Serotonin-induced proliferation of pulmonary arterysmooth muscle cells is serotonin transporter and ERK pathway dependent

AIM: To investigate the effect of serotonin transporter (5-HTT)inhibitor fluoxetine and antisense oligodeoxynucleotide (ODN)to extracelluar signal-regulated kinases (ERKs) on pulmonary arterial smooth muscle cells (PASMCs) proliferation induced by 5-HT. METHODS: Liposomal transfection was used to introduce ODNs to ERK1/2 into cultured rat PASMCs and the transfection efficiency was measured by observing the uptake of the     

The serotonin transporter is present and functional in peripheral arterial smooth muscle

We tested the hypothesis that the 5-HT transporter (5-HTT) is present and functional in peripheral arterial smooth muscle. In aorta and mesenteric resistance arteries, real time RT-PCR and western analyses indicated the presence of 5-HTT mRNA and a 74 kDa 5-HTT protein. Immunohistochemistry localized the transporter to smooth muscle and endothelial cells. 5-HT and the metabolite 5-hydroxyindole acetic acid (5-HIAA) were detected in aorta, carotid, and superior mesenteric arteries using HPLC; the MAOA inhibitor pargyline significantly increased (over 400%) arterial 5-HT concentration. 5-HT was taken up by arteries in a time-dependent manner and uptake was independent of the endothelium, sympathetic nerves, and norepinephrine transporter. 5-HT-induced contraction of normal aorta was potentiated by the 5-HTT inhibitor fluvoxamine. A change in arterial 5-HTT function occurs in deoxycorticosterone (DOCA)-salt hypertension as the potency and threshold of 5-HT in contracting aorta from the DOCA-salt rat was increased by fluoxetine and fluvoxamine (1 micromol/L; DOCA fluvoxamine -log EC50 [mol/L] = 6.85 +/- 0.08, DOCA-control = 6.44 +/- 0.08); expression of transporter was significantly increased in aorta of DOCA salt rats (145% Sham). These studies show for the first time the presence of the 5-HTT in peripheral arterial smooth muscle and raise the question as to the function of the 5-HTT in regulating peripheral effects of 5-HT.     

Inhibitory effect of antisense oligodeoxynucleotide to p44／p42 MAPK on angiotensin II-induced hypertrophic response in cultured neonatal rat cardiac myocyte

AIM: To explore the inhibitory effect of antisense oligonucleotide (ODN) to mitogen activated protein kinase(MAPK) on cardiomyocyte hypertrophy induced by angiotensin Ⅱ (Ang Ⅱ). METHODS: A 17-mer phosphorothioate-protected antisense ODN directed against the initiation of translation sites of the p42 and p44 MAPK isoforms byliposomal transfection was applied to inhibit the translation of p44/p42 MAPK mRNA. The sense and random ODNs to p44/p42MAPK were used as sequence controls. Neonatal cardiac myocytes were exposed to Ang Ⅱ (10nmol/L) for 5 min and then harvested in lysis buffer for the measurement of the activity and the phosphorylated protein content of p44/p42MAPK that were tested by P-81 phosphocellulose filter paper method and Western blotting, respectively. The rate of protein synthesis by [^3H]leucine incorporation and the diameter of cell were measured after exposure to Ang Ⅱ for 24 h and 72 h, respectively. RESULTS: In cardiac myocyte Ang Ⅱ increased p44/p42MAPK activity and phosphorylated protein content by 140 % and 699 %, and also increased [^3H]leucine incorporation and cell diameter by 40 % and 27 %. c-fos and c-myc mRNAs were induced significantly after exposure to Ang Ⅱ. Antisense ODN to p44/p42MAPK (0.2 μmol/L) reduced Ang Ⅱ-induced MAPK activity by 30 %,and phophorylated MAPK protein expression by 59 % in cardiac myocyte, and inhibited c-fos and c-myc mRNA expression induced by Ang Ⅱ by 44 % and 43 %, respectively. The diameter and the rate of protein synthesis of cardiac myocyte induced by Ang Ⅱ were decreased by 16 % and 22 % after pretreatment with antisense ODN to p44/p42MAPK. CONCLUSION: Antisense ODN to p44/p42 MAPK inhibited the increase of rate of protein synthesis,and the augmentation of cell diameter and expression of c-fos and c-myc mRNA induced by Ang Ⅱ in culturedcardiac myocytes, p44/p42 MAPK played a critical role in the hypertrophic response induced by Ang Ⅱ in cultured neonatal rat cardiac myocytes.     

