Lithium and valproic acid treatments reduce PKC activation and receptor-G protein coupling in platelets of bipolar manic patients

Dysregulated protein kinase C (PKC) distribution and activation, and abnormal receptor-G protein coupling, have been implicated in the pathophysiology of bipolar affective disorder (BD). The therapeutic effectiveness of lithium has also been correlated with its ability to reduce PKC activation and G protein-mediated signaling. We examine the cellular distribution and activation of PKC and receptor-G protein coupling in blood platelets from normal controls, patients with BD mania or schizophrenia during treatment-free state, and after lithium or valproic acid administration. PKC activity was measured under basal and 50 nM phorbol 12-myristate, 13-acetate (PMA), 1 microM serotonin or 0.5 U/ml thrombin-stimulated conditions. The coupling of G proteins to serotonin or thrombin receptors were assessed by serotonin or thrombin-mediated [35S]GTPgammaS binding to membrane Galpha proteins. The results demonstrate that membrane-associated PKC activity and stimulus-induced PKC translocation are increased in BD manic, whereas stimulus-elicited PKC translocation is attenuated in schizophrenic patients. Lithium and valproic acid treatments attenuated the stimulus-induced PKC translocations to a similar degree and decreased PKC activity in both cytosolic and membranous fractions after two weeks of drug administration. An increase in 5-HT or thrombin stimulated [35S]GTPgammaS binding to Galpha proteins was detected in BD manic but not in schizophrenic patients although basal [35S]GTPgammaS binding was not different across the diagnostic groups. Lithium and valproic acid treatments similarly reduced receptor-G protein coupling with comparable time courses. Thus, increased membrane-associated PKC, cytosol to membrane PKC translocation and receptor-G protein coupling in platelets of BD manic patients were alleviated by lithium or valproic acid treatments.     

Increased association of brain protein kinase C with the receptor for activated C kinase-1 (RACK1) in bipolar affective disorder.

BACKGROUND: Membrane protein kinase C (PKC) activity is increased in frontal cortex of subjects with bipolar affective disorder, and lithium was demonstrated to inhibit PKC translocation to membranes. Protein kinase C is anchored to the membrane via the receptor for activated C kinase-1 (RACK1), suggesting that interactions between these proteins may be altered in bipolar disease. METHODS: The levels of RACK1 coimmunoprecipitating with PKC isozymes were compared in homogenates of frontal cortex slices from postmortem bipolar subjects and matched control subjects. RESULTS: Receptor for activated C kinase-1 was located exclusively in membranes and, in control brains, the levels of RACK1 that coimmunoprecipitated with most PKC isozymes were increased by stimulation with the PKC activator, phorbol 12-myristate, 13-acetate (PMA). The association of RACK1 with membrane gammaPKC and zetaPKC was increased under basal conditions in bipolar relative to control brains. Stimulation with PMA increased the amount of RACK1 that coimmunoprecipitated with the alpha, beta, gamma, delta, and varepsilonPKC isozymes, but not zetaPKC, in bipolar tissues over that elicited in control tissues. CONCLUSIONS: These data suggest that the increased association of RACK1 with PKC isozymes may be responsible for the increases in membrane PKC and in its activation that were previously observed in frontal cortex of bipolar affective disorder brains.     

Decreased protein kinase C (PKC) in platelets of pediatric bipolar patients: effect of treatment with mood stabilizing drugs

Pediatric bipolar disorder (PBD) is a major public health concern, however, its neurobiology is poorly understood. We, therefore, studied the role of protein kinase C (PKC) in the pathophysiology of bipolar illness. We determined PKC activity and immunolabeling of various PKC isozymes (i.e., PKC alpha, PKC betaI, PKC betaII, and PKC delta) in the cytosol and membrane fractions of platelets obtained from PBD patients and normal control subjects. PKC activity and PKC isozymes were also determined after 8 weeks of pharmacotherapy of PBD patients (n=16) with mood stabilizers. PKC activity and the protein expression of PKC betaI and betaII, but not PKC alpha or PKC delta, were significantly decreased in both membrane as well as cytosol fractions of platelets obtained from medication-free PBD patients compared with normal control subjects. Eight weeks of pharmacotherapy resulted in significantly increased PKC activity but no significant changes in any of the PKC isozymes in PBD patients. These results indicate that decreases of specific PKC isozymes and decreased PKC activity may be associated with the pathophysiology of PBD and that pharmacotherapy with mood stabilizing drugs results in an increase and normalization of PKC activity along with improvement in clinical symptoms.     

