Mu-opioid receptor activation induces transcriptional plasticity in the central extended amygdala

Addiction develops from the gradual adaptation of the brain to chronic drug exposure, and involves genetic reprogramming of neuronal function. The central extended amygdala (EAc) is a network formed by the central amygdala and the bed nucleus of the stria terminalis. This key site controls drug craving and seeking behaviors, and has not been investigated at the gene regulation level. We used Affymetrix microarrays to analyze transcriptional activity in the murine EAc, with a focus on mu-opioid receptor-associated events because these receptors mediate drug reward and dependence. We identified 132 genes whose expression is regulated by a chronic escalating morphine regimen in the EAc from wild-type but not mu-opioid receptor knockout mice. These modifications are mostly EAc-specific. Gene ontology analysis reveals an overrepresentation of neurogenesis, cell growth and signaling protein categories. A separate quantitative PCR analysis of genes in the last of these groups confirms the dysregulation of both orphan (Gpr88) and known (DrD1A, Adora2A, Cnr1, Grm5, Gpr6) G protein-coupled receptors, scaffolding (PSD95, Homer1) and signaling (Sgk, Cap1) proteins, and neuropeptides (CCK, galanin). These transcriptional modifications do not occur following a single morphine injection, and hence result from long-term adaptation to excessive mu receptor activation. Proteins encoded by these genes are classically associated with spine modules function in other brain areas, and therefore our data suggest a remodeling of EAc circuits at sites where glutamatergic and monoaminergic afferences interact. Together, mu receptor-dependent genes identified in this study potentially contribute to drug-induced neural plasticity, and provide a unique molecular repertoire towards understanding drug craving and relapse.

Transcriptome analysis identifies genes with enriched expression in the mouse central extended amygdala

The central extended amygdala (EAc) is an ensemble of highly interconnected limbic structures of the anterior brain, and forms a cellular continuum including the bed nucleus of the stria terminalis (BNST), the central nucleus of the amygdala (CeA) and the nucleus accumbens shell (AcbSh). This neural network is a key site for interactions between brain reward and stress systems, and has been implicated in several aspects of drug abuse. In order to increase our understanding of EAc function at the molecular level, we undertook a genome-wide screen (Affymetrix) to identify genes whose expression is enriched in the mouse EAc. We focused on the less-well known BNST-CeA areas of the EAc, and identified 121 genes that exhibit more than twofold higher expression level in the EAc compared with whole brain. Among these, 43 genes have never been described to be expressed in the EAc. We mapped these genes throughout the brain, using non-radioactive in situ hybridization, and identified eight genes with a unique and distinct rostro-caudal expression pattern along AcbSh, BNST and CeA. Q-PCR analysis performed in brain and peripheral organ tissues indicated that, with the exception of one (Spata13), all these genes are predominantly expressed in brain. These genes encode signaling proteins (Adora2, GPR88, Arpp21 and Rem2), a transcription factor (Limh6) or proteins of unknown function (Rik130, Spata13 and Wfs1). The identification of genes with enriched expression expands our knowledge of EAc at a molecular level, and provides useful information to toward genetic manipulations within the EAc.

Gene expression is altered in the lateral hypothalamus upon activation of the mu opioid receptor

The lateral hypothalamus (LH) is a brain structure that controls hedonic properties of both natural rewards and drugs of abuse. Mu opioid receptors are known to mediate drug reward, but whether overstimulation of these receptors impacts on LH function has not been studied. Here we have used a genome-wide microarray approach to identify LH responses to chronic mu opioid receptor activation at the transcriptional level. We have subjected wild-type and mu opioid receptor knockout mice to an escalating morphine regimen, which produces severe physical dependence in wild-type but not mutant animals. We have analyzed gene profiles in LH samples using the 430A.2 Affymetrix array and identified a set of 25 genes whose expression is altered by morphine in wild-type mice only. The regulation was confirmed for a subset of these genes using real-time quantitative PCR on samples from independent treatments. Altered expression of aquaporin 4, apolipoprotein D, and prostaglandin synthase is indicative of modified LH physiology. The regulation of two signaling genes (the serum glucocorticoid kinase and the regulator of G protein signaling 4) suggests that neurotransmission is altered in LH circuitry. Finally, the downregulation of apelin may indicate a potential role for this neuropeptide in opioid signaling and hedonic homeostasis. Altogether, our study shows that chronic mu opioid receptor stimulation induces gene expression plasticity in the LH and provides a unique collection of mu opioid receptor-dependent genes that potentially contribute to alter reward processes in addictive diseases.

Bcl2, a transcriptional target of p38alpha, is critical for neuronal commitment of mouse embryonic stem cells

Mouse embryonic stem (ES) cells remain pluripotent in vitro when grown in the presence of leukemia inhibitory factor (LIF) cytokine. LIF starvation leads to cell commitment, and part of the ES-derived differentiated cells die by apoptosis together with caspase3-cleavage and p38alpha activation. Inhibition of p38 activity by chemical compounds (PD169316 and SB203580), along with LIF withdrawal, leads to different outcomes on cell apoptosis, giving the opportunity to study the influence of apoptosis on cell differentiation. By gene profiling studies on ES-derived differentiated cells treated or not with these inhibitors, we have characterized the common and specific set of genes modulated by each inhibitor. We have also identified key genes that might account for their different survival effects. In addition, we have demonstrated that some genes, similarly regulated by both inhibitors (upregulated as Bcl2, Id2, Cd24a or downregulated as Nodal), are bona fide p38alpha targets involved in neurogenesis and found a correlation with their expression profiles and the onset of neuronal differentiation triggered upon retinoic acid treatment. We also showed, in an embryoid body differentiation protocol, that overexpression of EGFP (enhanced green fluorescent protein)-BCL2 fusion protein and repression of p38alpha are essential to increase formation of TUJ1-positive neuronal cell networks along with an increase in Map2-expressing cells.

[Sacral root neuromodulation for the treatment of urinary incontinence reported to detrusor hyperactivity]

BACKGROUND AND PURPOSE

This paper reviews therapeutic sacral neuromodulation for treating urinary urge incontinence related to detrusor hyperactivity.

METHODS

We reported data from our department and from the international literature on topics such as the physiological basis of neuromodulation, techniques of testing, chronic implantation and clinical results.

RESULTS

In an intention to treat analysis , neuromodulation results varied from 21.5 to 25% globally. On implanted patients, the response rate varied from 40 to 88% and was stable. Sub-chronic test morbidity was very rare. Surgical revision rate was reported from 6.25 to 37.7%.

CONCLUSIONS

Neuromodulation strongly ameliorates approximately a third of all the patients with urge urinary incontinence due to detrusor hyperactivity. New technical improvements should lead to better results in the future.