Nanogranular TiN-ZrO₂ intermediate layer induced improvement of isolation and grain size of FePt thin films

The effects of TiN-ZrO₂ intermediate layer on the microstructures and magnetic properties of FePt films were investigated. The TiN-ZrO₂ intermediate layer was granular consisting of grains of solid solution of Ti(Zr)ON segregated by amorphous ZrO₂. By doping ZrO₂ into TiN intermediate layer, the FePt grains became better isolated from each other and the FePt grain size was reduced. For 20 vol. % ZrO₂ doping into TiN, the grain size decreased dramatically from 11. 2 nm to 6. 4 nm, and good perpendicular anisotropy was achieved simultaneously. For the FePt 4nm-SiO₂ 35 vol. % -C 20 vol. % films grown on top of the TiN-ZrO₂ 20 vol. % intermediate layer, well isolated FePt (001) granular films with coercivity higher than 18. 1 kOe and an average size as small as 6. 4 nm were achieved.

The prevalence of and risk factors for sleep-disordered breathing in an elderly Korean population

BACKGROUND

There are just a few epidemiological studies on sleep-disordered breathing (SDB) in the elderly, and the results are inconsistent.

STUDY OBJECTIVES

We sought to investigate the prevalence of and risk factors for SDB in a representative elderly population with the use of attended nocturnal polysomnography (NPSG).

METHODS

Among 6,959 individuals aged ≥ 60 years living in Yongin City, Korea, 696 subjects were selected using random sampling. All the subjects were invited to visit a hospital for NPSG, and SDB was defined as an apnea-hypopnea index ≥ 15.

RESULTS

Of the 696 participants investigated, 348 participants completed the sleep study and clinical evaluation. SDB was observed in 127 of the 348 participants, and the prevalence of SDB was 36.5% (52.6% in males and 26.3% in females). A body mass index ≥ 25 was associated with SDB in both male and female subjects, particularly in males, whereas snoring was independently associated with SDB in female participants only. In male participants, SDB was a significant risk factor for hypertension (p = 0.025).

CONCLUSIONS

SDB was found to be common among elderly Koreans, and it was more prevalent and severe in male than in female subjects. Health consequences of SDB in the elderly need to be further explored.

Relationships between sleep disturbances and gastroesophageal reflux disease in Asian sleep clinic referrals

OBJECTIVE

Studies on the association between gastroesophageal reflux disease (GERD) and sleep apnea syndrome (SAS) have reported conflicting results, and attention has not been paid to the relationship between GERD and other sleep disorders. The aim of the study was to evaluate the relationship between GERD and various aspects of sleep disturbances.

METHODS

A total of 564 subjects who were referred to a sleep laboratory were enrolled in the study. They underwent nocturnal polysomnography (NPSG), and they were asked to complete a GERD questionnaire. The questionnaire consisted of 14 items, and included questions on seven reflux symptoms, namely, heartburn, acid regurgitation, chest pain, hoarseness, globus sensation, coughing and epigastric soreness. Subjects reporting heartburn or acid regurgitation at least once a week were classified as having GERD.

RESULTS

Among 564 participants, 51 subjects (9.0%) were diagnosed as having GERD. GERD patients had higher scores in Beck depression inventory (p<.01), Epworth sleepiness scale (p=.03), Pittsburg sleep quality index (p<.01), more spontaneous arousals in NPSG, and more alcohol consumption than non-GERD patients. There was no association between presence of GERD, SAS-related variables, and body mass index (BMI). GERD was significantly associated with poor sleep quality (adjusted OR, 3.5; 95% CI, 1.3-9.3) and depressed mood (adjusted OR, 2.8; 95% CI, 1.5-5.3).

CONCLUSION

Poor subjective sleep and depressive symptoms are associated with the presence of GERD with no association between SAS, BMI and GERD. In managing patients with GERD, psychiatric and sleep symptoms need to be evaluated and appropriately treated.

An FMRI study investigating adolescent brain activation by rewards and feedback

OBJECTIVE

This study aimed to investigate the adolescent brain activation patterns in response to performance feedback (PF), social reward (SR) and monetary reward (MR) and their association with psychological factors.

