scholarly journals Lactational Anovulation in Mice Results From a Selective Loss of Kisspeptin Input to GnRH Neurons

Endocrinology ◽  
2014 ◽  
Vol 155 (1) ◽  
pp. 193-203 ◽  
Author(s):  
X. Liu ◽  
R.S.E. Brown ◽  
A.E. Herbison ◽  
D.R. Grattan
Keyword(s):  
Brain Slice ◽  
Third Ventricle ◽  
Late Pregnancy ◽  
Mrna Levels ◽  
Fiber Density ◽  
Selective Loss ◽  
Fold Reduction ◽  
Gnrh Neurons ◽  
Periventricular Area ◽  
Brain Slice Preparation

In mammals, lactation is associated with a period of infertility characterized by the loss of pulsatile secretion of GnRH and cessation of ovulatory cycles. Despite the importance of lactational infertility in determining overall fecundity of a species, the mechanisms by which the suckling stimulus suppresses GnRH secretion remain unclear. Because kisspeptin neurons are critical for fertility, the aim of this study was to test the hypothesis that reduced kisspeptin expression might mediate the lactation-induced suppression of fertility, using mouse models. In the rostral periventricular area of the third ventricle (RP3V), a progressive decrease in RP3V Kiss1 mRNA levels was observed during pregnancy culminating in a 10-fold reduction during lactation compared with diestrous controls. This was associated with approximately 60% reduction in the numbers of kisspeptin-immunoreactive neurons in the RP3V detected during lactation. Similarly, in the arcuate nucleus there was also a significant decrease in Kiss1 mRNA levels during late pregnancy and midlactation, and a notable decrease in kisspeptin fiber density during lactation. The functional characteristics of the RP3V kisspeptin input to GnRH neurons were assessed using electrophysiological approaches in an acute brain slice preparation. Although endogenous RP3V kisspeptin neurons were found to activate GnRH neurons in diestrous mice, this was never observed during lactation. This did not result from an absence of kisspeptin receptors because GnRH neurons responded normally to 100 nM exogenous kisspeptin during lactation. The kisspeptin deficit in lactating mice was selective, because GnRH neurons responded normally to RP3V gamma aminobutryic acid inputs during lactation. These data demonstrate that a selective loss of RP3V kisspeptin inputs to GnRH neurons during lactation is the likely mechanism causing lactational anovulation in the mouse.

scholarly journals Expression of type one cannabinoid receptor in different subpopulation of kisspeptin neurons and kisspeptin afferents to GnRH neurons in female mice

2021 ◽  
Author(s):  
Tamás Wilheim ◽  
Krisztina Nagy ◽  
Mahendravarman Mohanraj ◽  
Kamil Ziarniak ◽  
Masahiko Watanabe ◽  
...  
Keyword(s):  
Cannabinoid Receptor ◽  
Third Ventricle ◽  
Glutamate Transporter ◽  
Neuroendocrine Cells ◽  
Receptor Protein ◽  
Specific Expression ◽  
Female Mice ◽  
Gnrh Neurons ◽  
Periventricular Area ◽  
Cycle Dependent

AbstractThe endocannabinoids have been shown to target the afferents of hypothalamic neurons via cannabinoid 1 receptor (CB1) and thereby to influence their excitability at various physiological and/or pathological processes. Kisspeptin (KP) neurons form afferents of multiple neuroendocrine cells and influence their activity via signaling through a variation of co-expressed classical neurotransmitters and neuropeptides. The differential potency of endocannabinoids to influence the release of classical transmitters or neuropeptides, and the ovarian cycle-dependent functioning of the endocannabinoid signaling in the gonadotropin-releasing hormone (GnRH) neurons initiated us to study whether (a) the different subpopulations of KP neurons express CB1 mRNAs, (b) the expression is influenced by estrogen, and (c) CB1-immunoreactivity is present in the KP afferents to GnRH neurons. The aim of the study was to investigate the site- and cell-specific expression of CB1 in female mice using multiple labeling in situ hybridization and immunofluorescent histochemical techniques. The results support that CB1 mRNAs are expressed by both the GABAergic and glutamatergic subpopulations of KP neurons, the receptor protein is detectable in two-thirds of the KP afferents to GnRH neurons, and the expression of CB1 mRNA shows an estrogen-dependency. The applied estrogen-treatment, known to induce proestrus, reduced the level of CB1 transcripts in the rostral periventricular area of the third ventricle and arcuate nucleus, and differently influenced its co-localization with vesicular GABA transporter or vesicular glutamate transporter-2 in KP neurons. This indicates a gonadal cycle-dependent role of endocannabinoid signaling in the neuronal circuits involving KP neurons.

