scholarly journals Prenatal androgen treatment does not alter the firing activity of hypothalamic arcuate kisspeptin neurons in female mice

2021 ◽  
Author(s):  
Amanda G Gibson ◽  
Jennifer Jaime ◽  
Laura L Burger ◽  
Suzanne M Moenter
Keyword(s):  
Firing Rate ◽  
Polycystic Ovary ◽  
Developmental Trajectory ◽  
Dependent Manner ◽  
Gnrh Neuron ◽  
Neuron Firing ◽  
Firing Rates ◽  
Gnrh Neurons ◽  
Kndy Neurons

Neuroendocrine control of reproduction is disrupted in many individuals with polycystic ovary syndrome, who present with increased luteinizing hormone (LH), and presumably gonadotropin-releasing hormone (GnRH), release frequency, and high androgen levels. Prenatal androgenization (PNA) recapitulates these phenotypes in primates and rodents. Female offspring of mice injected with dihydrotestosterone (DHT) on gestational D16-18 exhibit disrupted estrous cyclicity, increased LH and testosterone, and increased GnRH neuron firing rate as adults. PNA also alters the developmental trajectory of GnRH neuron firing rates, markedly blunting the prepubertal peak in firing that occurs in 3wk-old controls. GnRH neurons do not express detectable androgen receptors and are thus probably not the direct target of DHT. Rather, PNA likely alters GnRH neuronal activity by modulating upstream neurons, such as hypothalamic arcuate neurons co-expressing kisspeptin, neurokinin B (gene Tac2), and dynorphin, aka KNDy neurons. We hypothesized PNA treatment changes firing rates of KNDy neurons in a similar age-dependent manner as GnRH neurons. We conducted targeted extracellular recordings (0.5-2h) of Tac2-identified KNDy neurons from control and PNA mice at 3wks of age and in adulthood. About half of neurons were quiescent (<0.005Hz). Long-term firing rates of active cells varied, suggestive of episodic activity, but were not different among groups. Short-term burst firing was also similar. We thus reject the hypothesis that PNA alters the firing rate of KNDy neurons. This does not preclude altered neurosecretory output of KNDy neurons, involvement of other neuronal populations, or in-vivo networks as critical drivers of altered GnRH firing rates in PNA mice.

scholarly journals Prenatal Androgenization Alters the Development of GnRH Neuron and Preoptic Area RNA Transcripts in Female Mice

Endocrinology ◽  
2020 ◽  
Vol 161 (11) ◽  
Author(s):  
Laura L Burger ◽  
Elizabeth R Wagenmaker ◽  
Chayarndorn Phumsatitpong ◽  
David P Olson ◽  
Suzanne M Moenter
Keyword(s):  
Protein Synthesis ◽  
Oxidative Phosphorylation ◽  
Polycystic Ovary ◽  
Affinity Purification ◽  
Developmental Trajectory ◽  
Late Gestation ◽  
Gnrh Neuron ◽  
Altered Expression ◽  
Increased Risk ◽  
Gnrh Neurons

Abstract Polycystic ovary syndrome (PCOS) is the most common form of infertility in women. The causes of PCOS are not yet understood and both genetics and early-life exposure have been considered as candidates. With regard to the latter, circulating androgens are elevated in mid–late gestation in women with PCOS, potentially exposing offspring to elevated androgens in utero; daughters of women with PCOS are at increased risk for developing this disorder. Consistent with these clinical observations, prenatal androgenization (PNA) of several species recapitulates many phenotypes observed in PCOS. There is increasing evidence that symptoms associated with PCOS, including elevated luteinizing hormone (LH) (and presumably gonadotropin-releasing hormone [GnRH]) pulse frequency emerge during the pubertal transition. We utilized translating ribosome affinity purification coupled with ribonucleic acid (RNA) sequencing to examine GnRH neuron messenger RNAs from prepubertal (3 weeks) and adult female control and PNA mice. Prominent in GnRH neurons were transcripts associated with protein synthesis and cellular energetics, in particular oxidative phosphorylation. The GnRH neuron transcript profile was affected more by the transition from prepuberty to adulthood than by PNA treatment; however, PNA did change the developmental trajectory of GnRH neurons. This included families of transcripts related to both protein synthesis and oxidative phosphorylation, which were more prevalent in adults than in prepubertal mice but were blunted in PNA adults. These findings suggest that prenatal androgen exposure can program alterations in the translatome of GnRH neurons, providing a mechanism independent of changes in the genetic code for altered expression.

