Rock music improvisation shows increased activity in Broca's area and its right hemisphere homologue related to spontaneous creativity.

OBJECTIVE: The neural correlates of creativity are not well understood. Using an improvised guitar task, we investigated the role of Broca's area during spontaneous creativity, regardless of individual skills, experience, or subjective feelings. RESULTS: Twenty guitarists performed improvised and formulaic blues rock sequences while hemodynamic responses were recorded using functional near-infrared spectroscopy. We identified a new significant response in Broca's area (Brodmann area [BA] 45L) and its right hemisphere homologue during improvised playing but not during formulaic playing. Our results indicate that bilateral BA45 activity is common during creative processes that involve improvisation across all participants, regardless of subjective feelings, skill, age, difficulty, history, or amount of practice. While our previous results demonstrated that the modulation of the neural network according to the subjectively experienced level of creativity relied on the degree of deactivation in BA46L, our current results independently show a common concurrent activity in BA45 in all participants. We suggest that this is related to the sustained execution of improvisation in "motor control," analogous to motor planning in speech control.

Attractin deficiency causes metabolic and morphological abnormalities in slow-twitch muscle.

Skeletal muscle fibers are classified as slow-twitch and fast-twitch fibers, which have different reactive oxygen species (ROS) metabolism and mitochondrial biogenesis. Recently, Attractin (Atrn), which encodes secreted (sAtrn) and transmembrane (mAtrn)-type proteins, has been shown to be involved in free radical scavenging. Although Atrn has been found in skeletal muscle, little is known about the expression levels and function of Atrn in each muscle fiber type. Therefore, we investigate sAtrn and mAtrn expression levels in the slow-twitch soleus (sol) and fast-twitch extensor digitorum longus (EDL) muscles as well as the morphology and expression levels of antioxidant enzymes and functional mitochondrial markers using Atrn-deficient muscles. Both types of Atrn were expressed in the sol and EDL. mAtrn was mainly expressed in the adult sol, whereas sAtrn expression levels did not differ between muscle types. Moreover, mAtrn in the sol was abundantly localized in the subsarcolemmal area, especially in the myoplasm near mitochondria. Atrn-deficient Zitter rats showed muscle fiber atrophy, myofibril misalignment, mitochondrial swelling and vacuolation in the sol but not EDL. Furthermore, the Atrn-deficient sol exhibited a marked reduction in antioxidant enzyme SOD1, GPx1, catalase and Prx6 and mitochondrial functional protein, UCP2, expression. Even Atrn-deficient EDL showed a significant reduction in Prx3, Prx6, UCP2 and UCP3 expression. These data indicate that Atrn-deficiency disturbs ROS metabolism in skeletal muscles. In particular, mAtrn is involved in metabolism in the slow-twitch sol muscle and mAtrn-deficiency may cause ROS imbalance, resulting in morphological abnormalities in the muscle.

Effects of methylazoxymethanol-induced micrencephaly on parvalbumin-positive GABAergic interneurons in the rat rostral basolateral amygdala.

The amygdala plays a crucial role in anxiety-related behavior and various neuropsychiatric disorders. The offspring of dams, administered methylazoxymethanol acetate (MAM) intraperitoneally at gestational day 15, exhibit micrencephaly and anxiety-related behavior, such as hyperactivity in rearing and crossing behavior, alongside a distinct Fos expression profile in the basolateral (BLA) and central amygdala. However, the histochemical underpinnings of these changes remain to be elucidated. To determine the histochemical alterations in MAM-induced model rats, we performed Nissl staining, immunohistochemistry for parvalbumin (PV) or calbindin (Calb), and immunohistochemistry for PV in conjunction with in situ hybridization for glutamate decarboxylase (GAD). We compared immunoreactivity in the BLA between normal and MAM-induced model rats and observed a significant decrease in the number of PV-positive neurons in MAM-induced model rats; however, no significant differences in the number of Nissl- and Calb-positive neurons were observed. We did not detect any significant between-group differences with regards to the effects of environmental enrichment on the number of PV-positive neurons in the BLA. Double-labeling for GAD and PV revealed that many PV-positive neurons colocalized with digoxigenin-GAD65/67 signals. In addition, GAD/PV double-positive neurons and the total number of GAD-positive neurons in the BLA were lower in the MAM-induced model rats. These results indicate that histochemical alterations observed in the BLA of the MAM-induced model rats may attribute to an aberrant GABAergic inhibitory system.

