Similar age-related changes of free intracellular calcium in lymphocytes and central neurons: Effects of Alzheimer's disease

Summary Several studies suggest that alterations of cytosolic free calcium concentration ([Ca²⁺]_i) are involved in the pathophysiology of aging and Alzheimer's disease (AD). However, only few data are presently available giving detailed information about specific characteristics of age-related or AD-specific changes in cellular Ca²⁺-homeostasis. To allow a comprehensive evaluation of age-related changes in [Ca²⁺]_i, we performed parallel investigations in central mouse brain cells and mouse spleen lymphocytes of young and aged animals and also in human lymphocytes and granulocytes of young and aged donors and additionally of AD patients. In aged animals, basal [Ca²⁺]_i was decreased in brain cells but increased in spleen lymphocytes. No age-related alterations in baseline [Ca²⁺]_i was found in human lymphocytes or granulocytes. However, comparison of activation-induced rise in [Ca²⁺]_i revealed parallel age-related changes in the different cell-types investigated. The increase in [Ca²⁺]_i after depolarization of mouse brain cells with KCl and after stimulation of mouse lymphocytes with phytohaemagglutinin (PHA) was significantly impaired in aged animals. Moreover, activation of human lymphocytes with PHA also revealed a reduced increase in [Ca²⁺]_i in cells of aged donors. In lymphocytes of AD-patients there was a tendency to higher basal [Ca²⁺]_i compared to their aged matched controls, but no specific alterations in [Ca²⁺]_i could be found after stimulation with PHA. Also no age-related or AD-specific changes were found in granulocytes after stimulation with N-fomyl-methionyl-leucyl-phenylalanine (fMLP). Since K⁺- and PHA-induced rise in [Ca²⁺]_i is mainly mediated by Ca²⁺-influx, whereas fMLP-stimulated rise in [Ca²⁺]_i is mainly due to intracellular Ca²⁺-release, our findings might indicate that age-related disturbances of Ca²⁺-homeostasis especially affect mechanisms involved in Ca²⁺-influx. The corresponding age-related alterations in mouse brain cells, mouse spleen lymphocytes and human lymphocytes after cell activation suggest a similar impairment of Ca²⁺-homeostatis in these cells and might justify the speculation that Ca²⁺-homeostasis in the aged human brain is affected in a comparable fashion.     

Effect of hyperosmolarity on agonist-induced increases of intracellular calcium in human platelets

BACKGROUND: Hypertonic solutions are useful for the management of hypovolemic shock but cause impairment in platelet function. This effect would reduce the ischemia/reperfusion damage caused by activated platelets, but it could be the cause of aggravating blood loss in case of uncontrolled hemorrhage. In this paper, it was studied if osmotic shrinkage of platelets affects the changes in intracellular calcium concentration ([Ca(2+)](i)) induced by thrombin or adenosine 5' diphosphate (ADP). Furthermore, it was investigated if hypertonic solutions change the mobilization from intracellular stores or the calcium entry. Previous reports from our laboratory described that the capacitative calcium entry is increased by alkalization and also that hyperosmolarity has an alkalinizing effect on human platelets so it was hypothesized that hyperosmolarity would be able to modify agonist-induced calcium entry. MATERIAL AND METHODS: To study the response to agonists, platelets loaded with 2'7'-bis(carboxyethyl)-5(6)-carboxy-fluorescein (FURA 2) were incubated at 37 degrees C for 500 s in a N-2-hidroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES)-buffered solution with 1 mM CaCl(2). The osmolarity of the solution was elevated by the addition of 200 mM mannitol or sucrose and after the stimulation with 0.1 IU/ml of thrombin or 100 microM ADP, [Ca(2+)](i) increases were compared. Platelets incubated in zero calcium/EGTA were stimulated with these agonists or with 0.1 microM thapsigargin to separately study the effect of hyperosmolarity on both calcium mobilization from intracellular stores and extracellular calcium entry. RESULTS: It was found that hypertonic solutions decrease the [Ca(2+)](i) peak induced by the agonist: The increase of [Ca(2+)](i) in the presence of 200 mM mannitol produced by 100 microM ADP was 62+/-6% and response to 0.1 IU/ml thrombin was 74+/-7% of the increase in isotonic control solution. In the case of ADP, both mobilization and calcium entry were reduced to 66+/-3% and 65+/-6% of isotonic control, respectively. In the case of thrombin, only the mobilization showed a significant change (79+/-2% of parallel control). In platelets depleted by thapsigargin, the capacitative calcium entry was increased in hypertonic mannitol (174+/-25% of the isotonic control). Similar results were obtained with hypertonic sucrose solutions. CONCLUSIONS: In spite of the stimulatory effect of hyperosmolarity on capacitative calcium entry observed in platelets in which the calcium stores were depleted with thapsigargin, the full response of intracellular calcium to the agonists tested (ADP and thrombin) was reduced by an increase in osmolarity. The decreased Ca(2+) mobilization observed may play a role in the reduction in hypertonic media of accompanying platelets responses such as aggregation or shape change.     

