Areas Of Rat Brain Research Articles

Neurophysiological and Neurochemical Effects of the Putative Cognitive Enhancer (S)-CE-123 on Mesocorticolimbic Dopamine System.

Treatments for cognitive impairments associated with neuropsychiatric disorders, such as attention deficit hyperactivity disorder or narcolepsy, aim at modulating extracellular dopamine levels in the brain. CE-123 (5-((benzhydrylsulfinyl)methyl) thiazole) is a novel modafinil analog with improved specificity and efficacy for dopamine transporter inhibition that improves cognitive and motivational processes in experimental animals. We studied the neuropharmacological and behavioral effects of the S-enantiomer of CE-123 ((S)-CE-123) and R-modafinil in cognitive- and reward-related brain areas of adult male rats. In vivo single unit recordings in anesthetized animals showed that (S)-CE-123, but not R-modafinil, dose-dependently (1.25 to 10 mg/kg i.v.) reduced firing of pyramidal neurons in the infralimbic/prelimbic (IL/PrL) cortex. Neither compound the affected firing activity of ventral tegmental area dopamine cells. In freely moving animals, (S)-CE-123 (10 mg/kg i.p.) increased extracellular dopamine levels in the IL/PrL, with different patterns when compared to R-modafinil (10 mg/kg i.p.); in the nucleus accumbens shell, a low and transitory increase of dopamine was observed only after (S)-CE-123. Neither (S)-CE-123 nor R-modafinil initiated the emission of 50-kHz ultrasonic vocalizations, a behavioral marker of positive affect and drug-mediated reward. Our data support previous reports of the procognitive effects of (S)-CE-123, and show a minor impact on reward-related dopaminergic areas.

Long Term Cognitive Impairment and Increased Inflammation following Mild Traumatic Brain Injury using the CHIMERA Model

IntroductionTraumatic brain injury (TBI) affects a vast number of people worldwide. Mild TBI (mTBI), including concussions, accounts for most of the TBI cases. mTBI patients experience enduring symptoms, including headaches, mild cognitive dysfunction, emotional instability, psychiatric symptoms, and increased risk of neurodegenerative disease. Repetitive closed head impact model of engineered rotational acceleration (rCHIMERA) is a recently developed nonsurgical animal model of TBI that primarily produces diffuse axonal injury characterized by white matter inflammation and axonal damage, which mimic the mTBI in humans. However, the majority of studies on rCHIMERA were conducted in mice, which are not suitable for assessment of complex behavior.MethodsThis study was designed to validate our rCHIMERA‐induced rat mTBI model using advanced and cutting‐edge behavioral tests and immunofluorescence staining of key biomarkers of TBI. Adult male Sprague‐Dawley rats (~350 g) were divided into sham and injured groups. All rats were anesthetized with dexmedetomidine (IV, 0.2 mg/kg/hr). Following anesthesia, the rats designated for injury received 6 closed‐head impacts of 2 Joules (J) energy over 3 days with 1‐day interval (3 impacts on days 1 & 3, with 30‐seconds between impacts, and rested on day 2). The sham rats were handled the same way as the injured without the impacts. The rats were subsequently subjected to a battery of behavioral tests at specified time points post‐injury: neurological severity score (NSS), automated home‐cage (CleverSys), behavioral spectrometer (Biobserve), rotarod test, and fear conditioning. Histological assessment of the injury was performed in targeted rat brain areas from sham and injured rats. Immunohistochemistry staining for amyloid precursor protein (APP), ionized calcium‐binding adapter molecule 1 (Iba‐1) and glial fibrillary acidic protein (GFAP) were used to determine axonal damage, inflammatory response and astrocytic activation, respectively, in sham and injured rats. The weights of the rats were also monitored for the duration of the studies.Results3 months after mTBI, there was no significant difference in body weight and NSS between sham and injured rats. Injury did not affect motor activity and motor learning with the rotarod test, but did impair associative fear learning and memory in fear conditioning tests 4 weeks and 3 months after mTBI (n=9 shams and 9 mTBI). APP immunohistochemistry in the injured brains revealed induced diffusive axonal injury in the the cortex. The number of GFAP positive cells was increased in the prefrontal cortex and hippocampus after injury and the astrocytes showed distinct hypertrophic morphology. The number of Iba‐1 positive cells was also increased after injury, indicating enhanced inflammation.ConclusionThe results suggest that our mTBI model in rats induces short‐term changes in affect and activity, long‐term cognitive impairments, and histological changes. These observations validate the CHIMERA, using the rat, as a model that replicates clinical mTBI.Support or Funding InformationThis work is supported by the Advancing a Healthier Wisconsin Endowment (#5520444) to AC.

