Exploring cerebral structural and functional abnormalities in a mouse model of post-traumatic headache induced by mild traumatic brain injury.

Mild traumatic brain injury (mTBI)-induced post-traumatic headache (PTH) is a pressing public health concern and leading cause of disability worldwide. Although PTH is often accompanied by neurological disorders, the exact underlying mechanism remains largely unknown. Identifying potential biomarkers may prompt the diagnosis and development of effective treatments for mTBI-induced PTH. In this study, a mouse model of mTBI-induced PTH was established to investigate its effects on cerebral structure and function during short-term recovery. Results indicated that mice with mTBI-induced PTH exhibited balance deficits during the early post-injury stage. Metabolic kinetics revealed that variations in neurotransmitters were most prominent in the cerebellum, temporal lobe/cortex, and hippocampal regions during the early stages of PTH. Additionally, variations in brain functional activities and connectivity were further detected in the early stage of PTH, particularly in the cerebellum and temporal cortex, suggesting that these regions play central roles in the mechanism underlying PTH. Moreover, our results suggested that GABA and glutamate may serve as potential diagnostic or prognostic biomarkers for PTH. Future studies should explore the specific neural circuits involved in the regulation of PTH by the cerebellum and temporal cortex, with these two regions potentially utilized as targets for non-invasive stimulation in future clinical treatment.

Dexamethasone alleviates motion sickness in rats in part by enhancing the endocannabinoid system.

Low-dose dexamethasone has been widely used for the prevention of nausea and vomiting after chemotherapy and surgical procedures and to treat motion sickness due to its minimal adverse effects, but the mechanisms underlying its anti-motion sickness effects are poorly understood. Previous studies have demonstrated that the endocannabinoid system is suppressed by motion sickness but stimulated by dexamethasone. The aim of the present study was to determine whether dexamethasone has an anti-motion sickness effect in rats and to elucidate the mechanism of this action. We used HPLC-MS/MS to measure the plasma concentrations of anandamide and 2-arachidonoylglycerol+1-arachidonoylglycerol, and we employed real-time quantitative PCR (qRT-PCR) and/or Western blot analysis to assay the expression of N-acylphosphatidyl-ethanolamine hydrolyzing phospholipase D, sn-1-selective diacylglycerol lipase, fatty acid hydrolase, monoacylglycerol lipase and endocannabinoid CB1 receptor in the dorsal vagal complex and stomach of rats exposed to a motion sickness protocol. The results showed that dexamethasone lowered the motion sickness index and restored the levels of endogenous cannabinoids and the expression of the endocannabinoid CB1 receptor, which declined after the induction of motion sickness, in the dorsal vagal complex and stomach.

Temporal change in NMDA receptor signaling and GABAA receptor expression in rat caudal vestibular nucleus during motion sickness habituation.

Repeated exposure to a provocative motion stimulus leads to motion sickness habituation indicative of the existence of central processes to counteract the disturbing properties of the imposed motion. In the present study, we attempt to investigate whether NMDA and GABA(A) receptors in rat caudal vestibular nucleus neurons are involved in motion sickness habituation induced by repeated Ferris-wheel like rotation in daily session (2h/d). We showed that defecation response increased and spontaneous locomotion decreased within 4 sessions (sickness phase). They recovered back to the control level after 7 sessions (habituation phase). Western blot analysis found that NMDA receptor signal molecules: calmodulin protein kinase II and cAMP response element-binding protein (CREB) were both activated during sickness phase, while a prolonged CREB activation was also observed during habituation phase. Real-time quantitative PCR revealed an increase in c-fos and a decrease in Arc mRNA level during sickness phase. We also found an increase in GABA(A) receptor α1 subunit (GABA(A) α1) protein level in this stage. These results suggested that altered NMDA receptor signaling and GABA(A) receptor expression level in caudal vestibular nucleus were associated with motion sickness habituation. Furthermore, immunofluorescence and confocal laser scanning microscopy showed that the number of GABA(A) α1 immunolabeled neurons in caudal vestibular nucleus increased while the number of GABA(A) α1/Arc double labeled neurons and the average amount of Arc particle in soma of these neurons decreased during sickness phase. It suggested that GABA(A) receptor level might be negatively regulated by Arc protein in caudal vestibular nucleus neurons.

Acute hyperglycemia is related to gastrointestinal symptoms in motion sickness: an experimental study.