scholarly journals Ovarian Androgens Maintain High GnRH Neuron Firing Rate in Adult Prenatally-Androgenized Female Mice

Endocrinology ◽  
2019 ◽  
Vol 161 (1) ◽  
Author(s):  
Eden A Dulka ◽  
Laura L Burger ◽  
Suzanne M Moenter
Keyword(s):  
Firing Rate ◽  
Fluorescent Protein ◽  
Polycystic Ovary ◽  
Neuron Activity ◽  
Gnrh Neuron ◽  
Neuron Firing ◽  
Dependent Change ◽  
Gnrh Release ◽  
Green Fluorescent ◽  
Reproductive Cycles

Abstract Changes in gonadotropin-releasing hormone (GnRH) release frequency from the brain help drive reproductive cycles. In polycystic ovary syndrome (PCOS), persistent high GnRH/luteinizing hormone (LH) frequency disrupts cycles and exacerbates hyperandrogenemia. Adult prenatally-androgenized (PNA) mice exhibit increased GnRH neuron firing rate, elevated ovarian androgens, and disrupted cycles, but before puberty, GnRH neuron activity is reduced in PNA mice compared with controls. We hypothesized that ovarian feedback mediates the age-dependent change in GnRH neuron firing rate in PNA vs control mice. Extracellular recordings of green fluorescent protein (GFP)-identified GnRH neurons were made 5 to 7 days after sham-surgery, ovariectomy (OVX), or, in adults, after OVX plus replacement of sub-male androgen levels with dihydrotestosterone implants (OVX + DHT). In 3-week-old mice, OVX did not affect GnRH neuron firing rate in either group. In adult controls, OVX increased GnRH neuron firing rate, which was further enhanced by DHT. In adult PNA mice, however, OVX decreased GnRH neuron firing rate, and DHT restored firing rate to sham-operated levels. In contrast to the differential effects of ovarian feedback on GnRH neuron firing rate, serum LH increased after OVX in both control and PNA mice and was not altered by DHT. Pituitary gene expression largely reflected changes expected with OVX, although in PNA but not control mice, DHT treatment increased Lhb expression. These results suggest prenatal androgen exposure programs marked changes in GnRH neuron regulation by homeostatic steroid feedback. PNA lowers GnRH neuron activity in low-steroid states (before puberty, OVX), and renders activity in adulthood dependent upon ongoing exposure to elevated ovarian androgens.

scholarly journals Androgens Increase Gonadotropin-Releasing Hormone Neuron Firing Activity in Females and Interfere with Progesterone Negative Feedback

Endocrinology ◽  
2006 ◽  
Vol 147 (3) ◽  
pp. 1474-1479 ◽  
Author(s):  
Justyna Pielecka ◽  
Samuel D. Quaynor ◽  
Suzanne M. Moenter
Keyword(s):  
Animal Models ◽  
Firing Rate ◽  
Negative Feedback ◽  
Brain Slices ◽  
Neuron Activity ◽  
Gnrh Neuron ◽  
Firing Activity ◽  
Neuron Firing ◽  
Gnrh Neurons ◽  
Gaba Transmission

GnRH neurons are the central regulators of fertility, and their activity is modulated by steroid feedback. In women with hyperandrogenemic infertility and in animal models of these disorders, elevated androgen levels interfere with progesterone (P) negative feedback. Our previous work showed that steroids altered the frequency and amplitude of γ-aminobutyric acid (GABA) transmission to GnRH neurons. Specifically, P inhibited GABA transmission, which can excite GnRH neurons, whereas dihydrotestosterone (DHT) increased GABA transmission. In this study the GnRH neuron firing rate was examined in the same animal models. Adult (&gt;2 months) female mice were ovariectomized and treated for 8–12 d with implants containing estradiol (E), E and P, E and DHT, or E, P, and DHT. Targeted extracellular recordings were used to examine the long-term firing activity of green fluorescent protein-identified GnRH neurons in brain slices from these mice. In comparing E alone to E plus P animals, P increased the percentage of time that GnRH neurons were quiescent and reduced the area under the curve of the firing rate and the instantaneous firing frequency, suggesting that P provides additional negative feedback over E alone. The addition of DHT markedly increased GnRH neuron activity in both the presence and absence of P. DHT also altered the firing pattern of GnRH neurons, such that peaks in the firing rate detected by the Cluster8 algorithm were approximately doubled in frequency and amplitude. These data support and extend our previous findings and are consistent with the hypothesis that the changes in GABAergic transmission observed in these animal models impact upon the activity of GnRH neurons, and central androgen action probably stimulates GnRH release.