Concurrent tissue oxymetry and blood flowmetry to assess the effect of drugs on cerebral oxygen metabolism

An Oxylite/LDF system (Oxford Optronix, UK) driven by a sensor made of optical fibres for the tissue oxygen tension (pO2) and for the Laser Doppler Blood Flow (BF) was implemented. This has allowed pO2 and BF real time measurements in discrete brain areas of anaesthetised rats that were then challenged with exogenous oxygen (O2) and carbon dioxide (CO2). The results gathered were compared with data obtained following treatment with drugs that have excitatory influence upon the brain activity such as amphetamine or with a central nervous system (CNS) depressant such as CI-966. Altogether these experiments support the methodology for in vivo investigation of pharmacological effects on cerebral oxygen metabolism and could provide new understandings on the effects of psychostimulants and anticonvulsants on selected brain regions.

Long-Term Effects of Hypoxia-Reoxygenation on Thioredoxins in Rat Central Nervous System.

Oxidative stress induced by the oxidative pathway dysregulation following ischemia/ reperfusion has been proposed as an important cause of neuronal death and brain damage. The proteins of the thioredoxin (Trx) family are crucial mediators of protein function regulating the intracellular hydrogen peroxide levels and redox-sensitive post-translational protein changes. To analyze the expression and distribution of fourteen members of the Trx family, potentially essential for the regeneration upon long-term brain damage, in a perinatal hypoxia-ischemia rat model induced by common carotid artery ligation. The right common carotid artery (CCA) was exposed by an incision on the right side of the neck, isolated from nerve and vein, and permanently ligated. Sham-surgery rats underwent right CCA surgical exposure but no ligation. Euthanasia was administered to all rats at 30, 60, and 90 days of age. Protein expression and distribution of fourteen members of the Trx family and related proteins (Grx1, Grx2, Grx3, Grx5, Prx1, Prx2, Prx3, Prx4, Prx5, Prx6, Trx1, Trx2, TrxR1, TrxR2) was examined in the most hypoxia susceptible rat brain areas, namely, cerebellum, corpus striatum, and the hippocampus. The thioredoxin proteins displayed a complex, cell-type, and tissue-specific expression pattern following ischemia/reperfusion. Even 60 days after ischemia/reperfusion, Western blot analysis showed a persistent expression of Trx1 and Grx2 in several brain areas. The Trx family of proteins might contribute to long-term survival and recovery supporting their therapeutic use to curtail ischemic brain oxidative damage following an ischemia/reperfusion insult. Characterization of ischemia/reperfusion oxidative brain damage and analysis of the involved mechanisms are required to understand the underneath processes triggered by ischemia/reperfusion and to what extent and in what way thioredoxins contribute to recovery from brain hypoxic stress.

The impact of p38 MAPK, 5-HT/DA/E signaling pathways in the development and progression of cardiovascular diseases and heart failure in type 1 diabetes

