedly by day 4 and were undetectable 8 days after the implants were introduced (negative feedback).

scholarly journals Changes in LH secretion in response to an estradiol challenge in male- and female-oriented rams and in ewes

Reproduction ◽  
2008 ◽  
Vol 135 (5) ◽  
pp. 733-738 ◽  
Author(s):  
F Stormshak ◽  
C T Estill ◽  
J A Resko ◽  
C E Roselli
Keyword(s):  
Sexual Behaviors ◽  
Sexual Attraction ◽  
Neural Mechanisms ◽  
Sexual Receptivity ◽  
Male And Female ◽  
Lh Surge ◽  
Female Type ◽  
Initial Reduction ◽  
17Β Estradiol ◽  
Lh Secretion

Two experiments were conducted to determine whether an estradiol challenge could cause a female-type LH surge in castrated male- and female-oriented rams (MORs and FORs). Administration of 17β-estradiol to castrated MORs and FORs and ovariectomized ewes caused an initial reduction in LH secretion followed for 12–20 h by a surge release of LH in the ewes. No surge release of LH occurred in the MORs and FORs. The pattern of changes in LH secretion within rams and ewes did not differ between the breeding and nonbreeding seasons. Treatment failed to elicit female-typical receptive sexual behaviors in the rams but did stimulate increased sexual receptivity in the ewes as determined by the measures of responsiveness to the teaser ram. Overall, no differences were found in hypothalamic–hypophyseal function in response to exogenous estradiol between MORs and FORs. These data are interpreted to suggest that in contrast to sexual attraction, the neural mechanisms controlling the LH surge and female receptivity are defeminized in MORs.

Reciprocity of Liking following Face-to-Face Encounters with Attractive and Unattractive others

1986 ◽  
Vol 59 (2) ◽  
pp. 599-609 ◽  
Author(s):  
Warner Wilson ◽  
Wilma Henzlik
Keyword(s):  
Negative Feedback ◽  
Introductory Psychology ◽  
Female Students ◽  
The Other ◽  
Strong Tendency ◽  
Male And Female ◽  
Face To Face ◽  
Opposite Sex

48 male and female students in introductory psychology engaged in a get acquainted conversation with a confederate of the opposite sex. After the conversation, the experimenter asked each person to rate the other and indicated that they would then see each other's ratings as a part of the acquaintance process. Immediately after the first ratings were exchanged, however, the experimenter asked both subjects for a second confidential rating. According to prior instructions, the confederate gave either positive (7 to 9) or negative (3 to 6) preliminary ratings. The second rating, which was of liking, showed a strong tendency for the subjects to reciprocate the favorability of the first ratings made of them by the confederate. Attractive more than unattractive confederates were better liked. In contrast to previous research, however, data showed no tendency for subjects to respond more strongly to positive or negative feedback from an attractive rather than from an unattractive other.

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