scholarly journals A deep convolutional visual encoding model of neuronal responses in the LGN

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Eslam Mounier ◽  
Bassem Abdullah ◽  
Hani Mahdi ◽  
Seif Eldawlatly
Keyword(s):  
Firing Rate ◽  
Visual Information ◽  
Visual Stimulation ◽  
Neuronal Population ◽  
Neuronal Firing ◽  
Electrode Arrays ◽  
Deep Convolutional Neural Networks ◽  
Firing Rates ◽  
Spatiotemporal Representation

AbstractThe Lateral Geniculate Nucleus (LGN) represents one of the major processing sites along the visual pathway. Despite its crucial role in processing visual information and its utility as one target for recently developed visual prostheses, it is much less studied compared to the retina and the visual cortex. In this paper, we introduce a deep learning encoder to predict LGN neuronal firing in response to different visual stimulation patterns. The encoder comprises a deep Convolutional Neural Network (CNN) that incorporates visual stimulus spatiotemporal representation in addition to LGN neuronal firing history to predict the response of LGN neurons. Extracellular activity was recorded in vivo using multi-electrode arrays from single units in the LGN in 12 anesthetized rats with a total neuronal population of 150 units. Neural activity was recorded in response to single-pixel, checkerboard and geometrical shapes visual stimulation patterns. Extracted firing rates and the corresponding stimulation patterns were used to train the model. The performance of the model was assessed using different testing data sets and different firing rate windows. An overall mean correlation coefficient between the actual and the predicted firing rates of 0.57 and 0.7 was achieved for the 10 ms and the 50 ms firing rate windows, respectively. Results demonstrate that the model is robust to variability in the spatiotemporal properties of the recorded neurons outperforming other examined models including the state-of-the-art Generalized Linear Model (GLM). The results indicate the potential of deep convolutional neural networks as viable models of LGN firing.

scholarly journals Both Estrogen and Androgen Modify the Response to Activation of Neurokinin-3 and κ-Opioid Receptors in Arcuate Kisspeptin Neurons From Male Mice

Endocrinology ◽  
2015 ◽  
Vol 157 (2) ◽  
pp. 752-763 ◽  
Author(s):  
Kristen A. Ruka ◽  
Laura L. Burger ◽  
Suzanne M. Moenter
Keyword(s):  
Estrogen Receptor ◽  
Firing Pattern ◽  
Pulse Generator ◽  
Brain Slices ◽  
Gonadal Steroids ◽  
Gnrh Neuron ◽  
Male Mice ◽  
Neurokinin B ◽  
Neuron Firing ◽  
Kndy Neurons

Abstract Gonadal steroids regulate the pattern of GnRH secretion. Arcuate kisspeptin (kisspeptin, neurokinin B, and dynorphin [KNDy]) neurons may convey steroid feedback to GnRH neurons. KNDy neurons increase action potential firing upon the activation of neurokinin B receptors (neurokinin-3 receptor [NK3R]) and decrease firing upon the activation of dynorphin receptors (κ-opioid receptor [KOR]). In KNDy neurons from intact vs castrated male mice, NK3R-mediated stimulation is attenuated and KOR-mediated inhibition enhanced, suggesting gonadal secretions are involved. Estradiol suppresses spontaneous GnRH neuron firing in male mice, but the mediators of the effects on firing in KNDy neurons are unknown. We hypothesized the same gonadal steroids affecting GnRH firing pattern would regulate KNDy neuron response to NK3R and KOR agonists. To test this possibility, extracellular recordings were made from KNDy neurons in brain slices from intact, untreated castrated or castrated adult male mice treated in vivo with steroid receptor agonists. As observed previously, the stimulation of KNDy neurons by the NK3R agonist senktide was attenuated in intact vs castrated mice and suppression by dynorphin was enhanced. In contrast to observations of steroid effects on the GnRH neuron firing pattern, both estradiol and DHT suppressed senktide-induced KNDy neuron firing and enhanced the inhibition caused by dynorphin. An estrogen receptor-α agonist but not an estrogen receptor-β agonist mimicked the effects of estradiol on NK3R activation. These observations suggest the steroid modulation of responses to activation of NK3R and KOR as mechanisms for negative feedback in KNDy neurons and support the contribution of these neurons to steroid-sensitive elements of a GnRH pulse generator.

