Questionnaire survey on sleep habits of 3-year-old children in Asahikawa City: Comparison between 2005 and 2020.

BACKGROUND: Good sleep is essential for children's healthy growth. In 2005, we conducted a questionnaire survey on children's sleep habits and their background, targeting parents who attended health checkups for their 3-year-old children in Asahikawa City, Hokkaido. In 2020, we performed a secondary survey, including additional questions regarding media usage. We analyzed changes in children's sleep environment by comparing the results of both surveys. METHODS: Children from 500 families (n = 420; 219 males, 201 females; mean age, 3.6 years) who underwent 3.5-year-old health checkups (per the changed schedule in 2015) in Asahikawa City from July 2020 to November 2020 and their parents who had completely answered the questionnaire were included. RESULTS: The proportion of children who used childcare support system such as nursery schools or kindergarten increased from 30% in the previous survey to 95% in the present survey. The mean nocturnal sleep duration of children was 9.33 h in the present survey, 0.77 h shorter than that in the previous survey; similar to the previous survey results, it was significantly short (8.71 h) in children who went to bed after 10 PM. Moreover, it was significantly short in children who watched television for more than two hours or used media within two hours before going to bed or if parents used smartphones or watched motion pictures for >30 min/day. The rate of consulting pediatricians regarding sleep problems decreased from 3% to 2.4%. CONCLUSION: Parents' lifestyles greatly influenced children's sleep habits in 2020. Pediatricians should actively participate in managing children's sleep problems.

Fathers' Involvement in Rearing Children With Profound Intellectual and Multiple Disabilities.

The aim of this study was to explore father's involvement in rearing a child with profound intellectual and multiple disabilities (PIMD). In-depth, semi-structured interviews were conducted with seven fathers in Japan, and the data were analyzed using a qualitative inductive method. The relationship between the parents, in the context of childrearing, influenced father's involvement with their child with PIMD. Fathers improved their self-confidence in childrearing by discussing and sharing about their child's conditions and caregiving approaches with their spouse. Moreover, fathers' experience of being acknowledged and entrusted by their spouse with childrearing motivated and enhanced their involvement. On the contrary, fathers struggled with concerns regarding their family's future, the balance between childrearing and work, and their own health status. The current findings contribute to nurses' understanding of father's involvement in childrearing a child with PIMD and the development of support focusing on the parental dyadic relationship and coparenting behavior.

Focal frontal epileptiform discharges in a patient with eyelid myoclonia and absence seizures.

Eyelid myoclonia with absences is classified as a unique type of generalized seizure. Its pathogenesis is proposed to involve the functional abnormalities in cortical-subcortical networks. Here, we describe the case of a 7-year-old boy who had eyelid myoclonia with absences, along with focal motor seizures. Video-EEG monitoring demonstrated eyelid myoclonia associated with 4- to 5-Hz generalized polyspike-waves preceded by focal frontal discharges. Interictal EEG showed focal epileptiform discharges over the frontal regions. Our case suggests an important role of the frontal lobe in the generation of eyelid myoclonia with absences.

Electroclinical features of epileptic encephalopathy caused by SCN8A mutation.

Voltage-gated sodium channel Nav 1.6, encoded by the gene SCN8A, plays a crucial role in controlling neuronal excitability. SCN8A mutations that cause increased channel activity are associated with seizures. We describe a patient with epileptic encephalopathy caused by de novo SCN8A mutation (c.5614C>T, p.Arg1872Trp). Seizures began 10 days after birth at which time brain magnetic resonance imaging (MRI) and electroencephalography (EEG) were normal. Seizure recurrence increased with age, leading to the development of frequent status epilepticus from 1 year of age. Seizure type included generalized tonic seizures and focal motor seizures. EEG first showed focal epileptic activity at the age of 4 months, and thereafter showed multifocal spikes. Serial MRI demonstrated brain atrophy, which appeared to progress with seizure aggravation. Clinical features that may give a clue to the diagnosis include normal EEG despite frequent seizures in early infancy and an increase in epileptic activity that occurs with aging.

Exploring the beliefs of Japanese mothers caring for a child with disabilities.

The purpose of this study was to describe the beliefs of Japanese mothers caring for a child with disabilities to advance knowledge about beliefs of Japanese families experiencing illness. A semistructured interview was conducted with eight mothers who had a child with disabilities (physical, intellectual, and/or developmental). The interview invited their reflections about "mutual thoughts of family members" and family relationships in the context of daily life of caring for a child with disabilities. Data were qualitatively analyzed inductively and deductively and compared with the Common Tentative Framework of Japanese Family Beliefs developed from previous research. The analyses highlighted new understandings of the influence of Japanese cultural and societal beliefs on the family's experience of having a child with disabilities. Clinical implications are discussed and directions for future research suggested.

