Biomedical subjects
C Alling
Publications and source records attributed to C Alling.
Mechanisms of adaptation to the effects of ethanol on activation of phospholipase C in NG 108-15 cells.
In this study the effect of different times of exposure to ethanol (1-7 days, 100 mM) on bradykinin and GTP(S)-stimulated activation of phospholipase C in NG 108-15 cells and on the binding of [3H]bradykinin to its receptors was investigated. Ethanol attenuated both agonist and GTP-analogue-induced hydrolysis of phosphoinositides for a period of up to 4 days of treatment, while exerting no effect on binding to bradykinin receptors. However, after 7 days of exposure to ethanol, the agonist-induced activation of phospholipase C was completely resistant to the inhibitory effects of alcohol. This finding correlated to a change in the affinity of the bradykinin receptor population after 7 days of treatment. The results indicate that bradykinin-induced breakdown of phosphatidylinositol 4,5-bisphosphate adapts to the effects of ethanol, after long-term treatment. Possible adaptative changes taking place at the level of the G protein(s), may induce a shift in the affinity of the receptor population and, consequently, serve as a compensatory mechanism to counteract the inhibitory effect of ethanol.
Serotonin-stimulated phosphoinositide hydrolysis in platelets from post-withdrawal alcoholics.
It has previously been reported that serotonin-stimulated second messenger formation is inhibited in platelets from alcoholics undergoing detoxification. Serotonin-stimulated signal transduction was therefore analysed in platelets from young post-withdrawal alcoholics to elucidate whether the previously reported inhibition is a state or trait marker of alcoholism. No difference between post-withdrawal alcoholics and controls was found with regard to serotonin-stimulated [32P]-phosphatidylinositol 4,5-bisphosphate hydrolysis or [32P]-phosphatidic acid formation. The results indicate that the inhibited serotonin2 receptor function seen in alcoholics undergoing detoxification is a state-dependent rather than a trait-dependent marker.
Prediction of suicidal behavior from biologic tests.
Biochemical studies related with suicidal behavior have mainly dealt with monoaminergic and corticosteroidal measures. We used some of these measures in a study of 61 suicide attempters who, except for occasional doses of benzodiazepines, had been medication free for a mean of 16 days. The monoamine metabolites 5-hydroxyindoleacetic acid, homovanillic acid, and 3-methoxy-4-hydroxyphenylglycol were measured in lumbar cerebrospinal fluid (CSF). We found that violent suicide attempters (N = 18) had 5-hydroxyindoleacetic acid concentrations below the median of all patients, whereas the concentrations of 3-methoxy-4-hydroxyphenylglycol were mainly above the median. We found no significant differences between violent and nonviolent (N = 43) attempters concerning CSF homovanillic acid, 24-hour urinary norepinephrine-epinephrine and cortisol, activity of monoamine oxidase in platelets, or post-dexamethasone plasma cortisol. Four patients completed suicide, and 3 of them had CSF 5-hydroxyindoleacetic acid concentrations at or below the median. All completed suicides had CSF 3-methoxy-4-hydroxyphenylglycol concentrations above the median. Urinary measures and platelet monoamine oxidase activity of completed suicides were in the higher concentration ranges. Patients who repeated suicidal behavior after the index investigation had low 24-hour urinary cortisol levels more often than those who did not repeat. Because our subgroups of patients are small, we cannot draw any firm conclusions about the value of our CSF and urinary biochemical findings predicting suicidal behavior. However, our CSF findings in violent suicide attempters are similar to those observed in other studies.
A method for maintaining constant ethanol concentrations in cell culture media.
The present study reports on the development of a model for maintaining constant ethanol concentrations over time in cell culture media. When neuroblastoma x glioma cells (NG 108-15) were grown in ethanol containing media under standard cultivation conditions in the incubator at 37 degrees C, a 90% evaporation was observed after 24 hr. To counteract evaporation, the cell culture dishes were placed inside polystyrene boxes together with an open dish containing an appropriate amount of ethanol. By using such procedure, the decrease in ethanol concentration in the culture media was completely avoided. Cultivating cells in ethanol-free media inside sealed plastic boxes did not change their viability, growth rate, protein and phospholipid composition of the cells or the pH of the media, compared to cultures grown outside the boxes.
Cerebrospinal fluid levels of monoamine metabolites in panic disorder.
The cerebrospinal fluid (CSF) levels of the serotonin metabolite 5-hydroxyindoleacetic acid (5HIAA), the noradrenaline metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG), and the dopamine metabolite homovanillic acid (HVA) did not differ significantly in a group of patients with panic disorder (n = 17) as compared to age- and sex-matched normal controls (n = 17). While CSF concentrations of HVA and 5HIAA were significantly correlated in both patients and controls, CSF MHPG levels were significantly correlated with the concentrations of CSF 5HIAA and HVA only in patients. In a small number of subjects (n = 5), successful reduction of anxiety attacks by administration of clomipramine or imipramine (50-150 mg/day) for at least 2 months was associated with a significant decrease in CSF concentrations of 5HIAA and MHPG, but not HVA.
