Pivotal Role of Slitrk1 in Adult Striatal Cholinergic Neurons in Mice: Implication in Tourette Syndrome

OBJECTIVE

The SLIT and NTRK-like 1 (SLITRK1) gene mutation and striatal cholinergic interneurons (ChIs) loss are associated with Tourette syndrome (TS). ChIs comprise only 1 to 2% of striatal neurons but project widely throughout the stratum to impact various striatal neurotransmission, including TS-related dopaminergic transmission. Here, we link striatal Slitrk1, ChI function, and dopaminergic transmission and their associations with TS-like tic behaviors.

METHODS

Slitrk1-KD mice were induced by bilaterally injecting Slitrk1 siRNA into their dorsal striatum. Control mice received scrambled siRNA injection. Their TS-like tic behaviors, prepulse inhibition, sensory-motor function and dopamine-related behaviors were compared. We also compared dopamine and ACh levels in microdialysates, Slitrk protein and dopamine transporter levels, and numbers of Slitrk-positive ChIs and activated ChIs in the striatum between two mouse groups, and electrophysiological properties between Slitrk-positive and Slitrk-negative striatal ChIs.

RESULTS

Slitrk1-KD mice exhibit TS-like haloperidol-sensitive stereotypic tic behaviors, impaired prepulse inhibition, and delayed sensorimotor response compared with the control group. These TS-like characteristics correlate with lower striatal Slitrk1 protein levels, fewer Slitrk1-containing ChIs, and fewer activated ChIs in Slitrk1-KD mice. Based on their electrophysiological properties, Slitrk1-negative ChIs are less excitable than Slitrk1-positive ChIs. Slitrk1-KD mice have lower evoked acetylcholine and dopamine levels, higher tonic dopamine levels, and downregulated dopamine transporters in the striatum, increased apomorphine-induced climbing behaviors, and impaired methamphetamine-induced hyperlocomotion compared with controls.

INTERPRETATION

Slitrk1 is pivotal in maintaining striatal ChIs activity and subsequent dopaminergic transmission for normal motor functioning. Furthermore, conditional striatal Slitrk1-KD mice may serve as a translational modality with aspects of TS phenomenology. ANN NEUROL 2023.

Exposome of attention deficit hyperactivity disorder in Taiwanese children: exploring risks of endocrine-disrupting chemicals

BACKGROUND

Attention-deficit hyperactivity disorder (ADHD) is diagnosed in ~7% of school-aged children. The role of endocrine-disrupting chemicals (EDC) and oxidative stress in ADHD etiology are not clear.

OBJECTIVE

Assessment of the associations between simultaneous exposure to multiple compounds and ADHD in children.

METHODS

The case-control study included 76 clinically diagnosed ADHD cases and 98 controls, aged 4-15 years old. Concentrations quartiles of urinary metabolites of acrylamide, acrolein, nonylphenol, phthalates, and organophosphate pesticides and biomarkers of oxidative stress were used to fit logistic regressions for each compound and weighted quantiles sum (WQS) regression for the mixture.

RESULTS

Positive dose-response relationships with ADHD were observed for 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA) (odds ratio(OR)_Q4 = 3.73, 95%CI [1.32, 11.04], p_trend = 0.003), dimethyl phosphate (DMP) (OR_Q4 = 4.04, 95%CI [1.34, 12.94], p_trend = 0.014) and diethyl phosphate (OR_Q4 = 2.61, 95%CI = [0.93, 7.66], p_trend = 0.030), and for the mixture of compounds (OR_WQS = 3.82, 95%CI = [1.78, 8.19]) with the main contributions from HNE-MA (28.9%) and DMP (18.4%).

CONCLUSIONS

The dose-response relationship suggests enhanced susceptibility to EDC burden in children even at lower levels, whereas the main risk is likely from organophosphate pesticides. HNE-MA is recommended as a sensitive biomarker of lipid peroxidation in the further elucidation of the oxidative stress role in ADHD etiology.

