STYK1/NOK correlates with ferroptosis in non-small cell lung carcinoma.

Serine Threonine Tyrosine Kinase 1 (STYK1) presents oncogenic properties in many studies, and emerging evidence suggests that ferroptosis serve as a novel tumor suppressor. However, the interplay between STYK1 and ferroptosis in NSCLC remains unclear. Our aim is to illustrate the expression of ferroptotic regulator Glutathione peroxidase 4 (GPX4) in NSCLC and the relationship between STYK1 and ferroptosis. Herein, results based on ONCOMINE database, clinical specimens, and cellular manipulation revealed GPX4 was upregulated in NSCLC tissues and cell lines, and high GPX4 expression predicted worse prognosis. High STYK1 expression predicted worse OS and was related to high GPX4 in NSCLC tissues; overexpression of STYK1 in lung cancer cell line SW900 upregulated the expression of GPX4, promoted proliferation, and attenuated diverse mitochondrial abnormalities specific to ferroptosis, whereas knockdown of GPX4 exacerbated such attenuations without affecting cell proliferation. Taken together, ferroptosis as an anti-tumor factor is inhibited in NSCLC, and targeting ferroptosis could be a novel therapeutic strategy for the management of NSCLC; furthermore, regulating ferroptosis could be another cancerous mechanism of STYK1.

Motor hyperactivity of the iron-deficient rat - an animal model of restless legs syndrome.

BACKGROUND: Abnormal striatal dopamine transmission has been hypothesized to cause restless legs syndrome. Dopaminergic drugs are commonly used to treat restless legs syndrome. However, they cause adverse effects with long-term use. An animal model would allow the systematic testing of potential therapeutic drugs. A high prevalence of restless legs syndrome has been reported in iron-deficient anemic patients. We hypothesized that the iron-deficient animal would exhibit signs similar to those in restless legs syndrome patients. METHODS: After baseline polysomnographic recordings, iron-deficient rats received pramipexole injection. Then, iron-deficient rats were fed a standard rodent diet, and polysomnographic recording were performed for 2 days each week for 4 weeks. RESULTS: Iron-deficient rats have low hematocrit levels and show signs of restless legs syndrome: sleep fragmentation and periodic leg movements in wake and in slow-wave sleep. Iron-deficient rats had a positive response to pramipexole treatment. After the iron-deficient rats were fed the standard rodent diet, hematocrit returned to normal levels, and sleep quality improved, with increased average duration of wake and slow-wave sleep episodes. Periodic leg movements decreased during both waking and sleep. Hematocrit levels positively correlated with the average duration of episodes in wake and in slow-wave sleep and negatively correlated with periodic leg movements in wake and in sleep. Western blot analysis showed that striatal dopamine transporter levels were higher in iron-deficient rats. CONCLUSIONS: The iron-deficient rat is a useful animal model of iron-deficient anemic restless legs syndrome. © 2017 International Parkinson and Movement Disorder Society.

EGFR mutations in surgically resected fresh specimens from 697 consecutive Chinese patients with non-small cell lung cancer and their relationships with clinical features.

We aimed to reveal the true status of epidermal growth factor receptor (EGFR) mutations in Chinese patients with non-small cell lung cancer (NSCLC) after lung resections. EGFR mutations of surgically resected fresh tumor samples from 697 Chinese NSCLC patients were analyzed by Amplification Refractory Mutation System (ARMS). Correlations between EGFR mutation hotspots and clinical features were also explored. Of the 697 NSCLC patients, 235 (33.7%) patients had tyrosine kinase inhibitor (TKIs) sensitive EGFR mutations in 41 (14.5%) of the 282 squamous carcinomas, 155 (52.9%) of the 293 adenocarcinomas, 34 (39.5%) of the 86 adenosquamous carcinomas, one (9.1%) of the 11 large-cell carcinomas, 2 (11.1%) of the 18 sarcomatoid carcinomas, and 2 (28.6%) of the 7 mucoepidermoid carcinomas. TKIs sensitive EGFR mutations were more frequently found in female patients (p < 0.001), non-smokers (p = 0.047) and adenocarcinomas (p < 0.001). The rates of exon 19 deletion mutation (19-del), exon 21 L858R point mutation (L858R), exon 21 L861Q point mutation (L861Q), exon 18 G719X point mutations (G719X, including G719C, G719S, G719A) were 43.4%, 48.1%, 1.7% and 6.8%, respectively. Exon 20 T790M point mutation (T790M) was detected in 3 squamous carcinomas and 3 adenocarcinomas and exon 20 insertion mutation (20-ins) was detected in 2 patients with adenocarcinoma. Our results show the rates of EGFR mutations are higher in all types of NSCLC in Chinese patients. 19-del and L858R are two of the more frequent mutations. EGFR mutation detection should be performed as a routine postoperative examination in Chinese NSCLC patients.

