Article

Coupling of Neuronal Nitric Oxide Synthase to NMDA Receptors via Postsynaptic Density-95 Depends on Estrogen and Contributes to the Central Control of Adult Female Reproduction

Institut de Médecine Prédictive et de Recherche Thérapeutique, Université du Droit et de la Santé Lille 2, Lille, Nord-Pas-de-Calais, France
The Journal of Neuroscience : The Official Journal of the Society for Neuroscience (Impact Factor: 6.34). 07/2007; 27(23):6103-14. DOI: 10.1523/JNEUROSCI.5595-06.2007
Source: PubMed

ABSTRACT

Considerable research has been devoted to the understanding of how nitric oxide (NO) influences brain function. Few studies, however, have addressed how its production is physiologically regulated. Here, we report that protein-protein interactions between neuronal NO synthase (nNOS) and glutamate NMDA receptors via the scaffolding protein postsynaptic density-95 (PSD-95) in the hypothalamic preoptic region of adult female rats is sensitive to cyclic estrogen fluctuation. Coimmunoprecipitation experiments were used to assess the physical association between nNOS and NMDA receptor NR2B subunit in the preoptic region of the hypothalamus. We found that nNOS strongly interacts with NR2B at the onset of the preovulatory surge at proestrus (when estrogen levels are highest) compared with basal-stage diestrous rats. Consistently, estrogen treatment of gonadectomized female rats also increases nNOS/NR2B complex formation. Moreover, endogenous fluctuations in estrogen levels during the estrous cycle coincide with changes in the physical association of nNOS to PSD-95 and the magnitude of NO release in the preoptic region. Finally, temporary and local in vivo suppression of PSD-95 synthesis by using antisense oligodeoxynucleotides leads to inhibition of nNOS activity in the preoptic region and disrupted estrous cyclicity, a process requiring coordinated activation of neurons containing gonadotropin-releasing hormone (the neuropeptide controlling reproductive function). In conclusion, our findings identify a novel steroid-mediated molecular mechanism that enables the adult mammalian brain to control NO release under physiological conditions.

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    • "The diffusion coefficients for NO and cGMP were those used previously (Wood et al. 2011) and NO was subject to first-order decay (rate constant = 150 s −1 ) in each compartment. In B, the peak NO concentration in each hemisphere is plotted as a function of the concentration of NO-activated guanylyl cyclase (GC) together with the concentrations obtained by solving analytically the equation for diffusion from a disc surface (Carslaw & Jaeger, 1986outside a synapse (Fig. 1) suggests that the principal way it functions would be with effective synapse specificity. This picture, however, ignores the anatomical realities of the arrangement of synapses in the brain. "
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    ABSTRACT: Nitric oxide (NO) functions widely as a transmitter/diffusible second messenger in the central nervous system, exerting physiological effects in target cells by binding to specialized guanylyl cyclase-coupled receptors, resulting in cGMP generation. Despite having many context-dependent physiological roles and being implicated in numerous disease states, there has been a lack of clarity about the ways that NO operates at the cellular and subcellular levels. Recently, several approaches have been used to try to gain a more concrete, quantitative, understanding of this unique signalling pathway. These approaches have included analysing the kinetics of NO receptor function, real-time imaging of cellular NO signal transduction in target cells, and the use of ultrasensitive detector cells to record NO as it is being generated from native sources in brain tissue. The current picture is that, when formed in a synapse, NO is likely to act only very locally, probably mostly within the confines of that synapse, and to exist only in picomolar concentrations. Nevertheless, closely neighbouring synapses may also be within reach, raising the possibility of synaptic crosstalk. By engaging its enzyme-coupled receptors, the low NO concentrations are able to stimulate physiological (submicromolar) increases in cGMP concentration in an activity-dependent manner. When many NO-emitting neurones or synapses are active simultaneously in a tissue region, NO can act more like a volume transmitter to influence, and perhaps coordinate, the behaviour of cells within that region, irrespective of their identity and anatomical connectivity. This article is protected by copyright. All rights reserved.
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    • "Both male and female pups were used for experiments. Even though, circulating testosterone at birth is already higher in males as compared to females (Amateau and McCarthy 2004), hormone exposure is too short to mediate masculinization of the P0 male brain and to promote irreversible changes in hormone-sensitive neurons (Finn et al. 1996). After decapitation and removal of the brain, the meninges and optic chiasm were discarded and the preoptic region was isolated under a binocular magnifying glass with Wecker's scissors (Moria, France). "
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    ABSTRACT: Estrogens and nitric oxide (NO) exert wide-ranging effects on brain function. Recent evidence suggested that one important mechanism for the regulation of NO production may reside in the differential coupling of the calcium-activated neuronal NO synthase (nNOS) to glutamate NMDA receptor channels harboring NR2B subunits by the scaffolding protein post-synaptic density-95 (PSD-95), and that estrogens promote the formation of this ternary complex. Here, we demonstrate that 30-min estradiol-treatment triggers the production of NO by physically and functionally coupling NMDA receptors to nNOS in primary neurons of the rat preoptic region in vitro. The ability of estradiol to activate neuronal NO signaling in preoptic neurons and to promote changes in protein-protein interactions is blocked by ICI 182,780, an estrogen receptor antagonist. In addition, blockade of NMDA receptor NR2B subunit activity with ifenprodil or disruption of PSD-95 synthesis in preoptic neurons by treatment with an anti-sense oligodeoxynucleotide inhibited the estradiol-promoted stimulation of NO release in cultured preoptic neurons. Thus, estrogen receptor-mediated stimulation of the nNOS/PSD-95/NMDA receptor complex assembly is likely to be a critical component of the signaling process by which estradiol facilitates coupling of glutamatergic fluxes for NO production in neurons.
    Full-text · Article · Mar 2009 · Journal of Neurochemistry
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    • "Interestingly, we have recently reported that estrogens promote cyclic fluctuations in the association between nNOS and the NMDA receptor subunit 2B (NR2B) in the preoptic region of the hypothalamus in female rats during the ovarian cycle (d'Anglemont de Tassigny et al. 2007). Thus, one mechanism involved in the regulation by estradiol of nNOS activity in neurons may reside in its increased coupling to PSD-95/NR2B complex to facilitate the access to the Ca 2+ -calmodulin located just underneath the NMDA receptor. "

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