The effect of chronic administration of corticosterone on anxiety- and depression-like behavior and the expression of GABA-A receptor alpha-2 subunits in brain structures of low- and high-anxiety rats

The aim of this study was to examine changes in rat emotional behavior and determine differences in the expression of GABA-A receptor alpha-2 subunits in brain structures of low- (LR) and high-anxiety (HR) rats after the repeated corticosterone administration. The animals were divided into LR and HR groups based on the duration of their conditioned freezing in a contextual fear test. Repeated daily administration of corticosterone (20 mg/kg) for 21 days decreased activity in a forced swim test, reduced body weight and decreased prefrontal cortex corticosterone concentration in both the LR and HR groups. These effects of corticosterone administration were stronger in the HR group in comparison with the appropriate control group, and compared to LR treated and LR control animals. Moreover, in the HR group, chronic corticosterone administration increased anxiety-like behavior in the open field and elevated plus maze tests. The behavioral effects in HR rats were accompanied by a decrease in alpha-2 subunit density in the medial prefrontal cortex (prelimbic cortex and frontal association cortex) and by an increase in the expression of alpha-2 subunits in the basolateral amygdala. These studies have shown that HR rats are more susceptible to anxiogenic and depressive effects of chronic corticosterone administration, which are associated with modification of GABA-A receptor function in the medial prefrontal cortex and basolateral amygdala. The current data may help to better understand the neurobiological mechanisms responsible for individual differences in changes in mood and emotions induced by repeated administration of high doses of glucocorticoids or by elevated levels of these hormones associated with chronic stress or affective pathology.

On the role of sex steroids in biological functions by classical and non-classical pathways. An update

The sex steroid hormones (SSHs) play several roles in regulation of various processes in the cardiovascular, immune, muscular and neural systems. SSHs affect prenatal and postnatal development of various brain structures, including regions associated with important physiological, behavioral, cognitive, and emotional functions. This action can be mediated by either intracellular or transmembrane receptors. While the classical mechanisms of SSHs action are relatively well examined, the physiological importance of non-classical mechanism of SSHs action through membrane-associated and transmembrane receptors in the brain remains unclear. The most recent summary describing the role of SSHs in different body systems is lacking. Therefore, the aim of this review is to discuss classical and non-classical signaling pathways of testosterone and estradiol action via their receptors at functional, cellular, tissue level and to describe the effects on various body systems and behavior. Particular emphasis will be on brain regions including the hippocampus, hypothalamus, frontal cortex and cerebellum.

Evaluating the effect of multiple sclerosis lesions on automatic brain structure segmentation

In recent years, many automatic brain structure segmentation methods have been proposed. However, these methods are commonly tested with non-lesioned brains and the effect of lesions on their performance has not been evaluated. Here, we analyze the effect of multiple sclerosis (MS) lesions on three well-known automatic brain structure segmentation methods, namely, FreeSurfer, FIRST and multi-atlas fused by majority voting, which use learning-based, deformable and atlas-based strategies, respectively. To perform a quantitative analysis, 100 synthetic images of MS patients with a total of 2174 lesions are simulated on two public databases with available brain structure ground truth information (IBSR18 and MICCAI'12). The Dice similarity coefficient (DSC) differences and the volume differences between the healthy and the simulated images are calculated for the subcortical structures and the brainstem. We observe that the three strategies are affected when lesions are present. However, the effects of the lesions do not follow the same pattern; the lesions either make the segmentation method underperform or surprisingly augment the segmentation accuracy. The obtained results show that FreeSurfer is the method most affected by the presence of lesions, with DSC differences (generated - healthy) ranging from - 0.11 ± 0.54 to 9.65 ± 9.87, whereas FIRST tends to be the most robust method when lesions are present (- 2.40 ± 5.54 to 0.44 ± 0.94). Lesion location is not important for global strategies such as FreeSurfer or majority voting, where structure segmentation is affected wherever the lesions exist. On the other hand, FIRST is more affected when the lesions are overlaid or close to the structure of analysis. The most affected structure by the presence of lesions is the nucleus accumbens (from - 1.12 ± 2.53 to 1.32 ± 4.00 for the left hemisphere and from - 2.40 ± 5.54 to 9.65 ± 9.87 for the right hemisphere), whereas the structures that show less variation include the thalamus (from 0.03 ± 0.35 to 0.74 ± 0.89 and from - 0.48 ± 1.08 to - 0.04 ± 0.22) and the brainstem (from - 0.20 ± 0.38 to 1.03 ± 1.31). The three segmentation approaches are affected by the presence of MS lesions, which demonstrates that there exists a problem in the automatic segmentation methods of the deep gray matter (DGM) structures that has to be taken into account when using them as a tool to measure the disease progression.