Serotonin or 5-HT, DA and E, all monoamine neurotransmitters, work also as hormones, plays crucial role in the brain and body. This 5-HT, DA and E increased significantly, and regulated by activated p38 MAPK in type I diabetes mellitus (T1DM), and that has been shown to involve in metabolic disorders as well as cardiovascular diseases, leading to heart failure. Even though these molecules are being considered for clinical trials in the treatments of various cardiovascular diseases, the synergistic-pathophysiological mechanisms of these p38 MAPK and neurotransmitters on target molecules, cells and tissues in heart failure are not completely understood in T1DM. However, T1DM results in metabolic dysregulation, impairment/loss of insulin secretion, hyperglycemia and acidosis. These changes are widely reported to be involved in abnormal functions of receptors, which provide binding site for signaling molecules. We are constantly focusing on the mechanisms of alloxan-induced-diabetes, glucose-induced-hyperglycemia and ammonium chloride-induced-acidosis (non-diabetic hyperglycemia (NDH) and non-diabetic acidosis (NDA), respectively) on the levels and functions of neurotransmitters and p38 MAPK. Here, in this review, we are proposing the mechanisms of insulin and/or some of the pharmacological agents on the level and functions of p38 MAPK and neurotransmitters in various areas of rat brain under diabetic or its associated conditions, which leads to cardiovascular dysfunctions. Targeting these molecules/pathways may be useful in the treatment of cardiovascular diseases and diabetes mediated heart failure.

Altered functional connectivity of the insula in a rat model of recurrent headache.

Migraine is a pain disorder accompanied by various symptoms. The insula, a “cortical hub,” is involved in many functions. Few studies have focused on the insula in migraine. We explored the resting-state functional connectivity between the insula and other brain areas in rats subjected to repeated meningeal nociception which was commonly used as animal model of migraine. Inflammatory soup was infused through supradural catheters in conscious rats. The rats were subdivided based on the frequency of the inflammatory soup infusions. Magnetic resonance imaging data were acquired on rats 21 days after inflammatory soup infusion and functional connectivity seeded on the insula was analyzed. In the low-frequency inflammatory soup group, magnetic resonance imaging was performed again 1 h after the glyceryl trinitrate injection following baseline scanning. The cerebellum showed increased functional connectivity with the insula in the inflammatory soup groups. The insula showed increased functional connectivity with the medulla and thalamus in the ictal period in the low-frequency inflammatory soup rats. In the high-frequency inflammatory soup group, several areas showed increased functional connectivity with the insula, including the pons, midbrain, thalamus, temporal association cortex, and retrosplenial, visual, and sensory cortices. Our findings support the hypothesis that the headache phase of migraine depends on the activation and sensitization of the trigeminovascular system, and that the chronification of migraine may be related to higher brain centers and limbic cortices. The insula may be a new target for treatment of migraine.

Neurotoxicity of green- synthesized magnetic iron oxide nanoparticles in different brain areas of wistar rats

AimsThe aim of the present study was to evaluate the toxicity of magnetic iron oxide nanoparticles (MIONs) which were synthesized using carob leaf extract on various brain areas of Wistar rats. Main methodsCarob leaf synthesized-MIONs were characterized using different techniques: Dynamic Light Scattering (DLS), Transmission Electron Microscope (TEM), UV–vis spectrophotometer, Fourier Transform infrared (FTIR), X-Ray Diffraction (XRD) and Atomic Force Microscope (AFM). The toxicity of MIONs in vivo was evaluated by: monitoring rat’s body weight, measuring iron content in different brain areas, evaluating some oxidative stress parameters, estimating acetylcholinesterase (AChE) in addition to histopathological investigations. Key findingsThe present study demonstrated no body weight changes of MIONs- treated rats. According to the conditions of the present study, the hippocampus and striatum were the most affected areas and demonstrated neuronal degeneration due to MIONs exposure. MIONs treatment of Wistar rats, also affected the iron homeostasis in both striatum and midbrain by decreasing iron content in these areas. The least affected areas were thalamus and cerebellum. The histopathological examination of brain areas demonstrated moderate neuronal degeneration in hippocampus and striatum, mild neuronal degeneration in cortex and slight degeneration in hypothalamus and pons-medulla areas were detected. SignificanceThe results suggested that MIONs have a toxic impact on different brain areas and the effect varies according to the brain area.