scholarly journals Genetic Deletion of Esr1 in the Mouse Preoptic Area Disrupts the LH Surge and Estrous Cyclicity

Endocrinology ◽  
2019 ◽  
Vol 160 (8) ◽  
pp. 1821-1829 ◽  
Author(s):  
Robert Porteous ◽  
Allan E Herbison
Keyword(s):  
Estrogen Receptor ◽  
Third Ventricle ◽  
Estrogen Receptor Α ◽  
Adeno Associated Virus ◽  
Estrous Cycles ◽  
Lh Surge ◽  
Periventricular Nucleus ◽  
Gnrh Neurons ◽  
Estrous Cyclicity ◽  
Periventricular Area

Abstract Estrogen receptor α (ESR1) is critical for the generation of the preovulatory LH surge. Experiments in rodents have indicated a role for neurons located in the anteroventral periventricular area and preoptic periventricular nucleus [termed the rostral periventricular area of the third ventricle (RP3V)] in surge generation. In the current study, we aimed to examine whether ESR1 expressed by RP3V neurons was necessary for the LH surge. The estrous cycles of mice with estrogen receptor α (Esr1) exon 3 flanked by LoxP sites (Esr1 flox) and controls were monitored before and after bilateral stereotactic injection of adeno-associated virus encoding Cre recombinase into the RP3V. This resulted in 84% and 72% decreases in ESR1-immunoreactive cell numbers in the anteroventral periventricular area and preoptic periventricular nucleus, respectively, with no changes in the arcuate nucleus. Beginning three weeks after the adeno-associated virus injection, Esr1 flox mice began to show a loss of estrous cyclicity going, primarily, into constant estrus. Wild-type mice and Esr1 flox mice with injections outside the RP3V or unilateral ablations of ESR1 continued to exhibit normal estrous cycles. Mice were then gonadectomized and given an estradiol replacement regimen to generate the LH surge. This resulted in an absence of cFOS expression in GnRH neurons (1 ± 1% vs 28 ± 4% of GnRH neurons; P < 0.01) and markedly reduced LH surge levels (2.5 ± 0.6 vs 9.1 ± 1.0 ng/mL; P < 0.01) in Esr1 flox mice compared with controls. These results demonstrate that neurons expressing ESR1 within the RP3V are critical for the generation of the LH surge and estrous cyclicity in the mouse.

scholarly journals GnRH Neuron Firing and Response to GABA in Vitro Depend on Acute Brain Slice Thickness and Orientation

Endocrinology ◽  
2012 ◽  
Vol 153 (8) ◽  
pp. 3758-3769 ◽  
Author(s):  
Stephanie Constantin ◽  
Richard Piet ◽  
Karl Iremonger ◽  
Shel Hwa Yeo ◽  
Jenny Clarkson ◽  
...  
Keyword(s):  
Brain Slice ◽  
Gabab Receptor ◽  
Gabab Receptors ◽  
In Vivo Studies ◽  
Slice Thickness ◽  
Gnrh Neuron ◽  
Slice Preparation ◽  
Gnrh Neurons ◽  
Brain Slice Preparation

The GnRH neurons exhibit long dendrites and project to the median eminence. The aim of the present study was to generate an acute brain slice preparation that enabled recordings to be undertaken from GnRH neurons maintaining the full extent of their dendrites or axons. A thick, horizontal brain slice was developed, in which it was possible to record from the horizontally oriented GnRH neurons located in the anterior hypothalamic area (AHA). In vivo studies showed that the majority of AHA GnRH neurons projected outside the blood-brain barrier and expressed c-Fos at the time of the GnRH surge. On-cell recordings compared AHA GnRH neurons in the horizontal slice (AHAh) with AHA and preoptic area (POA) GnRH neurons in coronal slices [POA coronal (POAc) and AHA coronal (AHAc), respectively]. AHAh GnRH neurons exhibited tighter burst firing compared with other slice orientations. Although α-Amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) excited GnRH neurons in all preparations, γ-aminobutyric acid (GABA) was excitatory in AHAc and POAc but inhibitory in AHAh slices. GABAA receptor postsynaptic currents were the same in AHAh and AHAc slices. Intriguingly, direct activation of GABAA or GABAB receptors respectively stimulated and inhibited GnRH neurons regardless of slice orientation. Subsequent experiments indicated that net GABA effects were determined by differences in the ratio of GABAA and GABAB receptor-mediated effects in “long” and “short” dendrites of GnRH neurons in the different slice orientations. These studies document a new brain slice preparation for recording from GnRH neurons with their extensive dendrites/axons and highlight the importance of GnRH neuron orientation relative to the angle of brain slicing in studying these neurons in vitro.

