Journal of Neuroscience Research最新文献

Dopamine (DA) signaling is evoked by both food and drugs that humans come to abuse. Moreover, physiological state (e.g., hunger versus satiety) can modulate the response. However, there is great heterogeneity among DA neurons. Limited studies have been performed that could resolve the interaction between physiological state and drug responsivity across groups of DA neurons. Here, we measured the activity of neurons in transgenic Tg (th2:GCaMP7s) zebrafish larva that expresses a calcium indicator (GCaMP7s) in A11 (posterior tuberculum) and a part of A14 (caudal hypothalamus and intermediate hypothalamus) DA populations located in the hypothalamus of the larval zebrafish. Fish were recorded in one of two physiological states: ad-libitum fed (AL) and food deprived (FD) and before and after acute exposure to different doses of the stimulant drug amphetamine (0, 0.7, and 1.5 μM). We quantified fluorescence change, activity duration, peak rise/fall time, and latency in the calcium spikes of the DA neurons. Our results show that baseline DA neuron activity amplitude, spike duration, and correlation between inter- and intra-DA neurons were higher in the FD than in the AL state. Dose-dependent AMPH treatment further increased the intensity of these parameters in the neuron spikes but only in the FD state. The DA activity correlation relatively increased in AL state post-AMPH treatment. Given that hunger increases drug reactivity and the probability of relapse to drug seeking, the results support populations of DA neurons as potential critical mediators of the interaction between physiological state and drug reinforcement.

Adolescent Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a disabling illness of unknown etiology. Increasing evidence suggests hypothalamic involvement in ME/CFS pathophysiology, which has rarely been explored using magnetic resonance imaging (MRI) in the condition. This work aimed to use MRI to examine hypothalamus connectivity in adolescents with ME/CFS and explore how this relates to fatigue severity and illness duration. 25 adolescents with ME/CFS and 23 healthy controls completed a neuroimaging protocol consisting of structural and multishell diffusion-weighted imaging sequences, in addition to the PedsQL Multidimensional Fatigue Scale to assess fatigue severity. Information about illness duration was acquired at diagnosis. Preprocessing and streamlines tractography was performed using QSIPrep combined with a custom parcellation scheme to create structural networks. The number (degree) and weight (strength) of connections between lateralized hypothalamus regions and cortical and subcortical nodes were extracted, and relationships between connectivity measures, fatigue severity, and illness duration were performed using Bayesian regression models. We observed weak-to-moderate evidence of increased degree, but not strength, of connections from the bilateral anterior-inferior (left: pd [%] = 99.18, median [95% CI] = −22.68[−40.96 to 4.45]; right: pd [%] = 99.86, median [95% CI] = −23.35[−38.47 to 8.20]), left anterior-superior (pd [%] = 99.33, median [95% CI] = −18.83[−33.45 to 4.07]) and total left hypothalamus (pd [%] = 99.44, median [95% CI] = −47.18[−83.74 to 11.03]) in the ME/CFS group compared with controls. Conversely, bilateral posterior hypothalamus degree decreased with increasing ME/CFS illness duration (left: pd [%] = 98.13, median [95% CI]: −0.47[−0.89 to 0.03]; right: pd [%] = 98.50, median [95% CI]:-0.43[−0.82 to 0.05]). Finally, a weak relationship between right intermediate hypothalamus connectivity strength and fatigue severity was identified in the ME/CFS group (pd [%] = 99.35, median [95% CI] = −0.28[−0.51 to 0.06]), which was absent in controls. These findings suggest changes in hypothalamus connectivity may occur in adolescents with ME/CFS, warranting further investigation.