Cytosolic free [Ca2+] in single T-lymphocytes from depressed patients and healthy controls

Summary Human lymphocytes are widely used as peripheral models for central neurones. Alterations in immune function have been reported in depressed patients, e.g. mitogen-induced proliferation is impaired during depression. One possible causative mechanism could be altered [Ca²⁺]_i regulation. Phytohaemagglutinin (PHA)-induced rise of [Ca²⁺]_i has been found to be diminished in lymphocyte suspensions from depressed patients (Ecker et al., this issue). We measured PHA-induced rise of [Ca²⁺]_i in single Fura-2 AM-loaded T11⁺ lymphocytes of patients with major depression and controls to further analyse [Ca²⁺]_i regulation in depression.The [Ca²⁺]_i of resting lymphocytes was 57±2 nmol/l (mean ± SEM). There was no difference in resting [Ca²⁺]_i of resting lymphocytes of patients and controls. PHA evoked an increase of [Ca²⁺]_i an 7 out of 14 cells from control subjects up to 400–500 nmol/l. In contrast, only 4 out of 13 cells from depressed patients showed an increase of [Ca²⁺]_i up to 200 nmol/l. In a small fraction of cells from both groups the [Ca²⁺]_i signal is oscillating.Our preliminary data confirm alteration of [Ca²⁺]_i regulation in lymphocytes of depressed patients.     

Carbon monoxide inhibits capacitative calcium entry in human platelets

The cytosolic calcium concentration in human platelets is elevated by several agonists via receptor-operated mechanisms involving both Ca(2+) release from intracellular stores and Ca(2+) entry. In order to get a mechanistic insight in the effect of carbon monoxide (CO)-containing solutions, this work examines the changes in [Ca(2+)](i) induced by 100 microM adenosine 5'diphosphate (ADP), 0.1 IU/ ml thrombin, 0.5 microM thapsigargin or 0.5 microM ionomycin in human platelets. In a saline solution bubbled with CO, the increase of [Ca(2+)](i) produced by thrombin was 72+/-4% of the response evoked in the control solution (CO-free) and the response elicited by ADP was 64+/-8% of the control. When a mixture of 5% CO/95% N(2) was used, the responses were 70+/-7% of control for thrombin and 79+/-6% of control for ADP. The mobilization of stored calcium produced by thrombin in a calcium-free solution and the increase of [Ca(2+)](i) produced by subsequent introduction of 1 mM extracellular calcium were both reduced in the presence of CO (82+/-6% and 78+/-5% of control, respectively). Similar reductions in the presence of CO were found when platelets were stimulated by ADP (62+/-8% and 60+/-8% for mobilization in calcium-free media and calcium entry, respectively). Although the change in [Ca(2+)](i) induced by ionomycin in the presence of extracellular calcium was almost the same in the absence or presence of CO (97+/-5% of control), the entry induced by depletion of reservoirs with the ionophore undergoes a significant reduction in a solution bubbled with CO (84+/-5% of control). In agreement with the concept that CO has a direct inhibitory effect on capacitative calcium entry, a reduction to 47+/-6% of control was obtained when sarco/endoplasmic reticulum ATPase was blocked by thapsigargin. Diverse mechanisms could be responsible for the effect of CO on calcium entry. On the one hand, a decrease in the calcium release from intracellular stores or an increase in the rate of its back-sequestration could occur, being the reduction of capacitative calcium entry an indirect consequence of a diminished emptying of reservoirs. On the other hand, CO could have a direct inhibitory effect on the pathway that produces the calcium entry. The decrease in the Ca(2+) signal in the presence of CO evoked by receptor-independent emptying of reservoirs indicates that a direct effect of CO on capacitative calcium entry participates in the antiaggregatory properties of CO. The proposal that CO inhibits directly store-operated calcium influx widens the potential mechanisms by which heme oxygenase regulates cell functions.     