Effects of sodium oxybate on hypocretin/orexin and locus coeruleus neurons.

Long-term use of sodium oxybate (SXB), (also called gamma-hydroxybutyrate [GHB]) attenuates the cataplexy and sleepiness of human narcolepsy. We had previously found that chronic opiate usage in humans and long-term opiate administration to mice significantly increased the number of detected hypocretin/orexin (Hcrt) neurons, decreased their size, and increased Hcrt level in the hypothalamus. We also found that opiates significantly decreased cataplexy in human narcoleptics as well as in narcoleptic mice and that cessation of locus coeruleus neuronal activity preceded and was tightly linked to cataplectic attacks in narcoleptic dogs. We tested the hypothesis that SXB produces changes similar to opiates and now report that chronic SXB administration significantly increased the size of Hcrt neurons, the reverse of what we had seen with opiates in humans and mice. Levels of Hcrt in the hypothalamus were nonsignificantly lower, in contrast to the significant increase in hypothalamic Hcrt level after opiates. SXB decreased tyrosine hydroxylase levels in the locus coeruleus, the major descending projection of the hypocretin system, also the reverse of what we saw with opioids. Therefore despite some similar effects on narcoleptic symptomatology, SXB does not produce anatomical changes similar to those elicited by opiates. Analysis of changes in other links in the cataplexy pathway might further illuminate SXB's mechanism of action on narcolepsy.

Striatal mechanism of the restless legs syndrome.

STUDY OBJECTIVES: Brain iron deficiency has been reported to be associated with the restless legs syndrome (RLS). However, 30%-50% of RLS patients do not respond to iron therapy, indicating that mechanisms other than brain iron deficiency may also participate in this disease. The striatum is known to be involved in the modulation of motor activity. We speculated that dysfunction of the striatum may induce RLS. METHODS: Two groups, wild-type (WT) and iron-deficient (ID) rats were used. Each group was divided into two subgroups, control and N-methyl-d-aspartate striatal-lesioned. After baseline recording, striatal-lesioned wild-type (WT-STL) and striatal-lesioned iron-deficient (ID-STL) rats were given pramipexole and thioperamide injections. Iron-deficient and ID-STL rats were then given a standard rodent diet for 4 weeks, and their sleep and motor activity were recorded. RESULTS: WT-STL rats showed periodic leg movements (PLM) in wake, an increase in PLM in slow wave sleep (SWS), a decrease in rapid-eye-movement sleep, and a decrease in the daily average duration of episodes in SWS. The sleep-wake pattern and motor activity did not differ between ID and ID-STL rats. Thioperamide or pramipexole injection decreased PLM in sleep and in wake in WT-STL rats and ID-STL rats. Unlike ID rats, whose motor hyperactivity can be reversed by iron replacement, PLM in wake and in sleep in ID-STL rats were not fully corrected by iron treatment. CONCLUSIONS: Lesions of the striatum generate RLS-like activity in rats. Dysfunction of the striatum may be responsible for failure to respond to iron treatment in some human RLS patients.

Substantia nigra pars reticulata-mediated sleep and motor activity regulation.

STUDY OBJECTIVES: The substantia nigra pars reticulata (SNR) is a major output nucleus of the basal ganglia. Animal studies have shown that lesions of the SNR cause hyposomnia and motor hyperactivity, indicating that the SNR may play a role in the control of sleep and motor activity. METHODS: Eight 8- to 10-week-old adult male Sprague-Dawley rats were used. After 3 days of baseline polysomnographic recording, dialysates were collected from the lateral SNR across natural sleep-wake states. Muscimol and bicuculline were microinfused into the lateral SNR. RESULTS: We found that GABA release in the lateral SNR is negatively correlated with slow wave sleep (SWS; R = -0.266, p < 0.01, n = 240) and positively correlated with waking (R = 0.265, p < 0.01, n = 240) in rats. Microinfusion of muscimol into the lateral SNR decreased sleep time and sleep quality, as well as eliciting motor hyperactivity in wake and increased periodic leg movement in SWS, while bicuculline infused into the lateral SNR increased sleep and decreased motor activity in SWS in rats. Muscimol infusion skewed the distribution of inter-movement intervals, with most between 10 and 20 s, while a flat distribution of intervals between 10 and 90 s was seen in baseline conditions. CONCLUSIONS: Activation of the lateral SNR is important for inducing sleep and inhibiting motor activity prior to and during sleep, and thus to the maintenance of sleep. Abnormal function of the lateral SNR may cause hyposomnia and motor hyperactivity in quiet wake and in sleep.