Midazolam treatment before re-exposure to contextual fear reduces freezing behavior and amygdala activity differentially in high- and low-anxiety rats

The aim of this study was to examine the effects of benzodiazepine (midazolam) administration on rat conditioned fear responses and on local brain activity (c-Fos and CRF expressions) of low- (LR) and high- (HR)anxiety rats after the first and second contextual fear test sessions. The animals were divided into LR and HR groups based on the duration of their conditioned freezing response in the first contextual fear test. The fear-re-conditioned LR and HR animals (28 days later) had increased freezing durations compared with those durations during the first conditioned fear test. These behavioral effects were accompanied by increased c-Fos expression in the medial amygdala (MeA), the basolateral amygdala (BLA), and the paraventricular hypothalamic nuclei and elevated CRF expression in the MeA. All these behavioral and immunochemical effects of fear re-conditioning were stronger in the LR group compared with the effects in the HR group. Moreover, in the LR rats, the re-conditioning led to decreased CRF expression in the primary motor cortex (M1) and to increased CRF expression in the BLA. The pretreatment of rats with midazolam before the second exposure to the aversive context significantly attenuated the conditioned fear response, lowered the serum corticosterone concentration, decreased c-Fos and CRF expressions in the MeA and in the BLA, and increased CRF complex density in M1 area only in the LR group. These studies have demonstrated that LR rats are more sensitive to re-exposure to fear stimuli and that midazolam pretreatment was associated with modified brain activity in the amygdala and in the prefrontal cortex in this group of animals. The current data may facilitate a better understanding of the neurobiological mechanisms responsible for individual differences in the psychopathological processes accompanying some anxiety disorders characterized by stronger reactivity to re-exposure to stressful challenges, e.g., posttraumatic stress disorder.

Role of endocannabinoid system in dopamine signalling within the reward circuits affected by chronic pain

The association between chronic pain, depression and anxiety has gained particular attention due to high rates of comorbidity. Recent data demonstrated that the mesolimbic reward circuitry is involved in the pathology of chronic pain. Interestingly, the mesolimbic reward circuit participates both in pain perception and in pain relief. The endocannabinoid system (ECS) has emerged as a highly relevant player involved in both pain perception and reward processing. Targeting ECS could become a novel treatment strategy for chronic pain patients. However, little is known about the underlying mechanisms of action of cannabinoids at the intersection of neurochemical changes in reward circuits and chronic pain. Because understanding the benefits and risks of cannabinoids is paramount, the aim of this review is to evaluate the state-of-art knowledge about the involvement of the ECS in dopamine signalling within the reward circuits affected by chronic pain.

Psychosocial stress inhibits additional stress-induced hyperexpression of NO synthases and IL-1β in brain structures

BACKGROUND

The aim of this study was to compare the expression of interleukin-1β (IL-1β), neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS) in the prefrontal cortex (PFC), hippocampus (HIP) and hypothalamus (HT) during chronic crowding (CS) (psychosocial) and restraint (RS) (physico-psychological) stress. Adaptational changes of these stress mediators to a subsequent acute RS, in two models of chronic stress were investigated.

METHODS

Rats were crowded (24 in one cage) or restrained in metal tubes for 10min twice a day for 3, 7, and 14 consecutive days and decapitated. For determination of adaptational changes the chronically crowded and restrained rats 24h after the last stress session were subjected to a single 10min RS. The IL-1β, nNOS and iNOS protein levels in brain structures samples were analyzed by Western blot procedure.

RESULTS

Chronic CS for 3days did not markedly change the subsequent acute stress induced expression of nNOS, iNOS and IL-1β protein level in PFC and iNOS protein level in HT. CS markedly decreased the expression of nNOS, iNOS and IL-1β in HIP. By contrast, parallel chronic RS, significantly increased the subsequent acute stress-induced expression of iNOS and IL-1β in PFC and considerably increased iNOS level in HT.

CONCLUSION

Chronic psychosocial stress, may protect against possible harmful action of hyperproduction of iNOS and iNOS derived nitric oxide (NO) mainly in PFC and HIP. By contrast, chronic physico-psychosocial stress may strongly potentiate additional stress-induced harmful effects of NOS and IL-1β hyperproduction.