Halothane-induced intracellular calcium release in cholinergic cells

Low concentrations of halothane and isoflurane can release acetylcholine in an extracellular Ca²⁺-independent manner. In the present study, a cholinergic cell line (SN56) was used to examine whether release of calcium from intracellular stores occurs in the presence of halothane. Changes in intracellular calcium concentration ([Ca²⁺]_i) were measured using fluo-3, a fluorescent calcium-sensitive dye and laser scanning confocal microscopy. Halothane, at sub-anesthetic concentrations (14, 28, 40 and 56 μM), increased [Ca²⁺]_i in SN56 cells. This effect remained even when the cells were perfused with medium lacking extracellular calcium, suggesting the involvement of intracellular Ca²⁺ sources. SN56 cells responded to ryanodine by increasing [Ca²⁺]_i and this effect was blocked by dantrolene, an inhibitor of Ca²⁺-release from ryanodine-sensitive stores. The effect of halothane was attenuated after the increase in [Ca²⁺]_i induced by ryanodine and it was suppressed by dantrolene, suggesting the participation of ryanodine-sensitive stores. Using cyclopiazonic acid, a Ca²⁺-ATPase inhibitor, we investigated whether the depletion of intracellular Ca²⁺ stores interfered with the effect of halothane. Cyclopiazonic acid significantly decreased the increase in [Ca²⁺]_i induced by the volatile anesthetic. It is suggested that sub-anesthetic concentrations of halothane may increase [Ca²⁺]_i by releasing Ca²⁺ from intracellular stores in cholinergic cells.     

Intracellular calcium signalling in peripheral cells of patients with bipolar affective disorder

Summary Consistent with previous studies, elevated free intracellular calcium ion concentrations ([Ca²⁺]_i) were found in blood platelets and lymphocytes of patients with mania and bipolar depression. Incubation with an ultrafiltrate of plasma from patients with bipolar illness had no effect on intracellular calcium ion concentration in platelets from normal subjects, suggesting that elevated [Ca²⁺]_i is not due to a circulating factor. As was true in an earlier study of the effect of lithium on platelets, incubation with therapeutic levels of carbamazepine lowered [Ca²⁺]_i in lymhocytes from affectively ill patients but not controls. Increased [Ca²⁺]_i in peripheral cells may reflect a diffuse change in cellular homeostasis and may contribute to mixtures as well as rapid alternations of activity of affective, behavioral and physiologic systems in bipolar illness. Correction of the abnormality may at least be a marker of a relevant therapeutic action if it is not the action itself.     

Serotonin-induced decrease of intracellular Ca<Superscript>2+</Superscript> release in platelets of bulimic patients normalizes during treatment

Numerous symptoms related to eating disorders have been shown to be influenced by serotonergic (5-HT) functioning, with the 5-HT_2A receptor subtype being one of the most relevant involved in the pathophysiology of bulimia nervosa (BN). In line with this, Ca²⁺ mobilization as mediated by 5-HT₂ receptors in platelets was shown to serve as a peripheral model for central nervous 5-HT functioning. Here, the 5-HT-induced intracellular Ca²⁺ mobilization in platelets was measured in 13 female normal weight bulimic patients (14–18 years) upon admission and at the end of inpatient treatment. Findings were compared to 21 age-matched healthy female adolescents. 5-HT-induced Ca²⁺ release was significantly decreased in bulimic patients upon admission and normalized during inpatient treatment. Antidepressive medication caused a significant improvement. The data provide further evidence that altered 5-HT₂ receptor functioning is involved in the pathophysiological underpinnings in BN.     

