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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., LEWzizi rats present with pronounced choroid plexus iron overload in conjunction with elevated levels of iron and cell‐free haemoglobin in the blood and increased RBC fragility. In several human diseases of diverse aetiologies, a pronounced accumulation of iron in choroid plexuses has already been described. Our study highlights the importance of choroid plexuses as iron entry sites into the CNS and their linkage with peripheral iron loads and alterations in red blood cell biology.

Functional neurologic disorders feature nervous system symptoms that cannot be explained by a neurological disease or other medical condition. The patient described here was a 21-year-old Japanese woman who was initially diagnosed with a functional neurologic disorder based on numbness and weakness of the limbs with no abnormalities in routine examinations. Further detailed examinations revealed monocytes in cerebrospinal fluid (CSF), and electroencephalography revealed widespread, low-voltage, slow waves with concentrated spindle waves. Thus, encephalitis was suspected, and steroid pulse therapy was initiated. Her symptoms subsequently improved. Afterward, CSF analysis was positive for serum anti-GQ1b IgG antibodies. We made a final diagnosis of Bickerstaff's brainstem encephalitis (BBE). Our report describes the difficult differentiation of functional neurologic disorders from BBE. Physicians and psychiatrists should be aware of BBE.

In Parkinson's disease (PD) patients, the factors related to weight loss remain unclear.To investigate determinants of low body mass index (BMI) in PD patients.We identified factors associated with low BMI in PD patients in a multicenter case-control study. A total of 435 PD patients and 401 controls were included.The mean BMI was significantly lower in PD patients than in controls (22.0±3.4 kg/m2 vs. 25.4±4.3 kg/m2), with an adjusted odds ratio (AOR) of 3.072 (95% CI, 2.103-4.488; p 0.001) for low BMI (22 kg/m2) in PD. Compared to the high-BMI PD group (22 kg/m2), the low-BMI PD group (22 kg/m2) had more women; a longer disease duration; higher revised Movement Disorder Society Unified PD Rating Scale (MDS-UPDRS) II and IV scores; an increased levodopa equivalent dose (LED); and increased constipation, visual hallucination, dysphagia, dyskinesia and wearing off rates. There were no between-group differences in depression, anhedonia, apathy, sleep problems and daytime sleepiness. Multivariable analysis showed that visual hallucination (AOR, 2.408; 95% CI, 1.074-5.399; p = 0.033) and the MDS-UPDRS IV (AOR, 1.155; 95% CI, 1.058-1.260; p = 0.001) contributed to low BMI after controlling for clinical factors. In a second model, visual hallucination (AOR, 2.481; 95% CI, 1.104-5.576; p = 0.028) and dyskinesia (sum of the MDS-UPDRS 4.3-4.6) (AOR, 1.319; 95% CI, 1.043-1.668; p = 0.021) significantly contributed to low BMI.PD patients were 3 times more likely than healthy controls to have a low BMI. Motor complications, particularly dyskinesia, and visual hallucination were significantly associated with low BMI in PD patients.

Background We aimed to evaluate the effect of zonisamide (ZNS) on motor symptoms and nonmotor symptoms such as depressive symptoms and sleep problems in Parkinson’s disease (PD) patients with or without tremor. Methods We conducted a 3‐month, open‐label study to assess the effects of ZNS on motor symptoms, depressive symptoms and sleep problems. Twenty levodopa‐treated PD patients with motor fluctuation completed the study. Patients received 25–50 mg/day of ZNS and were assessed for the Japanese version of the Movement Disorder Society Revision of the Unified PD Rating Scale (MDS‐UPDRS) parts I, III, and IV, PD Sleep Scale (PDSS)‐2, Beck depression inventory‐2 (BDI‐II), and PD Questionnaire (PDQ‐8) at baseline and after 1, 2 and 3 months of treatment. Patients were categorized into the tremor group and nontremor group to assess changes in clinical parameters. Results At 3 months, the scores on the MDS‐UPDRS parts I, III and IV significantly improved and off‐time reduced compared to baseline. Additionally, the PDSS‐2 total score significantly decreased at 3 months. Although there were no significant differences in changes in UPDRS part I, III, or IV between the groups after ZNS treatment, the tremor group had significant improvements in PDSS‐2 at 3 months and BDI‐II at 1, 2 and 3 months compared with the nontremor group. Conclusion We showed the beneficial effects of ZNS on motor symptoms and sleep problems in levodopa‐treated PD patients with motor fluctuation. ZNS may be more effective for several nonmotor symptoms in PD patients with tremor compared with those without tremor., In this 3‐month open‐label study, we showed the beneficial effects of zonisamide (ZNS) on motor symptoms and sleep problems in levodopa‐treated PD patients with motor fluctuation. ZNS was more effective for sleep disturbances and depressive symptoms in PD patients with tremor compared with those without tremor.