Antisense down-regulation of thymidylate synthase to suppress growth and enhance cytotoxicity of 5-FUdR, 5-FU and Tomudex in HeLa cells.

1. Thymidylate synthase (TS), the key enzyme in de novo synthesis of thymidine, is an important target for antitumour chemotherapy. It was hypothesized that antisense oligonucleotide down-regulation of TS mRNA would decrease TS levels and enhance the cytotoxicity of inhibitors of TS, including the pyrimidine analogues 5-fluorouracil (5-FU) and 5-fluorodeoxyuridine (5-FUdR), and the folate analogue Tomudex (ICI D1694; N-(5-[N-(3, 4-dihydro-2-methyl-4-oxoquinazolin-6-ylmethyl)-N-methylamino ]-2-theon yl-L-glutamic acid). 2. 2'-Methoxyethoxylated, phosphorothioated 20-mer oligodeoxynucleotides (ODNs), complementary to various sequences in TS mRNA, were synthesized, along with control oligomers consisting of the same, respective bases in randomized order, against which all the biological effects were compared. Following a 6-h transfection of HeLa cells using polycationic liposome at 3 microg ml(-1), ODN 83 (50 nM), complementary to a region in the 3'-untranslated region of the TS mRNA, decreased TS mRNA levels by approximately 70% within 24 h. ODN 83 also decreased TS enzyme activity, as measured by binding of TS to radiolabelled 5-fluorodeoxyuridine monophosphate. In addition to inhibiting proliferation by up to approximately 40%, ODN 83 enhanced the cytotoxicity of Tomudex or 5-FU, added 1 day following transfection, by 50 - 60%. ODN 83 also enhanced sensitivity to 5-FUdR by 70%, but did not affect the toxicity of cisplatin, chlorambucil, melphalan, doxorubicin, ionizing radiation, paclitaxel, or irinotecan. 3. These data indicate that antisense ODN down-regulation of TS can inhibit human tumour cell proliferation and enhance the efficacy of TS-targeted drugs.     

反义碱性成纤维细胞生长因子寡核苷酸对血管紧张素Ⅱ诱导培养的 …

AIM: To study the effect of antisense basic fibroblast growth factor (bFGF) oligonucleotides (ODN) transfection on the growth of cultured aortic smooth muscle cells (SMC) in spontaneously hypertensive rats (SHR). METHODS: Using cationic liposome-mediated method, antisense bFGF ODN were introduced into SMC, bFGF gene expression was detected by Northern blotting, cell hyperplasia was evaluated by [3H] thymidine incorporation and cell counting. RESULTS: Transfection of antisense bFGF ODN (5 mumol.L-1) almost completely inhibited enhanced bFGF mRNA expression and inhibited cell proliferation induced by angiotensin II (Ang 1 mumol.L-1). In basal state and Ang-stimulated state, [3H]thymidine incorporation was inhibited by 26.5% (P < 0.01) and 42.0% (P < 0.01) and cell number was inhibited by 17.3% (P < 0.01) and by 22.2% (P < 0.01), respectively. CONCLUSION: The transfection of antisense bFGF ODN into cultured SMC effectively suppressed bFGF mRNA expression and inhibited the SMC proliferation induced by Ang.     