Human herpesvirus-6 infection-associated acute encephalopathy without skin rash.

BACKGROUND: Human herpesvirus-6 (HHV-6) is the etiological agent of exanthema subitum-associated encephalopathy, which usually occurs in children younger than 3 years. Brain imaging shows various abnormalities. PATIENT: A previously healthy 4-year-old girl developed acute encephalopathy with clinical features consisting of fever, repetitive seizures, and a disturbance of consciousness. The patient did not show skin rash suggestive of exanthema subitum during the course of her illness. The primary HHV-6 infection was diagnosed based on the absence of IgG against HHV-6 and identification of the virus DNA in the acute phase serum and a significant increase of the anti-HHV-6 IgG titers in the convalescent phase sera. Diffusion-weighted images showed transient high signal intensity in the bilateral periventricular white matter and splenium of the corpus callosum and in the gray matter structures such as the bilateral basal ganglia and thalami. Upon therapy with steroid and γ-globulin, the patient recovered without any neurological deficits. CONCLUSION: Primary HHV-6 infection can cause acute encephalopathy without exanthema subitum. The etiological diagnosis is possible only by examining the blood and cerebrospinal fluid, when the patient shows no skin rash. This condition should be included in the differential diagnosis of acute encephalopathy even in patients older than 3 years.

Improved prefrontal activity in AD/HD children treated with atomoxetine: a NIRS study.

BACKGROUND/AIMS: Atomoxetine (ATX), a selective norepinephrine reuptake inhibitor, is the first approved non-stimulant drug for treatment of attention deficit/hyperactivity disorder (AD/HD). The present study examined the effects of long-term treatment with ATX on prefrontal hemodynamic activity in AD/HD children during a continuous performance task (CPT) using near-infrared spectroscopy (NIRS). METHODS: Prefrontal hemodynamic activity was measured in 12 children with AD/HD during experimental sessions conducted before and 6 months or more after starting ATX treatment. The average maintenance dose of ATX was 1.6 mg/kg/day. Fourteen age-matched typically developing children participated as a control group. RESULTS: In the control group, the CPT induced a significant increase in oxygenated hemoglobin (oxy-Hb) concentration in the bilateral dorsolateral prefrontal cortex (DLPFC). In the AD/HD group in the pre-ATX condition, the CPT did not induce a significant increase in oxy-Hb concentration in any of the NIRS channels, but induced a significant decrease in oxy-Hb concentration in the left ventrolateral prefrontal cortex (VLPFC). In the AD/HD group in the post-ATX condition, significant activation was observed in the right DLPFC and the decrease in oxy-Hb concentration in the left VLPFC disappeared. CONCLUSIONS: These results suggest that long-term treatment with ATX improved prefrontal hemodynamic activity in AD/HD children, and NIRS may be useful for assessment of the prefrontal hemodynamic response to ATX treatment.

Glycemic control and motor development in a patient with intermediate DEND.

The most common cause of neonatal diabetes, KCNJ11 gene mutation, can manifest as a neurological disorder. The most severe form consists of a constellation of developmental delay, epilepsy, and neonatal diabetes (DEND). Intermediate DEND (iDEND) refers to a milder presentation without epilepsy. We present a child with iDEND, for whom insulin injections were replaced with glibenclamide therapy at 17 months of age because of poor glycemic control and delayed motor development. Three months after initiation of glibenclamide, HbA1c decreased from 10.2% to 5.6%. Continuous glucose monitoring indicated that blood glucose fluctuations were suppressed while on glibenclamide. Furthermore, after initiating glibenclamide therapy, the developmental quotient (DQ) for motor ability markedly improved from 60 to 91, whereas the DQ for language and adoptive ability remained as they had been before the sulfonylurea treatment. Sulfonylurea treatment improved glycemic control and motor development in the present patient.

Benign infantile convulsion as a diagnostic clue of paroxysmal kinesigenic dyskinesia: a case series.