METHODS

Functional magnetic resonance imaging (fMRI) was performed while middle school boys (n=15) performed tests pertained to PF, SR and MR. The brain activation pattern in each condition was investigated, and the extent of brain activation in each of the three conditions was compared at once.

RESULTS

The caudate and the dorsal prefrontal area were activated in all three conditions. Furthermore, the cuneus showed significantly greater activation in the PF condition than the SR or MR condition. And the self - related areas, such as the right precentral gyrus and paracenral lobule, were more activated in the SR condition than the PF or MR condition. The left middle frontal gyrus was more activated in the MR condition than the PF or SR condition.

CONCLUSION

Not only various reward stimuli but also feedback stimulus might commonly activate dorsal prefrontal and subcortical area in adolescents. Moreover, several different brain activation patterns were also observed in each condition. The results of this study could be applied to planning of learning and teaching strategy for adolescents in various ways.

Abnormal brain activation of adolescent internet addict in a ball-throwing animation task: possible neural correlates of disembodiment revealed by fMRI

While adolescent internet addicts are immersed in cyberspace, they are easily able to experience 'disembodied state'. The purposes of this study were to investigate the difference of brain activity between adolescent internet addicts and normal adolescents in a state of disembodiment, and to find the correlation between the activities of disembodiment-related areas and the behavioral characteristics related to internet addiction. The fMRI images were taken while the addiction group (N=17) and the control group (N=17) were asked to perform the task composed with ball-throwing animations. The task reflected on either self-agency about ball-throwing or location of a ball. And each block was shown with either different (Changing View) or same animations (Fixed View). The disembodiment-related condition was the interaction between Agency Task and Changing View. Within-group analyses revealed that the addiction group exhibited higher activation in the thalamus, bilateral precentral area, bilateral middle frontal area, and the area around the right temporo-parietal junction. And between-group analyses showed that the addiction group exhibited higher activation in the area near the left temporo-parieto-occipital junction, right parahippocampal area, and other areas than the control group. Finally, the duration of internet use was significantly correlated with the activity of posterior area of left middle temporal gyrus in the addiction group. These results show that the disembodiment-related activation of the brain is easily manifested in adolescent internet addicts. Internet addiction of adolescents could be significantly unfavorable for their brain development related with identity formation.

Improvement of EEG slowing in OSAS after CPAP treatment

OBJECTIVES

This study was done to investigate change of electroencephalography (EEG) slowing and its relationship to daytime sleepiness and cognitive functions by continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea syndrome (OSAS).

METHODS

We enrolled thirteen male subjects with severe OSAS, and all the subjects were treated with CPAP for 3 months. Quantitative EEG (QEEG) and neuropsychological tests were performed before and after CPAP treatment.

RESULTS

After CPAP treatment, delta absolute power decreased in the frontal, central, parietal and temporal regions and the slowing ratio was reduced in the frontal region. The Epworth Sleepiness Scale (ESS) score was reduced after CPAP treatment. Reduction in the ESS score was correlated with a decrease in delta absolute power in the frontal region (r=0.559) and a decrease in slowing ratio in frontal, central, parietal, and temporal regions (frontal, r=0.650; other regions, r=0.603). Results of neuropsychological tests assessing memory and attention were improved after CPAP treatment.

CONCLUSIONS

EEG slowing was decreased across all cerebral regions in patients with severe OSAS after CPAP treatment accompanied by improvement of cognitive functions involving several brain areas. These findings suggest that CPAP can induce improvement of cerebral function in OSAS without regional specificity.

Modest changes in cerebral glucose metabolism in patients with sleep apnea syndrome after continuous positive airway pressure treatment

BACKGROUND

Decreased cerebral glucose metabolism has been reported in patients with sleep apnea syndrome (SAS), but it has yet to be decided whether cerebral glucose metabolism in SAS can be altered by continuous positive airway pressure (CPAP) treatment.

OBJECTIVE

The aim of this study was to evaluate cerebral glucose metabolism changes in patients with SAS after CPAP treatment.