Genetic variation in 5-hydroxytryptamine transporter expression causes adaptive changes in 5-HT₄ receptor levels

Genetic variation in 5-HT transporter (5-HTT) expression is a key risk factor for psychiatric disorder and has been linked to changes in the expression of certain 5-HT receptor subtypes. This study investigated the effect of variation in 5-HTT expression on 5-HT? receptor levels in both 5-HTT knockout (KO) and overexpressing (OE) mice using autoradiography with the selective 5-HT? receptor radioligand, [3H]SB207145. Compared to wild-type (5-HTT?/?) controls, homozygous 5-HTT KO mice (5-HTT?/?) had reduced 5-HT? receptor binding site density in all brain regions examined (35-65% of 5-HTT?/?). In contrast, the density of 5-HT? receptor binding sites was not significantly different between heterozygous 5-HTT KO mice (5-HTT?/?) and 5-HTT?/? mice. The 5-HT synthesis inhibitor p-chlorophenylalanine (250 mg/kg twice daily for 3 d) abolished the difference in 5-HT? binding between 5-HTT?/? and 5-HTT?/? mice in all brain regions. Compared to wild-type (WT) littermate controls, 5-HTT OE mice had increased 5-HT? binding density across all brain regions, except amygdala (118-164% of WT) and this difference between genotypes was reduced by the 5-HTT inhibitor, fluoxetine (20 mg/kg twice daily, 3 d). Together, these findings suggest that variation in 5-HTT expression causes adaptive changes in 5-HT? receptor levels which are directly linked to alterations in 5-HT availability.     

间尼索地平对5-羟色胺诱导大鼠肺动脉平滑肌细胞增殖和迁移的影响及其机制

目的探讨间尼索地平(m-Nis)对5-羟色胺(5-HT)诱导的大鼠肺动脉平滑肌细胞(PASMCs)增殖和迁移的影响,并深入研究其作用机制。方法采用植块法培养大鼠PASMCs。实验分为6组:空白对照组、5-HT(1μmol·L-1)组,m-Nis(10-5、10-6、10-7、10-8mol.L-1)组。噻唑蓝(MTT)比色法、Transwell迁移小室法分别测定PASMCs的增殖和迁移,Western blot法检测大鼠PASMCs中增殖细胞核抗原(PCNA)的蛋白表达及细胞外信号调节激酶1和2(ERK1/2)的磷酸化水平,研究m-Nis对ERK1/2/MAPK信号通路的影响。结果不同浓度m-Nis明显抑制了5-HT诱导的大鼠PASMCs增殖(P<0.05或P<0.01)和迁移(P<0.01),并呈现一定的浓度依赖性;另外,Western blot结果显示m-Nis对5-HT诱导的大鼠PASMCs中PCNA的蛋白表达有不同程度的抑制作用(P<0.05或P<0.01),10-5,10-6,10-7mol.L-1m-Nis还明显抑制了5-HT诱导的大鼠PASMCs中ERK1/2磷酸化水平的升高,p-ERK1/2/ERK1/2比值均有不同程度地降低(P<0.05或P<0.01)。结论m-Nis对5-HT诱导的大鼠PASMCs增殖和迁移有明显的抑制作用,可能与其抑制PCNA蛋白表达及ERK1/2/MAPK信号通路有关。     

Desensitization of 5-HT(1A) autoreceptors by a low chronic fluoxetine dose effect of the concurrent administration of WAY-100635.

Using microdialysis, receptor autoradiography and in situ hybridization, we examined the effects of fluoxetine alone or with WAY-100635 on: (a) extracellular 5-HT in frontal cortex; and (b) density and sensitivity of 5-HT(1A) autoreceptors in rat brain. WAY-100635 (0.3 mg/kg, s.c.) doubled the increase in extracellular 5-HT produced by fluoxetine (3 mg/kg, i.p.) in frontal cortex. Two-week minipump treatments with these daily doses significantly raised extracellular 5-HT to 275 +/- 33% (fluoxetine) and 245 +/- 10% (fluoxetine plus WAY-100635) of controls. Fluoxetine 3 mg/kg.day desensitized dorsal raphe 5-HT(1A) autoreceptors, an effect prevented by the concurrent WAY-100635 administration. However, WAY-100635 (alone or with fluoxetine) did not change 5-HT(1A) autoreceptor sensitivity. The density of 5-HT(1A) receptors and its encoding mRNA, was unaffected by these treatments. These results suggest that prolonged blockade of 5-HT(1A) receptors in vivo prevents the autoreceptor desensitization induced by fluoxetine but does not result in receptor sensitization.     

