BACKGROUND & AIMS: Psychological stress in early childhood has been implicated in the pathophysiology of functional dyspepsia but the mechanism is unclear. This study investigates the effect of early psychological stress on the regulation of satiety function in adulthood using an animal model of neonatal maternal separation stress (NMSS). / CONCLUSIONS: Psychological stress in early life leads to aberrant ghrelin profile and dysregulation of feeding behavior in response to acute psychological or physiological stress in adulthood. / METHODS: Sprague-Dawley (SD) rats underwent 3-hour daily maternal separation (MS) from postnatal day 2 to 22 and were weaned. The rats with no MS served as non-handling controls. Three experiments were conducted on these rats on day 60: (1) Water avoidance stress (WAS); (2): Feeding after overnight fasting and (3) Feeding after overnight fasting and WAS. Serial blood samples were collected for acylated ghrelin (AG) assay. In experiments (1) and (2), tissues from the stomach and hypothalamus were harvested additionally for evaluation of ghrelin expression. In experiments (2) and (3), calorie intake was also monitored at regular time intervals. / RESULTS: Experiment (1): MS rats had significantly higher mRNA ghrelin in hypothalamus (1.012 +/- 0.098 vs 0.618 +/- 0.071, P = 0.009) and plasma AG level (141.6 +/- 28.92 pg/mL vs 97.69 +/- 38.21 pg/mL, P = 0.014) in baseline non-stressed conditions. After WAS, MS rats had further increase in plasma AG level and gastric ghrelin expression. Experiment (2): After overnight fasting, the initial calorie intake was significantly higher in MS rats (at 3 mins: 1.303 +/- 0.293 kcal vs 0.319 +/- 0.159 kcal, P= .011; at 8 mins: 2.578 +/- 0.207 kcal vs 1.299 +/- 0.416 kcal, p = 0.019) but it dropped abruptly afterward and no difference in overall calorie intake over 28 minutes was found. The postprandial plasma AG level and gastric mRNA ghrelin were significantly lower in MS rats (95.92 +/- 12.71 pg/mL vs 154.01 +/- 14.53 pg/mL, p = 0.010). Experiment (3): After both fasting and WAS, the MS rats had significantly higher calorie intake in the first hour (17.24 +/- 1.10 kcal vs 11.95 +/- 1.20 kcal, P= 0.006) but it dropped substantially afterward with significantly lower cumulative calorie intake at 3 hours (at 3 hr: 19.44 +/- 1.50 kcal vs 26.49 +/- 2.25 kcal, P = 0.023). The calorie intake in MS rats remained significantly lower than that of controls up to 48 hours (168.1 +/- 4.76 kcal vs 220.8 +/- 8.27 kcal, P< 0.001). / Cheung, Kwan Yui Cynthia. / Adviser: Justin C.Y. Wu. / Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 138-154). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Obstructive sleep apnea (OSA) is a common breathing and sleeping disorder, characterized by repeated episodes of airway obstruction during sleep resulting in intermittent hypoxia (IH). From clinical reports, patients with OSA are associated with behavioral and neuropsychological deficits, including impaired spatial learning memory and cognitive deficiencies. Previous studies proposed that reactive oxygen species (ROS) and apoptosis caused by intermittent hypoxia (IH) contributed to this cognitive deficits. However, the exact mechanism is still poorly understood and not settled. / The endoplasmic reticulum (ER) is a cellular organelle in which all secretory and integral membrane proteins are folded and is also the site where proteins are post-translationally modified in ATP-dependent chaperone-mediated processes. In this study, we hypothesized that ER stress in the hippocampus is initiated in the OSA via elevated levels of ROS. Four groups of adult male mice were used, with two of them exposed to normoxia as control, and the other two exposed to IH treatment, each receiving either vehicle or tauroursodeoxycholic acid (TUDCA), an ER stress inhibitor. Eight-armed radial maze was used to investigate the performance of reference memory during the whole IH/normoxia treatment. After behavior test, long-term potentiation (LTP) was measured to investigate synaptic plasticity in hippocampus. Furthermore, ER stress-associated pro-apoptotic effectors were detected by Western blotting, and ultra-structure of rough ER and the morphology of hippocampal dendritic spines and synapses in the hippocampal CA1 area