Background We investigated the prevalence and impact of restless legs syndrome (RLS) and leg motor restlessness (LMR) in patients with Parkinson's disease (PD) in a multicenter study. Methods A total of 436 PD patients and 401 age- and sex-matched controls were included in this study. RLS was diagnosed based on four essential features. LMR was diagnosed when a participant exhibited the urge to move his or her legs but did not meet the four essential features of RLS. Results The RLS prevalence did not differ between PD patients and controls (3.4% vs. 2.7%), while LMR prevalence was significantly higher in PD patients than in controls (12.8% vs. 4.5%). PD patients with RLS or LMR had a higher prevalence of excessive daytime sleepiness (EDS) (50.7%, vs. 6.9%), probable REM sleep behavior disorder (38.0% vs. 3.4%) and PD-related sleep problems (49.3% vs. 20.7%) than controls with RLS or LMR. RLS/LMR preceding PD onset was related to an older age of PD onset. Conclusion Our study revealed an increased prevalence of LMR but not RLS in PD patients. LMR could be an early manifestation of PD; however, whether LMR is within the range of RLS or whether LMR and RLS constitute different entities in PD requires further studies.

Objectives To investigate the impact of sleep disturbances on Parkinson’s disease (PD) clinical motor subtypes and disease-related disability in a multicentre setting. Methods We report a cross-sectional relationship between sleep-related symptoms and clinical motor subtypes (tremor dominant (TD); intermediate; postural instability and gait disturbances (PIGDs)) identified in a multicentre study, including 436 patients with PD and 401 age-matched controls. PD-related sleep problems (PD-SP), excessive daytime sleepiness (EDS) and probable REM sleep behaviour disorder (pRBD) were evaluated using the PD sleep scale (PDSS)-2, Epworth Sleepiness Scale (ESS) and RBD screening questionnaire-Japanese version (RBDSQ-J), respectively. Results PD-SP (PDSS-2 ≥18; 35.1% vs 7.0%), EDS (ESS ≥10; 37.8% vs 15.5%) and pRBD (RBDSQ-J ≥5; 35.1% vs 7.7%) were more common in patients with PD than in controls. The prevalence of restless legs syndrome did not differ between patients with PD and controls (3.4% vs 2.7%). After adjusting for age, sex, disease duration and Movement Disorder Society-Unified PD Rating Scale (MDS-UPDRS) part III score, the PIGD group had higher PDSS-2 and ESS scores than the TD group. The RBDSQ-J scores did not differ among the TD, intermediate and PIGD groups. A stepwise regression model predicting the MDS-UPDRS part II score identified the Hoehn and Yahr stage, followed by the number of sleep-related symptoms (PD-SP, EDS and pRBD), disease duration, MDS-UPDRS part III score, PIGD subtype, depression and MDS-UPDRS part IV score as significant predictors. Conclusion Our study found a significant relationship between sleep disturbances and clinical motor subtypes. An increased number of sleep-related symptoms had an impact on disease-related disability.

Objective The characteristics of olfactory impairment in Parkinson's disease (PD), multiple system atrophy (MSA) and progressive supranuclear palsy (PSP) have not been determined in detail. We assessed the olfactory function among PD, MSA and PSP patients. Methods A card-type odor identification test, Open Essence (OE, Wako, Japan), which consists of 12 different odorants familiar to Japanese subjects, was administered to 98 PD patients, 32 MSA patients, 17 PSP patients and 96 control subjects ≥50 years of age. Results The PD patients had significantly lower OE scores than the other groups. The OE scores of the MSA and PSP patients fell between those of the PD patients and the control subjects. A cut-off OE score of 6 was beneficial for differentiating PD patients from controls with 84.7% sensitivity and 85.4% specificity. A cut-off OE score of 4 had 60.2% sensitivity and 77.6% specificity for differentiating PD patients from MSA and PSP patients. The correct answer rates for the curry, Japanese orange and perfume odorants in the PD patients were lower than those in the MSA and PSP patients and controls. The PD patients also had the highest ratio of "not detected" choices across the 12 odors. Conclusion Marked olfactory impairment was a feature of the patients with PD, while mild olfactory impairment was observed in those with MSA or PSP. The answer patterns and the specific odorants may also be useful in differentiating PD from related disorders.