Induction of aberrant agonistic behavior by a combination of serotonergic and dopaminergic manipulation in rats.

Serotonin (5-HT) and dopamine (DA) are involved in the regulation of social behaviors. However, the effects of their interactions on social behavior are not well understood. In this study, rats received a serotonergic neurotoxin injection into the raphe nuclei and/or systemic administration of L-3, 4-dihydroxyphenylalanine (L-DOPA), and their agonistic behaviors were investigated using the resident-intruder (RI) paradigm. Rats in the DA + /5-HT-group, which were administered both monoaminergic treatments, exhibited intense jump and flight responses to intruders. These behaviors were not observed in rats that received either 5-HT lesions or L-DOPA treatment only. To address the neural basis of these aberrant behaviors, we compared c-Fos immunoreactivity in the brain among the different groups. The DA + /5-HT-group had c-Fos activation in areas related to anti-predatory defensive behaviors, such as the ventromedial hypothalamic nucleus, premammillary nucleus, and periaqueductal gray. Moreover, this group had increased c-Fos expression in the ventroposterior part of the anterior olfactory nucleus (AOVP). To test the involvement of this area in the aberrant behaviors, cytotoxic lesions were performed in the AOVP prior to the monoaminergic treatments, and subsequent behaviors were examined using the RI test. The AOVP-lesioned DA + /5-HT-rats had attenuation of the aberrant behaviors. Together, these results suggest that the AOVP is involved in the generation of the aberrant defensive behaviors, and that 5-HT/DA balance is important in the regulation of social behaviors.

Calbindin-Positive Neurons Co-express Functional Markers in a Location-Dependent Manner Within the A11 Region of the Rat Brain.

The A11 region plays a role in numerous physiological functions, including pain and locomotor activity, and consists of a variety of neurons including GABAergic, calbindin positive (Calb+), and dopaminergic (DA) neurons. However, the neurochemical nature of Calb+ neurons and their regulatory role in the A11 region remain largely unknown. In this study, we examined the kind of functional markers co-expressed in the Calb+ neurons using sections from 8-week-old rats. To examine a marker related to classical neurotransmitters, we performed in situ hybridization for vesicular glutamate transporter 2 (vGluT2) or glutamate decarboxylase (GAD) 65 and 67, in conjunction with Calb immunohistochemistry. We found cellular co-expression of Calb with vGluT2 or GAD65/67 throughout the A11 region. Nearly all Calb+/GAD65/67+ neurons were found in the rostral-middle aspect of the A11 region. In contrast, Calb+/vGluT2+ neurons were found predominantly in the middle-caudal aspect of the A11 region. For receptors and neuropeptides, we performed immunohistochemistry for androgen receptor (AR), estrogen receptors (ERα and ERß), and calcitonin gene-related peptide (CGRP). We found that Calb+ neurons co-expressed AR in the rostral aspect of the A11 region in both male and female rats. However, we rarely find cellular co-expression of Calb with ERα or ERß in this region. For CGRP, we found both Calb+ neurons with or without CGRP expression. These results demonstrate that Calb+ neurons co-express many functional markers. Calb+ neurons have a distinct distribution pattern and may play a variety of regulatory roles, depending on their location within the A11 region.

Iron accumulation in the choroid plexus, ependymal cells and CNS parenchyma in a rat strain with low-grade haemolysis of fragile macrocytic red blood cells.