were observed. / LTP was impaired in the hippocampus after IH treatment, which was rescued by TUDCA. Furthermore, ER stress-associated pro-apoptotic effectors, CHOP and caspase-12, were up-regulated after chronic IH treatment and was abolished by co-infusion of TUDCA. Meanwhile, increased cleaved-caspase-3 after chronic IH treatment was reduced by TUDCA via increased expression of Bcl-2. On the other hand, ultrastructural analysis of rough ER in the hippocampal CA1 revealed IH-induced ER luminal swelling, and was attenuated by TUDCA. In addition, the length of synaptic active zone was significantly reduced after chronic IH treatment and was partially rescued by the application of TUDCA. Golgi staining also showed a decrease in mature dendritic spines in IH group, and reversed by TUDCA. In behavioral analysis, the number of reference memory errors significantly increased after IH treatment and rescued by TUDCA injection. Overall, the data suggest a critical role of ER stress underlying the impairment of long-term synaptic plasticity and neurocognitive deficits in chronic IH. Targeting ER stress could be a potential therapeutic strategy for neural dysfunction in OSA. / On the other hand, neuronal firing, especially robust persistent activity of neuron in hippocampus, is critical role in memory formation. Increased ROS induced by IH has been implicated in long-term potentiation of neural activity. IH could be involved in a variety of K⁺ channels which eventually leads to excitotoxicity by increased Ca2⁺-dependent glutamate release. Although the results were just shown in acute IH treatment, the chronic effect of IH on the firing frequency of hippocampus is still unknown. / Therefore, to investigate the effect of chronic IH treatment on firing activities and local field potentials of hippocampal neurons, implantation of multi-channel micro-wires electrode array into hippocampus of OSA model rat was performed to monitor spontaneous discharge. The results were shown the firing frequency of pyramidal neurons (PNs) was significantly elevated after 8 hours IH in second and third days, on the other hand, interneurons (INs) seem to be more sensitive to intermittent hypoxia since the higher firing frequency was sustained from third day to seventh day after 8 hours IH, however, at the end of 14 days IH treatment, the firing frequencies of PNs and INs are all both dramatically reduced. Meanwhile, the results in this part will enable us to understand the exact change of firing pattern and local field potential during intermittent hypoxia. The percentage of complex burst spikes was decreased after 14 days IH in PNs and the power of theta rhythms was also impaired. It suggests that the disorder of neuronal pattern and the change of local field potential are associated with cognitive impairment in OSA model. After 1 week recovery, the firing frequency of PNs was rescued again, but not for that of INs. We also found that the power of theta rhythms which had an important role in memory formation was weaker after 2 weeks IH treatment, however, the precise mechanism was still unknown. From the effect of intermittent hypoxia on spontaneous discharges and LFP of hippocampal neurons in free moving rat, it may reveal some roles of IH in cognitive impairment via disorder neuronal function in CA1 region. / 阻塞性睡眠呼吸暫停(OSA) 是一種常見的睡眠障礙疾病，這種疾病的主要特徵是在睡眠過程中反復發作的氣道阻塞，從而導致间歇性缺氧(IH)。從臨床報導中發現，OSA患者表現出行為和神經心理缺陷，包括空間學習記憶的受損和認知缺陷。通過之前的研究表明，活性氧(ROS)的增多和細胞凋亡是間歇性缺氧所引起認知功能障礙的主要機制之一，然而，其具體的機制仍不清楚。 / 作為細胞重要的細胞器，內質網是分泌蛋白和膜蛋白折疊組裝的主要場所，同時，由ATP依賴的分子伴侶所介導的蛋白質翻譯後修飾這一過程也主要在內置網中完成。在本課題中，我們假設在OSA模型的海馬組織中，內質網應激的啟動是由於缺氧引起的與活性氧(ROS)的升高。在本課題中，我們使用了四組成年雄性小鼠，其中兩組作為正常對照組，分別接受生理鹽水和牛磺去氧膽酸（一種常用的內質網抑制劑）的腹腔注射，另外兩組接受缺氧處理，同時也分別接受照生理鹽水和牛磺去氧膽酸注射。八臂放射迷宮被用來研究參考記憶的表現。行為學結束之後，長時程增強(LTP)用來測定海馬的突觸可塑性。用免疫印跡的方法檢測內質網應激的相關凋亡蛋白的表達情況，並且觀察海馬CA1區域中，內質網超微結構和海馬樹突棘數目及突觸形態的變化。 / 從實驗結果中，LTP在缺氧後減弱，而TUDCA能夠部分恢復由於缺氧所導致的LTP的降低。除此之外，內質網應激相關的促凋亡蛋白(CHOP和caspase-12)在缺氧組中表達升高，但是在TUDCA組中有所減低，同時，我們還發現，TUDCA也能夠減低缺氧組中cleaved-caspase-3的表達，而這一作用，可能與提高Bcl-2蛋白的表達（一個可標記的抗凋亡蛋白）有關。在間歇性缺氧組的海馬CA1區域中，粗面內質網出現管腔的腫脹，這一超微結構的變化表明在內質網出現官腔中有的許多未折疊蛋白聚集，並通過TUDCA的注射能夠降解未折疊蛋白來緩解這一現象的發生。同時，在IH處理後，突觸超微結構也發生了形態上的變化。突觸活性區的長度在IH處理組中顯著減少，但是在TUDCA組中有一定程度的恢復。高爾基染色顯示，成熟樹突棘（海馬突觸可塑性的結構基礎）的數目在間歇性缺氧組中有所下降，而在TUDCA治療後，成熟樹突棘的數目有所上升。我們發現參考記憶錯誤次數在缺氧後都有明顯的升高，而在注射TUDCA後，參考記憶錯誤次數都有所降低。