The Effects of Cyclosporin A on the Signal Transduction System in the Rat Brain / 대한정신약물학회지

The most important molecular mechanisms of intraneuronal signal transduction are those mediated by calcium and reversible protein phosphorylation. Although many studies pursued the activation of the protein kinases in the nervous system, there are only few reports focused on the protein phosphatases. In this article, the authors report the effects of cyclosporin A (CSA), an inhibitor of calcineurin, on the calcium signaling-related molecules such as ERKs, calmodulin-dependent kinase II (CaMKII) and CREB in the rat hippocampus. The authors also report the effects of cyclosporin A on the electroconvulsive shock (ECS)-induced seizure and the activation of ERKs. Calcineurin is a protein phosphatase that is abundant in the brain and regulated by calcium and calmodulin. It is proposed that calcineurin plays central roles in the synaptic plasticity and neuronal apoptosis. CSA (50 mg/kg) increased the phosphorylation of ERK, CaMKII and CREB. The treatment of of CSA increased the duration of tonic phase of seizure induced by ECS and augmented the phosphorylation of ERKs after ECS. These results suggested the protective role of calcineurin against the excessive electrical and molecular activities in the brain.

Post-transcriptional control of c-erb B-2 overexpression in stomach cancer cells

The growth factor receptor oncogene, c-erb B-2, is frequently overexpressed in the adenocarcinomas of breast, ovary, lung and stomach. Although the mechanism of erb B-2 overexpression is thought as the result of transcriptional upregulation in many primary human carcinomas, expression rate of c-erb B-2 at mRNA level is usually lower than the level of translated protein. We also found that the expression of erb B-2 in SNU-1 stomach cancer cells was greater at post-transcription level (Bae et al., 1993). To explore the underlying mechanism of erb B-2 protein overexpression, we have chosen two cells lines, SNU-1 and SNU-16 where transcription rate of erb B-2 was closely resemble to each other while expressed protein levels were quite different. The synthesis rate of erb B-2 protein in SNU-1 cells was faster than SNU-16 cells while levels of erb B-2 mRNA were found to be similar in both cell lines. The half-life of the expressed erb B-2 protein was not significantly different in both cell lines. Analysis of the 5' untranslated region (UTR) of erb B-2 mRNA (-1approximately-323) showed no sequence abnormality in both cell lines. However, ribonuclease protection assay using cloned 5 UTR sequence revealed that the size of 5' UTR of erb B-2 mRNA which associate with transcription initiation site(s) in SNU-1 cells was longer than that in SNU-16. These results suggest that the increased erb B-2 protein synthesis rate possibly due to the redundant selection of transcription initiation might be a mechanism of erb B-2 overexpression in SNU-1 cells.

Activation of JNK and p38 in rat hippocampus after kainic acid induced seizure

Kainic acid, an analogue of glutamate, causes limbic seizures and induces cell death in the rat brain. We examined the activation of MAPK family kinases; ERKs, JNKs and p38 kinase in rat hippocampus after KA treatment. Activation of all three kinases were observed at 30 min after the treatment, but, in contrary to ERK phosphorylation, which lasted up to 3 h, the phosphorylation of JNK and p38 returned to the basal level by 2 h. The phosphorylation of' upstream kinases for the MAPK family was distinct. The phosphorylation of MEK1 clearly increased at 30 min but diminished rapidly thereafter. The phosphorylation of MKK6 was also increased but reached peak at 2 h after KA treatment. However, the phosphorylation of other upstream kinases, SEK1 and MKK3, gradually decreased to 3 h after KA treatment. These results indicate that the KA activates all of the three MAPK family kinases with different time patterns and suggest the possibility that MKK3 and MKK6, and SEK1 may not be the upstream kinases for p38 and JNK in rat hippocampus.