Iron accumulation in the CNS is associated with many neurological diseases via amplification of inflammation and neurodegeneration. However, experimental studies on iron overload are challenging, since rodents hardly accumulate brain iron in contrast to humans. Here, we studied LEWzizi rats, which present with elevated CNS iron loads, aiming to characterise choroid plexus, ependymal, CSF and CNS parenchymal iron loads in conjunction with altered blood iron parameters and, thus, signifying non-classical entry sites for iron into the CNS. Non-haem iron in formalin-fixed paraffin-embedded tissue was detected via DAB-enhanced Turnbull Blue stainings. CSF iron levels were determined via atomic absorption spectroscopy. Ferroportin and aquaporin-1 expression was visualised using immunohistochemistry. The analysis of red blood cell indices and serum/plasma parameters was based on automated measurements; the fragility of red blood cells was manually determined by the osmotic challenge. Compared with wild-type animals, LEWzizi rats showed strongly increased iron accumulation in choroid plexus epithelial cells as well as in ependymal cells of the ventricle lining. Concurrently, red blood cell macrocytosis, low-grade haemolysis and significant haemoglobin liberation from red blood cells were apparent in the peripheral blood of LEWzizi rats. Interestingly, elevated iron accumulation was also evident in kidney proximal tubules, which share similarities with the blood-CSF barrier. Our data underscore the importance of iron gateways into the CNS other than the classical route across microvessels in the CNS parenchyma. Our findings of pronounced choroid plexus iron overload in conjunction with peripheral iron overload and increased RBC fragility in LEWzizi rats may be seminal for future studies of human diseases, in which similar constellations are found.

Microhemorrhage in a Rat Model of Neonatal Shaking Brain Injury: Correlation between MRI and Iron Histochemistry.

Previous studies have shown that neonatal shaking brain injury (SBI) causes transient microhemorrhages (MHs) in the gray matter of the cerebral cortex and hippocampus. Iron deposits and iron-uptake cells are observed surrounding MHs in this SBI model, suggesting local hypoxic-ischemic conditions. However, whether the shaken pups suffered systemic hypoxic-ischemic conditions has remained uncertain. Further, histopathological correlations of MHs on magnetic resonance imaging (MRI) are still unclear. The present study examined MHs after neonatal SBI using a combination of histochemical and susceptibility-weighted imaging (SWI) analyses. Systemic oxygen saturation analyses indicated no significant difference between shaken and non-shaken pups. MHs on postnatal day 4 (P4) pups showed decreased signal intensity on SWI. Iron histochemistry revealed that these hypointense areas almost completely comprised red blood cells (RBCs). MHs that appeared on P4 gradually disappeared by P7-12 on SWI. These resolved areas contained small numbers of RBCs, numerous iron-positive cells, and punctate regions with iron reaction products. Perivascular iron products were evident after P12. These changes progressed faster in the hippocampus than in cortical areas. These changes in MHs following neonatal SBI may provide new insights into microvascular pathologies and impacts on brain functions as adults.

Neonatal shaking brain injury changes psychological stress-induced neuronal activity in adult male rats.

Neonatal shaking brain injury (SBI) leads to increases in anxiety-like behavior and altered hormonal responses to psychological stressors as adults. These abnormalities are hypothesized to be due to a change in sensitization in neuronal circuits as a consequence of neonatal SBI. We examined the effects of neonatal SBI on neuronal activity in the anxiety- and/or stress-related areas of adult rats using Fos immunohistochemistry. Exposure to a novel elevated plus maze (EPM) resulted in a marked increase in Fos expression in the parvocellular (PVNp) and magnocellular parts of the paraventricular nucleus and the ventral part of the bed nucleus of the stria terminalis (vBNST) of shaken rats (S group) compared to non-shaken control rats (C group). On the contrary, Fos expression was significantly lower in the medial nucleus of the amygdala and the ventral subiculum (vS) of S group rats than C group rats exposed to EPM. Although we found no significant correlation in the number of Fos-expressing cells in the vBNST and PVNp in the C group rats, these numbers were significantly correlated in the S group rats. Furthermore, in the S group rats, but not in the C group rats, the number of Fos-expressing cells in the vBNST was inversely correlated with that in the vS. Interestingly, previous neuronal tracing studies have demonstrated direct projections from the vS to the vBNST and from the vBNST to the PVNp. The present data suggest that neonatal SBI can alter neuronal activity in anxiety- and/or stress-related neuronal circuits.

Minocycline Alleviates Cluster Formation of Activated Microglia and Age-dependent Dopaminergic Cell Death in the Substantia Nigra of Zitter Mutant Rat.