Brain structure segmentation in the presence of multiple sclerosis lesions

Intensity-based multi-atlas segmentation strategies have shown to be particularly successful in segmenting brain images of healthy subjects. However, in the same way as most of the methods in the state of the art, their performance tends to be affected by the presence of MRI visible lesions, such as those found in multiple sclerosis (MS) patients. Here, we present an approach to minimize the effect of the abnormal lesion intensities on multi-atlas segmentation. We propose a new voxel/patch correspondence model for intensity-based multi-atlas label fusion strategies that leads to more accurate similarity measures, having a key role in the final brain segmentation. We present the theory of this model and integrate it into two well-known fusion strategies: Non-local Spatial STAPLE (NLSS) and Joint Label Fusion (JLF). The experiments performed show that our proposal improves the segmentation performance of the lesion areas. The results indicate a mean Dice Similarity Coefficient (DSC) improvement of 1.96% for NLSS (3.29% inside and 0.79% around the lesion masks) and, an improvement of 2.06% for JLF (2.31% inside and 1.42% around lesions). Furthermore, we show that, with the proposed strategy, the well-established preprocessing step of lesion filling can be disregarded, obtaining similar or even more accurate segmentation results.

•

We present an approach to improve multi-atlas brain parcellation of MS patients.

•

We integrate our model into 2 well-known segmentation strategies.

•

Our model improves the segmentation on the lesion areas.

•

The improvement on the lesion areas is also reflected in the global performance.

•

With our model, lesion filling can be omitted, obtaining at least similar results.

Antidepressant-Like Effect of the Endogenous Neuroprotective Amine, 1MeTIQ in Clonidine-Induced Depression: Behavioral and Neurochemical Studies in Rats

Biogenic amines such as norepinephrine, dopamine, and serotonin play a well-described role in the treatment of mood disorders especially depression. Animal models are widely used to study antidepressant-like effect in rodents; however, it should be taken into account that pharmacological models do not always answer to the complexity of the disease processes. This study verified the behavioral (forced swim test (FST), locomotor activity test) and neurochemical effects (monoamines metabolism) of a low dose of clonidine (0.1 mg/kg i.p.) which was used as an experimental model of depression. In such pharmacological model, we investigated the antidepressant-like effect of an endogenous neuroprotective amine, 1-methyl-1,2,3,4-tetrahydroisoquinoline (1MeTIQ) administered in a dose of 25 mg/kg (i.p.) before clonidine in the behavioral and neurochemical tests carried out in rats. The behavioral study has shown that clonidine produced depression in the locomotor activity test but did not cause pro-depressive effect in the FST. 1MeTIQ produced antidepressant-like effect in the FST and completely antagonized clonidine-induced sedation in the locomotor activity test. Neurochemical data demonstrated that clonidine produced a significant inhibition of monoamine metabolism in the central nervous system. The release of dopamine, noradrenaline, and serotonin as well as the rate of their metabolism were diminished in the investigated brain structures (frontal cortex, hypothalamus, and striatum). 1MeTIQ completely antagonized the clonidine-induced depression of monoaminergic systems and restored their levels to the control values. 1MeTIQ as an endogenous neuroprotective compound with a distinct antidepressant-like activity in rodents produces hope on the efficiency of antidepressant medicines for future practical clinical use.

Withdrawal from repeated administration of a low dose of reserpine induced opposing adaptive changes in the noradrenaline and serotonin system function: a behavioral and neurochemical ex vivo and in vivo studies in the rat

Reserpine is an inhibitor of the vesicular monoamine transporter 2 (VMAT2) and monoamine releaser, so it can be used as a pharmacological model of depression. In the present paper, we investigated the behavioral and neurochemical effects of withdrawal from acute and repeated administration of a low dose of reserpine (0.2 mg/kg) in Wistar Han rats. We demonstrated the behavioral and receptor oversensitivity (postsynaptic dopamine D1) during withdrawal from chronic reserpine. It was accompanied by a significant increase in motility in the locomotor activity test and climbing behavior in the forced swim test (FST). Neurochemical studies revealed that repeated but not acute administration the a low dose of reserpine triggered opposing adaptive changes in the noradrenergic and serotonin system function analyzed during reserpine withdrawal, i.e. 48 h after the last injection. The tissue concentration of noradrenaline was significantly decreased in the hypothalamus and nucleus accumbens only after repeated drug administration (by about 20% and 35% vs. control; p<0.05, respectively). On the other hand, the concentration of its extraneuronal metabolite, normetanephrine (NM) increased significantly in the VTA during withdrawal both from acute and chronic reserpine. The serotonin concentration was significantly reduced in the VTA after chronic reserpine (by about 40% vs. the control group, p<0.05) as well as its main metabolite, 5-HIAA (by about 30% vs. control; p<0.05) in the VTA and hypothalamus. Dopamine and its metabolites were not changed after acute or chronic reserpine administration. In vivo microdialysis studies clearly evidenced the lack of the effect of a single dose of reserpine, and its distinct effects after chronic treatment on the release of noradrenaline and serotonin in the rat striatum. In fact, the withdrawal from repeated administration of reserpine significantly increased an extraneuronal concentration of noradrenaline in the rat striatum but at the same time produced a distinct fall in the extraneuronal serotonin in this brain structure. On the basis of the presented behavioral and neurochemical experiments, we suggest that chronic administration of reserpine even in such low dose which not yet acted on the release of monoamines but produced an inhibition of VMAT2 caused a long-lasting disadvantageous effect of plasticity in the brain resembling depressive disorders.