Patients with Parkinson disease (PD) often show restless legs syndrome (RLS), leg motor restlessness (LMR) and other leg restlessness (OLR) related to sensorimotor symptoms. Here, we describe 5 patients who presented with leg restlessness as an early manifestation of PD. In case 1, the patient had leg restlessness that was not LMR or RLS and preceded the onset of motor symptoms by 1 year. In case 2, LMR preceded motor symptoms by 2 years. Case 3 had unilateral RLS symptoms on the left side of the body for 33 years. Two and a half years after the spread of RLS symptoms to the right leg with increased frequency of left-sided RLS symptoms, the patient developed PD at the age of 58 years. In cases 4 and 5, RLS symptoms preceded motor symptoms by 3 months and 1 month, respectively. All patients developed Parkinsonism within 3 years (median, 1.0 year; range 0.083–2.5 years) after initial onset or exacerbation of leg restlessness. All patients had frequent leg restlessness symptoms (6–7 days per week). In our series, the preceding leg restlessness was unilateral and confined to the dominant side of the subsequent Parkinsonism, or preceding leg restlessness was bilateral but dominant on the dominant side of the subsequent Parkinsonism. Clinicians should be aware that late-onset leg restlessness (>50 years of age) including RLS, LMR, and OLR, particularly if frequent and asymmetrical, can be an early nonmotor manifestation of PD.

Background Istradefylline, a selective adenosine A2A receptor antagonist, has been reported to improve daily “off time” and motor symptoms in patients with Parkinson's disease (PD). However, the effect of istradefylline on sleep problems has not been thoroughly investigated. Methods We evaluated the effect of istradefylline on daytime sleepiness, sleep disturbances, and motor symptoms in 22 PD patients who were affected by the wearing off phenomenon in an open-label, 3-month study. Participants received 20–40 mg/day istradefylline once daily (morning) over a 3-month period. The Epworth Sleepiness Scale (ESS), PD sleep scale (PDSS)-2 and PD Questionnaire (PDQ-8) were administered at baseline, 2 weeks, 1 month, 2 months and 3 months. At baseline and 3 months, patients were evaluated on the Movement Disorder Society Revision of the Unified PD Rating Scale (MDS-UPDRS) parts III and IV. Results Twenty-one patients (95.5%) completed the study. At 3 months, MDS-UPDRS part III (− 5.3, p = 0.0002) and part IV (− 2.5, p = 0.001) scores improved and off time decreased significantly (− 50.1 min, p = 0.0004). PDQ-8 scores were unchanged at 3 months. ESS scores decreased significantly at 2 months and 3 months (− 2.4 and − 3.3, respectively, p Conclusion Istradefylline improved daytime sleepiness in PD patients, possibly through its effect on enhancing alertness. In addition, the lack of significant changes in the total PDSS-2 scores over the study period suggests istradefylline had no negative impact on sleep.

Objective There are conflicting results regarding the frequency and clinical significance of sleep related breathing disorders in patients with Parkinson's disease (PD). The aim of this study was to investigate the relationship between snoring and its clinical correlates in patients with PD. Methods A total of 93 PD patients and 93 controls were analyzed from a previously conducted cross-sectional study. Snoring was defined as a snoring frequency of ≥ 2 days/week (a score of 2 or higher on the PD Sleep Scale-2 subitem 15). Excessive daytime sleepiness (EDS) was defined as an Epworth Sleepiness Scale score of ≥ 10. Results Snoring was more prevalent in the patients with PD than in the controls (14.0% vs. 1.1%). The PD patients who snored exhibited greater disease severity, worse scores on the motor section of the Unified Parkinson's Disease Rating Scale (UPDRS) and the Parkinson fatigue scale and more impaired scores in several domains of the Parkinson's Disease Questionnaire, including the domains of mobility, activities of daily living, emotional well-being, communication and bodily discomfort, when compared to those who did not snore. No between-group differences were found in EDS. A higher proportion of the UPDRS motor scores for bradykinesia was seen in the PD patients who snored compared to that observed in the PD patients who did not snore. Conclusion We found that snoring was more frequent in PD patients than in controls. Furthermore, snoring in PD patients was associated with disease severity, an impaired motor function and a decreased quality of life, although it was not associated with EDS.