Dynamics of clusterin protein expression in the brain and plasma following experimental traumatic brain injury

Progress in the preclinical and clinical development of neuroprotective and antiepileptogenic treatments for traumatic brain injury (TBI) necessitates the discovery of prognostic biomarkers for post-injury outcome. Our previous mRNA-seq data revealed a 1.8–2.5 fold increase in clusterin mRNA expression in lesioned brain areas in rats with lateral fluid-percussion injury (FPI)-induced TBI. On this basis, we hypothesized that TBI leads to increases in the brain levels of clusterin protein, and consequently, increased plasma clusterin levels. For evaluation, we induced TBI in adult male Sprague-Dawley rats (n = 80) by lateral FPI. We validated our mRNA-seq findings with RT-qPCR, confirming increased clusterin mRNA levels in the perilesional cortex (FC 3.3, p < 0.01) and ipsilateral thalamus (FC 2.4, p < 0.05) at 3 months post-TBI. Immunohistochemistry revealed a marked increase in extracellular clusterin protein expression in the perilesional cortex and ipsilateral hippocampus (7d to 1 month post-TBI), and ipsilateral thalamus (14d to 12 months post-TBI). In the thalamus, punctate immunoreactivity was most intense around activated microglia and mitochondria. Enzyme-linked immunoassays indicated that an acute 15% reduction, rather than an increase in plasma clusterin levels differentiated animals with TBI from sham-operated controls (AUC 0.851, p < 0.05). Our findings suggest that plasma clusterin is a candidate biomarker for acute TBI diagnosis.

Neonatal treatment with clomipramine modifies the expression of estrogen receptors in brain areas of male adult rats

The participation of estrogens in depression has been well recognized. To exert its effects, estradiol binds mainly to estrogen receptors ESR1 and ESR2 (α and β, respectively), expressed in brain regions including the hippocampus, limbic regions and hypothalamic nuclei. In rodents, modified estrogen receptors expression in brain areas have been implicated in different signs similar to those observed in depressive patients. Neonatal clomipramine (CMI) treatment is a pharmacological manipulation that generates behavioral and neurochemical changes that persist throughout adulthood and resemble human depression.The aim of this study was to analyze whether CMI neonatal treatment modifies the expression of nuclear ESR1 and ESR2 in the hippocampus, amygdala basolateral (BLA), amygdala medial (MeA), hypothalamic medial preoptic area (mPOA) and raphe nucleus in male rats. Our results indicate that CMI treatment significantly induced an mRNA increase of ESR1 in the hypothalamus, additionally produce a reduction in the mRNA ESR2 expression in raphe accompanied of an increase in hypothalamus and amygdala. CMI treated rats show more immunorreactive cells to ESR1 (ESR1-ir) in mPOA, BLA, MeA, together with a reduction of these cells in the hippocampal CA1 region. Moreover, an increase in the number of immunorreactive cells to ESR2 (ESR2-ir), in BLA and MeA, was observed in CMI treated rats. Additionally, the hippocampal CA2 region and raphe nucleus showed a decrease in these cells. Also, neonatal CMI treatment induced a decrease in the number of cells of the pyramidal layer in CA1. Overall, the results suggest that neonatal CMI treatment in rats (during brain development) induces changes in estrogen receptors in different brain areas involved with the regulation of depressive-like behaviors.

Antidepressants upregulate c-Fos expression in the lateral entorhinal cortex and hippocampal dorsal subiculum: Study in rats

Neural circuits involved in the development of depression are currently poorly understood. To provide insight into this issue, we evaluated the influence of seven clinically effective antidepressants on neuronal activity in thirty rat brain areas. Drugs belonging to all major groups of antidepressants (imipramine, reboxetine, fluoxetine, bupropion, mirtazapine, agomelatine, and phenelzine) were examined; since antidepressants typically require weeks of continued administration before they achieve a therapeutic effect, we administered these drugs for 21 days. The experiments were conducted with male Wistar rats. To identify the neuroanatomical targets for antidepressants, the alterations of c-Fos expression in different brain areas were measured using ELISA assay. The drugs were examined at doses sufficient to produce behavioral effect in the rat forced swim test (FST). All the drugs at the behaviorally relevant doses activated two brain areas, the lateral entorhinal cortex and dorsal subiculum of the hippocampus; none of the drugs affected the c-Fos expression in the medial orbital, prelimbic and infralimbic cortex, caudate putamen, nucleus accumbens core, bed nucleus of stria terminalis, hipothalamic paraventricular nucleus, medial amygdaloid nucleus, lateral habenula, substantia nigra pars compacta and pars reticulata, ventral tegmental area, hippocampal ventral subiculum, dorsal and ventral periaqueductal gray matters, and medial entorhinal cortex. These findings suggest that the stimulation of the lateral entorhinal cortex and hippocampal dorsal subiculum play a role in therapeutic effects of antidepressants.