Cytokine variations within brain structures in rats selected for differences in aggression

The present study examined the content of cytokines (IL-1β, IL-2, IL-6, IL-10) in the brain structures (the hypothalamus, striatum, frontal cortex, and hippocampus) in two rat lines selected for differences in fear-induced aggression at 2, 4, and 24 h after a peripheral injection of saline or lipopolysaccharide (LPS, 250 μg/kg). LPS stimulation elevated cytokine activity above baseline levels in both aggressive and nonaggressive rats, but the pattern, time course of cytokine changes, and their regional characteristics varied according to the animal aggressiveness. After LPS administration, aggressive rats showed increased levels of IL-1β in the hypothalamus at 2 and 4 h and in the frontal cortex at 4 and 24 h compared to LPS-treated nonaggressive line. IL-2 was increased in the frontal cortex and striatum of aggressive rats within 24 h, while IL-6 elevation in the hypothalamus was found at 4 h and in the frontal cortex at 2 and 4 h. In the hippocampus, the levels of IL-1β, IL-2, and IL-6 were lower in LPS-treated aggressive rats than in nonaggressive animals. The levels of anti-inflammatory cytokine IL-10 were also decreased in all brain structures of aggressive rats receiving LPS. The results indicate that genetic predisposition to increased aggression is associated with a time and region-dependent changes in the levels of pro- and anti-inflammatory cytokines.

Neuroanatomical Changes in Brain Structures Related to Cognition in Epilepsy: An Update

Understanding the microanatomical changes in brain structures is necessary for developing innovative therapeutic approaches to prevent/delay the cognitive impairment in epilepsy. We review here the microanatomical changes in the brain structures related to cognition in epilepsy. Here, we have presented the changes in major brain structures related to cognition, which helps the clinicians understand epilepsy more clearly and also helps researchers develop new treatment procedures.

Additive sex-specific influence of common non-synonymous DISC1 variants on amygdala, basal ganglia, and white cortical surface area in healthy young adults

The disrupted-in-schizophrenia-1 (DISC1) gene is known for its role in the development of mental disorders. It is also involved in neurodevelopment, cognition, and memory. To investigate the association between DISC1 variants and brain morphology, we analyzed the influence of the three common non-synonymous polymorphisms in DISC1 on specific brain structures in healthy young adults. The volumes of brain regions were determined in 145 subjects by magnetic resonance imaging and automated analysis using FreeSurfer. Genotyping was performed by high resolution melting of amplified products. In an additive genetic model, rs6675281 (Leu607Phe), rs3738401 (Arg264Gln), and rs821616 (Ser704Cys) significantly explained the volume variance of the amygdala (p = 0.007) and the pallidum (p = 0.004). A higher cumulative portion of minor alleles was associated with larger volumes of the amygdala (p = 0.005), the pallidum (p = 0.001), the caudate (p = 0.024), and the putamen (p = 0.007). Sex-stratified analysis revealed a strong genetic effect of rs6675281 on putamen and pallidum in females but not in males and an opposite influence of rs3738401 on the white cortical surface in females compared to males. The strongest single association was found for rs821616 and the amygdala volume in male subjects (p < 0.001). No effect was detected for the nucleus accumbens. We report-to our knowledge-for the first time a significant and sex-specific influence of common DISC1 variants on volumes of the basal ganglia, the amygdala and on the cortical surface area. Our results demonstrate that the additive model of all three polymorphisms outperforms their single analysis.