Motion sickness is caused by exposure to unfamiliar motions and typical symptoms of motion sickness include nausea and vomiting. To observe the metabolic and hormonal differences between nausea/vomiting (NAV) subjects and non-nausea/vomiting (NNV) ones, and to understand how the differences in metabolites and hormones affect the tolerance of organism to acceleration, 60 volunteers were exposed to repetitive acceleration using a 6-degree-of-freedom ship motion simulator. Meanwhile, 36 rats were randomly divided into three groups: an acceleration model group (n=14, exposed to acceleration), insulin group (n=14, intraperitoneal injection of insulin 30 min before exposure to acceleration), and control group (n=8). Gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF/MS) was applied to analyze the serum metabolites in human subjects. Serum glucocorticoid, insulin, and glucagon levels were determined by radioimmunoassay in the NAV and NNV subjects as well as in rats, and serum epinephrine level was determined by ELISA. After acceleration exposure, 9 metabolites, including L-histidine, L-ornithine, L-serine, L-tyrosine, pyroglutamic acid, fumaric acid, urea, n-dodecanoic acid and n-tetradecanoic acid, had different changes in the NAV and NNV groups. The serum levels of 4-hydroxy-L-proline, glucose, oleic acid and urea were significantly higher in the NAV group than in the NNV group after exposure; however, only the elevation degree of serum glucose was significantly greater in the NAV group than in the NNV group (P<0.05). Serum cortisol and epinephrine were increased in both groups. Before exposure, insulin level in the NAV group was significantly lower than that in the NNV group (P<0.05). After rotation exposure, rat serum glucose in the insulin group was significantly lower than that in the acceleration model group (P<0.001), and the motion sickness index was significantly lower than that in the acceleration model group (P<0.05). Our study provides the first evidence that stable glucose level can help to relieve gastrointestinal symptoms in motion sickness, and suggests that acute hyperglycemia is related to gastrointestinal symptoms in motion sickness.

[Relationships between constitutional types of traditional Chinese medicine and motion sickness in 145 ocean sailors].

OBJECTIVE: To investigate the relationships between constitutional types of traditional Chinese medicine (TCM) and motion sickness. METHODS: A survey of TCM constitutions in ocean sailors participating in a voyage was performed by using the TCM Constitution Questionnaire developed by Beijing University of Traditional Chinese Medicine, while the survey of motion sickness was operated by Graybiel's diagnostic criteria. The incidences of motion sickness among sailors with different types of constitutions were compared. RESULTS: Prior to the voyage, 50.3% of sailors exhibited a gentleness constitution, 14.5% were of dampness-heat constitution, 10.3% were of qi-stagnation constitution, whereas the percentages of qi-deficiency, yang-deficiency, yin-deficiency, blood-stasis and special diathesis constitutions were 6.2%, 7.6%, 6.2%, 4.1% and 0.7%, respectively. None exhibited a phlegm-dampness constitution. By the end of the 176-day voyage, the percentages of gentleness, dampness-heat, qi-depression, qi-deficiency, yang-deficiency, yin-deficiency, blood-stasis, special diathesis and phlegm-dampness constitutions were 33.8%, 13.8%, 13.1%, 11.0%, 6.9%, 9.7%, 4.1%, 0.7% and 6.9%, respectively. The incidence of motion sickness was 69.7% (101 sailors) during this voyage. The incidences of motion sickness among sailors with different types of constitutions before the voyage showed significant difference (P<0.001). The incidence of motion sickness was higher in the sailors with dampness-heat constitution than in those with gentleness constitution. CONCLUSION: Types of Chinese medical constitution can be related to susceptibility to motion sickness. Furthermore, ocean voyage may have an effect or influence on the type of Chinese medical constitution of sailors involved.

[Antimotion sickness effects of ginsenosides combined with dexamethasone in rats].

OBJECTIVE: To investigate the antimotion sickness effects of ginsenosides combined with dexamethasone in rats. METHODS: Fifty SD rats were randomly divided into 5 groups: normal saline, scopolamine-treated, ginsenosides-treated, dexamethasone-treated and ginsenosides plus dexamethasone-treated groups. There were 10 rats in each group. The rats in each group were fed with corresponding ingredients respectively, and then the rats were exposed to abnormal acceleration for one hour. The motion sickness index, the level of kaolin consumption and the course and time of spontaneous activity were observed. RESULTS: The motion sickness index and the level of kaolin consumption of acceleration-exposed rats in ginsenosides plus dexamethasone-treated group were significantly lower than those in normal saline group. And the course and time of spontaneous activity of acceleration-exposed rats in ginsenosides plus dexamethasone-treated group were significantly higher than those in normal saline group. The level of body weight increment of acceleration-exposed rats in ginsenosides plus dexamethasone-treated group was significantly higher than that in dexamethasone-treated group. CONCLUSION: Ginsenosides combined with dexamethasone can significantly increase tolerance to acceleration of rats, and the drug combination can decrease side effects of methylprednisolone, such as body weight loss.