INTRODUCTION: Paroxysmal kinesigenic dyskinesia is characterized by sudden attacks of involuntary movements. It is often misdiagnosed clinically as psychogenic illness, which distresses the patients to a great extent. A correct diagnosis will improve the quality of life in patients with paroxysmal kinesigenic dyskinesia because treatment with low doses of anticonvulsants is effective for eliminating the clinical manifestations. Paroxysmal kinesigenic dyskinesia can occur independently of or concurrently with benign infantile convulsion. Identification of PRRT2 as the causative gene of benign infantile convulsion and paroxysmal kinesigenic dyskinesia allows genetic confirmation of the clinical diagnosis. CASE PRESENTATION: We describe the clinical features of a Japanese family with either paroxysmal kinesigenic dyskinesia or benign infantile convulsion. A PRRT2 missense mutation (c.981C > G, p.Ile327Met) was identified in two patients with benign infantile convulsion and three patients with paroxysmal kinesigenic dyskinesia as well as in two unaffected individuals. Allowing incomplete penetrance in the mutation carriers, this mutation co-segregated completely with the phenotype. The patients with paroxysmal kinesigenic dyskinesia had been misdiagnosed with psychogenic illness for many years. They were correctly diagnosed with paroxysmal kinesigenic dyskinesia when their children visited a pediatrician for benign infantile convulsion. Treatment with carbamazepine controlled their involuntary movements completely. CONCLUSIONS: Paroxysmal kinesigenic dyskinesia is a treatable movement disorder that is often misdiagnosed clinically as psychogenic illness. It is important to note that two clinically distinct disorders, benign infantile convulsion and paroxysmal kinesigenic dyskinesia, are allelic conditions caused by PRRT2 mutations. Paroxysmal kinesigenic dyskinesia should be suspected in families with a child with benign infantile convulsion.

[Treatment with ramelteon for sleep disturbance in severely disabled children and young adults].

OBJECTIVE: The aim of this study was to determine the efficacy and safety of ramelteon for severely disabled children and young adults who had already been treated for sleep disturbance with melatonin at a dose of 3 mg. METHODS: Eleven patients, who were aged between 3-25 years and included 4 patients with cerebral palsy, -took 3-8 mg of ramelteon at bedtime, after a one-week of washout period. Sleep states were evaluated using sleep diaries recorded by caregivers or using actigraphs. RESULTS: Ramelteon was effective in 8 out of the 11 patients. Ramelteon was tolerated well except for mild daytime sleepiness in three patients. CONCLUSIONS: This preliminary study showed the efficacy and safety of ramelteon for sleep disturbance in severely disabled children and young adults. Further trials are necessary to determine optimal dosage and safety of ramelteon in children.

Epigenetic transcriptional activation of monocyte chemotactic protein 3 contributes to long-lasting neuropathic pain.

A multiplex analysis for profiling the expression of candidate genes along with epigenetic modification may lead to a better understanding of the complex machinery of neuropathic pain. In the present study, we found that partial sciatic nerve ligation most remarkably increased the expression of monocyte chemotactic protein 3 (MCP-3, known as CCL7) a total of 33 541 genes in the spinal cord, which lasted for 4 weeks. This increase in MCP-3 gene transcription was accompanied by the decreased trimethylation of histone H3 at Lys27 at the MCP-3 promoter. The increased MCP-3 expression associated with its epigenetic modification observed in the spinal cord was almost abolished in interleukin 6 knockout mice with partial sciatic nerve ligation. Consistent with these findings, a single intrathecal injection of recombinant proteins of interleukin 6 significantly increased MCP-3 messenger RNA with a decrease in the level of Lys27 trimethylation of histone H3 at the MCP-3 promoter in the spinal cord of mice. Furthermore, deletion of the C-C chemokine receptor type 2 (CCR2) gene, which encodes a receptor for MCP-3, failed to affect the acceleration of MCP-3 expression in the spinal cord after partial sciatic nerve ligation. A robust increase in MCP-3 protein, which lasted for up to 2 weeks after surgery, in the dorsal horn of the spinal cord of mice with partial sciatic nerve ligation was seen mostly in astrocytes, but not microglia or neurons. On the other hand, the increases in both microglia and astrocytes in the spinal cord by partial sciatic nerve ligation were mostly abolished in interleukin 6 knockout mice. Moreover, this increase in microglia was almost abolished by CCR2 gene deletion, whereas the increase in astrocytes was not affected in nerve-ligated mice that lacked the CCR2 gene. We also found that either in vivo or in vitro treatment with MCP-3 caused robust microglia activation. Under these conditions, intrathecal administration of MCP-3 antibody suppressed the increase in microglia within the mouse spinal cord and neuropathic pain-like behaviours after nerve injury. With the use of a functional magnetic resonance imaging analysis, we demonstrated that a single intrathecal injection of MCP-3 induced dramatic increases in signal intensity in pain-related brain regions. These findings suggest that increased MCP-3 expression associated with interleukin 6 dependent epigenetic modification at the MCP-3 promoter after nerve injury, mostly in spinal astrocytes, may serve to facilitate astrocyte-microglia interaction in the spinal cord and could play a critical role in the neuropathic pain-like state.