The aim of this study was to assess the validity and the reliability of the Japanese version of the Parkinson's disease sleep scale (PDSS)-2 and to use this scale to identify nocturnal symptoms and their impact on patient's quality of life.A cross-sectional, case-controlled study was conducted consisting of 93 patients with Parkinson's disease (PD) and 93 age- and gender-matched control subjects. The Japanese version of the PDSS-2 was used for the evaluation of nocturnal disturbances. The patient's quality of life was evaluated with the Parkinson's Disease Quality of Life questionnaire (PDQ-39) and their depressive symptoms were assessed with the Beck Depression Inventory-II (BDI-II), respectively. In addition, the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS) and Parkinson Fatigue Scale (PFS) were administered.As assessed using the PDSS-2, PD patients had significantly impaired scores compared with control subjects (15.0±9.7 vs. 9.1±6.6, p0.001). The ESS, BDI-II and PFS scores were significantly impaired in PD patients compared with controls. A satisfactory internal consistency and test-retest reliability score were obtained for the PDSS-2 total score (Cronbach's alpha=0.86). The PDSS-2 was correlated with the PSQI, ESS, BDI-II, PFS, PDQ-39 summary index, all of the PDQ-39 domains and Unified Parkinson's Disease Rating Scale part III. The frequency of restless legs syndrome (RLS) was not significantly different between PD patients and controls (5.5% vs. 2.2%), but nocturnal restlessness was significantly more frequent in PD patients than controls. Stepwise linear regression analyses revealed the PDQ-39 summary index and the PSQI global score as significant predictors for the PDSS-2 total score.Our study confirmed the usefulness of the Japanese version of the PDSS-2 that enables the comprehensive assessment of nocturnal disturbances in PD. The association between RLS and nocturnal restlessness in PD requires further study.

Anhedonia is one of the main non-motor symptoms in Parkinson's disease (PD); it is assessed using the Snaith-Hamilton pleasure scale (SHAPS). To assess anhedonia in the Japanese population, we prepared a Japanese language version of SHAPS (SHAPS-J), and evaluated its validity and reliability in 8 neurological centers. Seventy subjects (48 patients with PD and 22 healthy subjects) were enrolled in this study.The validity of the test was assessed by the correlation between SHAPS-J and the apathy scale, based on the fact that anhedonia is considered a symptom of apathy syndrome. Test-retest reliability and internal consistency were assessed by Cohen's kappa and Cronbach's alpha coefficients, respectively.In the evaluation of validity, the total scores obtained on SHAPS-J during the test and retest significantly correlated with scores on Item 4 in Part 1 of the unified Parkinson's disease rating scale (p0.0008 and p0.0036, respectively). Cohen's kappa coefficient was0.3 on all items (p0.0005 on all items). Cronbach's alpha coefficient was 0.90 at the baseline and 0.88 at the retest.These results indicate that SHAPS-J has good validity, test-retest reliability, and internal consistency, thus establishing an available measure of anhedonia in Japanese.

In order to elucidate the regeneration properties of serotonergic fibers in the hippocampus of methylazoxymethanol acetate (MAM)-induced micrencephalic rats (MAM rats), we examined serotonergic regeneration in the hippocampus following neonatal intracisternal 5,7-dihydroxytryptamine (5,7-DHT) injection. Prenatal exposure to MAM resulted in the formation of hippocampal heterotopia in the dorsal hippocampus. Immunohistochemical and neurochemical analyses revealed hyperinnervation of serotonergic fibers in the hippocampus of MAM rats. After neonatal 5,7-DHT injection, most serotonergic fibers in the hippocampus of 2-week-old MAM rats had degenerated, while a small number of serotonergic fibers in the stratum lacunosum-moleculare (SLM) of the hippocampus and in the hilus adjacent to the granular cell layer of the dentate gyrus (DG) had not. Regenerating serotonergic fibers from the SLM first extended terminals into the hippocampal heterotopia, then fibers from the hilus reinnervated the DG and some fibers extended to the heterotopia. These findings suggest that the hippocampal heterotopia exerts trophic target effects for regenerating serotonergic fibers in the developmental period in micrencephalic rats.