A New Gene Regulated by Electroconvulsive Shock in Rat Brains / 신경정신의학

OBJECTIVES: This study was performed to identify genes regulated by electroconvulsive shock (ECS) and to observe the pattern of expression of genes according to different developmental stages and brain regions. METHODS: ECS(130V, 0.5 sec) was given to male Sprague-Dawley rats with age of postnatal day 7 and 21(P7, P21 respectively). After screening genes regulated by ECS with mRNA differential display-PCR(DD-PCR), we selected one clone among them and observed the induction of this gene after ECS by time-dependent Northern blot analysis of rat brain of P7, P21 and adult rat cortex and hippocampus. RESULTS: By DD-PCR method, we have identified four clones whose expression was regulated by ECS. Among them, one(CP 10-2) was proved to be a new gene by sequencing and BLAST search. Its expression was increased after ECS in P7, P21, and adult rat brain. The expression of CP 10-2 reached peak level at 180 minutes after ECS in P7 rat brain, but was further increased until 360 minutes after ECS in P21 and adult rat brain. CONCLUSION: In this study, a new gene was identified in rat brain which showed up-regulated expression in response to ECS. Cloning and characterization of this new gene would be helpful to elucidate the effect of ECS in rat brain.

The Effect of Polygalasaponins in Polygalae Tenuifolia on Apomorphine-Induced Hyperlocomotions in Mice / 대한정신약물학회지

OBJECTIVE: This study was to investigate in vivo antidopaminergic activities of polygalasaponins which included in the roots of Polygalae tenuifolia, one of the natural plants prescribed to treat psychotic disorders in traditional medicine. METHODS: The chemical separations were conducted by chromatographies with various columns and the chemical structures were identified using spectroscopy, NMR and so on. The apomorphine-induced stereotyped behaviors and climbing behaviors in mice as animal models of psychotic disorders were applied to explore the antidopaminergic activity. RESULTS: The active compounds with antidopaminergic effects in the roots of Polygalae tenuifolia were identified as polygalasaponin A-D. The polygalasaponins showed to suppress the apomorphine-induced stereotyped behaviors and climbing behaviors in dose-related fashions. CONCLUSION: This study suggests that polygalasaponins might have antipsychotic activities. The natural products need to be explored extensively as sources of new medications in psychiatric fields. Further explorations for chemical and pharmacological properties of polygalasaponins are required.

Regulation of MAPK Activity by Seizure-induced MKP-1 in Rat Hippocampus / 신경정신의학

OBJECTIVES: Both electroconvulsive shock(ECS) and kainic acid-induced seizures activate mitogenactivated protein kinases(MAPKs)in rat hippocampus. They can also induce the expression of MAPK phosphatase-1(MKP-1)in rat hippocampus. MKP-1 is known as a specific MAPK deactivator. This study aimed to elucidate the role of MKP-1 in the deactivation of MAPKs in rat hippocampus. METHODS: In order to induce MKP-1 in the hippocampus, ECS was given to the rats. At the time points when MKP-1 was sufficiently induced, the second ECS was given to them and the subsequent phosphorylation or activation of MAPKs were measured in the hippocampus. A second group of rats were injected with kainic acid and the relationship between MKP-1 expression and MAPK phosphorylation was examined in their hippocampi. RESULTS: The expression of MKP-1 did not influence the phosphorylation or activation of MAPKs following ECS in rat hippocampus. Kainic acid-induced expression of MKP-1 did not significantly reduce the phosphorylation of MAPKs. CONCLUSION: MKP-1 did not play a significant role in the deactivation of MAPKs which were activated by ECS or kainic acid in rat hippocampus.