總之，這些結果證明，內質網應激在間歇性缺氧的所引起的長時程突觸可塑性減弱和神經認知功能的損傷起到關鍵的作用，而抑制內質網應激對OSA中的出現神經功能紊亂起到一定的預防和治療效果。 / 而另一方面，神經元的放電，特別是海馬中神經元穩定持久的放電形式，對記憶的形成起到關鍵的作用。間歇性缺氧所引起的ROS的升高對於長時程增強的神經活動存在一定的關係，因為，通過以往的研究發現，間歇性缺氧可以通過多種鉀離子通道的啟動，最終由於鈣離子依賴的谷氨酸釋放的增多从而導致興奮性毒性的神經遞質的釋放。而這些結果只在急性缺氧模型中發現，慢性的間歇性缺氧對海馬的放電頻率的影響仍是未知之數。 / 因此，為了探討長時程的間歇性缺氧對海馬神經元的放電頻率和局部場電位的影響，多管道微絲電極陣列植入OSA大鼠的海馬中來監控自發放電的影響。結果表明，錐體細胞的放電頻率在第二天和第三天的8小時的間歇性低氧後明顯的升高了。另一方面，我們觀察到中間神經元似乎對間歇性缺氧更敏感，因為，從第三天到第七天缺氧8小時後，神經元的放電頻率都明顯的增高。但是在間歇性缺氧14天后，錐體細胞和中間神經元的放電頻率都所有顯著性的減少。同時，這一部分結果準確表明了海馬神經元的放電模式和局部場電位在間歇性缺氧的模型的是如何變化的。我們發現錐體細胞所具有的複合簇狀放電的比例減少，同時，theta波(與記憶的形成有關)的能量也有所減低。而這種神經元活動和局部的場電位的異常變化可能與OSA模型中出現的總認知功能障礙有關。在恢復一周後，錐體細胞的放電頻率有所增加，基本上可以恢復到缺氧前的狀態，但是中間神經元的頻率卻沒有多大的改變, 但是，其具體機制仍不清楚。從間歇性缺氧對大鼠海馬神經元自發放電和場電位影響的結果，它揭示了間歇性缺氧通過擾亂海馬CA1區域神經元的功能從而導致認知功能損傷。 / Xu, Linhao. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 167-199). / Abstracts also in Chinese. / Title from PDF title page (viewed on 03, October, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

Background and purpose. Recent studies have shown that the children with severe nocturnal enuresis, or bedwetting, often have underlying bladder dysfunction as well as various types of brainstem disorders, including arousal inability, a deficient response to startle sounds, or prepulse inhibition. Since the pontine micturition centre is anatomically very close, even overlapping with the nuclei responsible for sleep arousal, one may speculate that there may be close inter-relationships between abnormal bladder function, brainstem dysfunction and sleep-arousal disturbance. We hypothesize that the brainstem function would be changed in response to alteration of bladder function. Using conventional-fill cystometric study, functional magnetic resonance imaging (fMRI) scanning and immunohistochemistry approaches, we propose to characterize the functional changes in the brainstem in response to altered bladder function (i.e. surgically reduced bladder capacity). / Conclusions. Our results showed that bladder dysfunction elicited by surgical reduction in bladder capacity can induce functional changes in the central nervous system. In response to surgical reduction in bladder capacity, deactivation in the vlPAG was detected suggesting that the vlPAG plays a role in the biofeedback of bladder dysfunction. / Data are expressed as the mean +/-1SD unless otherwise specified. Appropriate statistical tests were used for parametric and non-parametric testing between the groups by using the SPSS computer program. In all comparisons a statistical significance level of 95% (p<0.05) was chosen. / Immunohistochemistry study showed a significant decrease in the reaction of dopaminergic neuron in the correspondent regions, suggesting a dopaminergic dependent change in the vlPAG in response to the bladder dysfunction. / In addition, we will explore the use of electroacupuncture (EA), a traditional Chinese therapy that has been broadly used for treatment of bladder functional disorders, to modulate functional changes in the central nervous system. We hypothesize that functional change in various nuclei in the central nervous system that are responsible for micturition control can also be affected by acupuncture treatment. A further aim of this study was to identify brain areas involved in EA to acupoint Chiliao (BL 32), a special acupoint broadly used for the treatment of bladder disorders. / Materials and methods. The study was divided into four parts. Seventy-five male New Zealand white rabbits (14-16 weeks, mean body weight: 3.0-3.5 kg) were used. / Moreover, in this study, we also found a notable activation in the vlPAG and dlPONS in response to the acupuncture stimulations to acupoint Chiliao (BL 32). The changes were identical to that induced by the bladder distension, suggesting a neuromodulation in central nervous system in response to acupuncture therapy. / Results. Study I: Bladder dysfunction elicited by surgical reduction in bladder capacity. Compared to sham animals, the maximum cystometric capacity in animals with RBC operation was markedly decreased at week 4 (35.3+/-8.2 ml vs. 71.6+/-12.9 ml, p<0.05), and week 8 (46.2+/-12.1ml vs. 82.7+/-20.1 ml, p<0.05) groups respectively; however, the maximum voiding detrusor pressure was significantly increased at week 4 (24.4+/-7.0 vs.16.5+/-7.2 