Associative learning is necessary for airborne pheromones to activate sexual arousal-linked brain areas of female rats

In rodents, urine-borne male pheromones include volatile organic compounds (VOCs) and major urinary proteins (MUPs). In mice, the attraction of females to male odor is reportedly acquired through associative learning with MUPs in some studies. Here, we found that VOC and MUP sex pheromones were differentiated in rats at around 8 weeks of age and that females separated from males at weaning showed no preference for male urine odor after sexual maturity. Olfactory preferences could be gained in females after repeated experience of VOC pheromones alone as well as male urine or a blend of synthetic VOC pheromones and recombinant MUPs. However, differences in acquired olfactory preferences for male urine were further revealed by neuro-immuno-histochemical studies. The blend exhibited neural activation in the main olfactory system (MOS), accessory system (AOS), and the ventromedial hypothalamus (VMH), indicating sexual arousal, whereas the VOC alone only caused neural activation of MOS. We suggest that olfactory preference is generated through repeated experience of either VOCs or a blend of VOCs and MUPs, but the neural activations related to sexual arousal have to be acquired through associative learning with MUPs in female rats. When adult female rats were separated from males before maturity, they lost their attraction to male urine odor. Female preference to volatiles in male urine could be gained by repeated experience of volatile and protein pheromones. Brain regions related to sexual arousal were activated by male urine in females with experience of VOCs together with MUPs but not in those experienced with VOCs alone. Associative learning between VOC and MUP pheromones is necessary for male urine odor-induced FOS responses in the key regions for sexual arousal/excitement in female rats.

Epigenetic and autophagic changes after nerve agent exposure in the rat piriform cortex and hippocampus

The detrimental effects of organophosphate (OP) nerve agents have been reported but the mechanisms mediating these multiple effects are not well understood. Recent use of nerve agents in Syria and the UK illustrate their continuous threat to the modern world. Epigenetic and autophagy studies are useful to address the issues related to regulation of gene and protein expression by which nerve agents could impact on human health. These studies help to understand molecular mechanisms underlying the multiple neurotoxic effects of nerve agents. In the present study, changes in epigenetic (global DNA methylation and histone acetylation) and autophagic marker proteins were studied in the nerve agent sensitive rat brain areas (piriform cortex and hippocampus) after soman (1xLD50) exposure. Global DNA methylation analysis revealed that nerve agent induced hypomethylation in the brain regions at 1 and 7 days post exposure. In contrast, DNA hypermethylation was observed at 30 days post soman exposure, demonstrating a possible compensatory mechanism. Western blot analysis showed significant increase in the histone acetylation levels after soman exposure in the piriform cortex and hippocampus. The present study observed the changes in autophagic proteins of nerve agent poisoning for the first time to the best of our knowledge. Immunoreactivity levels of autophagic proteins (LC3-II, ATG-5 and p62) were transiently increased in the rat piriform cortex and hippocampus after soman exposure. In conclusion, this study provides insight into the epigenetic and autophagic changes in the brain following soman exposure and their possible role in the neuronal damage and development of multiple neurological effects.

Effect of Initial Aging and High-Fat/High-Fructose Diet on Mitochondrial Bioenergetics and Oxidative Status in Rat Brain.