Effect of neonatal hypoxia on the development of intraspinal serotonergic fibers in relation to spinal motoneurons.

Serotonin (5-hydroxytryptamine; 5-HT)-containing neurons trophically affect target neurons and modulate central nervous system neuronal activity. We studied effects of neonatal hypoxia on postnatal development of intraspinal 5-HT fibers in spinal motoneuron pools. Postnatal day (PND) 0 Sprague-Dawley rats received a hypoxic load and survivors were used for histological analyzes on PNDs 1, 7, and 14. Spinal motoneurons were labeled using choleratoxin B subunit as a retrograde neurotracer, and 5-HT fibers were detected immunohistochemically. On PND 1, 5-HT fibers were present in the lateral portion of the ventral horn at the cervical level, but were sparsely distributed at the lumbar level. On PND 14, cervical and lumbar level distributions were nearly identical. The 5-HT fibers and varicosities in close apposition to motoneurons increased from PNDs 1-14, however, the close apposition of cervical motoneurons was significantly different from lumbar motoneurons only on PND 1. Density of 5-HT fibers in control and hypoxic rats was not different on PND 1, while those in hypoxic rats were significantly reduced on PND 14. Close appositions of lumbar motoneurons were reduced more than cervical MNs after neonatal hypoxia. Neurodevelopmental deficit after neonatal hypoxia with a rostro-caudal gradient is associated with significant changes in the 5-HT system.

Silent exonic mutation in the acid-alpha-glycosidase gene that causes glycogen storage disease type II by affecting mRNA splicing.

Glycogen-storage disease type II (GSDII) is an autosomal recessive disorder caused by a deficiency of acid alpha-glucosidase (GAA). The residual GAA activity is largely related to the severity of the clinical course. Most patients with infantile-onset GSDII do not show any enzyme activity, whereas patients with the late-onset forms of GSDII show various degrees of GAA activity. We performed a molecular genetic study on a Japanese boy with childhood-onset GSDII. The patient was a compound heterozygote for a newly discovered splice-site c.546G>T mutation and a recurrent missense p.R600C mutation, which usually causes the fatal infantile form in a homozygous state. The c.546G>T mutation, which did not alter the amino-acid sequence, was positioned at the last base of exon 2. cDNA-sequencing analysis revealed that c.546G>T was a leaky splice mutation, leading to the production of a normally spliced transcript, which was responsible for the low-level (approximately 10%) expression of the active enzyme in the patient's fibroblasts.

[Questionnaire survey on sleep habit of 3-year-old children in Asahikawa City].

The present study surveyed the sleep habits of 3-year-old children in Asahikawa city using questionnaires completed by a parent during children's medical check-ups. Questionnaires were collected from the parents of 404 children (209 males, 195 females; mean age, 3.1 years) enrolled in this survey. Among these children, the mean bedtime was 9.6 PM with 145 children (36%) going to bed after 10 PM. On the other hand, the mean wake-up time was 7.5 AM, with 123 children (30%) waking up after 8 AM. The mean nocturnal sleep duration was 10.1 hours. Nocturnal sleep durations in children that went to bed after 10 PM were significantly shorter than in children who went to bed earlier (p < 0.01). Seventy-three percent of the children had a daily afternoon nap. Twelve percent of these children usually awoke from their nap after 5 PM, and the mean bedtime for these children was 10.1 PM. A late bedtime was significantly correlated with parental complaints such as short-temper and poor appetite (p < 0.05). Although parents were concerned about night-time sleep conditions, they were not concerned about the daytime conditions which regulate children's sleep-wake rhythm, such as daylight exposure, daytime activity, and naps. While 24% of parents had complains regarding their children's sleep, only 3% had consulted with a doctor. Similar to the previous reports, the present findings demonstrate that children in Asahikawa city go to bed late and have decreased sleep duration. Since the establishment of a normal sleep-wake rhythm is essential for both physical and mental development in children, it is necessary to educate parents regarding the importance of children's sleep.

Transcriptomic analysis of nephrotoxicity induced by cephaloridine, a representative cephalosporin antibiotic.