cm water, p<0.05) and week 8 (27.7+/-8.p vs. 16.8+/-7.5 cm water, p<0.05) groups respectively, and their corresponding vesical pressure was also enhanced. Other parameters including maximum flow rate, and bladder emptying efficiency did not change significantly in between the sham and RBC subgroups. / Study I: Establishment of the dysfunctional bladder animal model with small bladder capacity. Forty rabbits underwent either sham operation (n=20) or operation for reduced bladder capacity (RBC) (n=20). The sham-operated and the RBC animals were further divided into two groups, i.e. four, and eight weeks after operation (n=10 in each sham and RBC subgroup). A conventional-fill cystometric study was performed on these animals whilst awake in order to evaluate the functional changes (if any) in response to surgical bladder capacity reduction, compared to sham subgroup. / Study II: Detection of functional changes in the brainstem in response to bladder dysfunction. FMRI scanning was performed at the brainstem region in sham-operated and RBC rabbits (12 in each group) at four weeks postoperatively. Bladder stimulation was provided by warm saline (37°C) infusion through a urethral catheter until bladder distended to 70% of the maximum capacity. Area(s) of brainstem activation were assessed by comparing the fMRI scans performed before and after warm saline infusion. / Study II: Functional changes in brainstem in response to bladder dysfunction. FMRI scanning results demonstrated that for the sham animals, there were two activated regions in the brainstem in response to bladder distention, one in the ventrolateral region of periaqueductal gray (vlPAG, 83.3%, 10/12), and the other in the dorsolateral region of pons (dlPONS, 91.7%, 11/12). In animals with RBC operation, only 25% (3/12) showed vlPAG activation compared to 83.3% (10/12) in sham group (p<0.05); however, 83.3% (10/12) of animals showed similar dlPONS activation compared to 91.7% in sham group (p>0.05). / Study III: Catecholaminergic neurotransmitters changes in the brainstem affected areas in response to bladder dysfunction. Brainstem immunohistochemistry results showed that a large number of dopaminergic neuron scattered throughout the whole vlPAG, rarely appeared in dlPAG (dorsolateral region of periaqueductal gray) (lambda +6.0 to +3.0 mm); and an abundant noradrenergic neurons were also accumulated in a restricted region of dlPONS (lambda +3.0 to 0 mm). Compared with the sham group, the density of TH-positive neurons in the vlPAG was significantly decreased in RBC group (38.38+/-4.71 vs.51.57+/-8.38/field, p<0.05); for the another region of dlPONS, although the density of TH-positive neurons decreased slightly in RBC group compared to sham group, the results showed no statistical difference between groups (106.89 +/- 21.61 vs.120.61 +/- 17.03/field, p>0.05). / Study III: Investigation of the catecholaminergic neurotransmitters changes in brainstem affected areas in response to bladder dysfunction. After fMRI examination, all animals were euthanized, and their brainstems were collected for immunohistochemistry study with tyrosine hydroxylase, dopamine-beta-hydroxylase assays to investigate the changes of catecholaminergic neurotransmitters including dopaminergic, noradrenergic and adrenergic in response to bladder dysfunction elicited by surgical reduction in bladder capacity. / Study IV: Electroacupuncture modulation via acupoint Chiliao (BL 32) on bladder and the brainstem activated sites. FMRI study showed that the two brainstem micturition centers of the vlPAG (72.7%, 8/11) and dlPONS (82.8%, 9/11) can be activated by EA on BL 32, and there were no significant difference compared with stimulation of bladder distention (72.7% vs. 83.3% in vlPAG and 82.8% vs. 91.7% in dlPONS respectively, p>0.05). Urodynamic results showed that, bladder contraction obviously evoked in response to EA on BL 32 (ON-EA state) compared to before EA state (OFF-EA state), displaying a significantly increased detrusor pressure (14.04+/-3.17 vs. 8.19+/-0.69 cm water, p<0.05) and vesical pressure (13.48+/-1.61vs. 7.90+/-0.81 cm water, p<0.05). In addition, dissection of BL 32 showed that the stem of S1 and S2 pass through the region 0.5 cm around the acupuncuture needle. / Study IV: Investigation of