METHODS

Thirteen middle-aged male patients with severe SAS [mean age 49.3 ± 7.2 years, mean apnea-hypopnea index (AHI) 60.4 ± 21.2] and 13 male controls (mean age 46.0 ± 9.4 years, mean AHI 4.1 ± 3.7) participated in the study. All 26 study subjects underwent fluorodeoxyglucose-positron emission tomography (FDG-PET), but SAS patients underwent FDG-PET twice, namely before and 3 months after acceptable CPAP usage.

RESULTS

Significant hypometabolism was observed in the bilateral prefrontal areas, left cuneus and left cingulate cortex of SAS patients before CPAP, and after CPAP, significant increases in cortical glucose metabolism were observed in the bilateral precentral gyri and left anterior cingulate cortex. However, these improvements in hypometabolism in both areas were insufficient to reach control levels, and hypometabolism in other regions persisted after CPAP treatment.

CONCLUSIONS

Reduced cerebral glucose metabolism in the precentral gyrus and the cingulate cortex in patients with SAS was modestly improved by acceptable CPAP treatment. The findings of this study suggest that acceptable CPAP usage cannot completely reverse reduced cerebral glucose metabolism in SAS patients. Further studies are required to evaluate the long-term effects of CPAP treatment with total compliance.

Amino-Nogo-A antagonizes reactive oxygen species generation and protects immature primary cortical neurons from oxidative toxicity

Nogo-A is originally identified as an inhibitor of axon regeneration from the CNS myelin. Nogo-A is mainly expressed by oligodendrocytes, and also by some neuronal subpopulations, particularly in the developing nervous system. Although extensive studies have uncovered regulatory roles of Nogo-A in neurite outgrowth inhibition, precursor migration, neuronal homeostasis, plasticity and neurodegeneration, its cell-autonomous functions in neurons are largely uncharacterized. Here, we show that HIV-1 trans-activating-mediated amino-Nogo-A protein transduction into cultured primary cortical neurons achieves an almost complete neuroprotection against oxidative stress induced by exogenous hydrogen peroxide (H(2)O(2)). Endogenously expressed neuronal Nogo-A is significantly downregulated upon H(2)O(2) treatment. Furthermore, knockdown of Nogo-A results in more susceptibility to acute oxidative insults and markedly increases neuronal death. Interacting with peroxiredoxin 2 (Prdx2), amino-Nogo-A reduces reactive oxygen species (ROS) generation and extracellular signal-regulated kinase phosphorylation to exert neuroprotective effects. Structure-function mapping experiments reveal that, out of NiG-Δ20, a novel region comprising residues 290-562 of amino-Nogo-A is indispensable for preventing oxidative neuronal death. Moreover, mutagenesis analysis confirms that cysteine residues 424, 464 and 559 are involved in the inhibition of ROS generation and neuroprotective role of amino-Nogo-A. Our data suggest that neuronal Nogo-A might play a cell-autonomous role in improving neuronal survival against oxidative insult through interacting with Prdx2 and scavenging of ROS.

The association of obesity with insulin resistance in male patients with obstructive sleep apnea syndrome in Korea

OBJECTIVE

Obstructive sleep apnea syndrome (OSAS) has been associated with cardiovascular complications and insulin resistance has been implicated in the pathogenesis and progression of atherosclerosis. We investigated whether insulin resistance is associated with OSAS independent of obesity.

METHODS

A total of 183 male patients with OSAS and 52 healthy controls were assessed by nocturnal polysomnography (NPSG). After NPSG, serum concentrations of total cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, glucose and insulin were measured. Insulin resistance was determined by calculating the homeostasis model assessment for insulin resistance (HOMA-IR).

RESULTS

Subjects were divided into normal control, mild-to-moderate OSA group (n=96) and severe OSA group (n=87). There were no significant differences among groups in age, body mass index (BMI), neck circumference or waist circumference. Serum concentrations of total cholesterol, LDL cholesterol, triglycerides, glucose, insulin and HOMA-IR scores of normal controls did not differ from those of the mild-to-moderate or severe OSAS groups. HOMA-IR significantly correlated with anthropometric variables, oxygen desaturation index, triglyceride and LDL cholesterol. Stepwise multiple linear regression analysis showed that waist circumference (β=0.35) and triglycerides (β=0.27) were significant determinants of HOMA-IR (adjusted R(2)=20%, p<0.01).