A Review of Neuroimaging Studies on Working Memory Paradigms in Patients with Bipolar Disorder

New brain technologies including neuroimaging studies are powerful means for providing new insights into clinical and cognitive neuroscience. Bipolar disorder is a severe chronic phasic mental disease characterized by various cognitive dysfunctions. Working memory is one prominent domain of cognitive impairment in bipolar disorder. Disruptions in working memory are observed even in euthymic bipolar patients which makes it a potential endophenotypic marker for the disorder. Finding such markers may help in providing firm neurobiological basis for psychiatric nosologies and symptomatic presentations. This review aims to summarize some of the important aspects of findings from functional magnetic resonance imaging studies on the activation of brain structures in relation to working memory paradigms.

Effects of dopamine D1 receptor activation and blockade on dopamine and noradrenaline levels in the rat brain

The noradrenergic and dopaminergic systems are associated with the motor system and have anatomical and functional connections that have not yet been studied. The present study aimed to examine the specific role of D1 receptors (D1Rs) on noradrenergic and dopaminergic responses in the rat brain. Male Wistar rats were assigned to eight groups to receive systemic injection of a D1R agonist (SKF-38393) at 0, 1, 5 or 10mg/kg or injection of a D1R antagonist (SCH-23390) at 0, 0.25, 0.5 or 1mg/kg. Dopamine (DA) and noradrenaline (NA) levels were measured using high-performance liquid chromatography. Injection of SKF-38393 alone at 1, 5 and 10mg/kg did not alter DA levels in the midbrain, cerebral cortex or pons, while it significantly increased these levels in the striatum (at 1 and 10mg/kg), hippocampus (at 1mg/kg) and cerebellum (at 1 and 5mg/kg). Administration of SKF-38393 at 1, 5, and 10mg/kg decreased the NA levels in the midbrain, pons, hippocampus (except at 1mg/kg) and cortex (except at 5mg/kg), whereas the opposite effect was observed in the striatum. SCH-23390 decreased the DA levels in the cortex (at 0.25 and 0.5mg/kg) and pons (at 0.5mg/kg). In contrast, 0.25, 0.5 and 1mg/kg SCH-23390 increased the DA levels in the cerebellum, whereas no differences from the control levels were observed for the DA levels in the striatum, midbrain and hippocampus. SCH-23390 at 0.5 and 1mg/kg increased the NA levels in the striatum. In contrast, the midbrain, hippocampus, cortex, pons and cerebellum did not exhibit altered NA levels. Our results demonstrate that the activation of D1Rs modulates the response of the noradrenergic system in nearly all of the investigated brain structures; thus, the blockade of D1Rs attenuates the effects induced by D1R activation.

Acute Impact of Selected Pyridoindole Derivatives on Fos Expression in Different Structures of the Rat Brain

The impacts of three pyridoindole derivatives (PDs), designated as PD144, PD143, and PD104, which have previously been shown to have antidepressant (PD144) and anxiolytic (PD143, PD104) properties, were investigated on the Fos expressions in 11 different rat brain areas, including the medial prefrontal cortex, striatum, septum, accumbens nucleus (shell, core), bed nucleus of the stria terminalis, hypothalamic paraventricular nucleus, central amygdala, locus coeruleus, dorsal raphe nucleus, and the solitary tract nucleus. Control rats received vehicle, while the other three groups the PDs in a dose of 25 mg/kg/b.w. The animals were transcardially perfused with a fixative 90 min after the treatments. Coronal sections of 40-µm thickness were processed for Fos-immunostaining by avidin-biotin-peroxidase complex and visualized by nickel-intensified diaminobenzidine complex. Fos-labeled sections were counterstained with neuropeptides including corticoliberine (CRH), oxytocin (OXY), vasopressin (AVP), and vasoactive intestinal polypeptide (VIP) and processed for immunofluorescence staining using Alexa Fluor 555 dye. In all the three groups of animals, the upregulation of PDs-induced Fos expression only in 2 of 11 brain areas was investigated, namely, in the hypothalamic paraventricular nucleus (PVN) and the central amygdaloid nucleus (CeA). The other brain structures studied were devoid of Fos expression. Counterstaining of the Fos-labeled CeA-containing sections with VIP antibody revealed that the Fos expression stimulated by the PDs was upregulated in all the CeA subdivisions (lateral, ventral, capsular), except the medial one. Dual immunoprocessings showed Fos/CRH-labeling in both the PVN and the amygdala and Fos/OXY in the PVN. No Fos/AVP colocalizations were seen in the PVN. The obtained data provide the first view on the intracerebral effects of three new PDs derivatives, which effects were restricted only to the PVN and CeA areas. The present data may help to improve our understanding of the impact of the selected PDs on the brain and to anticipate possible behavioral and neuroendocrine consequences.