Microglial activation is a component of neurodegenerative pathology. Here, we examine whether activated microglia participate in age-related dopaminergic (DA) cell death in the substantia nigra pars compacta (SNc) of the zitter (zi/zi) rat, a mutant characterized by deletion of the attractin gene. Confocal microscopy with double-immunohistochemical staining revealed activated microglia-formed cell-clusters surrounding DA neurons in the SNc from 2 weeks after birth. An immunoelectron microscopic study showed that the cytoplasm of activated microglia usually contains phagosome-like vacuoles and lamellar inclusions. Expression levels of the pro-inflammatory cytokines interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) were increased in the midbrain of 2-month-old zi/zi rats. Chronic treatment with the anti-inflammatory agent minocycline altered the morphology of the microglia, reduced cluster formation by the microglia, and attenuated DA cell death in the SNc, and reduced the expression of IL-1ß in the midbrain. These results indicate that activated microglia, at least in part and especially at the initial phase, contribute to DA cell death in the SNc of the zi/zi rat.

Hemodynamic responses related to intrinsically photosensitive retinal ganglion cells in migraine.

To clarify whether photoreception of intrinsically photosensitive retinal ganglion cells (ipRGCs) is related to migraine, we investigated the relationship between hemodynamic responses related to neural activity and visual stimulation of ipRGCs. It has been established that photoreception in ipRGCs is associated with photophobia in migraine. However, the relationship between visual stimulation of ipRGCs and hemodynamic responses in the visual cortex has not been clarified. Hemodynamic responses in the visual cortex were measured using functional near-infrared spectroscopy (fNIRS) as signals reflecting changes in oxygenated and deoxygenated hemoglobin concentrations. Different types of visual stimulation generated by a metamerism method were applied to the peripheral field of the eye of patients with migraine (N = 20) and healthy participants (N = 21). The stimulation intensity on the retina was controlled using an artificial pupil. In the primary visual cortex of patients with migraine, statistically significant changes in fNIRS signals dependent on visual stimulation intensity applied to ipRGCs were observed (p < 0.01), while no such changes were observed in healthy participants. These results reveal that visual stimulation of ipRGCs projecting to the primary visual cortex is involved in hemodynamic responses in patients with migraine, suggesting that ipRGCs, in addition to photometric values related to cones, are associated with migraine.

Prefrontal activation related to spontaneous creativity with rock music improvisation: A functional near-infrared spectroscopy study.

Understanding how the brain modulates improvisation has been the focus of numerous studies in recent years. Models have suggested regulation of activity between default mode and executive control networks play a role in improvisational execution. Several studies comparing formulaic to improvised sequences support this framework and document increases in activity in medial frontal lobe with decreased activity in the dorsolateral prefrontal cortex (DLPFC). These patterns can be influenced through training and neural responses may differ between in beginner and expert musicians. Our goal was to test the generalizability of this framework and determine similarity in neural activity in the prefrontal cortex during improvisation. Twenty guitarists performed improvised and formulaic sequences in a blues rock format while brain activity was recorded using functional near-infrared spectroscopy. Results indicate similar modulation in DLPFC as seen previously. Specific decreases of activity from left DLPFC in the end compared to beginning or middle of improvised sequences were also found. Despite the range of skills of participants, we also found significant correlation between subjective feelings of improvisational performance and modulation in left DLPFC. Processing of subjective feelings regardless of skill may contribute to neural modulation and may be a factor in understanding neural activity during improvisation.

Microglia pre-activation and neurodegeneration precipitate neuroinflammation without exacerbating tissue injury in experimental autoimmune encephalomyelitis.