Abnormalities in protein kinase C signaling and the pathophysiology of bipolar disorder

Protein kinase C (PKC) is a group of calcium and phospholipid-dependent enzymes, which plays a pivotal role in cell signaling systems. Recently accumulated evidence indicates that alterations in PKC activity play a significant role in the pathophysiology of bipolar disorder. A number of laboratories investigated the effect of mood stabilizers on the regulation of PKC activity in bipolar patients, in animals, and in cultured cells. Following chronic lithium treatment, PKC activation was significantly reduced in rat brains, as measured by the translocation of cytoplasmic PKC to the membrane compartment, or by quantitative binding of the PKC ligand, PDBu. The effect of the therapeutic concentration of lithium in attenuating PKC-dependent intracellular parameters was also demonstrated in cultured cells. More importantly, alterations in platelet PKC was shown in bipolar patients during the manic state of the illness. In comparison to patients with major depressive disorder, schizophrenia, or healthy controls, PKC activity was significantly increased in manic patients, suggesting that changes in PKC may be an illness-specific marker. Interestingly, enhanced PKC activity during mania was suppressed following mood-stabilizer treatment as manic symptoms improved. In parallel to the findings in platelets, postmortem studies demonstrate that membrane-associated PKC and stimulation-induced translocation of cytosolic enzyme to the membrane were also increased in frontal cortex of bipolar patients. Other studies suggest alterations in other signal transduction mechanisms in bipolar disorder. These include alterations in G protein activation, phosphatidylinositol (PI) signaling, cyclic AMP formation, and intracellular calcium homeostasis. The alterations of PKC activity in bipolar disorder may be related to changes in these other intracellular signaling mechanisms. Alternatively, the changes of PKC activity may be the core pathology of the illness. More studies are required to further characterize the association of PKC changes with bipolar disorder, using a proper neuronal model.     

Different effect of desipramine on protein kinase C in platelets between bipolar and major depressive disorders

Protein kinase C (PKC) activity was investigated in platelets from affective disorder subjects and healthy volunteers. The PKC activity of platelets incubated with desipramine was determined in vitro. The PKC activity of the major depressive disorder subjects and healthy volunteers was inhibited by desipramine, whereas that of the bipolar disorder subjects showed both inhibition and activation. In addition, the base PKC activity incubation with antidepressants of the major depressive disorder patients was significantly higher than of the bipolar disorder patients. These preliminary results suggest that the function of PKC may, at least in part, be associated with the mechanism of affective disorder.     

The preliminary study of monoamine oxidase activity in platelets in patients with schizophrenia and affective disorder]

This paper has studied the MAO activity in platelets of 52 schizophrenic patients and 44 affective disorder patients. The results indicate that the MAO activity in platelets of schizophrenic patients is lower than that of normal group, especially the chronic schizophrenic patients. It's no difference between the acute schizophrenic patients and normal group. The MAO activity in platelets of bipolar affective disorder patients is much lower than that of normal group. Platelet MAO activity in male bipolar affective disorder is lower than that of female's, that of bipolar-manic effective disorder is lower than that of bipolar-depressive effective disorder. The MAO activity in platelets of unipolar depression is even lower than that of normal group.     

Outcome of schizoaffective disorder at two long-term follow-ups: comparisons with outcome of schizophrenia and affective disorders

OBJECTIVE: This research assessed whether the outcome of schizoaffective disorder is more similar to that of schizophrenia or that of affective disorders. METHOD: The authors conducted a prospective follow-up study of 101 schizoaffective, schizophrenic, bipolar manic, and depressed patients assessed at three times: during hospitalization and 2 and 4-5 years later. The follow-up test battery involved detailed assessment of social functioning, work performance, symptoms, posthospital treatment, and rehospitalization. RESULTS: Outcome for schizoaffective patients 4-5 years after hospitalization differed significantly from that for patients with unipolar depression. However, the differences between schizoaffective and bipolar manic patients were more equivocal. Unlike the patients with bipolar disorder, only a limited number of patients with schizoaffective disorder showed complete recovery in all areas throughout the year preceding the 2-year follow-up and the year preceding the 4- to 5-year follow-up. The differences in outcome between schizoaffective and schizophrenic patients were also mixed. These two groups showed some similarities in outcome, but there were fewer schizoaffective than schizophrenic patients with uniformly poor outcome in all areas. CONCLUSIONS: Overall, schizoaffective patients showed some similarities to both schizophrenic and bipolar manic patients. Schizoaffective patients had somewhat better overall posthospital functioning than patients with schizophrenia, somewhat poorer functioning than bipolar manic patients, and significantly poorer functioning than patients with unipolar depression. The data suggest that when mood-incongruent, schizophrenic-like psychotic symptoms are present in the acute phase, they predict considerable difficulty in outcome, even when affective syndromes are also present, as in schizoaffective disorder. It is likely that schizoaffective disorder is not just a simple variety of affective disorder.     