Role of uptake inhibition and autoreceptor activation in the control of 5-HT release in the frontal cortex and dorsal hippocampus of the rat

1. Using brain microdialysis, we compared the relative role of 5-hydroxytryptamine (5-HT; serotonin) blockade and somatodendritic 5-HT(1A) and/or terminal 5-HT(1B) autoreceptor activation in the control of 5-HT output. 2. Fluoxetine (10 mg kg(-1) i.p.) doubled the 5-HT output in frontal cortex and dorsal hippocampus. The 5-HT(1A) receptor antagonist WAY 100635, (0.3 mg kg(-1) s.c.) potentiated the effect of fluoxetine only in frontal cortex (to approximately 500 % of baseline). 3. Methiothepin (10 mg kg(-1) s.c.) further enhanced the 5-HT rise induced by fluoxetine+WAY 100635, to 835+/-179% in frontal cortex and 456+/-24% in dorsal hippocampus. Locally applied, methiothepin potentiated the fluoxetine-induced 5-HT rise more in the former area. 4. The selective 5-HT(1B) receptor antagonist SB-224289 (4 mg kg(-1) i.p.) enhanced the effect of fluoxetine (10 mg kg(-1) i.p.) in both areas. As with methiothepin, SB-224289 (4 mg kg(-1) i.p.) further enhanced the 5-HT increase produced by fluoxetine+WAY 100635 more in frontal cortex (613+/-134%) than in dorsal hippocampus (353+/-59%). 5. Locally applied, fluoxetine (10 - 300 microM; EC(50)=28 - 29 microM) and citalopram (1 - 30 microM; EC(50)=1.0 - 1.4 microM) increased the 5-HT output two to three times more in frontal cortex than in dorsal hippocampus. These data suggest that the comparable 5-HT increase produced by systemic fluoxetine in frontal cortex and dorsal hippocampus results from a greater effect of reuptake blockade in frontal cortex that is offset by a greater autoreceptor-mediated inhibition of 5-HT release. As a result, 5-HT autoreceptor antagonists preferentially potentiate the effect of fluoxetine in frontal cortex.     

Regulation of ion transport by 5-hydroxytryptamine in rat colon

1. 5-Hydroxytryptamine (5-HT) modulates the motility and secretion of the gastrointestinal tract. To examine the direct effect of 5-HT on the secretions of colonic epithelial cells, a short-circuit current was used to measure electrolyte transport in the rat stripped distal colon. A neuronal Na+ channel blocker and a cyclo-oxygenase inhibitor were routinely added in experiments to abolish the effects of the enteric nervous system and endogenous prostaglandin, respectively. 2. Basolateral application of 5-HT (10 micromol/L) induced an increase in the short circuit current (ISC). Removal of extracellular Cl-, HCO3- or both resulted in a 59.6, 76.4 and 90% reduction of 5-HT-elicited responses, respectively. The Ca(2+)-dependent Cl- channel blocker 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) had no effect on the 5-HT-induced increase in ISC, but the selective cystic fibrosis transmembrane conductance regulator (CFTR) channel blocker glibenclamide (1 mmol/L) inhibited 5-HT-induced increases in ISC by approximately 92.9%. Removal of apical Na+ reduced the 5-HT-induced increase in ISC by 33.3%. 3. Basolateral pretreatment with 100 micromol/L bumetanide (an inhibitor of the Na(+)-K(+)-2Cl- cotransporter), 200 micromol/L DIDS (an inhibitor of the Na(+)-HCO3- transporter or the Cl-/HCO3- exchanger) or both decreased the DeltaISC induced by 5-HT by approximately 75.5, 59.0 and 86.3%, respectively. Removal of basolateral Na+ also reduced the current evoked by 5-HT. 4. The selective 5-HT4 antagonist GR113808 (1 micromol/L) totally abolished the 5-HT-induced increase in ISC, whereas 2-methyl-5-HT (100 micromol/L) induced a weak ISC response. 5. In conclusion, the present study has demonstrated that 5-HT can elicit Cl(-)- and HCO3- anion secretion and Na+ absorption by acting directly on colonic epithelial cells via 5-HT4 receptors.     