CONCLUSION

Insulin resistance was related to obesity itself rather than OSAS severity or nocturnal hypoxemia-related variables. In preventing cardiovascular complications in OSAS patients, weight reduction should be considered.

The association of oxidative stress with central obesity in obstructive sleep apnea

PURPOSE

The purpose of this paper is to evaluate concentrations of multiple oxidative stress and antioxidant status markers in patients with obstructive sleep apnea (OSA) and normal controls of comparable obesity.

METHODS

A total of 73 male subjects, recruited from a sleep clinic or advertisements, were enrolled in this study. All subjects underwent overnight polysomnography. The subjects were divided into normal control (n = 20), mild to moderate OSA (n = 31), and severe OSA (n = 22) with no difference in obesity. Blood was withdrawn from subjects, and markers of oxidative stress and antioxidant status, and parameters of glucose metabolism were assessed.

RESULTS

There was no significant difference in either oxidative stress or antioxidant status markers among the three groups. There was no significant correlation between the oxidative stress markers and the OSA variables. However, there were correlations between waist-to-hip ratio (WHR)-oxidized low-density lipoprotein cholesterol (oxLDL) (r = 0.424), WHR-glutathione peroxidase (GPX) (r = 0.318), WHR-total antioxidant status (TAS) (r = -0.317), and WHR-superoxide dismutase (SOD) (r = -0.338). In multiple regression analysis, WHR was a significant independent variable of oxLDL, GPX, TAS, and SOD.

CONCLUSIONS

The oxidative stress in OSA was related to central obesity rather than intermittent hypoxia or respiratory disturbances. To control cardiovascular complications in OSA, weight reduction should be a component in the treatment strategy.

The genetic factors affecting drinking behaviors of korean young adults with variant aldehyde dehydrogenase 2 genotype

OBJECTIVE

We determined whether aldehyde dehydrogenase 2 (ALDH2) activity alters the way in which drinking behaviors are affected by gene polymorphisms of other alcohol-metabolizing enzymes and serotonin-related proteins.

METHODS

Through a follow-up survey with a cohort comprising 551 university freshmen over a period of 6 years, we examined the genetic factors affecting drinking behaviors. In 2000, drinking behaviors were assessed and tryptophan hydroxylase (TPH) and ALDH2 gene polymorphisms were determined. Drinking behaviors were repeated in 2006 (n=150), and the gene polymorphisms of ADH1B, ADH1C, CYP2E1, 5-HTR2A 1438A/G, and 5-HTR2A IVS2 were also determined.

RESULTS

In 2000, the variant and wild-type ALDH2 groups exhibited little difference in terms of drinking frequency and problem drinking. Furthermore, some genotypes influenced only the variant group: ADH1B*2/*2 was associated with a lower drinking frequency, and CYP2E1 c2 allele was associated with an increased risk of problem drinking. In 2006, drinking frequency and risk of problem drinking were significantly lower in the variant group than in the wild-type group. However, the TPH AA genotype disturbed that difference, meaning that the subjects in the variant group had developed a similar level of risk of problem drinking to that in the wild-type group.

CONCLUSION

Korean university freshmen who were identified as a variant group drank as frequently as those in the wild-type group. For the subsequent 6 years they drank less frequently, thus decreasing the risk of problem drinking. However, that frequency drop was interrupted in those with gene polymorphisms such as ADH1B*1, CYP2E1 c2, and TPH A.