Human inflammatory or neurodegenerative diseases, such as progressive multiple sclerosis (MS), occur on a background of age-related microglia activation and iron accumulation as well as pre-existing neurodegeneration. Most experimental models for CNS diseases, however, are induced in rodents, which are naturally characterized by a homeostatic microglia phenotype, low cellular iron load and absence of neurodegeneration. Here, we show that naïve LEWzizi rats - Lewis rats with a zitter rat background - show a spontaneous phenotype partly mimicking the changes seen in human aging and particularly in the normal-appearing white and grey matter of patients with progressive MS. Using this model system, we further aimed to investigate (i) whether the acute monophasic MS model experimental autoimmune encephalomyelitis (EAE) transforms into chronic progressive disease and (ii) whether EAE-induced neuroinflammation and tissue damage aggravate on the LEWzizi background. We found that the pre-existing LEWzizi-specific pathology precipitated EAE-related neuroinflammation into forebrain areas, which are devoid of EAE lesions in normal Lewis rats. However, EAE-related tissue damage was neither modified by the LEWzizi-specific pathology nor did EAE-induced neuroinflammation modify the LEWzizi-related pathological process. Our data indicate that the interaction between pre-activated microglia and CD4+ autoreactive T cells during the induction and propagation of tissue damage in the CNS is limited.

Repeated mild shaking of neonates induces transient cerebral microhemorrhages and anxiety-related behavior in adult rats.

Growing evidence suggests that neonatal cerebral microhemorrhages (MHs) are implicated in neuropsychiatric diseases in adults. Although animal studies have identified the progression of the underlying mechanisms of MHs, few studies have investigated the histopathology and behavioral outcomes. In this study, we created an experimental rat model of MHs using a new experimental device for repeated mild shaking brain injury (SBI) in the neonatal period and examined temporal changes in MHs using susceptibility weighted imaging (SWI) and iron histochemistry. SWI demonstrated transient MHs in the gray matter of the cerebral cortex and hippocampus in injured rats. Iron histochemical staining demonstrated leakage of iron and iron-positive cells surrounding MHs. This staining pattern lasted for a long time and continued after disappearance of hemorrhagic signals on SWI. These data suggested the presence of iron-associated gray matter injury after MHs. In the open field test, these injured rats showed anxiety-related behavior as adults. This model may be useful for exploring the underlying mechanisms of changes that occur after MHs and the behavioral outcomes of repeated mild SBI in early development.

Role of neuronal nitric oxide synthase in slowly progressive dopaminergic neurodegeneration in the Zitter rat.

Neuronal nitric oxide synthase (nNOS) is involved in nigrostriatal dopaminergic (DA) neurodegeneration. However, little is known about the distribution patterns and functions of nNOS in slowly progressive DA neurodegeneration. Here we describe the spatiotemporal change in nNOS expression over the course of neurodegeneration and the effect of short- or long-term treatment with the nNOS inhibitor, 7-nitroindazole (7-NI), in zitter (zi/zi) rats. In the substantia nigra pars compacta (SNc), nNOS expression was significantly increased with progression of neurodegeneration. nNOS-immunoreactive (ir) cells were in the vicinity of tyrosine hydroxylase-ir (TH-ir) DA neurons, and some of these cells were also positive for calbindin. nNOS in the caudate-putamen (CPu) showed little difference during progression of neurodegeneration. However, immunoelectron microscopic analysis revealed that abundant TH-ir fibers in the CPu were degenerated due to compression by vacuoles that contained swollen neuronal and glial elements. Additionally, lipid peroxidation as a marker of membrane oxidation was significantly increased in zi/zi rats. Short-term 7-NI treatment attenuated the increase in lipid peroxidation and inhibited the vacuolation in the CPu. Moreover, long-term 7-NI treatment significantly protected TH-ir neurons in the SNc, and TH-ir fibers and DA contents in the CPu. These results show that nNOS exacerbates slowly progressive DA neurodegeneration, and the neuroprotective effects of 7-NI may result from suppression of membrane oxidation that causes abnormal membrane structures in zi/zi rats.

Anatomical variations of the torcular Herophili: macroscopic study and clinical aspects.