Middle age is an early stage of the aging process, during which the consumption of diets rich in saturated fats and/or simple sugars might influence brain function, but only few data are available on this issue. We therefore investigated the impact of a diet rich in saturated fat and fructose (HFF) on mitochondrial physiology in hippocampus and frontal cortex of middle-aged rats (1year old), by including a group of adult rats (90days) as a "negative control," lacking the putative effect of aging. Middle-aged rats were fed HFF or control diet for 4weeks. Mitochondrial function was analyzed by high-resolution respirometry and by assessing the amount of respiratory complexes. Markers of oxidative balance, as well as the protein content of uncoupling protein 2 (UCP2), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), and peroxisome proliferator-activated receptor alpha (PPARα), were also assessed. A decrease in the activity of complex I was detected in both brain areas of middle-aged rats. In hippocampus, mitochondrial respiratory capacity and complex IV content decreased with age and increased with HFF diet. Higher protein oxidative damage, decreased antioxidant defenses, and increased UCP2 and PGC-1α content were found in hippocampus of middle-aged rats. HFF feeding induced a significant reduction in the amount of UCP2, PGC-1α, and PPARα, together with higher protein oxidative damage, in both brain areas. Overall, our results point to middle age as a condition of early brain aging for mitochondrial function, with hippocampus being an area more susceptible to metabolic impairment than frontal cortex.

Cellular count changes in different rat brain areas due to early maternal separation

Objective: to identify whether maternal separation during breastfeeding (MSDB) affects the cellular count in different rat brain areas. The continuous mother-child interaction, adjusts and modulates the offspring behavioral response to environmental stimuli and also affects their development and homeostasis. Morphological and physiological changes in the offspring brains have been observed, including cell count differences in different brain areas with differences between males and females. Materials and methods: this study compared albino Wistar rats in a protocol of MSDB with a control group. Brain tissue was fixed with paraformaldehyde, cut in cryostat and either stained with Hematoxylin-Eosin (H&amp;E) or processed for immunohistochemistry against glial fibrillary acidic protein (GFAP). All sections were analyzed using a cell count protocol including statistical analysis with Students T test at a significance level of P ≤0.05. Results: the MSDB group of male subjects presented higher GFAP-marked cell count in primary motor cortex and hippocampus; while female subjects, showed less GFAP-marked cell count in these same areas. Conclusions: MSDB produces sex-specific changes in the number of glial cells especially in the primary motor cortex, this finding may be considered as associated factor of alterations in motor responses to stress in these subjects, in addition to other known causes such as the Hypothalamic-Pituitary-Adrenal Axis dysfunction.

Effects of chronic cocaine exposure on the circadian rhythmic expression of the clock genes in reward-related brain areas in rats

Drug addiction is a widespread social problem, which not only brings adverse consequences to the human body, but also causes great burden to the society. However, it's still unclear how the long-term and sustained cocaine exposure will affect clock genes’ expression in the reward related brain areas. We hypothesize that chronic cocaine exposure causes changes in the circadian rhythmic expression of clock genes in brain regions associated with reward, since previous studies have shown that cocaine use causes circadian disorders. Sprague-Dawley male rats were administrated with cocaine 20 mg/kg at ZT4 through intraperitoneal injection for 21 consecutive days. Twenty-four hours after the last cocaine administration brain samples were collected at 4-h intervals for 24 h (every 4h: ZT 0; ZT 4; ZT 8; ZT 12; ZT 16; ZT 20) to examine expression of rPer1, rPer2, rPer3, rCry, rBmal1 and rClock by quantitative real-time reverse-transcription polymerase chain reaction (RT-PCR). We found that chronic cocaine exposure to rats resulted in significantly disturbances in expression of clock genes in reward related brain areas compared to saline - treated rats. In cocaine-treated rats, rPer1 expression in the suprachiasmatic nucleus (SCN), prefrontal cortex (PFC) and ventral tegmental area (VTA); rPer2 expression in the nucleus accumbens (NAc) shell and hippocampus; rPer3 expression in the NAc core; rCry expression in the SCN and PFC; rBmal1 expression in the SCN and NAc core showed robust circadian rhythms that were essentially identical to those in control rats. However, robust circadian rhythm in rPer1 expression in the SCN and rCry expression in the PFC was nearly completely phase - reversed in cocaine-treated rats. A blunting of circadian oscillations of rPer1 expression occurred in the NAc core and shell and hippocampus; of rPer2 expression occurred in the SCN, PFC, NAc core and hippocampus; of rPer3 expression occurred in the SCN, PFC, NAc shell, hippocampus and VTA; of rCry expression occurred in the NAc core and shell, hippocampus and VTA; of rBmal1 expression occurred in the PFC, NAc shell, hippocampus and VTA in cocaine - treated rats. These rhythm changes accompanied by significant increase in rPer1, rPer2, rPer3 and rBmal1 in the PFC, rPer1, rPer2 and rBmal1 in the hippocampus; significant decrease in rPer2, rPer3 and rCry in the SCN, rPer3, rCry, rBmal1 and rClock in the NAc core compared to control rats. rClock expression in cocaine - treated rats showed no rhythmic change, identical to control rats.These results suggest that chronic cocaine exposure results in disturbances in clock genes’ expression in reward related areas.