Hepatitis E virus infection among domestic animals in eastern China

Hepatitis E virus (HEV) is a zoonotic pathogen of which several species of animal were reported as reservoirs. Antibodies to HEV and HEV RNA have been detected in some Chinese population and swine groups but few other domestic animals. In this study, to investigate the HEV prevalence, we tested sera from 788 pigs, 100 cows, 50 goats, 49 horses, 101 pet dogs, 105 chickens, 47 duck and 45 pigeons in eastern China for anti-HEV immunoglobulin G (IgG). We also tested 50% of the swine sera, all of sera from the other domestic animals and 13 Shanghai human sera which were positive for anti-HEV immunoglobulin M (IgM) for HEV RNA using reverse transcriptase-polymerase chain reaction. Our results indicated that 82.5% (222/269) of the sows, 53.9% (104/193) of the 4- to 6-month-old swine, 63.4% (168/265) of the 1- to 3-month-old swine, 55.7% (34/61) of the slaughterhouse swine, 24% (12/50) of the goats, 16.3% (8/49) of the horses, 17.8% (21/101) of the pet dogs, 6% (6/100) of the cows, 12.8% (6/47) of the ducks, 4.4% (2/45) of the pigeons and 1.9% (2/105) of the chickens exhibited positive for anti-HEV IgG. Inhibition assay confirmed the infection with HEV or HEV-like viruses in these domestic animals except pigeons and chickens. From the sera, we isolated 18 swine HEV strains, one horse HEV strain and two human HEV strains. Sequence analysis showed that the horse HEV isolate and one swine isolate belonged to genotype 3. The other isolates belonged to genotype 4. The two human isolates were phylogenetically closely related to eight of the swine isolates. In short, the presence of anti-HEV antibody had been confirmed in several species of domestic animals in eastern China and HEV RNA has been identified in swine, human and horse. This suggested that the authorities should pay more attention to the prevalence of HEV in eastern China.

Triorthocresyl phosphate-induced neuronal losses in lumbar spinal cord of hens--an immunohistochemistry and ultrastructure study

To investigate the neuronal losses of hens' spinal cords in the model of organophosphate-induced delayed neuropathy (OPIDN) and to analyze the impact of apoptosis on the pathogenesis of OPIDN. Adult hens were challenged with triorthocresyl phosphate (TOCP) at a single dose (750 mg/kg). Neuronal losses in the 3rd lumbar spinal cord (L3) were assessed by light-microscopy and electron-microscopy methods at different days post exposure, respectively. The typical OPIDN signs were seen in the TOCP-exposed hens at about 9th day. The number of large nerve cells declined gradually. And these cells were verified as neurons by immunostained with neuronal marker NeuN. The expression of FasL reached proximal at about 9th day, decreased from 14th day. Neurons in TOCP exposed groups displayed degenerative morphologies in electronic microscopy. Some neurons showed apoptotic-like ultrastructure profiles at 5th day. The nuclear membrane was complete with chromatin condensed to the margins of nuclear membrane like a crescent-shaped body. Mitochondria morphologic changes appeared early (5 d) following exposure to TOCP, and developed in a time-dependent fashion. Apoptosis might be involved in the development of OPIDN, and play a role in the pathogenesis of OPIDN.

Secondary degeneration reduced by inosine after spinal cord injury in rats

STUDY DESIGN

Assessment of the potential protective effects of inosine on an animal model of spinal cord injury.

OBJECTIVES

Our previous studies have demonstrated that inosine can directly protect neurons in vitro from zinc-induced injury and axotomized retinal ganglion cells of rats in vivo. This investigation was carried out to examine the possible protective effects of inosine on spinal cord secondary degeneration.

SETTING

Institute of Neurosciences, The Fourth Military Medical University, Xi'an, China.

METHODS

Compressive spinal cord injury (95-g load for 1 min) model was established in rats, and inosine was administrated beginning at different time points (2, 12, or 24 h) after spinal cord injury.

RESULTS

Using terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) technique and hematoxylin and eosin staining, our study demonstrated that administration of inosine as late as 12 h after injury significantly reduced the total volume of spinal cord degenerative areas and the number of apoptotic cells 3 days following the trauma.

CONCLUSION

Inosine can significantly reduce the spread of secondary degeneration and the cell death following spinal cord injury in adult rats. These findings may find a clinical application in the treatment of acute spinal cord injury.