Bradykinin potentiates 5-HT3 receptor-mediated current in rat trigeminal ganglion neurons

AIM: To explore the modulatory effect of bradykinin (BK) on 5-HT(3 )receptor-mediated current in trigeminal ganglion (TG) neurons in rats. METHODS: The whole-cell patch-clamp technique was used to record 5-HT-activated currents (I(5-HT)) in neurons freshly dissociated from rat TG. Drugs were applied by rapid solution exchange. RESULTS: The majority of the neurons examined responded to 5-HT applied externally with an inward current (76.3%, 74/97) that could be blocked by the 5-HT(3 )receptor antagonist, ICS-205,930 (10(-6) mol/L). In 66 of the 74 cells sensitive to 5-HT (89.2%), pretreatment for 30 s with BK (10(-6)-10(-10) mol/L) could potentiate I(5-HT) with the maximal modulatory effect occurring at 10(-7) mol/L BK (71.6%+/-4.9%). BK shifted the 5-HT concentration-response curve upwards with an increase of 68.9%+/-7.2% in the maximal current response, but with no significant change in the EC(50) value (19.1+/-3.2 mumol/L vs 20.9+/-3.5 micromol/L; t-test, P>0.05; n=8). BK potentiated I(5-HT) in a holding potential-independent manner and did not alter the reverse potential of I(5-HT). This BK-induced potentiation of I(5-HT) was almost completely blocked by Hoe 140 (5*10(-7) mol/L), a selective B2 BK receptor antagonist, and was removed after intracellular dialysis of GF-109203X (2 micromol/L), a selective protein kinase C (PKC) inhibitor, with the re-patch clamp. CONCLUSION: Pre-application of BK exerts an enhancing effect on I(5-HT) via a PKC-dependent pathway in rat TG neurons, which may explain the peripheral mechanism of pain and hyperalgesia caused by, for example, tissue damage and inflammation.     

Sp1反义寡核苷酸抑制Jurkat T细胞hTERT表达而抑制端粒酶活性(英文)

目的:研究转录因子Sp1反义寡核苷酸(ODN)对Jurkat T细胞端粒酶活性和端粒酶催化亚基hTERT表达的影响。方法:设计Sp1反义ODN并用脂质体转染细胞,用端粒酶PCR-ELISA方法检测端粒酶活性;用逆转录PCR方法检测Sp1和hTERT mRNA水平,用Western blot检测蛋白水平。结果:sp1反义ODN(1μmol/L)明显抑制Jurkat T细胞Sp1 mRNA和蛋白表达,抑制率分别为44.8％(P<0.05)和57％(P<0.01),并抑制hTERT mRNA表达,抑制率为43.7％(P<0.01);当浓度从0.25到2.0μmol/L,Sp1反义ODN对端粒酶活性抑制率从27.1％到64.6％,呈明显的剂量依赖性关系。结论:Sp1反义寡核苷酸通过抑制hTERT mRNA表达而抑制端粒酶活性。     

Lipid-based delivery of combinations of antisense oligodeoxynucleotides for the in vitro inhibition of HIV-1 replication