The effects of chronic treatment with the antioxidant hormone melatonin on degeneration of serotonergic fibers were studied in the striatum and olfactory tubercle of the zitter rat, which shows a loss-of-function mutation of the glycosylated transmembrane protein attractin. In these animals, serotonergic fibers in the striatum and olfactory tubercle undergo spontaneous and progressive degeneration as a result of abnormal metabolism of reactive oxygen species. Homozygous zitter (zi/zi) rats were provided ad libitum access to drinking water containing melatonin for 9 months (M) after weaning. High-performance liquid chromatography analysis revealed that melatonin treatment significantly increased serotonin in the caudate-putamen, (CPU), nucleus accumbens (NA) and olfactory tubercle (OT). Immunohistochemical staining for serotonin was consistent with the neurochemical data and further demonstrated substantially increased numbers of serotonergic nerve terminals in these areas. Aberrant serotonergic fibers characterized by swollen varicosities (>1 microm in diameter) were observed in the CPU and NA of 10 M zi/zi rats. The number of these fibers decreased after melatonin treatment ended. Furthermore, hyperinnervation of serotonergic fibers was observed in the OT of melatonin-treated zi/zi rats. These results suggest that melatonin protects serotonergic fibers and terminals in zitter rats and/or promotes their neuroplasticity.

Background Pain is a frequent, troublesome symptom of PD but is under-recognized and poorly understood. Aim We characterized pain prevalence, severity, and location in PD, to better understand its pathophysiology and improve diagnosis and treatment. Subjects and methods A cross-sectional controlled study was conducted at 19 centers across Japan. A total of 632 subjects with Mini-Mental State Examination scores ≥ 24 were enrolled, including 324 PD patients and 308 controls. Sex and mean age did not differ between the two groups. Demographic and clinical data were collected. Pain was assessed using questionnaires, the SF-36v2 bodily pain scale, and a body illustration for patients to indicate the location of pain in 45 anatomical areas. Results Pain prevalence in the PD group was 78.6%, significantly higher than in controls (49.0%), as was its severity. There was no correlation between SF-36v2 score and motor scores, such as Unified Parkinson's Disease Rating Scale III or Hoehn & Yahr scores. Pain distribution was similar between groups, predominantly in the lower back, followed by the gluteal region, lower legs, thighs, posterior neck, and shoulders. Conclusion Pain is a significant problem in the Japanese PD population and we discuss its pathophysiology.

We investigated the efficacy of the levodopa ( l- dopa) on cognitive function in patients with de novo Parkinson's disease (PD) using the event-related potential (ERP) measure and neuropsychological test batteries. We studied 20 PD patients who had never received anti-Parkinson medications. The ERP with auditory oddball P3 paradigm and neuropsychological tests such as Mini-Mental State Examination (MMSE), New Modified Wisconsin Card Sorting Test (WCST) and Trail Making Test were repeated in the patients before and after administration of levodopa plus benserazide daily 300 mg. For the ERP's components, reference-independent measures of global field power (GFP) were determined, and P3 GFP peak, peak latency and topography were assessed. After administration of levodopa, the patients revealed significant increase of the achieved categories and decrease of preservation errors in the WSCT, shortening of time in Trail Making Test although MMSE score showed no significant difference. The P3 GFP peak attenuated although there were no differences in peak latency or on scalp topography. These findings suggest that levodopa affect on the neural circuit connects frontal cortex with the striatum and normalizes its function, and it causes decrease of P3 GFP peak reflecting appropriate resource allocation. In addition, P3 GFP might be a more appropriate indicator than psychological tests.

Recent reports suggest that rhinorrhea, defined as the presence of a runny nose unrelated to respiratory infections, allergies, or sinus problems, occurs more frequently among patients with Parkinson's disease (PD) than among healthy controls. We conducted a questionnaire survey in a multicenter study throughout Japan and compared the frequency of rhinorrhea between 231 PD and 187 normal control (NC) subjects. After excluding patients with rhinitis or paranasal sinusitis, a total of 159 PD and 59 NC subjects were included in our analysis. Rhinorrhea occurred more frequently in PD patients than NC subjects (33.3% vs. 11.9%; P=0.01). Among PD patients, rhinorrhea was more common in men than women (P=0.005). Rhinorrhea was not correlated with disease duration, modified Hoehn and Yahr score, disease type (akinesia rigidity vs. tremor dominant), or cardiac sympathetic function (evaluated by (123)I-metaiodobenzylguanidine uptake). To our knowledge, this is the first multicenter study on the frequency of PD-related rhinorrhea in Asian countries.