STYK1/NOK Promotes Metastasis and Epithelial-Mesenchymal Transition in Non-small Cell Lung Cancer by Suppressing FoxO1 Signaling.

AIMS: Serine/threonine/tyrosine kinase 1 (STYK1) has been previously shown to have oncogenic properties, and emerging evidence suggests that STYK1 expression correlates with epithelial-mesenchymal transition (EMT). However, the mechanism of STYK1 involvement in oncogenesis remains unknown. The present study aimed to elucidate how STYK1 expression level relates to the metastasis, migration, invasion, and EMT in non-small cell lung cancer (NSCLC) and to determine the molecular mechanism of STYK1 effects. METHODS: Serine/threonine/tyrosine kinase 1 (STYK1) expression level and its relationship with the prognosis of NSCLC were determined using the ONCOMINE database and clinical cases. Non-small cell lung cancer cell lines with the overexpression or knockdown of STYK1 were established to determine whether STYK1 promotes cell migration, invasion, and EMT in vitro and in vivo. In addition, a constitutively active FoxO1 mutant (FoxO1AAA) was used to examine the role of FoxO1 in the STYK1-mediated upregulation of metastasis and EMT in NSCLC. RESULTS: Serine/threonine/tyrosine kinase 1 (STYK1) was upregulated in NSCLC tissues and cell lines, and its overexpression correlated with poor prognosis in patients with NSCLC after surgery. Enhanced expression of STYK1 potentiated the migration, invasion, and EMT in SW900 cells, thereby promoting metastasis, whereas knockdown of STYK1 inhibited these cellular phenomena in Calu-1 cells. Furthermore, STYK1 expression was positively related to the level of phosphorylated-FoxO1, whereas the constitutively active FoxO1 mutant protected against the positive effect of STYK1 overexpression on cell migration, invasion, and EMT. CONCLUSION: Serine/threonine/tyrosine kinase 1 (STYK1) was upregulated in NSCLC and correlated with poor clinical outcomes. In addition, STYK1 suppressed FoxO1 functions, thereby promoting metastasis and EMT in NSCLC.

Behavioral response and transmitter release during atonia elicited by medial medullary stimulation.

Activation of the medial medulla is responsible for rapid eye movement (REM) sleep atonia and cataplexy. Dysfunction can cause REM sleep behavior disorder and other motor pathologies. Here we report the behavioral effects of stimulation of the nucleus gigantocellularis (NGC) and nucleus magnocellularis (NMC) in unrestrained cats. In waking, 62% of the medial medullary stimulation sites suppressed muscle tone. In contrast, stimulation at all sites, including sites where stimulation produced no change or increased muscle tone in waking, produced decreased muscle tone during slow-wave sleep. In the decerebrate cat electrical stimulation of the NGC increased glycine and decreased norepinephrine (NE) release in the lumbar ventral horn, with no change in γ-aminobutyric acid (GABA) or serotonin (5-HT) release. Stimulation of the NMC increased both glycine and GABA release and also decreased both NE and 5-HT release in the ventral horn. Glutamate levels in the ventral horn were not changed by either NGC or NMC stimulation. We conclude that NGC and NMC play neurochemically distinct but synergistic roles in the modulation of motor activity across the sleep-wake cycle via a combination of increased release of glycine and GABA and decreased release of 5-HT and NE. Stimulation of the medial medulla that elicited muscle tone suppression also triggered rapid eye movements, but never produced the phasic twitches that characterize REM sleep, indicating that the twitching and rapid eye movement generators of REM sleep have separate brain stem substrates.

Striatal histamine mechanism in the pathogenesis of restless legs syndrome.