Atypical functional connectivity between the anterior cingulate cortex and other brain regions in a rat model of recurrent headache.

We explored the atypical functional connectivity between the anterior cingulate cortex and other brain areas in rats subjected to repeated meningeal nociception. The rat model was established by infusing an inflammatory soup through supradural catheters in conscious rats. Rats were subdivided according to the frequency of the inflammatory soup infusions. Functional connectivity analysis seeded on the anterior cingulate cortex was performed on rats 21 days after inflammatory soup infusion. Glyceryl trinitrate was injected following baseline scanning in the low-frequency inflammatory soup group and magnetic resonance imaging data were acquired 1 h after the injection. The rats exhibited nociceptive behavior after high-frequency inflammatory soup infusion. The anterior cingulate cortex showed increased functional connectivity with the cerebellum in the inflammatory soup groups. The medulla showed increased functional connectivity with the anterior cingulate cortex in the ictal period in the low-frequency inflammatory soup rats. Several areas showed increased functional connectivity with the anterior cingulate cortex in the high-frequency inflammatory soup group, including the pontine tegmentum, midbrain, thalamus, corpus callosum, hippocampus, and retrosplenial, visual, sensory, and motor cortices. This study indicated that the medulla participates in the early stage of a migraine attack and may be associated with the initiation of migraine. Sensitization of the trigeminal nociceptive pathway might contribute to the cutaneous allodynia seen in chronic migraine. Brain areas important for memory function may be related to the chronification of migraine. Electrophysiological studies should examine those migraine-related areas and provide new targets for migraine treatment and prevention.

Metabolomics profiling of methamphetamine addicted human serum and three rat brain areas.

Methamphetamine (METH) has already been a serious problem all over the world. The identification of related biomarkers and pathways is helpful to evaluate the degree of METH addiction, develop appropriate treatment during abstinence, and explore the mechanism. Here, it is the first time to perform metabolomics profiling of METH addicted human serum and three regions of METH-induced conditioned place preference (CPP) rat brain by using UHPLC-MS/MS and matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI), respectively. Untargeted metabolomics analysis demonstrated clear differences between METH abusers and the healthy control by finding 35 distinct expressed metabolites in serum, including 5 TCA intermediates, 17 amino acids and 13 other biomolecules, 15 of which were newly identified following METH exposure. By using MALDI-MSI, the relative quantification and distribution of 14 metabolites were investigated in the nucleus accumbens (NAc), dorsal hippocampus (dHPC) and ventral hippocampus (vHPC) of CPP rat brain. Taken together, METH addiction could influence energy metabolism, amino acids metabolism, and phospholipids metabolism. A multi-parameter model consisting of these related metabolites can be established as a METH addiction biomarker in the future. The mapping of phospholipids provided new insights into the mechanism of METH addiction. Notably, the trend of metabolite changes in NAc and dHPC was almost the same, while it was opposite between dHPC and vHPC. It seems that NAc and dHPC were the two regions more susceptible to METH administration in the brain. And dHPC and vHPC play different roles in METH addiction proved by metabolites mapping.