The Induction of Immediate Early Genes and Phosphorylation of p42, p44 MAPK and Elk-1 by Kainic Acid in Developing Rat Hippocampus / 신경정신의학

OBJECTIVES: In order to investigate the maturational process of intracellular signal transduction system in rat brain, we studied the induction of the immediate early genes(IEGs)c-fos, junB, and TIS1 in each developmental stage after kainic acid(KA)induced seizure in young rat hippocampus and then compared these with the results after electroconvulsive shock(ECS) And to elucidate the induction mechanism of c-fos via mitogen-activated protein kinase(MAPK)by KA in each developmental stage, we investigated the phosphorylation of p42, p44 MAPK and Elk-1 after KA treatment in young rat hippocampus. METHODS: We examined the induction patterns of IEGs by northern blot analysis, and the phosphorylation of p42, p44 MAPK and Elk-1 by immunoblotting in rat hippocampus at post-natal day 7, 14, and 21(P7, P14 & P21) respectively after intraperitoneal injection of KA. RESULTS: Unlike ECS, KA did not induce c-fos, junB, and TIS1 in P7 hippocampus. But these genes were apparently induced at P14 and to an adult level at P21. These three IEGs showed similar temporal patterns of induction in each developmental stage. Although the basal level of phosphorylated 42p, 44p MAPK was considerable in P7 rat hippocampus, the increase of phosphorylation after KA treatment was observed at P14 . While the phosphorylation of Elk-1 was detected with high basal level in P7 rat, the amount of phosphorylated Elk-1 was not changed after KA treatment. CONCLUSION: Our results suggest that the differences in IEGs induction patterns between KA and ECS may be due to the differences in the activated signal transduction pathways. And our results also implicate that the signal transduction system involved in MAPK phosphorylation after KA treatment mature with aging and c-fos induction via MAPK activation may be regulated through some pathways other than Elk-1 in rat hippocampus.

Expression of Guanine Deaminase in the Developing Rat Brain / 대한해부학회지

Guanine aminohydrolase (GAH; Guanine deaminase, EC 3.5.4.3) is an enzyme that has a role in purine catabolism. This enzyme produces xanthine and ammonia by hydrolysis of guanine, and xanthine is further degraded to uric acid and hydrogen peroxide by another enzyme, xanthine oxidase. Most of the enzymes involved in purine catabolism have been studied for their biological functions, physiological roles and amino acid sequences, and biochemical activity of GAH is known to be detected in various organs such as liver, kidney, small intestine and brain. Its activity is also known to be changed during brain development. In this study, we hoped to reveal expression pattern of GAH in developing rat brain by western blotting and immunohistochemistry. In western blotting, GAH immunoreactivity was not detected on 14-, 16- and 18-days-old fetal rat brains. Its reactivity was first detected from 20-days-old fetal rat brain and highly increased after birth. And it was maintained at steady level from 2 weeks after birth. In immunohistochemistry, no positive cells were found on 14- and 16-days-old fetal rat brain sections. A few GAH-immunoreactive cells appeared from 18-days-old fetal rat brain and they were localized at olfactory bulb, cerebral cortex, midbrain, pons and medulla. The 20-days-old fetal rat brain also showed immunoreactive cells at hippocampus and the staining intensity was still weak. Postnatal 2-days-old rat brain also showed immunoreactive cells at basal ganglia and the number of positive cells and staining intensity were increased. Thereafter, immunoreactivity appeared on many neuronal cells around various areas in the brain and nerve fibers also showed reactivity on postnatal brains. The number of positive cells decreased from 1 week after birth and a few positive cells were observed on olfactory bulb and cerebellum from 2 weeks after birth. In mature brain most of GAH were localized on nerve fibers and few positive cells could be found on olfatory bulb only. From these, we can suspect that GAH may have some functional relationship with nerve fibers.