Age-of-onset and genetic transmission in affective disorders

Age-of-onset data were gathered on first-degree relatives of 252 probands with bipolar and unipolar affective disorders. Early onset probands (younger than 40 at onset) had more early onset relatives and a greater risk for affective disorder among their relatives than late onset probands (40 or older). This indicates that age-of-onset is a familial factor correlated with the liability to affective illness. Multiple threshold models of inheritance were applied to the data using age-of-onset as a liability-threshold determinant. The hypothesis of autosomal single-major locus was ruled out. Multi-factorial-polygenic inheritance provided a better fit to the data. The data suggest that early and late onset affective disorders can be placed at different thresholds on a genetic environmental continuum and that the early onset form is more deviant genetically than the late onset type. The implications for genetic research in affective disorder are discussed.     

Inhibitory effect of CCK-8 and ceruletide on glutamate-induced rises in intracellular free calcium concentrations in rat neuron cultures

To study the mechanism by which cholecystokinin octapeptide (CCK-8) and its potent analogue, ceruletide, prevent glutamate-induced neuronal cell death in rat neuron cultures, we examined the effect of both peptides on glutamate-induced increases in the intracellular free calcium concentrations ([Ca2+]i), which are known to be a crucial trigger of the neurodegeneration induced by glutamate. CCK-8 itself did not alter [Ca2+]i in rat neuron cultures. Glutamate increased [Ca2+]i in neuron cultures rapidly and markedly. CCK-8 and ceruletide significantly suppressed the increases in [Ca2+]i induced by glutamate. The maximum inhibitory effects of CCK-8 and ceruletide at 10(-6) M reached 43 and 46% of the response to glutamate, respectively. Gastrin-I and CCK-4 also significantly attenuated the increases in [Ca2+]i induced by glutamate. The inhibitory effect of CCK-8 was completely blocked by the selective antagonist for CCK-B receptors, (+)L-365,260, but not by (-)L-364,718, which is a selective antagonist for CCK-A receptors. CCK-8 significantly suppressed [Ca2+]i response to kainate and high concentrations of extracellular K+, but not to N-methyl-D-aspartate. With cultured astrocytes, CCK-8 did not inhibit the increment of [Ca2+]i induced by glutamate. These findings clearly demonstrated that CCK-8 and ceruletide inhibit glutamate-induced increases in [Ca2+]i in neuron cultures through CCK-B receptors, suggesting that CCK-8 may participate in the central actions of glutamate.     

The influence of calcium transients on intracellular pH in cortical neurons in primary culture

The objective of this study was to assess the influence of Ca²⁺ influx on intracellular pH (pH_i) of neocortical neurons in primary culture. Neurons were exposed to glutamate (100–500 μM) or KCl (50 mM), and pH_i was recorded with microspectroflurometric techniques. Additional experiments were carried out in which calcium influx was triggered by ionomycin (2 μM) or the calcium ionophore 4-Br-A23187 (2 μM). Glutamate exposure either caused no, or only a small decrease in pH_i (ΔpH ≈ 0.06 units). When a decrease was observed, a rebound rise in pH_i above control was observed upon termination of glutamate exposure. In about 20% of the cells, the acidification was more pronounced (ΔpH ≈ 0.20 units), but all these cells had high control pH_i values, and showed gradual acidification. Exposure of cells to 50 mM KCl consistently increased pH_i. Since this increase was similar in the presence and nominal absence of HCO₃⁻, it probably did not reflect influx of HCO₃⁻ via a Na⁺-HCO₃⁻ symporter. Furthermore, since it occurred in the absence of external Ca²⁺ (or a measurable rise in Ca_i²⁺) it seemed independent of Ca²⁺ influx. It is tentatively concluded that the rise in pH_i was due to reduced passive influx of H⁺ along the electrochemical gradient, which is reduced by depolarization. In Ca²⁺-containing solutions, depolarization led to a rebound increase in pH_i above control. This, and the rebound found after glutamate transients, may reflect Ca²⁺-triggered phosphorylation and upregulation of the Na⁺/H⁺ antiporter which extrudes H⁺ from the cell. Ionomycin and 4-Br-A23187 gave rise to a large rise in Ca_i²⁺ and to alkalinization of the cell (ΔpH ≈ 0.5). Since amiloride or removal of Na⁺ from the external solution did not alter the rise in pH_i, it was probably not due to accelerated H⁺ extrusion. However, removal of Ca²⁺ from extracellular fluid prevented the rise, suggesting that it was secondary to Ca²⁺/2H⁺ exchange across plasma membranes.     