HPLC Neurotransmitter Analysis

High performance liquid chromatography (HPLC) is a powerful tool to measure neurotransmitter levels in specific tissue samples and dialysates from patients and animals. In this chapter, we list the current protocols used to measure neurotransmitters in the form of biogenic amines from murine brain samples.

A fully automated pipeline for brain structure segmentation in multiple sclerosis

Accurate volume measurements of the brain structures are important for treatment evaluation and disease follow-up in multiple sclerosis (MS) patients. With the aim of obtaining reproducible measurements and avoiding the intra-/inter-rater variability that manual delineations introduce, several automated brain structure segmentation strategies have been proposed in recent years. However, most of these strategies tend to be affected by the abnormal MS lesion intensities, which corrupt the structure segmentation result. To address this problem, we recently reformulated two label fusion strategies of the state of the art, improving their segmentation performance on the lesion areas. Here, we integrate these reformulated strategies in a completely automated pipeline that includes pre-processing (inhomogeneity correction and intensity normalization), atlas selection, masked registration and label fusion, and combine them with an automated lesion segmentation method of the state of the art. We study the effect of automating the lesion mask acquisition on the structure segmentation result, analyzing the output of the proposed pipeline when used in combination with manually and automatically segmented lesion masks. We further analyze the effect of those masks on the segmentation result of the original label fusion strategies when combined with the well-established pre-processing step of lesion filling. The experiments performed show that, when the original methods are used to segment the lesion-filled images, significant structure volume differences are observed in a comparison between manually and automatically segmented lesion masks. The results indicate a mean volume decrease of 1.13%±1.93 in the cerebrospinal fluid, and a mean volume increase of 0.13%±0.14 and 0.05%±0.08 in the cerebral white matter and cerebellar gray matter, respectively. On the other hand, no significant volume differences were found when the proposed automated pipeline was used for segmentation, which demonstrates its robustness against variations in the lesion mask used.

Fatigue following head and neck cancer radiotherapy: a systematic review of dose correlates

INTRODUCTIONS

Radical radiotherapy (RT) is the cornerstone of Head and Neck (H&N) cancer treatment, but it often leads to fatigue due to irradiation of brain structures, impacting patient quality of life.

OBJECTIVE

This study aimed to systematically investigate the dose correlates of fatigue after H&N RT in brain structures.

METHODS

The systematic review included studies that examined the correlation between fatigue outcomes in H&N cancer patients undergoing RT at different time intervals and brain structures. PubMed, Scopus, and WOS databases were used in the systematic review. A methodological quality assessment of the included studies was conducted following the PRISMA guidelines. After RT, the cohort of H&N cancer patients was analyzed for dose correlations with brain structures and substructures, such as the posterior fossa, brainstem, cerebellum, pituitary gland, medulla, and basal ganglia.

RESULT

Thirteen studies meeting the inclusion criteria were identified in the search. These studies evaluated the correlation between fatigue and RT dose following H&N RT. The RT dose ranged from 40 Gy to 70 Gy. Most of the studies indicated a correlation between the trajectory of fatigue and the dose effect, with higher levels of fatigue associated with increasing doses. Furthermore, five studies found that acute and late fatigue was associated with dose volume in specific brain structures, such as the brain stem, posterior fossa, cerebellum, pituitary gland, hippocampus, and basal ganglia.

CONCLUSION

Fatigue in H&N RT patients is related to the radiation dose received in specific brain areas, particularly in the posterior fossa, brain stem, cerebellum, pituitary gland, medulla, and basal ganglia. Dose reduction in these areas may help alleviate fatigue. Monitoring fatigue in high-risk patients after radiation therapy could be beneficial, especially for those experiencing late fatigue.

Revealing potential drug targets in schizophrenia through proteome-wide Mendelian randomization genetic insights

BACKGROUND

Schizophrenia (SCZ) is a severe, chronic mental disorder with no current cure. Identifying novel pharmacological targets is crucial for developing more effective treatments.

METHODS

We performed two-sample Mendelian randomization (MR) analyses to estimate the associations between cerebrospinal fluid (CSF) containing 154 proteins and plasma containing 734 proteins and risk of SCZ. Bidirectional MR analysis, steiger filtering, bayesian colocalization, phenotypic scanning, and validation analysis were examined to validate the assumptions of MR. For proteins significantly associated with SCZ identified by MR, we explored their potential impact on brain structures, including cortical surface area (SA), thickness (TH), and the volume of subcortical structures.