Developmental Changes in the Phosphorylation of CREB Following Electroconvulsive Shock in Rat Brain / 신경정신의학

OBJECTIVES: In order to understand the biological basis of neurodevelopmental perspectives of mental disorders, the authors investigated the developmental and regional changes in the phosphorylation of the transcription factor CREB following the electroconvulsive shock(ECS) in rat brain. METHODS: Rats of various age groups (7, 14, 21 days postnatal and adults) were given ECS and their hippocampi and cerebella were dissected at specified time points. The content of CREB and phosphorylated CREB were measured by immunoblot analysis. RESULTS: The amount of CREB increased in the hippocampus and decreased in the cerebellum according to the age. Baseline levels of CREB phosphorylation in both tissues were increased from postnatal 14 days, and it was proportional to the amount of CREB protein in the cerebellum. In the hippocampus, ECS increased the phosphorylation of CREB at postnatal 21 days, but in the cerebellum, ECS did not increased the phosphorylation of CREB in any age group. CONCLUSION: CREB mediated signal transduction pathways showed developmental and tissue-specific changes. ECS increased the phosphorylation of CREB in the hippocampus by postnatal 21 days, but not in the cerebellum. CREB activation is supposed to be related with the inducdion of c-fos after ECS in the hippocampus. However, the Ser-133 phosphorylation of CREB could not completely explain the developmental and tissue specificity of c-fos induction.

Alpha-2 Adrenoceptor Binding Profile of Natural Products Used to Treat Psychotic illnesses / 대한정신약물학회지

Natural products have long been major sources of pharmaceutical products in medicine. We have undertaken a series of studies designed to characterize the pharmacologic profiles of natural products used to treat psychotic illnesses in Korean traditional medicine. In our previous screening assays, we found that three of plant extracts (Coptidis j, Citrus u, and Phellodendron a) contain active components which show relatively potent binding to alpha-2 adrenoceptors. The present study is to explore pharmacologic activities of extracts as agonism or antagonism by G-protein modulations in radioligand receptor binding study. We have found that two extracts(Coptidis j and Phellodendron a) contain active ingredients which have antagonistic properties to alpha-2 adrenoceptors, whereas one plant extract (Citrus u) has agonistic properties. The demonstration of three plant extracts used to treat psychotic illnesses in Korea may help in the elucidation or their pharmacologic characteristics and provide insights for the development of new psychotropic drugs.

Effects of Polygalae Radix on Apomorphine-Induced Stereotyped Behaviors in Mice / 신경정신의학

OBJECTIVES: This study was to investigate in vivo activities of Polygalae Radix, a natural plant including active components having affinities to central nervous system receptors, using an animal model for psychotic disorders in terms of behavioral psychopharmacology. METHODS: The extracts of Polygalae Radix in two concentrations of 5.0mg/g and 0..5mg/g were administered to mice in order to explore the suppression of apomorphine-induced stereotyped behaviors visually and to compare with the effects of haloperidol and control. 10 mice were tested in each groups. RESULTS: The capacities of suppressing the apomorphine-induced stereotyped behaviors were observed in decreasing order of haloperidol, Polygalae Radix 5.0mg/g, Polygalae Radix 0..5mg/g and control. The extracts of Polygalae Radix in both concentrations suppressed apomorphine- induced stereotyped behaviors significantly, and Polygalae Radix 5.0mg/g was as potent as haloperidol. CONCLUSION: This suggests that Polygalae Radix contain some effective ingredients to influence the central dopamine pathway in vivo. The identification of the chemical structures and the exploration of the biochemical and pharmacological characteristics of active components are to be required through further studies.

Stress Among Chinese, Korean-Chinese and Korean High School Students: A Transcultural Study / 신경정신의학