海风藤对犬脑干缺血后细胞内钙含量和超微病理改变影响的研究

本研究选用犬基底动脉全段结扎脑干缺血模型，观察了海风藤对犬脑干缺血后脑组织细胞内钙含量和超微病理改变的影响，我们发现海风藤０．３ｇ／ｋｇ可明显降低犬脑干局灶性缺血后细胞内钙含量，改善缺血后神经元超微结构的损害，提示海风藤对脑干缺血具有保护作用。     

Increased platelet intracellular calcium concentration in patients with bipolar affective disorders

Using the fluorescent indicator Fura 2, we measured the free intracellular calcium ion concentration in blood platelets of patients with untreated mania, bipolar depression, and unipolar depression; patients who had recovered from bipolar depression or mania; and age- and sex-matched controls. The baseline intracellular calcium ion concentration was significantly increased in platelets from patients with mania compared with controls. The free intracellular calcium ion concentration after stimulation with platelet-activating factor and thrombin was significantly higher in platelets of manic and bipolar depressed patients than in all other groups. The degree to which intracellular calcium ion concentration increased over baseline after stimulation was significantly lower in unipolar than in bipolar patients. These findings suggest that platelets of manic and depressed bipolar patients have a similar enhancement of intracellular calcium ion activity that is distinctly different from the decreased ability of platelets of unipolar patients to mobilize intracellular calcium in response to stimulation.     

情感性障碍的预后与性别差异

目的探索不同性别情感性障碍的预后关系。方法对符合ＣＣＭＤ—２情感性障碍诊断标准的男性４５例，女性７２例患者进行出院后第７、８年后的随访研究。结果发现复发率、复发时间、再住院率、再住院时间、再住院次数、慢性化、死亡、ＧＡＳ评分、ＳＤＳＳ总分、结局状况等无性别差异。结论仅提示女性有更高的复发次数及自杀率外，其他方面无性别差异     

情感性精神障碍不同亚型的预后比较

目的探讨情感性精神障碍亚型与预后的关系。方法对１１７例情感性精神障碍患者进行出院８年后的随访调查，并将其分为单相抑郁症（２５例）、双相非混合／快速循环型（６６例）和双相混合／快速循环型（２６例）３组。结果双相混合／快速循环型的复发、自杀和慢性化的发生率均高于其它两组，大体评定量表评分低于其它两组，社会功能缺陷筛选量表总分高于其它两组。结局评定显示，双相混合／快速循环型最差，双相非混合／快速循环型一般，单相抑郁症最好。结论提示双相混合／快速循环型是情感性精神障碍预后较差的临床类型     

情感性精神障碍的气候影响-中国7地区流行病学资料再分析

目的：探讨气候因素与情感性精神障碍患病率间的关系。方法：回顾1993年中国7地区情感性精神障碍流行病学调查资料，分析其终生患病率与年平均气温、年平均日照时数、年平均降水量、纬度及所处的气候区之间关系。结果：以大庆、吉林、沈阳、北京4个地区为代表的温带地区的情感性精神障碍终生患病率及标化患病率均显著低于南京、上海、长沙3个地区为代表的亚热带地区；情感性精神障碍终生患病率及标化患病率与气候各因素问均无显著相关性。结论：气候因素会对情感性精神障碍的患病产生影响，不同气候地区的情感性精神障碍患病率间存在差异。     