Voltage-gated sodium channels, including Na_V1.7, Na_V1.8, and Na_V1.9, play important roles in pain transmission and chronic pain development. However, the specific mechanisms of their action remain unclear, highlighting the need for in vivo stimulation studies of these channels. Optogenetics, a novel technique for targeting the activation or inhibition of specific neural circuits using light, offers a promising solution. In our previous study, we used optogenetics to selectively excite Na_V1.7-expressing neurons in the dorsal root ganglion of mice to induce nocifensive behavior. Here, we further characterize the impact of nocifensive behavior by activation of Na_V1.7, Na_V1.8, or Na_V1.9-expressing neurons. Using CRISPR/Cas9-mediated homologous recombination, Na_V1.7–iCre, Na_V1.8–iCre, or Na_V1.9–iCre mice expressing iCre recombinase under the control of the endogenous Na_V1.7, Na_V1.8, or Na_V1.9 gene promoter were produced. These mice were then bred with channelrhodopsin-2 (ChR2) Cre–reporter Ai32 mice to obtain Na_V1.7–ChR2, Na_V1.8–ChR2, or Na_V1.9–ChR2 mice. Blue light exposure triggered paw withdrawal in all mice, with the strongest response in Na_V1.8–ChR2 mice. These light sensitivity differences observed across Na_V1.x–ChR2 mice may be dependent on ChR2 expression or reflect the inherent disparities in their pain transmission roles. In conclusion, we have generated noninvasive pain models, with optically activated peripheral nociceptors. We believe that studies using optogenetics will further elucidate the role of sodium channel subtypes in pain transmission.

Thalamocortical connectivity is associated with cognitive and affective processing. The role of thalamocortical connectivity in the pathomechanism of treatment-resistant depression (TRD) remains unclear. This study included 48 patients with TRD and 48 healthy individuals. We investigated thalamocortical connectivity by performing resting-state functional MRI with the bilateral thalamus as the seed. In addition, patients with TRD were evaluated using the Montgomery–Åsberg Depression Rating Scale (MADRS). Compared with the healthy individuals, the patients with TRD exhibited increased functional connectivity (FC) of the thalamus with the insula and superior temporal cortex and reduced the FC of the thalamus with the anterior paracingulate cortex and cerebellum crus II. Our study may support the crucial role of thalamocortical dysconnectivity in the TRD pathomechanism. However, the small sample size may limit the statistical power. A future study with a large sample size of patients with TRD would be required to validate our findings.

Attention-deficit/hyperactivity disorder (ADHD) and substance use disorders (SUD) are characterized by exacerbated motor and risk-related impulsivities, which are associated with decreased cortical activity. In rodents, the medial prefrontal cortex (mPFC) and nucleus accumbens (NAc) have been separately implicated in impulsive behaviors, but studies on the specific role of the mPFC-NAc pathway in these behaviors are limited. Here, we investigated whether heightened impulsive behaviors are associated with reduced mPFC activity in rodents and determined the involvement of the mPFC-NAc pathway in motor and risk-related impulsivities. We used the Roman High- (RHA) and Low-Avoidance (RLA) rat lines, which display divergent phenotypes in impulsivity. To investigate alterations in cortical activity in relation to impulsivity, regional brain glucose metabolism was measured using positron emission tomography and [¹⁸F]-fluorodeoxyglucose ([¹⁸F]FDG). Using chemogenetics, the activity of the mPFC-NAc pathway was either selectively activated in high-impulsive RHA rats or inhibited in low-impulsive RLA rats, and the effects of these manipulations on motor and risk-related impulsivity were concurrently assessed using the rat gambling task. We showed that basal [¹⁸F]FDG uptake was lower in the mPFC and NAc of RHA compared to RLA rats. Activation of the mPFC-NAc pathway in RHA rats reduced motor impulsivity, without affecting risk-related decision-making. Conversely, inhibition of the mPFC-NAc pathway had no effect in RLA rats. Our results suggest that the mPFC-NAc pathway controls motor impulsivity, but has limited involvement in risk-related decision-making in our current model. Our findings suggest that reducing fronto-striatal activity may help attenuate motor impulsivity in patients with impulse control dysregulation.