The associations among organophosphate pesticide exposure, oxidative stress, and genetic polymorphisms of paraoxonases in children with attention deficit/hyperactivity disorder

This study will help to clarify the relationship between organophosphate pesticides (OPs) and attention deficit/hyperactivity disorder (ADHD) related to oxidative stress and paraoxonases (PON) polymorphisms to further characterize the gene-environment interaction. This case-control study enrolled 85 children with ADHD and 96 control subjects. Urinary OP levels were analyzed by using gas chromatography-mass spectrometry (GC-MS). Oxidative stress biomarkers, such as 8-hydroxy-2-deoxyguanosine (8-OHdG), 8-nitroguanine (8-NO2-Gua), 8-iso-prostaglandin F2α (8-iso-PGF2α), and 4-hydroxy-2-nonenoic acid-mercapturic acid (HNE-MA), were analyzed by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP), and synergy index (S) were calculated to evaluate the additive interactions between OP exposure and PON genetic polymorphism on ADHD. A causal mediation analysis was conducted to clarify the mediation effects of oxidative stress due to OP exposure on ADHD. Children with ADHD had significantly higher DMP (238.95 nmol/g cre. vs. 164.83 nmol/g cre., p value = 0.01) and HNE-MA (30.75 μg/g cre. vs. 18.41 μg/g cre., p value<0.01) concentrations than control children. Children who carried the PON1 GG genotype (rs705379) had low urinary DMP levels, and the level increased with increasing numbers of allele variants. The risk for developing ADHD reached 2.06-fold (OR = 2.06, 95% CI:1.23-3.44) and 1.43-fold (OR = 1.45, 95% CI:1.04-2.03) when the DMP and HNE-MA levels increased by 1 natural log of the concentration, respectively. The estimated AP value was 0.66 (95% CI: 0.17-1.15), indicating that 66% of ADHD cases in DMP-exposed children with the PON1 CT/TT (rs705381) genotype were due to gene-environment interactions. No significant mediation of HNE-MA was observed between DMP exposure and the risk of ADHD. The estimated proportion mediated was only 7.0% (95% CI: -0.08-0.46). This research suggests the role of OP exposure in the occurrence of ADHD after adjusting for covariates.

The interactions among organophosphate pesticide exposure, oxidative stress, and genetic polymorphisms of dopamine receptor D4 increase the risk of attention deficit/hyperactivity disorder in children

OBJECTIVE

The aim of this study was to clarify the association between organophosphate pesticides (OPs) and attention-deficit/hyperactivity disorder (ADHD) related to oxidative stress and genetic polymorphisms.

METHODS

This case-control study enrolled 93 children with ADHD and 112 control children in north Taiwan. Six dialkyl phosphate (DAP) metabolites of OPs and oxidative stress biomarkers were analyzed. Polymorphisms of the dopamine receptor D4 gene (DRD4) were identified.

RESULTS

Children with ADHD had significantly higher dimethylphosphate (DMP, 236.69nmol/g cre. vs. 186.84nmol/g cre., p value = 0.01) and 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA, 28.95µg/g cre. vs. 16.55µg/g cre., p value<0.01) concentrations than control children. Children who carried DRD4 GA/AA genotypes (rs752306) were less likely than those who carried the DRD4 GG genotype to have ADHD (odds ratio [OR]: 0.45, 95% CI: 0.24-0.84). The estimated value of the AP (attributable proportion due to interaction) was 0.59 (95% CI: 0.13-1.05), indicating that 59% of ADHD cases in DMP-exposed children with the DRD4 GG genotype were due to the gene-environment interaction. After adjustment for other covariates, children who carried the DRD4 GG genotype, had been exposed to high DMP levels (more than the median), and had high HNE-MA levels had a significantly increased risk for developing ADHD (OR = 11.74, 95% CI: 2.12-65.04).

CONCLUSION

This study indicated a gene-environment interaction in the risk of ADHD in children. The association between DMP and ADHD in children might relate to the mechanism of lipid peroxidation. Dose-response relationships and the combined effects of OPs, oxidative stress, and genetic polymorphism on ADHD should not be neglected.

[Diagnostic value of carotid atherosclerosis score for ischemic stroke]

OBJECTIVE

To discuss the diagnostic value of carotid atherosclerosis score for ischemic stroke.

METHODS

In the study, 151 patients with ischemic stroke were enrolled, who were diagnosed by cranial CT scan or cranial MRI scan, and examined with carotid duplex ultrasound, and 151 healthy check-up cases matched by age and sex were chosen as control group, who were excluded ischemic stroke by cranial CT scan or cranial MRI scan. All the control cases were examined with carotid duplex ultrasound also. Intima-media thickness (IMT), the number of carotid plaques, the size of each plaque, the location of the plaque and each plaque's echo, texture, surface regularity were estimated by carotid duplex ultrasound.