STUDY OBJECTIVES: Restless legs syndrome (RLS) has been hypothesized to be generated by abnormal striatal dopamine transmission. Dopaminergic drugs are effective for the treatment of RLS. However, long-term use of dopaminergic drugs causes adverse effects. We used iron-deficient (ID) and iron-replacement (IR) rats to address the neuropathology of RLS and to determine if a histamine H3 receptor (H3R) antagonist might be a useful treatment. Histamine H3R antagonists have been shown to decrease motor activity. METHODS: Control and ID rats were surgically implanted with electrodes for polysomnographic recording. After 3 days of baseline polysomnographic recordings, rats were systemically injected with the H3R agonist, α-methylhistamine, and antagonist, thioperamide. Recordings were continued after drug injection. Striatal H3R levels from control, ID, and IR rats were determined by western blots. Blood from control, ID, and IR rats was collected for the measurement of hematocrit levels. RESULTS: α-Methylhistamine and thioperamide increased and decreased motor activity, respectively, in control rats. In ID rats, α-methylhistamine had no effect on motor activity, whereas thioperamide decreased periodic leg movement (PLM) in sleep. Sleep-wake states were not significantly altered under any conditions. Striatal H3R levels were highest in ID rats, moderate to low in IR rats, and lowest in control rats. Striatal H3R levels were also found to positively and negatively correlate with PLM in sleep and hematocrit levels, respectively. CONCLUSIONS: A striatal histamine mechanism may be involved in ID anemia-induced RLS. Histamine H3R antagonists may be useful for the treatment of RLS.

Surgical outcomes of stage IV non-small cell lung cancer: a single-center experience.

BACKGROUND: Increasing evidence has shown the effectiveness of surgery for stage IV non-small cell lung cancer (NSCLC). Present study aims to summarize the experience of our institution in dealing with advanced NSCLC in the context of multimodality therapy including lung surgery. METHODS: Patients underwent surgical resection for stage IV NSCLC diagnosed before or during surgery from January 2014 to June 2017 at Tangdu Hospital were included in this study. RESULTS: There were 88 stage IV NSCLC patients enrolled in this study. Among them, 35 patients with pleural metastases, 18 with brain oligometastases, 25 with extra-brain oligometastases and 10 with multiple metastatic sites or organs. For primary lung tumor, almost all (86/88) were resected with R0. For metastatic lesions, 53 patients received curative local treatment and 9 patients with partial treatment. There were 62 patients received adjuvant treatment, 10 patients received no adjuvant treatment and 16 patients with missing data of adjuvant treatment. The median overall survival of patients was 31.72 months. The estimated 3-year OS was 42.2%. Patients with pleural metastases and brain oligometastases got better outcomes than the ones with extra-brain oligometastases and multiple metastases (P<0.001). Patients with adjuvant epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) treatment had significantly better OS compared with those with adjuvant chemotherapy treatment (P=0.015). Besides, age <60 and cT1-2 were also associated with better survival. CONCLUSIONS: Surgery may be a considerable choice for stage IV NSCLC in the context of multimodality therapy.

Aberrantly High Expression Of NOK/STYK1 Is Tightly Associated With The Activation Of The AKT/GSK3ß/N-Cadherin Pathway In Non-Small Cell Lung Cancer.

PURPOSE: High metastasis is a leading risk factor for the survival of non-small cell lung cancer (NSCLC) and epithelial-mesenchymal transition (EMT) is a vital step of metastasis. The expression of novel oncogene with kinase domain (NOK) has been observed in some human malignancies, including non-small cell lung cancer (NSCLC); however, the biological function of NOK in NSCLC remains unclear. In the study, we explored the function of NOK in NSCLC, with an aim to elucidate the relevant underlying mechanisms. PATIENTS AND METHODS: We investigate the expression of NOK, p-Akt, p-GSK-3ß, E-cadherin and N-cadherin expression by immunohistochemical analysis using tissue microarrays of 72 paired NSCLC samples of cancerous and adjacent normal tissues. The associations between NOK expression and clinicopathological factors, overall survival, other proteins were assessed. Immunofluorescence analysis of NSCLC tissues was performed to study the location of NOK, Akt and GSK-3ß. Up or down-regulated of NOK were conducted in two NSCLC cell lines to analyze its impact on AKT/GSK3ß pathway. RESULTS: Statistical analysis revealed NOK expression increased in NSCLC tissues compared with normal tissues (P<0.05). It also showed that low NOK expression were associated with a higher possibility of non-lymphatic metastasis, an early pN stage and clinical stage (P<0.05). Moreover, NOK expression was positively correlated with the expression of oncogene p-Akt (Thr308), p-GSK-3ß (Ser9) and N-cadherin (P<0.05). Immunofluorescence analysis of NSCLC tissues revealed that NOK is co-located with Akt and GSK-3ß. Further study in NSCLC cell lines revealed that NOK overexpression can activate the AKT/GSK3ß pathway. Conversely, knockdown of NOK can suppress the AKT/GSK3ß pathway. CONCLUSION: Our results suggest that NOK overexpression correlated significantly with lymphatic metastasis, advanced pN and clinical stage in NSCLC. And NOK may promote EMT by activating the AKT/GSK3ß/N-cadherin pathway in NSCLC.