The ultimate speed of magnetic switching in granular recording media

In magnetic memory devices, logical bits are recorded by selectively setting the magnetization vector of individual magnetic domains either 'up' or 'down'. In such devices, the fastest and most efficient recording method involves precessional switching: when a magnetic field B(p) is applied as a write pulse over a period tau, the magnetization vector precesses about the field until B(p)tau reaches the threshold value at which switching occurs. Increasing the amplitude of the write pulse B(p) might therefore substantially shorten the required switching time tau and allow for faster magnetic recording. Here we use very short pulses of a very high magnetic field to show that under these extreme conditions, precessional switching in magnetic media supporting high bit densities no longer takes place at well-defined field strengths; instead, switching occurs randomly within a wide range of magnetic fields. We attribute this behaviour to a momentary collapse of the ferromagnetic order of the spins under the load of the short and high-field pulse, thus establishing an ultimate limit to the speed of deterministic switching and magnetic recording.

Dual excitatory and inhibitory effects of stimulation of intrinsic innervation of the anterior pituitary on adrenocorticotropic hormone release in the rat

The gland cells of the mammalian anterior pituitary are innervated by substantial amounts of nerve fibres, and there is evidence that the nerve fibres are functionally active. In the rat, the nerve fibres make typical excitatory synapses with corticotropes. The physiological significance of this synaptic relationship was investigated in the present study. The anterior pituitary of the rat was sliced and stimulated with electrical field in a chamber. The perfusate was continuously collected and immunoradioassayed for adrenocorticotropic hormone (ACTH). When the gland slices were stimulated at a high frequency of 10 Hz, there was a significant inhibition of ACTH secretion. Stimulation at a low frequency of 2 Hz resulted in a quick and transient excitation of ACTH release. The results indicate that stimulation of the nerve fibres in the anterior pituitary has dual excitatory and inhibitory effects on ACTH secretion.

Astrocytes in injured adult rat spinal cord may acquire the potential of neural stem cells

It has been well documented that in adult rats astrocytes in the subventricular zone and subgranular layer of the dentate gyrus are neural stem cells. Elsewhere in the CNS astrocytes are not generally recognized as stem cells. Here we describe nestin expression in a population of astrocytes in the spinal cord of adult rat following cord injury. In either hemitransectioned or longitudinally cut spinal cord, there was widespread nestin expression in astrocytes of both the gray and white matters. Isolation of the lateral part of the spinal cord from the central canal region, where stem cells may reside, could not block the appearance of nestin-immunoreactive astrocytes in the lateral cord, and none of them showed Fast DiI labeling after the central canal ependyma had been labeled by the dye, indicating that the nestin-immunoreactive astrocytes can evolve locally in the lateral cord. They were found to be undergoing a process of de-differentiation. Culture of the nestin-immunoreactive astrocytes of the lateral cord generated neurospheres, the cells of which had the ability of self-renewal, and were able to differentiate into neurons, astrocytes, or oligodendrocytes. Taken together, the results indicate that the astrocytes in injured adult rat spinal cord may acquire the potential of neural stem cells.

Phosphorylation of extracellular signal-regulated kinases 1/2 is predominantly enhanced in the microglia of the rat spinal cord following dorsal root transection

