Prenatal Androgens Defeminize Activation of GnRH Neurons in Response to Estradiol Stimulation

Wood, Ruth I.; Kim, Sung-Ji; Foster, Douglas L.

doi:10.1111/j.1365-2826.1996.tb00697.x

Cited by 16 publications

(4 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The specificity of the antibodies used has been previously assessed by the absorption test (see Alonso, 1988 for anti‐VP and anti‐OT; Arluison et al ., 1984 for anti‐TH; Bras et al ., 1986 for anti‐5HT, Lewis et al ., 1993 for monoclonal anti‐TH; Wood et al ., 1996 for anti‐cFos). Moreover, no fluorescence was detected in controls that consisted of (i) examining sections of brains that had not received injections of retrograde tracers, (ii) exciting each retrograde tracer with an inappropriate wave‐length, (iii) applying extravidin–CY3 onto sections of brains that had not received injections of the anterograde tracer BDA, and (iv) omitting the primary antibodies and applying the secondary antibodies alone.…”

Section: Methodsmentioning

confidence: 99%

Synchronization of oxytocin neurons in suckled rats: possible role of bilateral innervation of hypothalamic supraoptic nuclei by single medullary neurons

Moos

Marganiec²,

Fontanaud

et al. 2004

Eur J of Neuroscience

View full text Add to dashboard Cite

We have previously shown that oxytocin neurons located in the four hypothalamic magnocellular nuclei display synchronous bursts of action potentials before each milk ejection. The mechanisms involved in such a synchronization have, however, not yet been elucidated. In this study, we test the hypothesis of an extranuclear synchronization arising from a common extrahypothalamic input innervating bilateral magnocellular nuclei. First, two different retrograde tracers were injected into the right and left supraoptic nuclei of rats that were fixed 5-7 days later. Each tracer labelled numerous neurons in various brain regions ipsilateral or contralateral to the injection site, but colocalization of the two tracers within the same cell body could only be detected bilaterally in neurons in the ventromedial regions of the medulla oblongata. The axonal projections of these medullary neurons were then visualized by the unilateral microinjection of an anterograde tracer (BDA) within the ventromedial medulla oblongata. BDA-labelled axons afferent to the hypothalamus were found to branch towards both supraoptic nuclei through medial portions of the optic chiasma. Finally, in anaesthetized lactating rats, surgical lesions were placed medially through the optic chiasma and the electrical activity of oxytocin neurons in bilateral supraoptic nuclei was pair-recorded during suckling. The incidence of synchronous bursts in oxytocin neurons located within bilateral supraoptic nuclei were dramatically altered only when the medial portions of the optic chiasma were totally lesioned. Taken together, these data suggest that medullary neurons afferent to bilateral supraoptic nuclei are involved in the recruitment and synchronization of bursting in oxytocin neurons during suckling.

show abstract

Section: Methodsmentioning

confidence: 99%

Synchronization of oxytocin neurons in suckled rats: possible role of bilateral innervation of hypothalamic supraoptic nuclei by single medullary neurons

Moos

Marganiec²,

Fontanaud

et al. 2004

Eur J of Neuroscience

View full text Add to dashboard Cite

show abstract

“…Prenatal T-and DHT-treated sheep were generated by intramuscular administration of 100 mg of 1.2 mg/kg T propionate (Sigma-Aldrich Corp.) or 100 mg of DHT propionate (Steraloids, Inc.) suspended in cottonseed oil to pregnant ewes twice weekly from Days 30 to 90 of gestation. The doses of T and DHT were chosen to mimic doses used in all our earlier studies [31,32] to enable relating findings from this study to earlier outcomes. Control breeders , KDR, and FLT4 immunostaining in primordial/primary, preantral, and antral follicles.…”

Section: Breeding and Prenatal Treatmentmentioning

confidence: 99%

Developmental Programming: Does Prenatal Steroid Excess Disrupt the Ovarian VEGF System in Sheep?1

Ortega

Veiga-López

Sreedharan

et al. 2015

Biology of Reproduction

View full text Add to dashboard Cite

Prenatal testosterone (T), but not dihydrotestosterone (DHT), excess disrupts ovarian cyclicity and increases follicular recruitment and persistence. We hypothesized that the disruption in the vascular endothelial growth factor (VEGF) system contributes to the enhancement of follicular recruitment and persistence in prenatal T-treated sheep. The impact of T/DHT treatments from Days 30 to 90 of gestation on VEGFA, VEGFB, and their receptor (VEGFR-1 [FLT1], VEGFR-2 [KDR], and VEGFR-3 [FLT4]) protein expression was examined by immunohistochemistry on Fetal Days 90 and 140, 22 wk, 10 mo (postpubertal), and 21 mo (adult) of age. Arterial morphometry was performed in Fetal Day 140 and postpubertal ovaries. VEGFA and VEGFB expression were found in granulosa cells at all stages of follicular development with increased expression in antral follicles. VEGFA was present in theca interna, while VEGFB was present in theca interna/externa and stromal cells. All three receptors were expressed in the granulosa, theca, and stromal cells during all stages of follicular development. VEGFR-3 increased with follicular differentiation with the highest level seen in the granulosa cells of antral follicles. None of the members of the VEGF family or their receptor expression were altered by age or prenatal T/DHT treatments. At Fetal Day 140, area, wall thickness, and wall area of arteries from the ovarian hilum were larger in prenatal T- and DHT-treated females, suggestive of early androgenic programming of arterial differentiation. This may facilitate increased delivery of endocrine factors and thus indirectly contribute to the development of the multifollicular phenotype.