Background Increasing evidence provides a clear association between rapid eye movement sleep behavior disorders (RBD) and Parkinson’s disease (PD), but the clinical features that determine the co-morbidity of RBD and PD are not yet fully understood. Methods We evaluated the characteristics of nocturnal disturbances and other motor and non-motor features related to RBD in patients with PD and the impact of RBD on their quality of life. Probable RBD (pRBD) was evaluated using the Japanese version of the RBD screening questionnaire (RBDSQ-J). Results A significantly higher frequency of pRBD was observed in PD patients than in the controls (RBDSQ-J ≥ 5 or ≥ 6: 29.0% vs. 8.6%; 17.2% vs. 2.2%, respectively). After excluding restless legs syndrome and snorers in the PD patients, the pRBD group (RBDSQ-J≥5) showed higher scores compared with the non-pRBD group on the Parkinson’s disease sleep scale-2 (PDSS-2) total and three-domain scores. Early morning dystonia was more frequent in the pRBD group. The Parkinson’s Disease Questionnaire (PDQ-39) domain scores for cognition and emotional well-being were higher in the patients with pRBD than in the patients without pRBD. There were no differences between these two groups with respect to the clinical subtype, disease severity or motor function. When using a cut-off of RBDSQ-J = 6, a similar trend was observed for the PDSS-2 and PDQ-39 scores. Patients with PD and pRBD had frequent sleep onset insomnia, distressing dreams and hallucinations. The stepwise linear regression analysis showed that the PDSS-2 domain “motor symptoms at night”, particularly the PDSS sub-item 6 “distressing dreams”, was the only predictor of RBDSQ-J in PD. Conclusion Our results indicate a significant impact of RBD co-morbidity on night-time disturbances and quality of life in PD, particularly on cognition and emotional well-being. RBDSQ may be a useful tool for not only screening RBD in PD patients but also predicting diffuse and complex clinical PD phenotypes associated with RBD, cognitive impairment and hallucinations.

Environmental enrichment (EE) facilitates recovery from behavioral abnormalities and spatial memory disabilities in several neurological disease models. Exposure to EE improves spatial memory acquisition and enhances the survival of newly generated cells in the dentate gyri of adult rodents. However, the effects of EE on spatial learning and neurogenesis in the methylazoxymethanol acetate-induced microencephalic rat have not been investigated. Depletion of serotonin in the rat hippocampus is known to influence spatial memory and adult neurogenesis, suggesting a role for serotonin in these processes. To confirm this hypothesis, male methylazoxymethanol acetate-induced microencephalic rats were exposed to EE or conventional housing after weaning; half of these rats further received intracisternal 5,7-dihydroxytryptamine on postnatal day 3, to induce long-lasting depletion of serotonin. As adults, these microencephalic rats were observed using the Morris water maze test and examined for hippocampal neurogenesis. EE alleviated the impairment of spatial memory acquisition and enhanced neurogenesis in the dentate gyri of adult microencephalic rats. Injection of 5,7-dihydroxytryptamine during the neonatal period caused pronounced reductions in hippocampal serotonin levels in these rats. Long-lasting depletion of serotonin eliminated the EE-induced alleviation of spatial memory acquisition and neurogenesis impairment in microencephalic rats. The present results suggest that EE alleviates spatial memory performance deficits in microencephalic rats and further indicate that serotonin might be involved in the underlying mechanisms through increased hippocampal neurogenesis. These data provide new insights into therapeutic interventions for individuals with human migration disorders associated with learning disabilities.

Microglial activation has been associated with the pathogenesis of neurodegenerative disease. To characterize microglial responses in the zitter mutant rat, which shows progressive spongy degeneration, the development of microglial cells was investigated using ionized calcium-binding adaptor molecule (Iba1) antibody as a specific marker of microglial cells. Neurochemical analysis showed transiently increased Iba1 protein levels in the brains of developing Sprague-Dawley (SD) rats. However, high Iba1 protein readings continued in aged zitter rats. Immunohistochemical analysis revealed time-course differences in the transformation of microglia between SD and zitter rats and prolonged activation of microglial cells in the zitter rat. In the zitter rat, activated microglial cells characterized by swollen cell bodies and shorter, thicker processes were distributed throughout the brain from 2-weeks- to 2-months-old. After 2-months-old, numbers of activated microglial cells gradually decreased. However, these cells were not observed in SD rats. Iba1-immunoreactive cell-clusters organized by at least five activated microglial cells were also prominent in the zitter brain. These differences reflect the neuropathology of this mutant rat triggered by deletion of the attractin gene. The present data may thus suggest that microglial cells directly or indirectly contribute to progressive spongy degeneration in zitter mutant rats.