Peripheral serotonergic markers in patients with suicidal behavior.
Peripheral serotonergic parameters were studied in 17 patients with a history of suicidal behavior and in 17 age- and sex-matched healthy controls. Serotonin2 receptor function in platelets, measured as serotonin-induced [32P]phosphatidylinositol 4,5-bisphosphate hydrolysis, was significantly higher in patients than in age- and sex-matched controls. Increased serotonin2 receptor transduction was not correlated to psychiatric diagnosis, drug treatment or a history of violent suicide attempt. Monoamine oxidase activity was lower in platelets from patients with a history of suicidal behavior than in controls. In addition, whole blood serotonin was analyzed but no significant alterations were found in blood from patients.
Acidic phospholipids in synaptosomal plasma membranes during repeated episodes of physical ethanol dependence in the rat.
The effects of repeated episodes of ethanol intoxication and the hyperexcitable state of withdrawal on the synaptosomal concentration of acidic phospholipids were studied in rats. There was no indication that cumulative changes in the synaptosomal acidic phospholipid composition in general occurred during multiple episodes of ethanol intoxication and withdrawal. There was, however, a statistically significant decrease in acidic phospholipid concentration (phosphatidylinositol; PI) in synaptosomal membranes from animals revealing spontaneous convulsive behaviour during ethanol withdrawal. Hypothetically this may reflect an inability to increase acidic phospholipid membrane content and thus to adaptively increase the seizure threshold during withdrawal.
G proteins coupled to phospholipase C: molecular targets of long-term ethanol exposure.
Long-term ethanol exposure is known to inhibit bradykinin-stimulated phosphoinositide hydrolysis in cultures of neuroblastoma x glioma 108-15 cells. In the present study, [3H]bradykinin binding, GTP-binding protein function, and phospholipase C activity were assayed in cells grown for 4 days in 100 mM ethanol with the aim of elucidating the molecular target of ethanol on signal transduction coupled to inositol trisphosphate and diacylglycerol formation. Ethanol exposure reduced guanosine 5'-O-(3-thiotriphosphate) [GTP(S)]- and, to a lesser extent, NaF/AlCl3-stimulated phosphoinositide hydrolysis, whereas it had no effect on the enzymatic activity of a phosphatidylinositol 4,5-bisphosphate-specific phospholipase C. [3H]Bradykinin binding in the absence of GTP(S) was not influenced by ethanol exposure. However, the reduction in [3H]bradykinin binding seen in control cells after addition of GTP analogue was inhibited in cells grown in ethanol-containing medium. The results indicate that long-term ethanol exposure exerts its effects on receptor-stimulated phosphoinositide hydrolysis primarily at the level of the GTP-binding protein.
Continuous and intermittent exposure to ethanol: effect on NG 108-15 cell membrane phospholipids.
The effect of continuous and intermittent ethanol exposure on the phospholipid composition of Neuroblastoma x Glioma (NG 108-15) cell membranes was investigated. The cells were treated with ethanol for three weeks. Continuous ethanol exposure (150 mM) produced an increase (27%) in the amount of phosphatidylcholine, whereas intermittent ethanol treatment (150 mM) induced a 22% reduction of this lipid. Decreases of phosphatidylethanolamine plasmalogen (8.5%), phosphatidylinositol (16%) and phosphatidylserine (24%) were also seen after intermittent exposure. After binge administration, the concentration of total phospholipids was reduced by 17%, whereas continuous exposure produced a 19% increase. Both intermittent and continuous exposure induced a reduction in the total protein content. No changes in phosphatidic acid, sphingomyelin, phosphatidylcholine plasmalogen or phosphatidylethanolamine (diacyl form) were detected with either treatment. The importance of this study is that ethanol, irrespective of amount, can elicit different effects depending on the pattern of administration.
Effects of centrally administered neuropeptide Y (NPY) and NPY13-36 on the brain monoaminergic systems of the rat.
The effects of centrally administered NPY on the brain monoamine systems were investigated in the rat. Neuropeptide Y (0.2-5.0 nmol), its C-terminal 13-36 amino acid (a.a.) fragment, NPY13-36 (0.4-10.0 nmol), or saline were injected into the right lateral cerebral ventricle of unrestrained rats. After 1 h the animals were decapitated, and the brains were taken out. Two cortical regions ('frontal' and 'parietal'), the striatum, the hypothalamus, and the brain stem were dissected out. The tissue contents of noradrenaline (NA), dopamine (DA) and serotonin (5-HT), as well as of their major metabolites, 3-methoxy-4-hydroxy-phenylethylene glycol (MHPG), 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxy-indole acetic acid (5-HIAA) were measured. The most consistent finding was a dose-related increase of both DA and DOPAC levels after treatment with NPY. This effect was reproduced by NPY13-36 in cortical tissue, whereas, in the sub-cortical regions, NPY13-36 only reproduced the effects of NPY on the DOPAC levels. Less consistent effects were found on the NA systems, in which NA levels showed a tendency to increase following low, and decrease after high doses of NPY. These effects were largely reproduced by NPY13-36. In addition, NPY increased tissue levels of MHPG in frontal cortical tissue in a dose-related manner. The brain 5-HT systems were not affected.
