The Journal of neuroscience : the official journal of the Society for Neuroscience
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Randomized Controlled Trial Clinical Trial
Corticotropin-releasing factor receptor 1 antagonist alters regional activation and effective connectivity in an emotional-arousal circuit during expectation of abdominal pain.
Alterations in corticotropin-releasing factor (CRF) signaling pathways have been implicated in irritable bowel syndrome (IBS) pathophysiology. We aimed to (1) determine the effect of the selective CRF receptor 1 antagonist (CRF(1)) GW876008 relative to placebo, on regional activation and effective connectivity of a stress-related emotional-arousal circuit during expectation of abdominal pain using functional magnetic resonance imaging in human subjects with a diagnosis of IBS and healthy controls (HCs), and (2) examine GW876008 effects on state-trait anxiety and hypothalamic-pituitary-adrenal (HPA) axis response. Although there were no drug-related effects on peripheral HPA activity, significant central effects were observed in brain regions associated with the stress response. ⋯ The inhibitory effects of GW876008 in the hypothalamus in patients were moderated by anxiety; patients having average and high levels of state anxiety showed drug-related BOLD decreases. GW876008 represents a novel tool for elucidating the neuronal mechanisms and circuitry underlying hyperactivation of CRF/CRF(1) signaling and its role in IBS pathophysiology. The unique state anxiety effects observed suggest a potential pathway for therapeutic benefit of CRF(1) receptor antagonism for patients with stress-sensitive disorders.
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IL-1β and TNF are potential targets in the management of neuropathic pain after injury. However, the importance of the IL-1 and TNF systems for peripheral nerve regeneration and the mechanisms by which these cytokines mediate effects are to be fully elucidated. Here, we demonstrate that mRNA and protein levels of IL-1β and TNF are rapidly upregulated in the injured mouse sciatic nerve. ⋯ Notably, the infiltration of neutrophils was almost completely prevented in the sciatic nerve distal stump of mice lacking both IL-1R1 and TNFR1. Systemic treatment of mice with an anti-Ly6G antibody to deplete neutrophils, cells that play an essential role in the genesis of neuropathic pain, did not affect recovery of neurological function and peripheral axon regeneration. Together, these results suggest that targeting specific IL-1β/TNF-dependent responses, such as neutrophil infiltration, is a better therapeutic strategy for treatment of neuropathic pain after peripheral nerve injury than complete blockage of cytokine production.
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Randomized Controlled Trial Comparative Study
The phase of ongoing oscillations mediates the causal relation between brain excitation and visual perception.
Why does neuronal activity in sensory brain areas sometimes give rise to perception, and sometimes not? Although neuronal noise is often invoked as the key factor, a portion of this variability could also be due to the history and current state of the brain affecting cortical excitability. Here we directly test this idea by examining whether the phase of prestimulus oscillatory activity is causally linked with modulations of cortical excitability and with visual perception. Transcranial magnetic stimulation (TMS) was applied over human visual cortex to induce illusory perceptions (phosphenes) while electroencephalograms (EEGs) were simultaneously recorded. ⋯ This effect was observed in occipital regions around the site of TMS, as well as in a distant frontocentral region. In both regions, we found a systematic relationship between prepulse EEG phase and perceptual performance: phosphene probability changed by ∼15% between opposite phases. In summary, we provide direct evidence for a chain of causal relations between the phase of ongoing oscillations, neuronal excitability, and visual perception: ongoing oscillations create periodic "windows of excitability," with sensory perception being more likely to occur at specific phases.
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Comparative Study
Early prenatal stress epigenetically programs dysmasculinization in second-generation offspring via the paternal lineage.
Studies have linked sex-biased neurodevelopmental disorders, including autism and schizophrenia, with fetal antecedents such as prenatal stress. Further, these outcomes can persist into subsequent generations, raising the possibility that aspects of heritability in these diseases involve epigenetic mechanisms. Utilizing a mouse model in which we previously identified a period in early gestation when stress results in dysmasculinized and stress-sensitive male offspring, we have examined programming effects in second-generation offspring of prenatally stressed (F2-S) or control (F2-C) sires. ⋯ These developmental effects were associated with the transmission of a stress-sensitive phenotype and shortened anogenital distance in adult F2-S males. As confirmation that the miRNA environment is responsive to organizational testosterone, neonatal males administered the aromatase inhibitor formestane exhibited dramatic changes in brain miRNA patterns, suggesting that miRNAs may serve a previously unappreciated role in organizing the sexually dimorphic brain. Overall, these data support the existence of a sensitive period of early gestation when epigenetic programming of the male germline can occur, permitting transmission of specific phenotypes into subsequent generations.
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We previously demonstrated that the spinal cord κ-opioid receptor (KOR) and μ-opioid receptor (MOR) form heterodimers (KOR/MOR). KOR/MOR formation and the associated KOR dependency of spinal morphine antinociception are most robust during proestrus. Using Sprague Dawley rats, we now demonstrate that (1) spinal synthesis of estrogen is critical to these processes, and (2) blockade of either estrogen receptor (ER) α-, β-, or G-protein-coupled ER1 or progesterone receptor (PR) substantially reduces KOR/MOR and eliminates mediation by KOR of spinal morphine antinociception. ⋯ This indicates a sex steroid-dependent plasticity of spinal KOR functionality, which could explain the greater analgesic potency of KOR agonists in women versus men. We suggest that KOR/MOR is a molecular switch that shifts the function of KOR and thereby endogenous dynorphin from pronociceptive to antinociceptive. KOR/MOR could thus serve as a novel molecular target for pain management in women.