Metabolic profiles of serum samples from ground glass opacity represent potential diagnostic biomarkers for lung cancer.

BACKGROUND: Lung cancer is a leading cause of cancer deaths worldwide. Low-dose computed tomography (LDCT) screening trials indicated that LDCT is effective for the early detection of lung cancer, but the findings were accompanied by high false positive rates. Therefore, the detection of lung cancer needs complementary blood biomarker tests to reduce false positive rates. METHODS: In order to evaluate the potential of metabolite biomarkers for diagnosing lung cancer and increasing the effectiveness of clinical interventions, serum samples from subjects participating in a low-dose CT-scan screening were analyzed by using untargeted liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS). Samples were acquired from 34 lung patients with ground glass opacity diagnosed lung cancer and 39 healthy controls. RESULTS: In total, we identified 9 metabolites in electron spray ionization (ESI)(+) mode and 7 metabolites in ESI(-) mode. L-(+)-gulose, phosphatidylethanolamine (PE)(22:2(13Z,16Z)/15:0), cysteinyl-glutamine, S-japonin, threoninyl-glutamine, chlorate, 3-oxoadipic acid, dukunolide A, and malonic semialdehyde levels were observed to be elevated in serum samples of lung cancer cases when compared to those of healthy controls. By contrast, 1-(2-furanylmethyl)-1H-pyrrole, 2,4-dihydroxybenzoic acid, monoethyl carbonate, guanidinosuccinic acid, pseudouridine, DIMBOA-Glc, and 4-feruloyl-1,5-quinolactone levels were lower in serum samples of lung cancer cases compared with those of healthy controls. CONCLUSIONS: This study demonstrates evidence of early metabolic alterations that can possibly distinguish malignant ground glass opacity from benign ground glass opacity. Further studies in larger pools of samples are warranted.

Hypocretin (orexin) cell loss in Parkinson's disease.

It has recently been reported that Parkinson's disease (PD) is preceded and accompanied by daytime sleep attacks, nocturnal insomnia, REM sleep behaviour disorder, hallucinations and depression, symptoms which are frequently as troublesome as the motor symptoms of PD. All these symptoms are present in narcolepsy, which is linked to a selective loss of hypocretin (Hcrt) neurons. In this study, the Hcrt system was examined to determine if Hcrt cells are damaged in PD. The hypothalamus of 11 PD (mean age 79 +/- 4) and 5 normal (mean age 77 +/- 3) brains was examined. Sections were immunostained for Hcrt-1, melanin concentrating hormone (MCH) and alpha synuclein and glial fibrillary acidic protein (GFAP). The substantia nigra of 10 PD brains and 7 normal brains were used for a study of neuromelanin pigmented cell loss. The severity of PD was assessed using the Hoehn and Yahr scale and the level of neuropathology was assessed using the Braak staging criteria. Cell number, distribution and size were determined with stereologic techniques on a one in eight series. We found an increasing loss of hypocretin cells with disease progression. Similarly, there was an increased loss of MCH cells with disease severity. Hcrt and MCH cells were lost throughout the anterior to posterior extent of their hypothalamic distributions. The percentage loss of Hcrt cells was minimal in stage I (23%) and was maximal in stage V (62%). Similarly, the percentage loss of MCH cells was lowest in stage I (12%) and was highest in stage V (74%). There was a significant increase (P = 0.0006, t = 4.25, df = 15) in the size of neuromelanin containing cells in PD patients, but no difference in the size of surviving Hcrt (P = 0.18, t = 1.39, df = 14) and MCH (P = 0.28, t = 1.39, df = 14) cells relative to controls. In summary, we found that PD is characterized by a massive loss of Hcrt neurons. Thus, the loss of Hcrt cells may be a cause of the narcolepsy-like symptoms of PD and may be ameliorated by treatments aimed at reversing the Hcrt deficit. We also saw a substantial loss of hypothalamic MCH neurons. The losses of Hcrt and MCH neurons are significantly correlated with the clinical stage of PD, not disease duration, whereas the loss of neuromelanin cells is significantly correlated only with disease duration. The significant correlations that we found between the loss of Hcrt and MCH neurons and the clinical stage of PD, in contrast to the lack of a relationship of similar strength between loss of neuromelanin containing cells and the clinical symptoms of PD, suggests a previously unappreciated relationship between hypothalamic dysfunction and the time course of the overall clinical picture of PD.