RESULTS

MR analysis identified 13 protein-SCZ pairs at Bonferroni significance (P < 5.63 × 10-5). Notably, the genetically proxied protein level of neuromedin B (NMB) was associated with an increased risk for SCZ (odds ratio [OR] = 1.41; 95 % CI, 1.27 to 1.58; P = 6.68 × 10-10). Bayesian colocalization suggested that NMB shares genetic variations with SCZ. Further, NMB interacts with target proteins of current SCZ drugs and was validated in the UK Biobank. The genetically proxied NMB was positively associated with an increase in the surface area (SA) of the parahippocampal gyrus (β = 8.93 mm2, 95 % CI, 1.58 to 16.3, P = .02). Additionally, an increase in the genetically proxied SA of the parahippocampal gyrus was inversely associated with the risk of SCZ (OR = 0.996, 95 % CI, 0.993 to 0.999, P = .04).

CONCLUSIONS

The findings suggest that NMB may represent a promising target for pharmacological intervention in SCZ. This warrants further investigation into the specific constituents involved, which could have potential for follow-up studies.

Increased rubidium levels in brain regions involved in food intake in obese rats

The hypothalamus, particularly its ventromedial and lateral regions, plays a pivotal role in homeostatic appetite regulation and is therefore a significant brain structure in the development of obesity. Additionally, the development of obesity can be caused by improper hedonic regulation, which involves neural circuits and systems associated with pleasure and reward. Several studies indicate a possible link between rubidium (Rb) and obesity, despite this element is not being typically considered influential in vital life processes. The present study, therefore, aims to investigate whether excessive body fat in obese animals alters rubidium levels in brain regions directly or indirectly involved in appetite regulation. The research was conducted on high-calorie diet (HCD)-induced obese rats (OB, n = 8) and their lean counterparts (L, n = 8). The determination of Rb levels in brain areas was performed using synchrotron radiation-based X-ray fluorescence microanalysis (SRXRF). The obtained results show a significantly higher level of Rb in all brain areas examined, although the increase in this element in obese individuals was not the same in all structures. The largest relative difference (over 70%) was observed for the orbitofrontal cortex, and the smallest (about 35%) for the amygdala. Principal component analysis with linear projections demonstrated a clear differentiation between the brain structures of obese and non-obese individuals based on the full elemental composition of tissues, while Rb was the only element that distinguished the obese group in each of the examined brain structures. The results obtained clearly confirm the increase in Rb levels in the brain structures responsible for regulating appetite in obesity.

Brain structural changes in preschool children with MRI-negative epilepsy

PURPOSE

To investigate abnormalities in cortical and subcortical structures of the brain in preschool children with MRI-negative epilepsy.

METHODS

Cortical thickness, cortical mean curvature, cortical surface area, cortical volume, and volumes of subcortical structures were measured using Freesurfer software in preschool children with epilepsy and age-matched controls.

RESULTS

Findings showed cortical thickening in the left fusiform gyrus, left middle temporal gyrus, right suborbital sulcus, and right gyrus rectus, and cortical thinning mainly in the parietal lobe of preschool children with epilepsy compared to controls. The difference in cortical thickness in the left superior parietal lobule remained after correction for multiple comparisons and was negatively correlated with duration of epilepsy. Cortical mean curvature, surface area, and volume were mainly altered in the frontal and temporal lobes. Changes in mean curvature in the right pericallosal sulcus were positively correlated with age at seizure onset, and changes in mean curvature in the left intraparietal sulcus and transverse parietal sulcus were positively correlated with frequency of seizures. There were no significant differences in the volumes of the subcortical structures.

CONCLUSION

Changes in preschool children with epilepsy occur in the cortical rather than subcortical structures of the brain. These findings further our understanding of the effects of epilepsy in preschool children and will inform management of epilepsy in this patient population.

Taste aversion learning in the snail Cornu aspersum

The present study was conducted to provide evidence of conditioned taste aversion learning (CTA) in the snail Cornu aspersum, using quinidine as the aversive stimulus in a procedure of Pavlovian Conditioning of Tentacle Lowering. Subjects were split into two groups: paired and unpaired. During the devaluation phase, subjects from the "paired group" received the US followed by the quinidine exposure, while subjects from the "unpaired group" received the quinidine and, 30 min later, the US. Subjects which had received the US paired with the quinidine showed a decrease of the conditioned response (CR), in contrast to subjects which had received the quinidine and the US unpaired. These results provide a useful CTA procedure in terrestrial snails. The implication of the results for learning and the physiological correlates is discussed.