RESULTS

The IMT of the case group and the control group were (0.946±0.185) mm and (0.863±0.148) mm, and there were significant differences (P<0.001); The parameters of arterial plaque correlated with ischemic stroke were plaque's echo, texture and surface regularity, however the plaque size and location were not correlated with ischemic stroke. The median and quartile of carotid artery plaque score were 3 and 2 respectively in case group, 1 and 2 respectively in control group, and there were significant differences (P<0.001); The parameters of carotid arterial atherosclerosis associated with ischemic stroke were carotid artery plaque score,carotid stenosis degree and IMT, but not the number of carotid plaques. The median and quartile of carotid arterial atherosclerosis score were 5 and 4 respectively in case group, 2 and 4 respectively in control group, and there were significant differences (P<0.001); The area under the curve (AUC) for IMT, the number of carotid plaques, carotid artery plaque score and carotid arterial atherosclerosis score were 0.679, 0.677, 0.704 and 0.805,respectively (P<0.001). The accuracy of carotid atherosclerosis score was the highest.

CONCLUSION

Carotid artery plaque score and carotid atherosclerosis score can be used for the diagnosis of ischemic stroke, and the accuracy of carotid atherosclerosis score is higher.

Attention Deficit/Hyperactivity Disorder and Urinary Nonylphenol Levels: A Case-Control Study in Taiwanese Children

Objective

Nonylphenol (NP) belongs to the family of endocrine disruptors, and it is widely used in industrial applications and is ubiquitous in daily foods. Animal studies have suggested that NP exposure might promote motor hyperactivity, likely by causing deficits in dopaminergic neurons. However, research assessing NP exposure and epidemiology studies on human populations are limited. The aim of this study was to explore the association between child NP exposure and ADHD while considering particular covariants, such as lead levels and dopamine-related gene variations.

Methods

A case-control study was conducted on patients with clinically diagnosed ADHD; the Swanson, Nolan and Pelham, Fourth Revision (SNAP-IV) questionnaire was used to identify normal controls aged 4–15 years. Participants were examined for urinary NP concentrations, blood lead levels, and select single-nucleotide polymorphisms of two dopamine-related genes (D4 dopamine receptor, DRD4, and dopamine transporter, DAT1). Socio-demographic variables, maternal lifestyle factors during pregnancy and family medical history were obtained using a questionnaire.

Results

A total of 97 children with doctor-diagnosed ADHD and 110 normal controls were enrolled. The blood lead levels in both groups were similar (1.57±0.73 vs. 1.73±0.77 μg/dL, p = 0.15). No significant difference in urinary NP concentration was found between the children with ADHD and the control subjects (4.52±3.22 μg/g cr. vs. 4.64±2.95 μg/g cr., p = 0.43). ADHD was significantly more prevalent among males in this study (male to female ratio: 5:1 for the ADHD group and 1.3:1 for the control group, p<0.01). The analysis was repeated after excluding the females, but this had no effect on the association between NP and ADHD. The regression model, including or excluding females, indicated no increased odds of having ADHD in the context of NP exposure after adjusting for covariants.

Conclusion

This study indicated that NP exposure might not promote ADHD in children, even though children in Taiwan had relatively high levels of NP compared to those reported previously and those in developed nations.

Tourette syndrome in children: an updated review

Tourette syndrome (TS) is a common neuropsychiatric disorder in children characterized by multiple motor and vocal tics that fluctuate in severity and lasting for at least 1 year. Boys are more commonly affected than girls. Symptoms usually begin with simple motor or vocal tics which then evolve into more complex motor and vocal tics over time. Premonitory sensory urges are common in children over the age of 8 years, and these urges help distinguish tics from symptoms of other movement disorders. Common comorbidities of TS include attention deficit hyperactivity disorder, obsessive-compulsive disorder and learning difficulties. Several genes have been assessed as candidate genes for TS; environmental factors such as stress and streptococcal infections might also contribute to its etiology. The pathophysiology of TS mainly involves dysfunction of basal ganglia-related circuits and hyperactive dopaminergic innervations. A thorough history assessment and neurological examination are important for the correct diagnosis and differentiation from other movement disorders. Treatment for TS should focus on improving the patient's social functioning, minimizing the impairment from cormobid disorders, and controlling tics, if they are severe. Commonly used medications for TS include a2-adrenergic agonists and atypical neuroleptics. Habit reversal therapy is an effective option for TS, and repetitive transcranial magnetic stimulation may be a promising approach for severe cases.