The anatomical variations of the confluence of sinuses were examined, focusing on the continuity of the superior sagittal sinus (SSS) and the transverse sinuses (TSs). In the 142 specimens studied, there were 72 symmetric cases (50.7%) and 70 asymmetric cases (49.3%). The symmetric group (no dominant type) was categorized into 34 cases of bifurcation (23.9%) and 38 cases of confluence (26.8%). The asymmetric group was categorized into 54 cases of the right-dominant type (38.0%) and 16 cases of the left-dominant type (11.3%). The right-dominant type was further categorized into 38 partially-communicating (26.8%) and 16 non-communicating types (11.3%). The left-dominant type was categorized into 11 partially-communicating (7.7%) and 5 non-communicating types (3.5%). In summary, the SSS asymmetrically drained into one TS in about half of the cases studied. The right-dominant type was about three to four times as common as the left-dominant type. The draining pattern shown by the asymmetric group could provoke intracranial hypertension due to unilateral jugular vein obstruction. In order to avoid this risk in cases of neck dissection, jugular vein catheterization, or hypercoagulopathy, preoperative evaluations of the dural sinus variations via MR venography, three-dimensional CT, or plain X-ray of the skull are recommended.

Tyrosine hydroxylase afferents to the interstitial nucleus of the posterior limb of the anterior commissure are neurochemically distinct from those projecting to neighboring nuclei.

The interstitial nucleus of the posterior limb of the anterior commissure (IPAC) is exclusively innervated by tyrosine hydroxylase-immunoreactive (TH-IR) fibers as observed in the other nuclei of the rat forebrain such as the striatum and nucleus accumbens. Distinguishing TH-IR afferents to the IPAC from those projecting to neighboring nuclei has been difficult. However, we previously showed that the TH-IR fibers projecting to the IPAC were invulnerable to neurodegeneration in zitter mutant rats, whereas almost all TH-IR afferents fibers to the dorsolateral striatum were lost, indicating that these two groups of TH-IR afferents have distinct neurochemical properties. Here, to explore this observation further, we injected Fluorogold (FG) retrograde tracers to identify neurons projecting to the IPAC or dorsal striatum. We also determined the distribution of attractin mRNA and protein, causative factors for the pathological phenotypes of zitter mutant rats, within the normal rat midbrain. In rats injected with FG into the dorsal striatum, we detected many FG-positive neurons in the ventral aspect of the substantia nigra pars compacta (SNC). In contrast, many FG-positive neurons were observed in the dorsal aspect of the SNC of rats injected with FG into the IPAC. Immunohistochemistry and in situ hybridization studies of intact animals revealed that both attractin mRNA and protein were expressed at higher levels in the ventral aspect of the SNC, whereas both attractin mRNA and protein were expressed at lower levels in the dorsal aspect of the SNC. Taken together, these results indicate that TH-IR afferents to the IPAC have distinct neurochemical properties from those to the striatum and may account for the differential vulnerability to neurodegeneration observed in zitter mutant rats.

Anatomical variations of the recurrent artery of Heubner: number, origin, and course.

The clinical anatomy of the recurrent artery of Heubner (RAH) was examined, focusing on its number, origin, and course, in a large number of brain specimens. We studied 724 RAH in total from 357 brain specimens (714 hemispheres). In 98.74 % of 714 cases there were one or more RAHs, while it was absent in 1.26 % of cases. There was a single RAH in 96.22 % of cases, double in 2.38 % of cases, and triple in 0.14 % of cases. In this study, three origin types of the RAH were defined. We defined A1 and A2 segment of the anterior cerebral artery (ACA) as the artery from the origin of the ACA to the junction of the anterior communicating artery (AComA) and the artery from the junction of the AComA to the anterior border of the corpus callosum, respectively. In 76.2 % of 724 arteries, the RAH originated from the junction of the A1 and A2 segment of the ACA. In 16.3 %, the RAH originated from the A2 segment of the ACA. In 7.5 %, the RAH originated from the A1 segment of the ACA. The course of the RAH was superior to the A1 segment of the ACA in 30.1 % of 724 arteries, anterior in 62.2 %, and posterior in 7.7 %. It is of great importance for neurosurgeons to understand the detailed anatomical variations of the RAH before operating to prevent operative complications resulting in neurological deficits.

Effects of environmental enrichment on the activity of the amygdala in micrencephalic rats exposed to a novel open field.