23. A new adult rat brain slice preparation for ex vivo NMR spectroscopy studies of stroke

1994 ◽  
Vol 52 (1) ◽  
pp. A11
Author(s):  
M.T. Espanol ◽  
L. Litt ◽  
L.-H. Chang ◽  
T.L. James ◽  
P.R. Weinstein ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Rat Brain ◽  
Brain Slice ◽  
Ex Vivo ◽  
Slice Preparation ◽  
Adult Rat ◽  
Adult Rat Brain ◽  
Spectroscopy Studies ◽  
Rat Brain Slice ◽  
Brain Slice Preparation

scholarly journals Tonic Extrasynaptic GABAA Receptor Currents Control Gonadotropin-Releasing Hormone Neuron Excitability in the Mouse

Endocrinology ◽  
2011 ◽  
Vol 152 (4) ◽  
pp. 1551-1561 ◽  
Author(s):  
Janardhan P. Bhattarai ◽  
Seon Ah Park ◽  
Jin Bong Park ◽  
So Yeong Lee ◽  
Allan E. Herbison ◽  
...  
Keyword(s):  
Gabaa Receptor ◽  
Gabaa Receptors ◽  
Brain Slice ◽  
Resting Membrane Potential ◽  
Receptor Signaling ◽  
Gaba Transporter ◽  
Gnrh Neurons ◽  
Inward Currents ◽  
Synaptic Receptors ◽  
Tonic Current

Abstract It is well established that the GABAA receptor plays an important role in regulating the electrical excitability of GnRH neurons. Two different modes of GABAA receptor signaling exist: one mediated by synaptic receptors generating fast (phasic) postsynaptic currents and the other mediated by extrasynaptic receptors generating a persistent (tonic) current. Using GABAA receptor antagonists picrotoxin, bicuculline methiodide, and gabazine, which differentiate between phasic and tonic signaling, we found that ∼50% of GnRH neurons exhibit an approximately 15-pA tonic GABAA receptor current in the acute brain slice preparation. The blockade of either neuronal (NO711) or glial (SNAP-5114) GABA transporter activity within the brain slice revealed the presence of tonic GABA signaling in ∼90% of GnRH neurons. The GABAA receptor δ subunit is only found in extrasynaptic GABAA receptors. Using single-cell RT-PCR, GABAA receptor δ subunit mRNA was identified in GnRH neurons and the δ subunit–specific agonist 4,5,6,7-tetrahydroisoxazolo [5,4-c] pyridin-3-ol was found to activate inward currents in GnRH neurons. Perforated-patch clamp studies showed that 4,5,6,7-tetrahydroisoxazolo [5,4-c] pyridin-3-ol exerted the same depolarizing or hyperpolarizing effects as GABA on juvenile and adult GnRH neurons and that tonic GABAA receptor signaling regulates resting membrane potential. Together, these studies reveal the presence of a tonic GABAA receptor current in GnRH neurons that controls their excitability. The level of tonic current is dependent, in part, on neuronal and glial GABA transporter activity and mediated by extrasynaptic δ subunit–containing GABAA receptors.

Specificity in the Interaction of HVA Ca2+ Channel Types With Ca2+-Dependent AHPs and Firing Behavior in Neocortical Pyramidal Neurons

1998 ◽  
Vol 79 (5) ◽  
pp. 2522-2534 ◽  
Author(s):  
Juan Carlos Pineda ◽  
Robert S. Waters ◽  
Robert C. Foehring
Keyword(s):  
Brain Slice ◽  
Pyramidal Neurons ◽  
Repetitive Firing ◽  
Channel Blockers ◽  
Firing Behavior ◽  
Inward Currents ◽  
Functional Consequences ◽  
P Type ◽  
Brain Slice Preparation ◽  
Neocortical Pyramidal Neurons