Calcium function in affective disorders and healthy controls

Calcium metabolism has been reported to be disturbed in some forms of affective disorder. We studied concurrently a battery of calcium measures in 29 unipolar, 14 bipolar depressed, 11 manic, and 10 healthy control subjects. In addition to measures of extracellular calcium, we studied intracellular calcium concentration in platelets and measures that reflect cellular capability to maintain a low intracellular Ca++ concentration in red blood cells (RBCs) and platelets. Plasma calcium was lower in unipolar and manic patients than in control subjects. Platelet calcium concentration was lower in unipolar than bipolar depressed patients. RBC Ca++ adenosine triphosphatase (ATPase) was lower in unipolar and control subjects than in bipolar depressed and manic patients. Platelet Ca++ ATPase and Ca++ uptake were inversely correlated with severity of illness in unipolar patients. In bipolar depressed patients, RBC Ca++ ATPase and platelet Ca++ uptake were inversely correlated with severity. In addition to indicating abnormalities in calcium activity in affective disorders, the data suggest that unipolar and bipolar patients differ in several measures and may have different pathophysiological disturbances in calcium metabolism.     

Concurrent measures of protein kinase C and phosphoinositides in lithium-treated bipolar patients and healthy individuals: a preliminary study

This study examined the hypothesis that lithium inhibits the PI signaling pathway in humans during in vivo administration by concurrently measuring PKC isozymes and platelet membrane phosphoinositides in lithium-treated patients and healthy individuals. The platelet membrane and cytosolic levels of PKC alpha, beta I, beta II, delta, and epsilon were measured using Western blotting. The relative platelet membrane contents of phosphatidylinositol (PI), phosphatidylinositol-4-phosphate (PIP), and phosphatidylinositol-4,5-bisphosphate (PIP(2)) were measured with two-dimensional thin-layer chromatography. Nine euthymic lithium-treated bipolar subjects and 11 healthy control subjects were studied. Compared to control subjects, lithium-treated bipolar patients had significantly lower levels of cytosolic PKC alpha isozyme (t-test=-3.24, d.f.=17, P=0.01) and PIP(2) platelet membrane levels (t-test=-2.51, d.f.=18, P=0.02), and a trend toward reduced levels of cytosolic PKC beta II isozyme (t=-2.17, d.f.=17, P=0.05). There was no significant correlation between PIP(2) and any of the PKC isozymes. These preliminary findings suggest that chronic lithium treatment may decrease the levels of both cytosolic PKC alpha isozyme and membrane PIP(2) in platelets of bipolar disorder patients.     

Elevated basal and thapsigargin-stimulated intracellular calcium of platelets and lymphocytes from bipolar affective disorder patients measured by a fluorometric microassay.

BACKGROUND: A number of investigators have reported finding elevated basal and stimulated intracellular calcium levels in the platelets or lymphocytes of bipolar disorder patients. METHODS: Intracellular calcium was measured by a micro fura-2 fluorometric method in the platelets and lymphocytes of 30 affective disorder patients and 14 control subjects. RESULTS: We observed significantly elevated basal calcium concentrations in bipolar patient platelets and lymphocytes compared to control subjects. Bipolar patient platelet calcium responses to thrombin, serotonin, and thapsigargin were also significantly greater than control subjects. The peak calcium levels of lymphocytes of bipolar patients were greater than control subjects only when stimulated by thapsigargin. There were significant differences between bipolar and unipolar patients in basal and thapsigargin-stimulated calcium measures but not between bipolar I and bipolar II patients. Unmedicated versus medicated calcium measures were not significantly different. We also found little correlation between calcium measures and the severity of mood rating. CONCLUSIONS: Using this method, we were able to confirm and extend the work of others, indicating altered intracellular calcium homeostasis in the blood cells of bipolar disorder patients. In addition, our data suggest that storage operated calcium channels may be the source of the elevated intracellular calcium in platelets and lymphocytes of bipolar patients.     

Hyperserotonemia and platelet serotonin uptake and release in schizophrenia and affective disorders

The authors found that platelet serotonin concentrations were significantly elevated in patients with chronic schizophrenia and in patients with bipolar major depressive disorder. High-affinity serotonin uptake was significantly reduced only in patients with bipolar major depressive disorder. Thrombin-induced release of serotonin from platelets in any patient group was not different from that of normal control subjects. Platelet serotonin storage in chronic schizophrenic patients was also not different from that in normal control subjects. These platelet findings could not be explained by age, sex, or medication variables. The authors suggest that the pharmacodynamics of platelet serotonin may be different in chronic schizophrenia than in bipolar major depressive disorder.     

