Functional limb muscle innervation prior to cholinergic transmitter specification during early metamorphosis in Xenopus

In vertebrates, functional motoneurons are defined as differentiated neurons that are connected to a central premotor network and activate peripheral muscle using acetylcholine. Generally, motoneurons and muscles develop simultaneously during embryogenesis. However, during Xenopus metamorphosis, developing limb motoneurons must reach their target muscles through the already established larval cholinergic axial neuromuscular system. Here, we demonstrate that at metamorphosis onset, spinal neurons retrogradely labeled from the emerging hindlimbs initially express neither choline acetyltransferase nor vesicular acetylcholine transporter. Nevertheless, they are positive for the motoneuronal transcription factor Islet1/2 and exhibit intrinsic and axial locomotor-driven electrophysiological activity. Moreover, the early appendicular motoneurons activate developing limb muscles via nicotinic antagonist-resistant, glutamate antagonist-sensitive, neuromuscular synapses. Coincidently, the hindlimb muscles transiently express glutamate, but not nicotinic receptors. Subsequently, both pre- and postsynaptic neuromuscular partners switch definitively to typical cholinergic transmitter signaling. Thus, our results demonstrate a novel context-dependent re-specification of neurotransmitter phenotype during neuromuscular system development

Relationship between childhood physical abuse and clinical severity of treatment-resistant depression in a geriatric population

Introduction: We assessed the correlation between childhood maltreatment (CM) and severity of depression in an elderly unipolar Treatment-Resistant Depression (TRD) sample. Methods: Patients were enrolled from a longitudinal cohort (FACE-DR) of the French Network of Expert TRD Centres. Results: Our sample included 96 patients (33% of the overall cohort) aged 60 years or above, with a mean age of 67.2 (SD = 5.7). The majority of the patients were female (62.5%). The Montgomery and Asberg Depression Rating Scale (MADRS) and Quick Inventory Depression Scale-Self Report (QIDS-SR) mean scores were high, 28.2 (SD = 7.49) [MADRS score range: 0–60; moderate severity≥20, high severity≥35] and 16.5 (SD = 4.94) [IDS-SR score range: 0–27; moderate severity≥11, high severity≥16], respectively. Mean self-esteem scores were 22.47 (SD = 6.26) [range 0–30]. In an age- and sex-adjusted model, we found a positive correlation between childhood trauma (CTQ scores) and depressive symptom severity [MADRS (β = 0.274; p = 0.07) and QIDS-SR (β = 0.302; p = 0.005) scores]. We detected a statistically significant correlation between physical abuse and depressive symptom severity [MADRS (β = 0.304; p = 0.03) and QIDS-SR (β = 0.362; p = 0.005) scores]. We did not observe any significant correlation between other types of trauma and depressive symptom severity. We showed that self-esteem (Rosenberg scale) mediated the effect of physical abuse (PA) on the intensity of depressive symptoms [MADRS: b = 0.318, 95% BCa C.I. [0.07, 0.62]; QIDS-SR: b = 0.177, 95% BCa C.I. [0.04, 0.37]]. Preacher & Kelly’s Kappa Squared values of 19.1% (k2 = 0.191) and 16% (k2 = 0.16), respectively for the two scales, indicate a moderate effect. Conclusion: To our knowledge, this is the first study conducted in a geriatric TRD population documenting an association between childhood trauma (mainly relating to PA) and the intensity of depressive symptoms

Impact of gene/genome duplications on the evolution of the urotensin II and somatostatin families

International audienceThe present review describes the molecular evolution of two phylogenetically related families of neuropeptides, the urotensin II (UII) and somatatostatin (SS) families. The UII family consists of four paralogous genes called UII, URP, URP1 and URP2 and the SS family is composed of six paralogous genes named SS1, SS2, SS3, SS4, SS5 and SS6. All these paralogs are present in teleosts, while only four of them, UII, URP, SS1 and SS2 are detected in tetrapods. Comparative genomics showed that most of these genes, namely UII, URP, URP1 and URP2 on the one hand and SS1, SS2 and SS5 on the other hand arose through the 2R. In contrast, the teleost-specific 3R had a much more moderate impact since it only concerned the UII and SS1 genes, which once duplicated, generated a second UII copy and SS4, respectively. The two remaining genes, SS3 and SS6, arose through tandem duplications of the SS1 and SS2 genes respectively, probably in the stem lineage of actinopterygians, before the emergence of teleosts. The history of the UII and SS families has also been marked by massive gene lost, both in tetrapods and in teleosts, but only after the 3R in this latter lineage. Finally, ancestral UII and SS genes are thought to have arisen through tandem duplication of a single ancestral gene, largely before the 1R. An important challenge for the future will be to understand the physiological significance of the molecular diversity of these two families

Collecting traces of activity in orofacial muscles during auditory verbal hallucinations in schizophrenic patients

International audienceAt the conclusion of this session, the participants will have a better understanding of auditory hallucinations physiopathological mechanisms in schizophrenic psychosis

Characterization of the true ortholog of the urotensin II-related peptide (URP) gene in teleosts

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MOLECULAR EVOLUTION OF GPCRS: Somatostatin/urotensin II receptors

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Lambert et al 2018 Elife Raw data Figure 2

Measures of fluorescence signals from immuno-labeled spinal slice

Lambert et al 2018 Elife Raw data Figure 6

Measures of EMG responses evoked by motor nerve in isolated nerve-limb preparations - effects of cholinergic and glutamatergic antagonist perfusion. Measure of EMG response delay