OBJECT: In order to examine the interaction mechanisms of electroconvulsive shock(ECS) and antipsychotic drug at the level of molecular biology, we observed the effect of chlorpromazine pre-treatment on the activation of mitogen activated protein kinase(MAPBD induced by electroconvulsive shock(ECS) in rat hippocampus. METHODS: Male Sprague-Dawley rats were divided into 2 groups. To the experimental group chlorpromazine(20mg/kg) was given intraperitoneally, 3nd to the control disliked water was given instead. Thirty minutes later, ECS was given and the hippocampus was dissected out 2 minutes thereafter. Immunoblotting with antiphosphotyrosine antibody was carried out, and the signal intensity at 42kDa band was quantitized using densitometer. The obtained result was compared by student t-test between the experimental and the control group. The absolute amount of MAPK was measured by immunoblotting with anti-MAPK antibody. RESULT: The tyrosine phosphorylation of MAPK reached peak at 2 minutes after ECS. However, in the chlorpromazine pre-treated group, the peak level of MAPK tyrosine phosphorylation was significantly attenuated(t= -3.12, df= 14, p=0.008) compared to the control. In contrast to this, the absolute amount of MAPK did not differ between the pretreated and the control group. CONCLUSION: Chlorpromazine attenuated the tyrosine phosphorylation of MAPK by ECS. This finding seems to be related to the fact that chlorpromazine pre-treatment changed the c-fos expression by ECS in rat brain. Antipsychotic drug and ECS might interact at the level of MAPK signal transduction system, and this might explained the observed synergistic elect of two treatment modality.

The mechanism of c-erbB-2 gene product increase in stomach cancer cell lines

c-erbB-2 oncogene encodes a growth factor receptor whose amino acid sequence has extensive homology with human epidermal growth factor receptor. It is frequently overexpressed in human breast, ovary, lung, and stomach cancers, where its overexpression is related significantly to the prognosis. Tl investigate the possible role of c-erbB-2 oncogene in the oncogenesis of stomach cancer, we examined the genetic alterations of c-erbB-2 oncogene in 4 stomach cancer cell lines, SNU-1, SNU-5, SNU-16 and KATO III. There were no differences in c-erbB-2 mRNA level as well as c-erbB-2 gene copy number among them. But gp185-erbB-2, c-erbB-2 gene product, was increased from 2- to 4-fold in SNU-1 and SNU-5 cells, compared with that in SNU-16 or KATO III cells. Our results suggest that post-transcriptional regulation of gp185erbB-2 expression may underlie gp185erbB-2 overexpression in cancer cells.

p53 gene mutation in hepatocellular carcinoma from Korean patients and in established hepatocellular carcinoma cell lines / 대한암학회지

No abstract available.

Correlation of c-erbB-2 protein overexpression in human breast carcinoma with nodal status, tumor size, stage, age and survival / 대한암학회지

No abstract available.

Purification and Characterization of Guanine Aminohydrolase from Rat Cerebrum

Guanine aminohydrolase(GAH;EC 3. 5. 4. 3.) was partially purified 122-fold from rat cerebrum to a specific activity of 7.22 in its per mg protein with a recovery of 7.47% by fractionation with ammonium sulfate, chromatography on DEAE-cellulose and hydroxyapatite, gel filtration on Sephadex G-200, and isoelectric focusing(pH4-6). The molecular weight of partially purified rat cerebral guanine aminohydrolase was estimated to be 110,000. But, in the cerebral cytosol, a rather higher molecular weight form of the enzyme was identified. The activity of the higher molecular weight form of guanine aminohydrolase was increased by dialyzing the cytosol, and it was converted into the lower molecular weight form(M.W.110,000) by addition of 2-mercaptoethanol. The reaction velocity of partially purified guanine aminohydrolase of rat cerebrum disclosed a hyperbolic curve, with its KM being 6.0uM at pH 8.0. The preparation showed high substrate specificity:among the purine nucleotides, nucleosides and bases with amino group, only guanosine and guanine were deaminated by the enzyme, and the reaction rate of the enzyme displayed by guanosine was less than 10% of that by guanine. When observed under the equimolar concentration of the substrate, hypoxanthine as well as inosine inhibited the activity of the rat cerebral guanine aminohydrolase by 9.4 and 7.8%, respectively, while 5-aminoimidazole-4-carboxamide inhibited the activity of it by 38%. The activity was inhibited by p-hydroxymercuric benzoate as well. Complete loss of its activity was observed after 30 minutes incubation at 60 degrees C, suggesting the preparation was heat labile.