Clinical analysis of childhood occipital lobe epilepsy in 43 Taiwanese patients

Occipital lobe epilepsy in children can present as an idiopathic form (i.e., childhood epilepsy with occipital paroxysms) or as a symptomatic form. Forty-three children (18 boys, 25 girls) were divided into the idiopathic group or symptomatic group, according to the classification for epileptic seizures of the International League Against Epilepsy. Patients in the idiopathic group were further subdivided into the Panayiotopoulos or Gastaut type, according to clinical presentation. The idiopathic group consisted of 15 children (5 boys, 10 girls), of whom 11 were of the Panayiotopoulos type and 4 of the Gastaut type. The symptomatic group consisted of 28 children (13 boys, 15 girls). The average age of seizure onset in the idiopathic group was younger than in the symptomatic group (6.5 +/- 2.4 vs 8.5 +/- 3.0 years). Ictal vomiting was more common in the idiopathic group, and positive visual symptoms were more common in the symptomatic group. Mean epilepsy duration in the idiopathic group was shorter (5.7 +/- 5.3 vs 20.1 +/- 16.0 months), and the response to treatment was better. The average age of seizure onset was much younger in the Panayiotopoulos than in the Gastaut type (5.4 +/- 1.5 vs 9.5 +/- 1.5 years), and mean epilepsy duration was also shorter (3.9 +/- 4.2 vs 10.5 +/- 4.9 months). Seizure semiology can distinguish between idiopathic occipital lobe epilepsy and the symptomatic form with ictal vomiting and positive visual symptoms. In idiopathic occipital lobe epilepsy, the Panayiotopoulos type has better prognosis than the Gastaut type.

Screening for biliary atresia by infant stool color card in Taiwan

OBJECTIVE

We aimed to detect biliary atresia (BA) in early infancy to prevent additional liver damage because of the delay of referral and surgical treatment and to investigate the incidence rate of BA in Taiwan.

METHODS

A pilot study to screen the stool color in infants for the early diagnosis of BA was undertaken from March 2002 to December 2003. We had designed an "infant stool color card" with 7 numbers of different color pictures and attached it to the child health booklet. Parents were then asked to observe their infant's stool color by using this card. The medical staff would check the number that the parents chose according to their infant's stool color at 1 month of age during the health checkup and then send the card back to the stool color card registry center.

RESULTS

The average return rate was approximately 65.2% (78,184 infants). A total of 29 infants were diagnosed as having BA, and 26 were screened out by stool color card before 60 days of age. The sensitivity, specificity, and positive predictive value were 89.7%, 99.9%, and 28.6%, respectively. Seventeen (58.6%) infants with BA received a Kasai operation within 60-day age period. The estimated incidence of BA in screened newborns was 3.7 of 10,000.

CONCLUSIONS

The stool color card was a simple, efficient, and applicable mass screening method for early diagnosis and management of BA. The program can also help in estimating the incidence and creating a registry of these patients.

Acute disseminated encephalomyelitis in children: one medical center experience

Acute disseminated encephalomyelitis (ADEM) is a rare inflammatory demyelinating disease of the central nervous system. The experience in children is limited. We retrospectively reviewed our experience with 20 ADEM patients (10 females, 10 males) with age of onset before 18 years old in Taiwan to clarify the clinical manifestations, neuroimaging findings, and the relationship between ADEM and multiple sclerosis (MS). The age at onset ranged from 4 months to 15 years. Seventeen (85%) children had a recent infectious prodrome. Children presented most often with acute consciousness disturbance (70%) and motor deficits (55%). Seizures occurred in 10 (50%), but only one child developed epilepsy in follow-up. Brain magnetic resonance imaging (MRI) evaluations done in all patients revealed multifocal lesions, mainly in subcortical white matter (80%), brainstem (65%), basal ganglia (55%), cerebellum (45%), thalamus (40%), and periventricular white matter (35%). Spinal cord MRI was performed in 9 patients and all of them showed abnormal lesions. Eleven patients were treated with high-dose intravenous methylprednisolone pulse therapy, and only one had mild long-term neurological sequelae. Among the 20 patients, five had long-term neurological sequelae and one died. Three patients fit the criteria of multiphasic disseminated encephalomyelitis, in which two developed MS in follow-up. Another patient with ADEM turned out to be MS two years later. We concluded that seizures are not uncommon in ADEM, but the subsequent development of epilepsy is rare. Long-term prognosis of ADEM is generally good. Because recurrence of ADEM is not uncommon, long-term follow-up of those children with ADEM is needed to distinguish between ADEM and MS.