Interactions between cyclic AMP and inositol phosphate transduction systems in astrocytes in primary culture.
Astroglial cells in primary culture possess receptors with cyclic AMP and inositol phosphates (IP) as second messengers. The beta-receptor agonist, isoproterenol induces an increase in the accumulation of cyclic AMP, the alpha 2-receptor agonist clonidine inhibits the isoproterenol-induced accumulation of cyclic AMP, while the alpha 1-receptor agonist phenylephrine acts only on the inositol phosphate system. 5-Hydroxytryptamine (5-HT) stimulates, the formation of inositol phosphate, while isoproterenol and clonidine per se do not affect the inositol phosphate system. In the present paper the possibility of interactions between the cyclic AMP and the inositol phosphate transduction systems were investigated. In the presence of 10(-5) M 5-HT, in itself ineffective on the formation of cyclic AMP, isoproterenol stimulated the accumulation of cyclic AMP far more than in the absence of 5-HT. The potentiation was blocked by the 5-HT2 receptor antagonist ketanserin. On the other hand, there were no indications for a beta-receptor influence on the 5-HT-induced inositol phosphate formation. Stimulation of the alpha 2-receptor did not induce accumulation of inositol phosphate but significantly potentiated 5-HT2-receptor transduction, as measured by hydrolysis of phosphoinositide and formation of inositol phosphate. Stimulation by 5-HT also increased the formation of inositol phosphate after adrenergic stimulation and this effect was found to be synergistic at certain concentrations of adrenergic agonists. In addition, there was a statistically significant accumulation of cyclic AMP in the presence of both 5-HT and phenylephrine, none of which stimulated cyclic AMP alone. The results suggest specific interactions between the cyclic AMP and inositol phosphate systems on cultured astroglial cells.
Dose- and time-response effects of pantethine on open-field behavior, and on central neurotransmission in rats.
In this study the dose- and time-related effects of pantethine on open-field behavior and central neurotransmissions were investigated in rats. Pantethine administered in low doses (0.48-0.96 mM/kg SC) only marginally influenced the activity of the animals, but induced a significant decrease of hypothalamic noradrenaline level without influencing the concentrations of dopamine and DOPAC. Injected in higher doses (1.95-3.90 mM/kg SC), the compound produced a marked depression of both open-field activity and noradrenaline levels, but increased the concentrations of dopamine and DOPAC in the hypothalamus. Twelve hr after the administration of the substance, its effect was attenuated, and 24 hr after the treatment neither the behavioral nor the monoamine parameters differed significantly from the control values. Concerning the somatostatin, pantethine administered in high doses (1.95-3.90 mM/kg SC) decreased the striatal concentration of somatostatin 4 hr after the injection, and this effect was attenuated 24 hr after the treatment. These data suggest that the pantethine-induced behavioral changes are correlated with its effect on central catecholaminergic and somatostatinergic transmission.
Somatostatin28(15-28), but not somatostatin28(1-12), affects central monoaminergic neurotransmission in rats.
The effects of intracerebroventricularly (icv) administered somatostatin28(SS28) fragments, SS28(1-12) and SS28(15-28), were investigated on central monoaminergic neurotransmission in rats. SS28(15-28) did not significantly influence the hypothalamic and striatal noradrenaline concentrations. In a dose-related manner, SS28(15-28) significantly increased the dopamine, dihydroxyphenyl acetic acid DOPAC), and serotonin concentrations in hypothalamus, but did not modify these measures in striatum. The other SS28 metabolite, SS28(1-12), had no statistically significant effects on the monoamine neurotransmission. SS28(15-28) (6 and 9 nmol) induced barrel rotation, while SS28(1-12) was ineffective following administration over a wide dose-range (3-18 nmol). In conclusion, SS28(15-28) influences the hypothalamic monoaminergic transmission and causes barrel rotation, whereas SS28(1-12) has no neurochemical or behavioural effects in these tests.
Ethanol potentiates serotonin stimulated inositol lipid metabolism in primary astroglial cell cultures.