Pituitary thyrotropin response to thyrotropin-releasing hormone in affective illness: relationship to spinal fluid amine metabolites.

The authors studied pituitary thyrotropin, i.e., thyroid-stimulating hormone (TSH), response to thyrotropin-releasing hormone (TRH) in patients with primary affective disorder. There were no overall differences between either depressed or manic patients and normal controls; however, the TSH response was significantly lower in the unipolar depressed patients than in either bipolar depressed patients or normal subjects. Bipolar patients in the manic phase tended to have a lower response than bipolar depressed patients. In the unipolar group, the TSH response showed a significant negative correlation with the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the CSF. These neuroendocrine responses may constitute markers of specific monoamine dysfunction in subgroups of patients with affective illness.     

Schizoaffective mania reconsidered

Schizoaffective mania refers to a heterogeneous group of disorders characterized by mixtures of schizophrenic and manic (or bipolar) symptoms. Of the proposed diagnostic criteria, the Research Diagnostic Criteria (RDC) most clearly distinguish relevant subgroups. Family, clinical, and treatment studies suggest that the RDC's mainly affective subtype of schizoaffective mania is a variant of psychotic bipolar disorder. Limited available data suggest that the mainly schizophrenic subtype has a poorer prognosis and includes cases more closely related to schizophrenia. Schizoaffective mania also overlaps with proposed categories such as reactive and cycloid psychosis. It is premature to assume that all schizoaffective manic disorder represents a bipolar variant. Further studies that differentiate patients according to subtype, drug response, and course are needed.     

An fMRI study of affective state and medication on cortical and subcortical brain regions during motor performance in bipolar disorder

Structural neuroimaging studies have identified abnormalities in the basal ganglia in patients with bipolar disorder. Findings have been mixed with regard to affective state and have not elaborated on the role of medication on functional brain activity. The aims of the present study were to use functional magnetic resonance imaging (fMRI) to test whether depressed and manic bipolar disorder patients differ in terms of activity in cortical and subcortical brain areas and to examine the effects of psychotropic medication. Twenty-four bipolar disorder subjects and 13 healthy comparison subjects participated in an fMRI study of manual reaction time. Both manic and depressed subjects exhibited abnormally elevated blood oxygen level dependent BOLD responses in cortical and subcortical areas. Manic bipolar subjects had significantly higher BOLD responses in the left globus pallidus and significantly lower BOLD responses in the right globus pallidus compared with depressed bipolar patients. Correlational analyses revealed significant relationships between the severity of mania and activity within the globus pallidus and caudate. Patients off antipsychotic or mood-stabilizing medication exhibited significantly higher BOLD responses throughout the motor cortex, basal ganglia and thalamus compared with patients on these medications. These results suggest that affective state in bipolar disorder may be related to a disturbance of inhibitory regulation within the basal ganglia and that antipsychotics and/or mood stabilizers normalize cortical and subcortical hyperactivity.     

反复发作躁狂症与双相情感障碍躁狂相的血液流变学特点比较

目的 探讨反复发作躁狂症与双相情感障碍躁狂的血液流变学特点。方法 对住院患 在三天内进行采血检测，利用电脑对三者血流流变学数据进行比较研究。结果 反复发作躁狂症全血粘度，刚性指数比正常健康人高（Ｐ〈０．０５），而血浆压积却比正常健康人低（Ｐ〈０．０１），双相情感障碍躁狂相各项指标在常健康人无显著差异（Ｐ〉０．０５），反复发作躁狂症全血粘度，细胞压积，低切朱粘度比双相情感障碍躁狂相高（Ｐ〈０．０５）     

Activation of protein kinase C isozymes in primary mouse myotubes by carbachol

The activation of muscle PKC isozymes following treatment with carbachol, an acetylcholine receptor agonist, has been investigated. Primary mouse myotubes were treated with carbachol, and protein extracts from the cytosol and membrane fractions of the myotubes were subjected to Western blot analyses. Carbachol treatment resulted in a rapid translocation of PKC-theta; to the membrane. This effect was dependent on both carbachol concentration and incubation time. The treatment also resulted in a drastic increase of PKC-alpha in the cytosol followed by an increase of PKC-alpha in the membrane. The regulation of PKC-alpha in response to carbachol was quite distinct from that produced by the PKC activator, PMA, which rapidly translocated PKC-alpha from the cytosol to the membrane without any increases in PKC-alpha in the cytosol. Confocal microscopy demonstrated an enhanced membrane localization of PKC-theta; and overall increased intensity of PKC-alpha staining in the cytosol accompanied by a characteristic membrane staining of PKC-alpha in the myotubes treated with carbachol. Taken together, the results suggested that the activation of PKC isozymes in response to the receptor agonist is quite distinct, which indicates their diverse role in the muscle upon the release of neurotransmitter at the neuromuscular junction.     