Causal effect of air pollution on the risk of brain health and potential mediation by gut microbiota

OBJECTIVE

Epidemiologic investigations have examined the correlation between air pollution and neurologic disorders and neuroanatomic structures. Increasing evidence underscores the profound influence of the gut microbiota on brain health. However, the existing evidence is equivocal, and a causal link remains uncertain. This study aimed: to determine if there is a causal connection between four key air pollutants, and 42 neurologic diseases, and 1325 distinct brain structures; and to explore the potential role of the gut microbiota in mediating these associations.

METHODS

Univariable Mendelian randomization (UVMR) and multivariable Mendelian randomization (MVMR) models were deployed to estimate the causal impact of air pollutants (including particulate matter [PM] with aerodynamic diameters <2.5 μm [PM2.5], and <10 μm [PM10]; PM2.5 absorbance; and nitrogen oxides [NOx]) on brain health through various Mendelian randomization methodologies. Lastly, the mediating role of the gut microbiome in the connections between the identified pollutants and neurologic diseases and brain structures was systematically examined.

RESULTS

The potential causal associations of PM2.5, PM2.5 absorbance, PM10, and exposure to NOx, with the risks of intracerebral hemorrhage, hippocampal perivascular spaces, large artery strokes, generalized epilepsy with tonic-clonic seizures, Alzheimer's disease, multiple sclerosis, anorexia nervosa, post-traumatic stress disorder (PTSD), and 420 brain structures, were investigated by UVMR analysis. Following adjustment for air pollutants by MVMR analysis, the genetic correlations between PM10 exposure and PTSD and multiple sclerosis remained significant and robust. Importantly, we observed that phylum Lentisphaerae may mediate the association between PM10 and multiple sclerosis. Additionally, PM2.5 absorbance with a greater risk of reduced thickness in the left anterior transverse temporal gyrus of Heschl and a decreased area in the right sulcus intermedius primus of Jensen, mediated by genus Senegalimassilia and genus Lachnospiraceae UCG010, respectively. Finally, we provided evidence that Clostridium innocuum and genus Ruminococcus2 may partly mediate the causal effect of NOx on altered thickness in the left transverse temporal cortex and area in the right sulcus intermedius primus of Jensen, respectively.

CONCLUSION

This study established a genetic connection between air pollution and brain health, implicating the gut microbiota as a potential mediator in the relationship between air pollution, neurologic disorders, and altered brain structures.

Nine-month-long Social Isolation Changes the Levels of Monoamines in the Brain Structures of Rats: A Comparative Study of Neurochemistry and Behavior

Social isolation (SI) is chronic psycho-emotional stress for humans and other socially living species. There are few comparative studies that have measured monoamine levels in brain structures in male and female rats subjected to SI. Existing data is highly controversial. In our recent study, we investigated behavioral effects of SI prolonged up to 9 months on a rather large sample of 69 male and female Wistar rats. In the present study, we measured the levels of monoamines-norepinephrine (NE), dopamine (DA), 5-hydroxytryptamine (5-HT), and DA and 5-HT metabolites-in the brain structures of 40 rats from the same sample. The single-housed rats of both sexes showed hyperactivity and reduced reactivity to novelty in the Open Field test, and impaired passive avoidance learning. Regardless of their sex, by the time of sacrifice, the single-housed rats weighed less and had lower pain sensitivity and decreased anxiety compared with group-housed animals. SI decreased NE levels in the hippocampus and increased them in the striatum. SI induced functional activation of the DA-ergic system in the frontal cortex and hypothalamus, with increased DA and 3-methoxytyramine levels. SI-related changes were found in the 5-HT-ergic system: 5-HT levels increased in the frontal cortex and striatum, while 5-hydroxyindoleacetic acid only increased in the frontal cortex. We believe that SI prolonged for multiple months could be a valuable model for comparative analysis of the behavioral alterations and the underlying molecular processes in dynamics of adaptation to chronic psychosocial stress in male and female rats in relation to age-dependent changes.

The cerebellum and its connections to other brain structures involved in motor and non-motor functions: A comprehensive review

The cerebellum has a large network of neurons that communicate with several brain structures and participate in different functions. Recent studies have demonstrated that the cerebellum is not only associated with motor functions but also participates in several non-motor functions. It is suggested that the cerebellum can modulate behavior through many connections with different nervous system structures in motor, sensory, cognitive, autonomic, and emotional processes. Recently, a growing number of clinical and experimental studies support this theory and provide further evidence. In light of recent findings, a comprehensive review is needed to summarize the knowledge on the influence of the cerebellum on the processing of different functions. Therefore, the aim of this review was to describe the neuroanatomical aspects of the activation of the cerebellum and its connections with other structures of the central nervous system in different behaviors.