Pineda, Juan Carlos, Roberts S. Waters, and Robert C. Foehring. Specificity in the interaction of HVA Ca2+ channel types with Ca2+-dependent AHPs and firing behavior in neocortical pyramidal neurons. J. Neurophysiol. 79: 2522–2534, 1998. Intracellular recordings and organic and inorganic Ca2+ channel blockers were used in a neocortical brain slice preparation to test whether high-voltage–activated (HVA) Ca2+ channels are differentially coupled to Ca2+-dependent afterhyperpolarizations (AHPs) in sensorimotor neocortical pyramidal neurons. For the most part, spike repolarization was not Ca2+ dependent in these cells, although the final phase of repolarization (after the fast AHP) was sensitive to block of N-type current. Between 30 and 60% of the medium afterhyperpolarization (mAHP) and between ∼80 and 90% of the slow AHP (sAHP) were Ca2+ dependent. Based on the effects of specific organic Ca2+ channel blockers (dihydropyridines, ω-conotoxin GVIA, ω-agatoxin IVA, and ω-conotoxin MVIIC), the sAHP is coupled to N-, P-, and Q-type currents. P-type currents were coupled to the mAHP. L-type current was not involved in the generation of either AHP but (with other HVA currents) contributes to the inward currents that regulate interspike intervals during repetitive firing. These data suggest different functional consequences for modulation of Ca2+ current subtypes.

scholarly journals Pup removal suppresses estrogen-induced surges of LH secretion and activation of GnRH neurons in lactating rats

2006 ◽  
Vol 191 (1) ◽  
pp. 339-348 ◽  
Author(s):  
Atsushi Fukushima ◽  
Ping Yin ◽  
Maho Ishida ◽  
Nobuhiro Sugiyama ◽  
Jun Arita
Keyword(s):  
Third Ventricle ◽  
Acute Effect ◽  
Suppressive Effect ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Indwelling Catheter ◽  
Lh Surge ◽  
Gnrh Neurons ◽  
Double Immunohistochemical Staining ◽  
Lh Secretion

During lactation, the suckling stimulus exerts profound influences on neuroendocrine regulation in nursing rats. We examined the acute effect of pup removal on the estrogen-induced surge of LH secretion in ovariectomized lactating rats. Lactating and nonlactating cyclic female rats were given an estradiol-containing capsule after ovariectomy, and blood samples were collected through an indwelling catheter for serum LH determinations. In lactating, freely suckled ovariectomized rats, estrogen treatment induced an afternoon LH surge with a magnitude and timing comparable to those seen in nonlactating rats. Removal of pups from the lactating rats at 0900, 1100, or 1300 h, but not at 1500 h, suppressed the estrogen-induced surge that normally occurs in the afternoon of the same day. The suppressive effect of pup removal at 0900 h was completely abolished when the pups were returned by 1400 h. In contrast, pup removal was ineffective in abolishing the stimulatory effect of progesterone on LH surges. Double immunohistochemical staining for gonadotropin-releasing hormone (GnRH) and c-Fos, a marker for neuronal activation, revealed a decrease, concomitantly with the suppression of LH surges, in the number of c-Fos-immunoreactive GnRH neurons in the preoptic regions of nonsuckled rats. An LH surge was restored in nonsuckled rats when 0.1 μg oxytocin was injected into the third ventricle three times at 1-h intervals during pup removal. These results suggest that the GnRH surge generator of lactating rats requires the suckling stimulus that is not involved in nonlactating cyclic female rats.

Differential expression of Isk mRNAs in mouse tissue during development and pregnancy

1994 ◽  
Vol 267 (3) ◽  
pp. C700-C705 ◽  
Author(s):  
A. Felipe ◽  
T. J. Knittle ◽  
K. L. Doyle ◽  
D. J. Snyders ◽  
M. M. Tamkun
Keyword(s):  
Cardiac Tissue ◽  
Tumor Cell Line ◽  
Late Pregnancy ◽  
Perinatal Period ◽  
Mouse Tissue ◽  
Mouse Heart ◽  
Mrna Levels ◽  
Complete Study ◽  
Pregnancy And Delivery ◽  
Atrial Tumor

The molecular isoform of the cDNA clone Isk present in the AT-1 atrial tumor cell line was characterized by molecular cloning of Isk cDNA. Since Isk mRNA was found in mouse heart, kidney, and uterus, a complete study of its expression during development in the heart and kidney was performed, in addition to its expression in the uterus during pregnancy. In the heart, Isk showed a 4-fold upregulation during the perinatal period followed by a 20-fold decrease between birth and the adult state. Furthermore, the two 0.9- and 3.4-kb transcripts were differentially regulated after birth. In the kidney, Isk progressively increased 10-fold, reaching steady-state adult values at 21 days. Isk mRNA levels in the uterus increased threefold at late pregnancy and decreased sixfold rapidly after birth. The Isk gene is differentially expressed during development in kidney and cardiac tissue, and both Isk transcripts appeared to be differentially regulated. Furthermore, the drastic changes in transcript levels before delivery and after birth suggest that Isk plays a significant role in myometrium during late pregnancy and delivery.

Sign in / Sign up

Export Citation Format

Share Document