show abstract

“…The oestrogen positive‐feedback mechanism that leads to the pre‐ovulatory GnRH/LH surge is exhibited solely by the females of most species. Male rodents and sheep are unable to mount an LH surge in response to oestrogen positive feedback (11–15). The ability to exhibit oestrogen positive feedback appears to be determined by a sexually dimorphic neural circuit that is established in early neonatal life depending upon gonadal steroid exposure (11, 16–18).…”

Section: Basic Tenets Of Oestrogen Positive Feedbackmentioning

confidence: 99%

Oestrogen, Kisspeptin, GPR54 and the Pre‐Ovulatory Luteinising Hormone Surge

Clarkson

Herbison

2009

J Neuroendocrinology

148

View full text Add to dashboard Cite

The gonadotrophin-releasing hormone (GnRH) neurones are the final output cells of a complex neuronal network that controls mammalian fertility. Rising levels of oestrogen secreted from the maturing follicle during the follicular phase of the oestrous cycle (1) trigger a massive and prolonged increase in GnRH secretion from the median eminence (2-9). This surge in GnRH secretion evokes the luteinising hormone (LH) surge from the anterior pituitary gland that induces ovulation. The mechanisms by which the rising follicular-phase levels of oestrogen exert a positive-feedback influence on the GnRH neurones are beginning to be elucidated.The possible mechanisms and dynamics of the oestrogen positive-feedback mechanism have been reviewed recently (10). The purpose of this review is not to recount all previous work on the subject, but to briefly introduce the pertinent points and discuss them specifically with regard to the role of kisspeptin-GPR54 signalling in the pre-ovulatory LH surge. Basic tenets of oestrogen positive feedback Oestrogen positive feedback is sexually dimorphicThe oestrogen positive-feedback mechanism that leads to the preovulatory GnRH/LH surge is exhibited solely by the females of most species. Male rodents and sheep are unable to mount an LH surge in response to oestrogen positive feedback (11)(12)(13)(14)(15). The ability to exhibit oestrogen positive feedback appears to be determined by a sexually dimorphic neural circuit that is established in early neonatal life depending upon gonadal steroid exposure (11, 16-18). By Ovulation is central to mammalian fertility, yet the precise mechanism through which oestrogen triggers the gonadotrophin-releasing hormone (GnRH) surge that generates the pre-ovulatory luteinising hormone (LH) surge has remained elusive. The recent discovery that kisspeptin-GPR54 signalling is an essential regulator of the neuroendocrine axis at puberty has led investigators to evaluate the role of kisspeptin in the pre-ovulatory GnRH surge mechanism. Kisspeptin neurones are known to express oestrogen and progesterone receptors and have their cell bodies located in brain regions implicated in the positive-feedback mechanism in several mammalian species. In rodents, kisspeptin neurones located in the rostral periventricular area of the third ventricle (RP3V) are positively regulated by oestrogen and most likely are activated by oestrogen at the time of positive feedback. A similar scenario appears to exist for a sub-population of kisspeptin neurones located in the mediobasal hypothalamus of sheep and primates. The majority of GnRH neurones express GPR54, and kisspeptin causes an intense electrical activation of these cells. In concordance with this, kisspeptin administration in vivo results in an abrupt and prolonged release of LH in all mammalian species examined to date. Functional evidence from immunoneutralisation and knockout studies suggests that RP3V kisspeptin neurones projecting to GnRH neurones are an essential component of the surge mechanism in rodents. Taken togethe...

show abstract

Prenatal Androgens Defeminize Activation of GnRH Neurons in Response to Estradiol Stimulation

Cited by 16 publications

References 37 publications

Synchronization of oxytocin neurons in suckled rats: possible role of bilateral innervation of hypothalamic supraoptic nuclei by single medullary neurons

Synchronization of oxytocin neurons in suckled rats: possible role of bilateral innervation of hypothalamic supraoptic nuclei by single medullary neurons

Developmental Programming: Does Prenatal Steroid Excess Disrupt the Ovarian VEGF System in Sheep?1

Oestrogen, Kisspeptin, GPR54 and the Pre‐Ovulatory Luteinising Hormone Surge

Contact Info

Product

Resources

About