We evaluated a new approach to AIDS therapy by using combinations of oligodeoxynucleotides (ODNs), delivered with a lipid-based carrier system, that target different HIV viral genome sites. We identified some of the factors that seem to influence the effectiveness of a combination strategy in cell cultures including ODN concentrations, type of infection (acute vs chronic), backbone modification of the ODN, and the number of sequences. When delivered by the DLS carrier system, some advantages of using a combination of ODNs over treatment with only one ODN could be observed in acute infection assays but not in the chronic infection model. These results suggest that in the acute infection model, the 3 different antisense ODNs in the “cocktail” might block an early step of virus replication by combined inhibitory effects. Various combinations of phosphorothioate-modified (PS) and unmodified oligonucleotides delivered by the DLS system were compared for their antiviral activity in a long-term acute assay using HIV-1 (IIIB strain)-infected MOLT-3 cells. The most effective combination had 3 phosphorothioate antisense ODNs: Srev, SDIS, and SPac (>99% inhibition at 100 pM). However, the additive effect determined when using ODN combinations was rather low, revealing the high level of nonsequence specificity in HIV-1 cell culture models. Data illustrated the high sequence nonspecific activity of ODNs, especially when comparing activity of antisense ODNs with activity of random control sequence ODNs. The latter exhibited an inhibitory effect similar to that of antisense ODNs under our experimental conditions. Nevertheless, we demonstrated that it is possible to achieve high anti-HIV activity by using, in combination, picomolar range concentrations of antisense oligonucleotides complexed to a lipid-based carrier system such as the DLS system, without increasing cell toxicity.     

CCDPK反义寡核苷酸抑制bFGF诱导的大鼠血管平滑肌细胞增殖(英文)

AIM: To investigate the role of Ca(2+)-calmodulin dependent protein kinase (CCDPK) on basic fibroblast growth factor (bFGF)-induced vascular smooth muscle cell (VSMC) proliferation and the inhibitory effect of antisense CCDPK oligonucleotides (ODN). METHODS: Before being exposed to bFGF, cultured rat VSMC CCDPK activity was inhibited by pretreatment with either a phosphorothioate-protected 17-mer antisense CCDPK ODN-directed against the initiation of translation sites of the p42 and p44 CCDPK isoform or with CCDPK kinase inhibitor PD98059. All ODN were introduced into cells by liposomal transfection. DNA synthesis was measured by [3H]thymidine incorporation. P44- and p42-CCDPK protein expression and phosphorylation were measured by Western blot. RESULTS: PD98059 inhibited bFGF-induced phosphorylation of CCDPK and DNA synthesis. Antisense CCDPK ODN 0.2-0.8 mumol.L-1 reduced both p44- and p42-CCDPK expression and phosphorylation of CCDPK in a concentration-dependent manner and DNA synthesis induced by bFGF. Lipofectin alone or sense and random CCDPK ODN did not affect p44- and p42-CCDPK protein expression or bFGF-induced phosphorylation of CCDPK or DNA synthesis. CONCLUSION: bFGF-stimulated rat VSMC proliferation is mediated by CCDPK. The antisense CCDPK ODN can inhibit bFGF-induced VSMC proliferation through down-regulating p44- and p42-CCDPK level.     

丝裂素活化的蛋白激酶反义寡脱氧核苷酸防治血管内膜增殖

目的：探讨Ca^2 -钙调蛋白依赖性蛋白激酶（丝裂素活化的蛋白激酶）（CCDPK）在生长因子诱导体外培养大鼠血管平滑肌细胞增殖中的作用及反义CCDPK寡脱氧核苷酸（ODN）对球囊损伤后大白鼠血管内膜增生的抑制作用。方法：利用脂质体转染17－mer CCDPK反义ODN进入培养的血管平滑肌细胞以抑制CCDPK活性,设正义及随机ODN作对照。用蛋白质印迹法测定CCDPK表达。[^3H]胸腺嘧啶核苷酸掺入测定平滑肌细胞DNA合成。用2F球囊导管造成大白鼠颈动脉再狭窄模型,利用多聚胶F127－ODN系统由血管外膜部位给药。于损伤后2周取样,固定及HE染色观察内膜增生情况。FITC标记的ODN观察体内外给药方法的分布及吸收情况。结果：CCDPK反义ODN能明显抑制PDGF及ET诱导的CCDPK蛋白表达及[^3H]胸腺嘧啶核苷酸掺入。在大鼠颈动脉再狭窄模型,能明显抑制血管内膜增生。结论：CCDPK介导了PDGF及ET诱导的血管平滑肌细胞增殖。针对p42-和p44-CCDPK起始部位设计的17－mer反义ODN能有效抑制生长因子诱导的血管平滑肌细胞的增殖及球囊损伤大鼠血管内膜增生。     