Cephaloridine (CER) is a classical beta-lactam antibiotic that has long served as a model drug for the study of cephalosporin antibiotic-induced acute tubular necrosis. In the present study, we analyzed gene expression profiles in the kidney of rats given subtoxic and toxic doses of CER to identify gene expression alterations closely associated with CER-induced nephrotoxicity. Male Fischer 344 rats were intravenously injected with CER at three different dose levels (150, 300, and 600 mg/kg) and sacrificed after 24 h. Only the high dose (600 mg/kg) caused mild proximal tubular necrosis and slight renal dysfunction. Microarray analysis identified hundreds of genes differentially expressed in the renal cortex following CER exposure, which could be classified into two main groups that were deregulated in dose-dependent and high dose-specific manners. The genes upregulated dose dependently mainly included those involved in detoxification and antioxidant defense, which was considered to be associated with CER-induced oxidative stress. In contrast, the genes showing high dose-specific (lesion-specific) induction included a number of genes related to cell proliferation, which appeared to reflect a compensatory response to CER injury. Of the genes modulated in both manners, we found many genes reported to be associated with renal toxicity by other nephrotoxicants. We could also predict potential transcription regulators responsible for the observed gene expression alterations, such as Nrf2 and the E2F family. Among the candidate gene biomarkers, kidney injury molecule 1 was markedly upregulated at the mildly toxic dose, suggesting that this gene can be used as an early and sensitive indicator for cephalosporin nephrotoxicity. In conclusion, our transcriptomic data revealed several characteristic expression patterns of genes associated with specific cellular processes, including oxidative stress response and proliferative response, upon exposure to CER, which may enhance our understanding of the molecular mechanisms behind cephalosporin antibiotic-induced nephrotoxicity.

Molecular analysis and anticonvulsant therapy in two patients with glucose transporter 1 deficiency syndrome: a successful use of zonisamide for controlling the seizures.

Glucose transporter 1 (GLUT1) deficiency syndrome is caused by a deficit in glucose transport to the brain during the pre- and postnatal periods. Here, we report two cases of GLUT1 deficiency syndrome diagnosed on the basis of clinical features, reduced GLUT1 activities, and mutations in the GLUT1 gene. Patient 1 had a novel heterozygous 1bp insertion in exon 7 that resulted in a shift of the reading frame and the introduction of a premature stop codon at amino acid position 380. His clinical phenotype appeared to be more severe than that of Patient 2 who had a missense mutation in exon 8 resulting in an arginine-to-tryptophan substitution at amino acid position 333. Patient 1 had no meaningful words and could not walk unassisted, while Patient 2 could speak and walk unassisted. Both the patients developed seizures of various types that have been successfully treated with zonisamide. Although several antiepileptic drugs, including barbiturates, diazepam, chloralhydrate, and valproic acid, have been shown to inhibit GLUT1 function, the present study demonstrated no inhibitory effect of zonisamide on GLUT1-mediated glucose transport. Our data suggested that zonisamide might be preferable if add-on anticonvulsant therapy is required to control the seizures in patients with this disorder.

Actigraphic assessment of sleep disorders in children with chronic fatigue syndrome.

UNLABELLED: Children with chronic fatigue syndrome (CFS) often suffer from sleep disorders, which cause many physiological and psychological problems. Understanding sleep characteristics in children with CFS is important for establishing a therapeutic strategy. We conducted an actigraphic study to clarify the problems in sleep/wake rhythm and physical activity in children with CFS. METHODS: Actigraphic recordings were performed for 1-2 weeks in 12 CFS children. The obtained data were compared with those of healthy age-matched children used as the control. RESULTS: Sleep patterns were divided into two groups based on subjects' sleep logs: irregular sleep type and delayed sleep phase type. Compared to the control group, total sleep time was longer and physical activity was lower in both groups of CFS. Continuous sleep for more than 10h was not uncommon in CFS. In the irregular sleep type, impaired daily sleep/wake rhythms and disrupted sleep were observed. CONCLUSION: Using actigraphy, we could identify several characteristics of the sleep patterns in CFS children. Actigraphic analysis proved to be useful in detecting sleep/wake problems in children with CFS.

Toxicogenomics of drug-induced hemolytic anemia by analyzing gene expression profiles in the spleen.