Abnormalities of cyclic adenosine monophosphate signaling in platelets from untreated patients with bipolar disorder

BACKGROUND: Abnormalities in the cyclic adenosine monophosphate (cAMP)-dependent phosphorylation system have been recently reported in patients with bipolar disorder. We evaluated the immunoreactivity of the regulatory and catalytic subunits of cAMP-dependent protein kinase (protein kinase A) and 1 of its substrates, Rap1, in platelets from untreated euthymic, manic, and depressed patients with bipolar disorder and healthy subjects. METHODS: Platelets were collected from 112 drug-free patients with bipolar disorder (52 euthymic, 29 depressed, and 31 manic) and 62 healthy subjects. The levels of cAMP-dependent protein kinase and Rap1 were assessed by Western blot analysis, immunostaining, and computer-assisted imaging. RESULTS: The immunolabeling of the catalytic subunit of cAMP-dependent protein kinase was significantly different among groups (P<.001), with higher values in untreated depressed and manic patients with bipolar disorder compared with untreated euthymic patients with bipolar disorder and healthy subjects. No significant differences were found in the immunolabeling of the regulatory subunits (type I and type II) of cAMP-dependent protein kinase. The immunolabeling of Rap1 was significantly higher (P<.001) in untreated euthymic, depressed, and manic patients than in healthy persons. CONCLUSIONS: Levels of Rap1 and the catalytic subunit of cAMP-dependent protein kinase are altered in the platelets of bipolar patients. These findings may provide clues toward understanding the involvement of cAMP signaling in the pathogenesis of bipolar disorder.     

Rediagnosis of schizophrenia as bipolar affective illness

Ten patients in a Veterans Administration hospital who had been diagnosed and treated as schizophrenic were rediagnosed as having bipolar affective illness and were shown to be responsive to lithium. The authors feel that the diagnosis of schizophrenia is made too frequently and often is made with inadequate information. A further complicating factor in diagnosis is that some patients exhibit schizophrenia-like symptoms during the acute manic phase. The authors found that valuable aids to rediagnosis of such patients include a good premorbid and interepisodic adjustment, a history of depressive episodes, a family history of affective disorder, and a favorable response to a therapeutic trial on lithium carbonate.     

Effects of valproate on serotonin-induced intracellular calcium mobilization in human platelets

OBJECTIVE: Valproate (VPA) is effectively used in the treatment of bipolar disorder, although the mechanism of action is unclear. In patients with bipolar disorder, 5-hydroxytryptamine (5-HT)-induced intraplatelet calcium (Ca) mobilization has been shown to be enhanced. METHODS: We examined the effect of VPA on 5-HT-induced Ca response in the platelets of normal subjects, in the presence of a calmodulin antagonist W-7 (N-[6-aminohexyl]-5-chloro-1-naphthalenesulfonamide), a protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA) or PKC inhibitors staurosporine and bisindolylmaleimide II. RESULTS: VPA inhibited the 5-HT-induced Ca response in a concentration-dependent manner. For calmodulin pathways, W-7 enhanced the 5-HT-stimulated Ca response, which was not affected by VPA. For PKC pathways, PMA reduced the Ca response, although both PKC inhibitors had no effect. PMA, staurosporine or bisindolylmaleimide II reversed the inhibitory effect of VPA on the Ca response, while W-7 did not modify it. CONCLUSION: These findings suggest the possibility that the mechanism of action of VPA may be partly related to PKC signalling.     

A longitudinal study of thought disorder in manic patients

To study the persistence of thought disorder in manic patients, 34 manic patients were compared with 30 schizophrenic and 30 nonpsychotic patients on four indexes of thought pathology at two phases of disorder: during the acute inpatient phase and one year after hospitalization. Patients were also compared with a control sample of 34 normal subjects. The data indicated that during the acute in hospital phase, both manic and schizophrenic patients were severely thought disordered; at follow-up, a subsample of manic patients showed severe thought disorder; despite the severe thought disorder found at follow-up in some manic and schizophrenic patients, both groups showed a significant reduction of thought pathology at follow-up; and there was a trend for a larger reduction of thought disorder in manic than in schizophrenic patients. The difference, however, was not significant when initial levels of severity were controlled.