Serotonin-stimulated activation of phospholipase C in primary astroglial cell cultures was studied as a mean of evaluating the effect of acute ethanol exposition on this signal transduction system. The addition of 50-150 mM ethanol prior to stimulation with 10(-5) M serotonin led to a potentiation of the serotonin-induced [3H]-inositol phosphate formation and an increased incorporation of [3H]-inositol into the three phosphoinositides studied. This potentiating effect of ethanol was observed only when ethanol was added together with serotonin. No stimulatory effect of ethanol per se was found. Furthermore, ethanol had no effect on arginine-vasopressin, bradykinin or phenylephrine stimulated inositol lipid metabolism.
Ethanol alters the transfer of arachidonic acid to ethanolamine plasmalogens in C-6 glioma cells.
In this study, the effects of ethanol exposure on uptake and metabolism of arachidonic acid by C-6 glioma cells in culture was examined. Labeled arachidonic acid was effectively taken up by the phospholipids of these cells and radioactivity was initially incorporated into phosphatidylinositols and phosphatidylcholines, reaching a peak between 4 and 6 hours. However, the labeling of ethanolamine plasmalogens continued to show an increase with time after labeled arachidonic acid has been exhausted in the medium. Since over 90% of labeled arachidonic acid was already taken up by the cells after 4 hours of exposure, the continued increase in labeling of ethanolamine plasmalogens is attributed to a transacylation mechanism. Cells grown in 150 mM ethanol for 2 days did not show a change in the overall incorporation of labeled arachidonic acid into phospholipids but showed a significant increase in labeling of ethanolamine plasmalogens, which was marked by a concomitant decrease in labeling of phosphatidylcholines. Ethanol exposure also resulted in a significant increase in the transfer of labeled arachidonic acid to triacylglycerols. Changes in phospholipid and triacylglycerol labeling pattern positively correlated with increasing ethanol concentration from 75 to 300 mM. Besides, most ethanol effects were readily noticeable after 24 hours of exposure. These data suggest a specific effect of ethanol on promoting the transacylase process for biosynthesis of ethanolamine plasmalogens as well as the acyltransferase for biosynthesis of triacylglycerols.
Influence of cysteamine and cysteine on open-field behaviour, and on brain concentrations of catecholamines, somatostatin, neuropeptide Y, and corticotropin releasing hormone in the rat.
Cysteamine (1.95 or 3.90 mM/kg) administered subcutaneously (sc) markedly decreased the open-field activity of the rats, while the structurally related amino acid cysteine had only minor influence. Cysteamine (1.95 or 3.90 mM/kg) reduced the noradrenaline and increased the dopamine and dihydroxyphenyl acetic acid (DOPAC) levels in the hypothalamus. In striatum the drug decreased both the noradrenaline (1.95 or 3.90 mM/kg) and dopamine (3.90 mM/kg) levels without influencing the DOPAC content. Neither the hypothalamic nor the striatal catecholamines are influenced by administration of equimolar doses of cysteine. Cysteamine (1.95 or 3.90 mM/kg) decreased the somatostatin levels both in the hypothalamus and in the striatum without influencing neuropeptide Y (NPY) and corticotropin releasing hormone (CRH) concentrations. Cysteine administered in equimolar doses did not influence the peptide levels in these brain structures. These data suggest that the cysteamine-induced behavioural changes are related to the decrease of brain noradrenaline and somatostatin concentrations. The structurally related amino acid cysteine does not influence the behaviour or the central monoaminergic and peptidergic concentrations in the hypothalamus and striatum of rats.
Effects of cysteamine and pantethine on open-field behavior, hypothalamic catecholamine concentrations, and somatostatin-induced barrel rotation in rats.
Cysteamine administered in a dose of 1.95 mM/kg subcutaneously (SC) markedly reduced several open-field behaviors (locomotion, rearing, grooming and defecation), while pantethine, administered in an equimolar dose, reduced the locomotion only. However, administered in a dose of 3.90 mM/kg (SC), pantethine also markedly reduced all open-field parameters. Cysteamine, and to less extent pantethine, reduced noradrenaline, and increased dopamine and DOPAC concentrations in the hypothalamus. It is discussed whether the lower potency of pantethine on open-field behaviors and hypothalamic catecholaminergic neurotransmission is connected with the limited activity of pantetheinase, the cysteamine-generating enzyme. Intracerebroventricularly (ICV) administered somatostatin did not influence the pantethine-induced (1.95 mM/kg SC) behavioral changes in the open-field test. It is possible that the peptide did not reach at the receptor sites in a sufficient concentration because of the reduced endogenous somatostatin content, or that the pantethine-induced noradrenaline depletion is connected with the ineffectiveness of somatostatin. Furthermore, pretreatment with cysteamine (1.95 mM/kg SC) or pantethine (1.95 mM/kg or 3.90 mM/kg SC) attenuated the somatostatin-induced (10 micrograms ICV) barrel rotation, suggesting that the level of endogenous somatostatin may play a role in the pathogenesis of this motor disturbance.