16 research outputs found
Reduced basal ganglia Ī¼-opioid receptor availability in trigeminal neuropathic pain: A pilot study
Abstract
Background
Although neuroimaging techniques have provided insights into the function of brain regions involved in Trigeminal Neuropathic Pain (TNP) in humans, there is little understanding of the molecular mechanisms affected during the course of this disorder. Understanding these processes is crucial to determine the systems involved in the development and persistence of TNP.
Findings
In this study, we examined the regional Ī¼-opioid receptor (Ī¼OR) availability in vivo (non-displaceable binding potential BPND) of TNP patients with positron emission tomography (PET) using the Ī¼OR selective radioligand [11C]carfentanil. Four TNP patients and eight gender and age-matched healthy controls were examined with PET. Patients with TNP showed reduced Ī¼OR BPND in the left nucleus accumbens (NAc), an area known to be involved in pain modulation and reward/aversive behaviors. In addition, the Ī¼OR BPND in the NAc was negatively correlated with the McGill sensory and total pain ratings in the TNP patients.
Conclusions
Our findings give preliminary evidence that the clinical pain in TNP patients can be related to alterations in the endogenous Ī¼-opioid system, rather than only to the peripheral pathology. The decreased availability of Ī¼ORs found in TNP patients, and its inverse relationship to clinical pain levels, provide insights into the central mechanisms related to this condition. The results also expand our understanding about the impact of chronic pain on the limbic system.http://deepblue.lib.umich.edu/bitstream/2027.42/112555/1/12990_2012_Article_533.pd
Brief Report: Excitatory and Inhibitory Brain Metabolites as Targets of Motor Cortex Transcranial Direct Current Stimulation Therapy and Predictors of Its Efficacy in Fibromyalgia
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110535/1/art38945.pd
Reduced basal ganglia Ī¼-opioid receptor availability in trigeminal neuropathic pain: A pilot study
Abstract Background Although neuroimaging techniques have provided insights into the function of brain regions involved in Trigeminal Neuropathic Pain (TNP) in humans, there is little understanding of the molecular mechanisms affected during the course of this disorder. Understanding these processes is crucial to determine the systems involved in the development and persistence of TNP. Findings In this study, we examined the regional Ī¼-opioid receptor (Ī¼OR) availability in vivo (non-displaceable binding potential BPND) of TNP patients with positron emission tomography (PET) using the Ī¼OR selective radioligand [11C]carfentanil. Four TNP patients and eight gender and age-matched healthy controls were examined with PET. Patients with TNP showed reduced Ī¼OR BPND in the left nucleus accumbens (NAc), an area known to be involved in pain modulation and reward/aversive behaviors. In addition, the Ī¼OR BPND in the NAc was negatively correlated with the McGill sensory and total pain ratings in the TNP patients. Conclusions Our findings give preliminary evidence that the clinical pain in TNP patients can be related to alterations in the endogenous Ī¼-opioid system, rather than only to the peripheral pathology. The decreased availability of Ī¼ORs found in TNP patients, and its inverse relationship to clinical pain levels, provide insights into the central mechanisms related to this condition. The results also expand our understanding about the impact of chronic pain on the limbic system.</p
Reduced basal ganglia Ī¼-opioid receptor availability in trigeminal neuropathic pain: A pilot study
<p>Abstract</p> <p>Background</p> <p>Although neuroimaging techniques have provided insights into the function of brain regions involved in Trigeminal Neuropathic Pain (TNP) in humans, there is little understanding of the molecular mechanisms affected during the course of this disorder. Understanding these processes is crucial to determine the systems involved in the development and persistence of TNP.</p> <p>Findings</p> <p>In this study, we examined the regional Ī¼-opioid receptor (Ī¼OR) availability <it>in vivo</it> (non-displaceable binding potential BP<sub>ND</sub>) of TNP patients with positron emission tomography (PET) using the Ī¼OR selective radioligand [<sup>11</sup>C]carfentanil. Four TNP patients and eight gender and age-matched healthy controls were examined with PET. Patients with TNP showed reduced Ī¼OR BP<sub>ND</sub> in the left nucleus accumbens (NAc), an area known to be involved in pain modulation and reward/aversive behaviors. In addition, the Ī¼OR BP<sub>ND</sub> in the NAc was negatively correlated with the McGill sensory and total pain ratings in the TNP patients.</p> <p>Conclusions</p> <p>Our findings give preliminary evidence that the clinical pain in TNP patients can be related to alterations in the endogenous Ī¼-opioid system, rather than only to the peripheral pathology. The decreased availability of Ī¼ORs found in TNP patients, and its inverse relationship to clinical pain levels, provide insights into the central mechanisms related to this condition. The results also expand our understanding about the impact of chronic pain on the limbic system.</p
Building up analgesia in humans via the endogenous Ī¼-opioid system by combining placebo and active tDCS: a preliminary report.