Environmental enrichment (EE) mediates recovery from sensory, motor, and cognitive deficits and emotional abnormalities. In the present study, we examined the effects of EE on locomotor activity and neuronal activity in the amygdala in control and methylazoxymethanol acetate (MAM)-induced micrencephalic rats after challenge in a novel open field. Control rats housed in EE (CR) showed reduced locomotor activity compared to rats housed in a conventional cage (CC), whereas hyperactivity was seen in MAM rats housed in a conventional cage (MC) and in MAM rats housed in EE (MR). Novel open field exposure in both CC and MC resulted in a marked increase in Fos expression in the anterior and posterior parts of the basolateral amygdaloid nucleus, basomedial nucleus, and medial nucleus, whereas these increases in expression were not observed in CR. The effect of EE on Fos expression in the amygdala was different in MR exposed to a novel open field compared to CR. Furthermore, we observed a quite different pattern of Fos expression in the central nucleus of the amygdala between control and MAM rats. The present results suggest that neuronal activity in the amygdala that responds to anxiety is altered in MAM rats, especially when the rats are reared in EE. These alterations may cause behavioral differences between control and MAM rats.

Three Types of A11 Neurons Project to the Rat Spinal Cord.

The A11 dopaminergic cell group is the only group among the A8-A16 dopaminergic cell groups that includes neurons innervating the spinal cord, and a decrease in dopaminergic transmission at the spinal cord is thought to contribute to the pathogenesis of restless legs syndrome. However, the mechanisms regulating the neuronal activity of A11 dopaminergic neurons remain to be elucidated. Unraveling the neuronal composition, distribution and connectivity of A11 neurons would provide insights into the mechanisms regulating the spinal dopaminergic system. To address this, we performed immunohistochemistry for calcium-binding proteins such as calbindin (Calb) and parvalbumin (PV), in combination with the retrograde tracer Fluorogold (FG) injected into the spinal cord. Immunohistochemistry for Calb, PV, or tyrosine hydroxylase (TH), a marker for dopaminergic neurons, revealed that there were at least three types of neurons in the A11 region: neurons expressing Calb, TH, or both TH and Calb, whereas there were no PV-immunoreactive (IR) cell bodies. Both Calb- and PV-IR processes were found throughout the entire A11 region, extending in varied directions depending on the level relative to bregma. We found retrogradely labeled FG-positive neurons expressing TH, Calb, or both TH and Calb, as well as FG-positive neurons lacking both TH and Calb. These findings indicate that the A11 region is composed of a variety of neurons that are distinct in their neurochemical properties, and suggest that the diencephalospinal dopamine system may be regulated at the A11region by both Calb-IR and PV-IR processes, and at the terminal region of the spinal cord by Calb-IR processes derived from the A11 region.

Enhanced alcohol-drinking behavior associated with active ghrelinergic and serotoninergic neurons in the lateral hypothalamus and amygdala.

Central ghrelin is required for the rewarding properties of drug abuse. We investigated whether alcohol affects ghrelinergic, dopaminergic, and serotoninergic neurons and growth hormone secretagogue receptor 1A (GHS-R1A) levels in the reward system of the brain. Alcohol-naïve C57BL/6J mice received 2g/kg ethanol (EtOH) intraperitoneally (i.p.). Plasma ghrelin levels decreased between 1 and 4h. We investigated the effects of EtOH administration on plasma ghrelin levels in two different animal models at 1, 3, and 10months of age. Plasma ghrelin levels decreased following the EtOH treatment in 1- and 3-month-old short-term (1-day) alcohol vapor-exposed (STA) mice. In contrast, EtOH administration increased plasma ghrelin levels in 1- and 3-month-old long-term (20-day) alcohol vapor-exposed (LTA) mice. In vivo ghrelin release in the lateral hypothalamus (LH) increased in STA and LTA mice after the i.p. administration of EtOH. EtOH increased in vivo dopamine (DA), but not serotonin (5-HT) release in the LH of STA mice, and increased in vivo DA and 5-HT release in the LH of LTA mice. GHS-R1A mRNA expression and GHS-R1A protein levels in the LH were increased in LTA mice. The number of GHS-R1A-immunoreactive cells was greater in the LH and amygdala of LTA mice. These results support the neurobiological correlation between the development of drinking behavior and activation of ghrelinergic and serotonergic neurons in the LH. The activation of ghrelinergic systems in the amygdala may also induce an increase in 5-HT release in the LH during long-term alcohol intake.