Distribution of HAP1-immunoreactive Cells in the Retrosplenial–retrohippocampal Area of Adult Rat Brain and Its Application to a Refined Neuroanatomical Understanding of the Region

Huntingtin-associated protein 1 (HAP1) is a neural interactor of huntingtin in Huntington’s disease and interacts with gene products in a number of other neurodegenerative diseases. In normal brains, HAP1 is expressed abundantly in the hypothalamus and limbic-associated regions. These areas tend to be spared from neurodegeneration while those with little HAP1 are frequently neurodegenerative targets, suggesting its role as a protective factor against apoptosis. In light of the relationship between neurodegenerative diseases and deterioration of higher nervous activity, it is important to definitively clarify HAP1 expression in a cognitively important brain region, the retrosplenial–retrohippocampal area. Here, HAP1 expression was evaluated immunohistochemically over the retrosplenial cortex, the subicular complex, and the entorhinal and perirhinal cortices. HAP1-immunoreactive (ir) cells were classified into five discrete groups: (1) a distinct retrosplenial cell cluster exclusive to the superficial layers of the granular cortex, (2) a conspicuous, thin line of cells in layers IV/V of the “subiculum-backing cortex,” (3) a group of highly immunoreactive cells associated with the medial entorhinal–subicular corner, (4) pericallosal cells just below layer VI and adjacent to the white matter, and (5) other sporadic, widely-disseminated HAP1-immunoreactive cells. HAP1 was found to be the first marker for the complex subiculum-backing cortex and a precise marker for several subfields in the retrosplenial–retrohippocampal area, verified through comparative staining with other neurochemicals. HAP1 may play an important role in protecting these cortical structures and functions for higher nervous activity by increasing the threshold to neurodegeneration and decreasing vulnerability to stress or aging.

The chronic effect of pulsed 1800 MHz electromagnetic radiation on amino acid neurotransmitters in three different areas of juvenile and young adult rat brain.

The extensive use of mobile phones worldwide has raised increasing concerns about the effects of electromagnetic radiation (EMR) on the brain due to the proximity of the mobile phone to the head and the appearance of several adverse neurological effects after mobile phone use. It has been hypothesized that the EMR-induced neurological effects may be mediated by amino acid neurotransmitters. Thus, the present study investigated the effect of EMR (frequency 1800 MHz, specific absorption rate 0.843 W/kg, power density 0.02 mW/cm2, modulated at 217 Hz) on the concentrations of amino acid neurotransmitters (glutamic acid, aspartic acid, gamma aminobutyric acid, glycine, taurine, and the amide glutamine) in the hippocampus, striatum, and hypothalamus of juvenile and young adult rats. The juvenile and young adult animals were each divided into two groups: control rats and rats exposed to EMR 1 h daily for 1, 2, and 4 months. A subgroup of rats were exposed daily to EMR for 4 months and then left without exposure for 1 month to study the recovery from EMR exposure. Amino acid neurotransmitters were measured in the hippocampus, striatum, and hypothalamus using high-performance liquid chromatography. Exposure to EMR induced significant changes in amino acid neurotransmitters in the studied brain areas of juvenile and young adult rats, being more prominent in juvenile animals. It could be concluded that the alterations in amino acid neurotransmitters induced by EMR exposure of juvenile and young adult rats may underlie many of the neurological effects reported after EMR exposure including cognitive and memory impairment and sleep disorders. Some of these effects may persist for some time after stopping exposure.

HPLC electrochemical detection and quantification of monoamines and their metabolites in rat brain tissue samples.

The monitoring of monoamines and their metabolites in CNS samples can be very valuable in pharmaceutical and biomedical research. A specific high performance liquid chromatography, coupled to a coulometric electrochemical detection method, for the assay of monoamines (dopamine, norepinephrine, epinephrine and serotonin) and their metabolites in rat brain tissue samples was developed. The chromatographic separation was achieved on a C8 reversed phase column with a mobile phase consisting of 0.1 M sodium formate buffer, 5 mM sodium 1-heptanesulfonate, 0.17 mM ethylenediaminetetraacetic acid disodium salt and 5% v/v acetonitrile (pH ±4.0). The detection was achieved through electrochemical detection, with a coulometric cell potential setting of +650 mV. The flow-rate was at 1 ml/min and the total run time was 50 min. The method was validated according to validation guidelines. The method was found to be linear (R2 > 0.99) over the analytical range (5 to 200 ng/ml) for all monoamines and their metabolites. All the other validation parameters were acceptable and within range. The method was applied to three rat brain areas (pre-frontal cortex, hippocampus and striatum), where the monoamines (except for epinephrine) and their metabolites were easily detected.