The present study was initiated to investigate the role of extracellular signal-regulated kinases (ERK) 1/2 signaling pathway in the early response of spinal cord and associated dorsal root ganglion (DRG) to rhizotomy by using Western blotting and immunohistochemical techniques in a rat model of L3 and L4 dorsal root transection. The results showed that there were a considerable amount of total and phosphorylated ERK 1/2 protein in both spinal cord and DRG in normal animals killed under pentobarbital anesthesia. The total ERK 1/2 distributed in both glia and neurons, while phosphorylated ERK 1/2 dominantly existed in the latter in the gray matter of spinal cord, as demonstrated with double immunofluorescent staining. Twenty-four and forty-eight hours after axotomy, the phosphorylation level of ERK 1/2 in the operation side of dorsal spinal cord was much higher than that in the contralateral side, while the total ERK 1/2 level seemed unchanged. The increased expression of Fos protein was also seen in the dorsal spinal cord at lesion side twelve and twenty-four hours after axotomy. Double fluorescent staining proved that the phosphorylated ERK 1/2 positive cells in the ipsilateral dorsal spinal cord after axotomy predominantly were microglia and small portion was oligodendrocytes, whereas the Fos expression was mainly in neurons. In normal DRG, most neurons, especially the medium and small-sized ones, and the satellite cells contained total ERK 1/2-like immunoreactivity, whereas only a small portion of neurons and satellite cells contained phosphorylated ERK 1/2. After unilateral dorsal rhizotomy, there were no detectable changes for the phosphorylation of ERK 1/2 in either neurons or satellite cells in DRG.Collectively, the present results suggest that both ERK and Fos signal pathways involve the cellular activation in the spinal cord following dorsal rhizotomy, with ERK mainly in microglia and Fos in neurons. The increase of phosphorylation of ERK 1/2 in microglia of spinal cord after rhizotomy implicates that ERK signaling pathway involves intracellular activity of microglia responding to the experimental injury.

The striatal GABA-ergic neurons expressing substance P receptors in the basal ganglia of mice

By using a double immunofluorescence, we have examined the distribution of striatal GABAergic neurons that expressed substance P receptor (SPR) in the basal ganglia of adult C57 mice. The distribution of GABA-immunoreactive neurons completely or partially overlapped with that of SPR-immunoreactive neurons in the striatum (i.e. the caudate-putamen), globus pallidus, ventral pallidum, and nucleus accumbens. Neurons showing both GABA- and SPR-immunoreactivities were, however, predominantly found in the caudate-putamen, and most of them were characterized by their large-sized aspiny neuronal profile. Semi-quantification indicated that only about 13% of the total GABA-immunoreactive neurons (including large and medium-sized) displayed SPR-immunoreactivity, and these double-labeled neurons constituted about 31% of the total SPR-immunoreactive cells in the striatum. Neurons double-labeled with GABA- and SPR-immunoreactivities were hardly detected in other aforementioned regions of the basal ganglia. In addition, double immunofluorescence also showed co-localization of SPR- with glutamic acid decarboxylase-immunoreactivity, but not with parvalbumin-immunoreactivity, in the striatal neurons. Taken together with previous reports, the present study has suggested that a sub-population of striatal GABA-ergic neurons, most possibly GABA-ergic interneurons, may also receive direct physiological modulation by tachykinins through SPR in the basal ganglia of mammals.

Significant up-regulation of nestin protein in the neostriatum of MPTP-treated mice. Are the striatal astrocytes regionally activated after systemic MPTP administration?

We are interested in the possible role of central glial cells in pathogenesis of Parkinson's disease of mammals. Parkinsonism model was induced by systemic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration, and the reactive glial cells were examined by immunocytochemical visualization of nestin protein in the brains and spinal cords of C57 mice. Abundant nestin-like immunoreactivity was predominately found in the caudate putamen of MPTP-treated mice and about 481-fold of nestin-like immunoreactive cells increased compared with that of control animals, indicating that significant up-regulation of nestin protein occurred in these regions. Majority of nestin-like immunoreactive cells characterized with astrocytic profiles of multiple, radical and hypotrophic processes, and showed a distribution and dynamic patterns similar to that of glial fibrillary acid protein (GFAP)-immunoreactive cells in the caudate putamen. Double immunofluorescence confirmed that 100% of nestin-like immunoreactive cells exhibited GFAP-immunoreactivity while nestin/GFAP double-labeled cells constituted about 84% of total GFAP-immunoreactive cells in the caudate putamen, indicating these nestin-like immunoreactive cells belong to a reactive population of the astrocytes. On the other hand, no obvious changes of nestin- or GFAP-like immunoreactivities were detected in the globus pallidus, the substantia nigra and the ventral tegmental area after MPTP-treatment. The results have provided morphological evidence for the regional activation of astrocytic glial cells following systemic MPTP administration, suggesting that a large population of reactive striatal astrocytes might play an important role in initial pathogenesis or acute stage of Parkinson's disease in mammals.