scholarly journals Suppression of the GnRH Pulse Generator by Neurokinin B Involves a κ-Opioid Receptor-Dependent Mechanism

Endocrinology ◽  
2012 ◽  
Vol 153 (10) ◽  
pp. 4894-4904 ◽  
Author(s):  
P. Grachev ◽  
X. F. Li ◽  
J. S. Kinsey-Jones ◽  
A. L. di Domenico ◽  
R. P. Millar ◽  
...  
Keyword(s):  
Opioid Receptor ◽  
Pulse Generator ◽  
Pulse Frequency ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Neurokinin B ◽  
Kndy Neurons ◽  
Lh Secretion ◽  
Dose Dependent

Abstract Neurokinin B (NKB) and its receptor (NK3R) are coexpressed with kisspeptin, Dynorphin A (Dyn), and their receptors [G-protein-coupled receptor-54 (GPR54)] and κ-opioid receptor (KOR), respectively] within kisspeptin/NKB/Dyn (KNDy) neurons in the hypothalamic arcuate nucleus (ARC), the proposed site of the GnRH pulse generator. Much previous research has employed intracerebroventricular (icv) administration of KNDy agonists and antagonists to address the functions of KNDy neurons. We performed a series of in vivo neuropharmacological experiments aiming to determine the role of NKB/NK3R signaling in modulating the GnRH pulse generator and elucidate the interaction between KNDy neuropeptide signaling systems, targeting our interventions to ARC KNDy neurons. First, we investigated the effect of intra-ARC administration of the selective NK3R agonist, senktide, on pulsatile LH secretion using a frequent automated serial sampling method to obtain blood samples from freely moving ovariectomized 17β-estradiol-replaced rats. Our results show that senktide suppresses LH pulses in a dose-dependent manner. Intra-ARC administration of U50488, a selective KOR agonist, also caused a dose-dependent, albeit more modest, decrease in LH pulse frequency. Thus we tested the hypothesis that Dyn/KOR signaling localized to the ARC mediates the senktide-induced suppression of the LH pulse by profiling pulsatile LH secretion in response to senktide in rats pretreated with nor-binaltorphimine, a selective KOR antagonist. We show that nor-binaltorphimine blocks the senktide-induced suppression of pulsatile LH secretion but does not affect LH pulse frequency per se. In order to address the effects of acute activation of ARC NK3R, we quantified (using quantitative RT-PCR) changes in mRNA levels of KNDy-associated genes in hypothalamic micropunches following intra-ARC administration of senktide. Senktide down-regulated expression of genes encoding GnRH and GPR54 (GNRH1 and Kiss1r, respectively), but did not affect the expression of Kiss1 (which encodes kisspeptin). We conclude that NKB suppresses the GnRH pulse generator in a KOR-dependent fashion and regulates gene expression in GnRH neurons.

scholarly journals Impairments in the reproductive axis of female mice lacking estrogen receptor β in GnRH neurons

2018 ◽  
Vol 315 (5) ◽  
pp. E1019-E1033 ◽  
Author(s):  
Horacio J. Novaira ◽  
Ariel L. Negron ◽  
Jones B. Graceli ◽  
Silvia Capellino ◽  
Andrew Schoeffield ◽  
...  
Keyword(s):  
Mouse Models ◽  
Reproductive Function ◽  
Stimulation Test ◽  
Abnormal Development ◽  
Gnrh Neuron ◽  
Serum Luteinizing Hormone ◽  
Reproductive Axis ◽  
Gnrh Neurons ◽  
Serum Gonadotropin