Hemolytic anemia is a serious adverse effect of therapeutic drugs that is caused by increased destruction of drug-damaged erythrocytes by macrophages in the spleen and liver. We previously applied a toxicogenomic approach to the toxicity by analyzing microarray data of the liver of rats dosed with two hemolytic agents: phenylhydrazine and phenacetin. In the present study, we analyzed gene expression profiles in the spleen, the primary organ for destruction of damaged erythrocytes, of the same models in order to identify splenic gene expression alterations that could be used to predict the hematotoxicity. Microarray analyses revealed hundreds of genes commonly deregulated under all severe hemolytic conditions, which included genes related to splenic events characteristic of the hematotoxicity, such as proteolysis and iron metabolism. Eleven upregulated genes were selected as biomarker candidates, and their expression changes were validated by quantitative real-time PCR. The transcript levels of most of these genes showed strong correlation with the results of classical toxicological assays (e.g., histopathology and hematology). Furthermore, hierarchical clustering analysis suggested that altered expression patterns of the 11 genes sensitively reflected the erythrocyte damage even under a condition that caused no decrease in erythrocyte counts. Among the selected genes, heme oxygenase 1 was one of the most promising biomarker candidates, the upregulation of which on the protein level was confirmed by immunohistochemistry. These results indicate that altered splenic expression of a subset of genes may allow detection of drug-induced hemolytic anemia, with better sensitivity than that of erythrocyte counts in the blood.

A toxicogenomic approach revealed hepatic gene expression changes mechanistically linked to drug-induced hemolytic anemia.

A variety of pharmaceutical compounds causes hemolytic anemia as a significant adverse effect and this toxicity restricts the clinical utility of these drugs. In this study, we applied microarray technology to investigate hepatic gene expression changes associated with drug-induced hemolytic anemia and to identify potential biomarker genes for this hematotoxicity. We treated female Sprague-Dawley rats with two hemolytic anemia-inducing compounds: phenylhydrazine and phenacetin. Hepatic gene expression profiles were obtained using a whole-genome oligonucleotide microarray with pooled RNA samples from individual rats within each dose group and analyzed in comparison with hepatic histopathology, hematology, and blood chemistry data. We identified a small subset of genes that were commonly deregulated in all the severe hemolytic conditions, some of which were considered to be involved in hepatic events characteristic of hemolytic anemia, such as hemoglobin biosynthesis, heme metabolism, and phagocytosis. Among them, we selected six upregulated genes as putative biomarkers, and their expression changes from microarray measurements were confirmed by quantitative real-time PCR using RNAs from individual animals. They were Alas2, beta-glo, Eraf, Hmox1, Lgals3, and Rhced. Expression patterns of all these genes showed high negative and positive correlation against erythrocyte counts and total bilirubin levels in circulation, respectively, suggesting that these genes may be the potential biomarkers for hemolytic anemia. These findings indicate that drug-induced hemolytic anemia may be detected based on hepatic changes in the expression of a subset of genes that are mechanistically linked to the hematotoxicity.

Postnatal development of brainstem serotonin-containing neurons projecting to lumbar spinal cord in rats.

We quantified postnatal changes in brainstem serotonin (5-hydroxytryptamine, 5-HT)-containing neurons projecting to lumbar spinal cord. The medulla-spinal cord descending neurons were identified by a retrograde neurotracer, choleratoxin B subunit (CTb), and 5-HT neurons were stained by immunohistochemistry. Double-labeled neurons were assumed to be 5-HT neurons projecting to the lumbar spinal cord, and were quantitatively analyzed in each raphe nucleus in the medulla. The following results were obtained: (1) At PND 3, numerous CTb-labeled neurons (CTLN) were already present in the raphe pallidus (B1), while few CTLN were seen in raphe obscurus (B2) and raphe magnus (B3). CTLN then rapidly increased in number and were separately distributed after PND 7 in B3 and after PND 14 in B2. (2) At PND 3, numerous 5-HT-containing neurons were already present in B1-B3, with 23.4% and 14.0% of them labeled with CTb in B1 and B2, respectively, while there were few double-labeled neurons in B3. From PND 3 to 28, although the proportion of double-labeled to 5-HT neurons remained unchanged in B1 and B2, that in B3 rapidly increased from 5.8% at PND 7 to 28.8% at PND 14. Previous studies have shown that the 5-HT neurons in B3 send fibers mainly to the dorsal horn, while those in B1 and B2 send fibers mainly to the ventral horn at all spinal cord levels. Taken together, the present findings suggest that the brainstem 5-HT systems influence the ventral horn of the spinal cord, where spinal motoneurons exist earlier than in the dorsal horn. The functional significance of these early 5-HT systems in motor development and/or disabilities is discussed.