寡核苷酸聚赖氨酸修饰物的脂质体制备及其对HepG2细胞的细胞毒活性研究

目的研究反义寡核苷酸的聚赖氨酸修饰物对脂质体包封率的影响及对HepG2细胞活性的初步测定。方法利用反义药物的聚赖氨酸修饰物,采用薄膜分散法制备反义寡核苷酸及其聚赖氨酸修饰物的脂质体;紫外分光光度法测定包封率的差异并考察对HepG2细胞细胞毒活性的影响。结果高密度正电荷的聚赖氨酸与带负电荷的反义寡核苷酸偶联后,脂质体的载药量大大增加,并且细胞的摄入量增加,对HepG2细胞生长具有抑制作用。结论聚赖氨酸修饰物增加了反义寡核苷酸的脂质体包封率,有效诱导人肝癌细胞的凋亡作用。     

Antisense oligonucleotides targeted to the p53 gene modulate liver regeneration in vivo.

The rapidly proliferating cells of the regenerating liver after partial hepatectomy (PH) present a reproducible in vivo model to study the functional role of the tumor suppressor gene p53. The present study uses the rat 70% PH model along with systemic administration of three different structural types of antisense oligonucleotides (ODNs) designed to suppress p53 expression. We tested the hypothesis that antisense ODNs can inhibit the expression of p53, resulting in the loss of the G(1)-S cell cycle checkpoint and an altered pattern of liver regeneration. Intraperitoneal administration of 5 mg/kg/day antisense phosphorothioate ODN after 70% PH resulted in reduced expression of the p53 protein in the regenerating liver. There were concomitant increases in weight gain of remnant-regenerating liver and expression of proliferating cell nuclear antigen and p21(waf-1) compared with either saline or 5 mg/kg/day mispaired phosphorothioate ODN treatment. Flow cytometric analysis of DNA content of isolated hepatocytes revealed a reduction in the G(0)/G(1) cell population and accumulation of cells with more than 4n DNA in antisense-treated rats. The regenerating livers had significantly diminished cytochrome P-450 (CYP) enzyme activities. Rats treated with p53 antisense ODNs, but not saline or mispair ODN controls, had significantly elevated CYP activities. These observations functionally link the expression of p53 with diminished expression of several CYP isoforms in the liver regeneration model.     

Effects of fluoxetine and norfluoxetine on 5-hydroxytryptamine metabolism in blood platelets and brain after administration to rats

The effects of intraperitoneal administration of fluoxetine (2.5, 5, 10 or 20 mg kg(-1)) and norfluoxetine (10 mg kg(-1)) on 5-hydroxytryptamine (5-HT) and 5-hydroxyindole-3-acetic acid (5-HIAA) metabolism were examined in the blood platelets and brain of rats killed 3 h after a single dose. Several experiments were performed to evaluate the effect of norfluoxetine. Plasma 5-HT concentrations decreased significantly (48%) compared with control group results 3 h after administration of a single dose of fluoxetine (10 or 20 mg kg(-1)). Similar plasma 5-HT levels, 0.54+/-0.04 and 0.56+/-0.09 mg L(-1), respectively, were observed after administration of 10 mg kg(-1) fluoxetine or norfluoxetine. In the same way 5-HIAA levels in whole brain were similar, 0.36+/-0.03 and 0.34+/-0.01 microg(-1), respectively, after administration of fluoxetine or norfluoxetine. There was a good correlation between plasma and brain levels of fluoxetine (0.962) and norfluoxetine (0.957). The results suggest that fluoxetine and norfluoxetine lead to reduced levels of 5-HT in platelets and of 5-HIAA in the brain. Like the parent drug, norfluoxetine is a potent and selective inhibitor of 5-HT uptake.