Changes in inhibitory amino acid release linked to pontine-induced atonia: an in vivo microdialysis study.

We hypothesized that cessation of brainstem monoaminergic systems and an activation of brainstem inhibitory systems are both involved in pontine inhibitory area (PIA) stimulation-induced muscle atonia. In our previous study (Lai et al., 2001), we found a decrease in norepinephrine and serotonin release in motoneuron pools during PIA stimulation-induced muscle tone suppression. We now demonstrate an increase in inhibitory amino acid release in motor nuclei during PIA stimulation in the decerebrate cat using in vivo microdialysis and HPLC analysis techniques. Microinjection of acetylcholine into the PIA elicited muscle atonia and simultaneously produced a significant increase in both glycine and GABA release in both the hypoglossal nucleus and the lumbar ventral horn. Glycine release increased by 74% in the hypoglossal nucleus and 50% in the spinal cord. GABA release increased by 31% in the hypoglossal nucleus and 64% in the spinal cord during atonia induced by cholinergic stimulation of the PIA. As with cholinergic stimulation, 300 msec train electrical stimulation of the PIA elicited a significant increase in glycine release in the hypoglossal nucleus and ventral horn. GABA release was significantly increased in the hypoglossal nucleus but not in the spinal cord during electrical stimulation of the PIA. Glutamate release in the motor nuclei was not significantly altered during atonia induced by electrical or acetylcholine stimulation of the PIA. We suggest that both glycine and GABA play important roles in the regulation of upper airway and postural muscle tone. A combination of decreased monoamine and increased inhibitory amino acid release in motoneuron pools causes PIA-induced atonia and may be involved in atonia linked to rapid eye-movement sleep.

Physiological and anatomical link between Parkinson-like disease and REM sleep behavior disorder.

Parkinson's disease (PD) is a progressive neurodegenerative disease that is caused by a loss of neurons in the ventral midbrain. Parkinsonian patients often experience insomnia, parasomnias, and daytime somnolence. REM sleep behavior disorder (RBD) is characterized by vigorous movements during REM sleep, and may also be caused by neuronal degeneration in the central nervous system (CNS); however, the site of degeneration remains unclear. Both Parkinsonism and RBD become more prevalent with aging, with onset usually occurring in the sixties. Recent findings show that many individuals with RBD eventually develop Parkinsonism. Conversely, it is also true that certain patients diagnosed with Parkinsonism subsequently develop RBD. Postmortem examination reveals that Lewy bodies, Lewy neurites, and alpha-synuclein are found in brainstem nuclei in both Parkinsonism and RBD patients. In this article, we will discuss evidence that Parkinsonism and RBD are physiologically and anatomically linked, based on our animal experiments and other studies on human patients.

New pathways and data on rapid eye movement sleep behaviour disorder in a rat model.

OBJECTIVE: An abnormality in auditory evoked responses localised to the inferior colliculus (IC) has been reported in rapid eye movement (REM) sleep behaviour disorder (RBD) patients. The external cortex of the inferior colliculus (ICX) has been demonstrated not only to be involved in auditory processing, but also to participate in the modulation of motor activity. METHODS: Rats were surgically implanted with electrodes for electroencephalography (EEG) and electromyography (EMG) recording and guide cannulae aimed at the ICX for drug infusions. Drug infusions were conducted after the animals recovered from surgery. Polysomnographic recordings with video were analysed to detect normal and abnormal sleep states. RESULTS: Baclofen, a gamma-aminobutyric acid B (GABAB) receptor agonist, infused into the ICX increased phasic motor activity in slow-wave sleep (SWS) and REM sleep and tonic muscle activity in REM sleep; it also elicited RBD-like activity during the infusion and post-infusion period. In contrast, saclofen, a GABAB receptor antagonist, did not produce significant changes in motor activities in sleep. Baclofen infusions in ICX also significantly increased REM sleep during the post-infusion period, while saclofen infusions did not change the amount of any sleep-waking states. CONCLUSIONS: This study suggests that GABAB receptor mechanisms in the ICX may be implicated in the pathology of RBD.