晚发型情感性障碍的遗传方式探讨

目的探讨晚发型情感性障碍的遗传方式。方法对６７例３０岁以后首次发病的情感性障碍家系采用分离分析和多基因阈值理论进行遗传方式的探讨。结果加权平均遗传率为５３０％±１１６％,预期发病率为１４６％,与实际发病率１２７％比较无显著性差异。结论提示晚发型情感性障碍的遗传方式为多基因遗传方式。     

Relative humidity and affective disorders

INTRODUCTION: Looking at specific weather parameters over a period of time prior to hospital admissions may provide evidence of a link between weather conditions and some psychiatric conditions such as affective disorders. We examined the association between relative humidity (as well as other parameters such as sunshine hours, diurnal variations in temperature and rainfall) and psychiatric admissions in North Cheshire, UK. METHOD: The daily numbers of all psychiatric admissions in North Cheshire in a specified year were analysed in relation to meteorological data, which were measured at the meteorological office nearest to the study population. RESULTS: We found a significant inverse relationship (with time lag) between admissions for affective disorders and relative humidity in the week preceding admission. Changes in diurnal variations in temperature, sunshine hours and rainfall a few days before admission were also noted, but the findings did not achieve statistical significance for any diagnostic category. CONCLUSION: The effect of weather parameters on mental health is likely to be influenced by other seasonal factors, as well as non-climatic factors, predominantly social, that may have contributed to the study findings. Psychiatric admissions reflect the behaviour of patients, carers and medical professionals. The complexity of this behaviour and the day-of-the-week periodicity may have confounded variations associated with the weather. (Int J Psych Clin Pract 2002; 6: 147-153 )     

早发型情感性精神障碍的遗传方式探讨

探讨早发型情感性障碍的遗传方式。方法对１１３例３０岁以前首次发病的情感性精神障碍的家系，采用分离分析及多基因阈值理论进行遗传方式的探讨。结果遗传方式符合常染色体显性遗传及多基因遗传方式。结论提示早发型情感性精神障碍的遗传方式存在异质性     

Epidemiology of affective disorders in Florence. Preliminary results

A structured interview designed to detect affective disorders according to operational diagnostic criteria was administered to a representative sample of 639 people living in Florence. The 1 year prevalence percent was 1.7 for bipolar disorder, 0.31 for atypical bipolar disorder, 5.2 for major depression, 1.4 for cyclothymic disorder, 2.3 for dysthymic disorder (all diagnosed according to DSM III criteria) and 4.5 for minor depression (RDC criteria). The corresponding figures relative to the point prevalence were: 0.6, 0.16, 3.8, 0.47, 1.2, 0.31. The use of care services on the part of affective cases (none, GP, public psychiatric facilities, private psychiatrist, hospital) was also recorded.     

Muscarinic receptors modulate intracellular calcium level in chick sensory neurons

In the present work we have studied the variation of intracellular calcium levels induced by muscarinic agonists in chick dorsal root ganglia neurons. Muscarinic agonists such as muscarine and oxotremorine cause an increase of intracellular calcium levels in fura-2AM-loaded DRG neurons of E18 chick embryos. This increase was abolished following treatment with 1 microM atropine but not by 1 microM mecamylamine, indicating that the observed intracellular calcium increase, was dependent on muscarinic receptor activation. Stimulation in absence of external calcium or pre-incubation of the DRG cultures with thapsigargin or Mn(2+) demonstrated that [Ca(2+)](i) increase is mainly due to its release from intracellular stores. The use of selective antagonists of muscarinic receptor subtypes also indicated that M(1) and to a lesser extent M(3) receptor subtypes are responsible for the observed intracellular calcium mobilization. Finally pre-treatment of DRG cultures with pertussis toxin showed that the variation of [Ca(2+)](i) levels was dependent on PTX-insensitive G-protein. Moreover muscarinic agonists induce in DRG also the increase of IPs level, suggesting that the variations of intracellular calcium levels may be due at least in part to the activation of the phosphoinositide transduction pathway. In conclusion the reported observations demonstrate the activity of muscarinic receptors in sensory neurons, suggesting a functional role for acetylcholine in sensory transduction.