electroacupuncture modulation via acupoint Chiliao (BL 32) on bladder and the brainstem activated sites. FMRI scanning and urodynamic evaluation were performed respectively during ON/OFF EA on acupoint Chiliao (BL 32) on sham-operated animals (n=12) at four weeks post-operation. At last, dissection of acupoint BL 32 was performed on seven sham animals. / We also found that surgically induced bladder dysfunction, mainly displaying as reduced bladder capacity and maximum voiding detrusor pressure enhanced, was elicited at four to eight weeks after the surgical reduction in bladder capacity in rabbit. / Xiang Bo. / "August 2006." / Adviser: Chung Kwong Yeung. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1551. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 161-196). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / School code: 1307.

Mild head injury or concussion accounts for as many as 90% of all traumatic brain injuries and can sometime result in long-lasting and disabling post-concussion symptoms (PCS), even in the absence of detectable structural damage to the brain by morphological imaging. To date, the nature of persistent PCS following mild head injury remains poorly understood as objective and scientifically valid diagnostic tools are practically absent. This, in turn, likely accounts for missed diagnoses, prevents accurate assessment of the severity of the injury and creates difficulties for achieving proper patient management. / This dissertation describes 4 functional magnetic resonance imaging (fMRI) studies designed to establish whether there is a pathological basis to persistent PCS following cerebral concussion in male athletes. Study 1 was intended to evaluate the feasibility of using fMRI to detect changes in brain activation following concussion. The results showed that concussed athletes displayed reduced prefrontal activities compared to a healthy control group when performing a working memory task. In Study 2, we examined the relationship between self-reported PCS and the pattern of brain activity measured by fMRI. The severity of self-reported PCS was found to be associated with blood oxygen level dependent (BOLD) activation patterns in the region of interest: the higher the PCS score the lower the BOLD signal. In Study 3, we used serial fMRI approach to investigate brain activation pattern in the course of injury recovery. The results showed that symptom resolution was accompanied by a return to normal BOLD response patterns. Study 4 was designed to investigate the nature of depression, a common PCS, following concussion. Concussed athletes with depression showed less activation in the dorsolateral prefrontal cortex, and attenuated deactivation in the medial prefrontal region, consistent with functional neuroimaging findings in major depression. Again, depression severity correlated with the strength of the fMRI signal in the region of interests. / Taken together, these results demonstrate the value of functional MRI in the evaluation of cerebral concussion, and provide evidence of an underlying pathology in persistent PCS following concussion.

Studies suggest that deficits in central regulation of stretch reflex thresholds (SRT) underlie both spasticity and other disorders of motor control. We investigated intra- and inter-evaluator reliability to quantify spasticity based on tonic SRT (TSRT) and the relationship between TSRT and Modified Ashworth Scale (MAS, clinical assessment of resistance to stretch). Spasticity was evaluated in 20 subjects with chronic stroke-related spasticity in two different days, by three evaluators. Twenty different velocity-dependent dynamic SRT (angle where biceps brachii EMG signal increased for a given velocity of stretch) were recorded. TSRT (excitability of motoneurons at 0°/sec) was then computed. Spasticity was also estimated with MAS. Reliability was moderately good for subjects with moderately high spasticity (intra--evaluator: 0.46 to 0.68, inter--evaluator: 0.53 to 0.68). There was no correlation between TSRT and MAS since they measure different phenomena. TSRT is a promising new measure of spasticity. Further improvements for its quantification are suggested.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

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