The effect of estrogen on the differentiation and maintenance of reproductive tissues is mediated by two nuclear estrogen receptors (ERs), ERα, and ERβ. Lack of functional ERα and ERβ genes in vivo significantly affects reproductive function; however, the target tissues and signaling pathways in the hypothalamus are not clearly defined. Here, we describe the generation and reproductive characterization of a complete-ERβ KO (CERβKO) and a GnRH neuron-specific ERβKO (GERβKO) mouse models. Both ERβKO mouse models displayed a delay in vaginal opening and first estrus. Hypothalamic gonadotropin-releasing hormone (GnRH) mRNA expression levels in both ERβKO mice were similar to control mice; however female CERβKO and GERβKO mice had lower basal and surge serum gonadotropin levels. Although a GnRH stimulation test in both female ERβKO models showed preserved gonadotropic function in the same animals, a kisspeptin stimulation test revealed an attenuated response by GnRH neurons, suggesting a role for ERβ in normal GnRH neuron function. No alteration in estrogen-negative feedback was observed in either ERβKO mouse models after ovariectomy and estrogen replacement. Further, abnormal development of ovarian follicles with low serum estradiol levels and impairment of fertility were observed in both ERβKO mouse models. In male ERβKO mice, no differences in the timing of pubertal onset or serum luteinizing hormone and follicle-stimulating hormone levels were observed as compared with controls. Taken together, these data provide in vivo evidence for a role of ERβ in GnRH neurons in modulating puberty and reproduction, specifically through kisspeptin responsiveness in the female hypothalamic-pituitary-gonadal axis.

scholarly journals Input-independent homeostasis of developing thalamocortical activity

2021 ◽  
Author(s):  
Pouria Riyahi ◽  
Marnie A Phillips ◽  
Matthew T Colonnese
Keyword(s):  
Visual Processing ◽  
Background Activity ◽  
Silent Period ◽  
Prognostic Indicator ◽  
Cortical Activity ◽  
Progressive Increase ◽  
Developmental Trajectory ◽  
Primary Input ◽  
Firing Rates

ABSTRACTThe isocortex of all mammals studied to date shows a progressive increase in the amount and continuity of background activity during early development. In humans the transition from a discontinuous (mostly silent, intermittently bursting) cortex to one that is continuously active is complete soon after birth and is a critical prognostic indicator in newborns. In the visual cortex of rodents this switch from discontinuous to continuous background activity occurs rapidly during the two days before eye-opening, driven by activity changes in relay thalamus. The factors that regulate the timing of continuity development, which enables mature visual processing, are unknown. Here we test the role of the retina, the primary input, in the development of continuous spontaneous activity in the visual system of mice using depth electrode recordings of cortical activity from enucleated mice in vivo. Bilateral enucleation at postnatal day (P)6, one week prior to the onset of continuous activity, acutely silences cortex, yet firing rates and early oscillations return to normal within two days and show a normal developmental trajectory through P12. Enucleated animals showed differences in silent period duration and continuity on P13 that resolved on P16, and an increase in low frequency power that did not. Our results show that the timing of cortical activity development is not determined by the major driving input to the system. Rather, homeostatic mechanisms in thalamocortex regulate firing rates and continuity even across periods of rapid maturation.

scholarly journals A role for glial fibrillary acidic protein (GFAP)-expressing cells in the regulation of gonadotropin-releasing hormone (GnRH) but not arcuate kisspeptin neuron output

2021 ◽  
Author(s):  
Charlotte Vanacker ◽  
R. Anthony DeFazio ◽  
Charlene M. Sykes ◽  
Suzanne M. Moenter
Keyword(s):  
Arcuate Nucleus ◽  
Designer Drugs ◽  
Neuron Activity ◽  
Gnrh Neurons ◽  
Hypothalamic Arcuate Nucleus ◽  
Lh Release ◽  
Main Regulator ◽  
Kndy Neurons

AbstractGnRH neurons are the final central neural output regulating fertility. Kisspeptin neurons in the hypothalamic arcuate nucleus (KNDy neurons) are considered the main regulator of GnRH output. GnRH and KNDy neurons are surrounded by astrocytes, which can modulate neuronal activity and communicate over distances. Prostaglandin E2 (PGE2), synthesized primarily by astrocytes, increases GnRH neuron activity and downstream pituitary release of luteinizing hormone (LH). We hypothesized GFAP-expressing astrocytes play a role regulating GnRH and/or KNDy neuron activity and LH release. We used adenoassociated viruses to target designer receptor exclusively activated by designer drugs (DREADDs) to GFAP-expressing cells to activate Gq or Gi-mediated signaling. Activating Gq signaling in the preoptic area, near GnRH neurons, but not in the arcuate, increases LH release in vivo and GnRH firing in vitro via a mechanism in part dependent upon PGE2. These data suggest astrocytes can activate GnRH/LH release in a manner independent of KNDy neurons.

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