Transcranial Direct Current Stimulation (tDCS) is a method of non-invasive brain stimulation that has been frequently used in experimental and clinical pain studies. However, the molecular mechanisms underlying tDCS-mediated pain control, and most important its placebo component, are not completely established. In this pilot study, we investigated in vivo the involvement of the endogenous Ī¼-opioid system in the global tDCS-analgesia experience. Nine healthy volunteers went through positron emission tomography (PET) scans with [11C]carfentanil, a selective Ī¼-opioid receptor (MOR) radiotracer, to measure the central MOR activity during tDCS in vivo (non-displaceable binding potential, BPND)--one of the main analgesic mechanisms in the brain. Placebo and real anodal primary motor cortex (M1/2mA) tDCS were delivered sequentially for 20 minutes each during the PET scan. The initial placebo tDCS phase induced a decrease in MOR BPND in the periaqueductal gray matter (PAG), precuneus, and thalamus, indicating activation of endogenous Ī¼-opioid neurotransmission, even before the active tDCS. The subsequent real tDCS also induced MOR activation in the PAG and precuneus, which were positively correlated to the changes observed with placebo tDCS. Nonetheless, real tDCS had an additional MOR activation in the left prefrontal cortex. Although significant changes in the MOR BPND occurred with both placebo and real tDCS, significant analgesic effects, measured by improvements in the heat and cold pain thresholds, were only observed after real tDCS, not the placebo tDCS. This study gives preliminary evidence that the analgesic effects reported with M1-tDCS, can be in part related to the recruitment of the same endogenous MOR mechanisms induced by placebo, and that such effects can be purposely optimized by real tDCS
Ī¼ āOpioid activation in the midbrain during migraine allodynia ā brief report II
We investigated in vivo the allodynic response of the central Ī¼ āopioid system during spontaneous migraine headaches, following a sustained pain threshold challenge on the trigeminal ophthalmic region. Six migraineurs were scanned during the ictal and interictal phases using positron emission tomography ( PET ) with the selective Ī¼ āopioid receptor ( Ī¼ OR ) radiotracer [11C]carfentanil. Females were scanned during the midālate follicular phase of two separate cycles. Patients showed ictal trigeminal allodynia during the thermal challenge that was concurrent and positively correlated with Ī¼ OR activation in the midbrain, extending from red nucleus to ventrolateral periaqueductal gray matter. These findings demonstrate for the first time in vivo the high Ī¼ OR activation in the migraineurs' brains in response to their allodynic experience.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/107586/1/acn366.pd
Ī¼ āOpioid activation in the prefrontal cortex in migraine attacks ā brief report I
We evaluated in vivo the Ī¼ āopioid system during spontaneous episodic migraine headaches. Seven patients were scanned at different phases of their migraine using positron emission tomography with the selective Ī¼ āopioid receptor ( Ī¼ OR ) radiotracer [11C]carfentanil. In the ictal phase, there was Ī¼ OR activation in the medial prefrontal cortex, which was strongly associated with the Ī¼ OR availability level during the interictal phase. Furthermore, Ī¼ āopioid binding changes showed moderate negative correlation with the combined extension and severity of the attacks. These results indicate for the first time that there is high Ī¼ OR activation in the migraineurs' brains during headache attacks in response to their pain.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/107492/1/acn365.pd
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We evaluated in vivo the Ī¼ āopioid system during spontaneous episodic migraine headaches. Seven patients were scanned at different phases of their migraine using positron emission tomography with the selective Ī¼ āopioid receptor ( Ī¼ OR ) radiotracer [11C]carfentanil. In the ictal phase, there was Ī¼ OR activation in the medial prefrontal cortex, which was strongly associated with the Ī¼ OR availability level during the interictal phase. Furthermore, Ī¼ āopioid binding changes showed moderate negative correlation with the combined extension and severity of the attacks. These results indicate for the first time that there is high Ī¼ OR activation in the migraineurs' brains during headache attacks in response to their pain.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/107492/1/acn365.pd
Box plot representing tDCS (placebo and real) effects in the heat pain thresholds of both sides of the face.
<p>Statistically significant changes occurred in the heat pain thresholds of the left face (<i>p</i>ā=ā0.032).</p
Box plot illustrating cold pain thresholds variations related to placebo and real tDCS.
<p>Statistically significant changes occurred in the cold pain thresholds of the left face (<i>p</i>ā=ā0.012) throughout the experiment.</p