Serotonin regulates osteoclast differentiation through its transporter.

5-HTT mediates antidepressant-sensitive clearance of 5-HT after its release into neural synapses. We found increased expression of 5-HTT in RANKL-induced osteoclast-like cells. Fluoxetine ( Prozac ), an inhibitor of 5-HTT, reduced osteoclast differentiation but not activation. Reserpine, an inhibitor of 5-HT intracellular transport, potentiated differentiation. These results indicate a role for 5-HTT in osteoclast function and suggest that commonly used antidepressive agents may affect bone mass. INTRODUCTION: Interactions between the serotonergic and skeletal systems are suggested by various clinical observations but are poorly understood. MATERIALS AND METHODS: Using gene microarrays, we found that the serotonin transporter (5-HTT) was strongly expressed in RANKL-induced osteoclasts. Using RANKL stimulation of RAW264.7 cells and mouse bone marrow cells as a model system for osteoclast differentiation, we studied the possible role/s of the different components of the serotonin (5-HT) system on the differentiation process. RESULTS: Osteoclast 5-HTT exhibited typical 5-HT uptake activity that was inhibitable by Fluoxetine ( Prozac ) (Prozac). Fluoxetine ( Prozac ) reduced osteoclast differentiation but did not inhibit the activation of preformed osteoclasts, whereas the addition of 5-HT itself enhanced differentiation. Fluoxetine ( Prozac )-treated osteoclast precursors had reduced NF-kappa B activation and elevated inhibitory protein kappa B alpha (I kappa B alpha) levels compared with untreated cells. 5-HT, on the other hand, resulted in activation of NF-kappa B. Reserpine inhibition of intracellular transport of 5-HT into cytoplasmic vesicles potentiated RANKL-induced osteoclast formation, suggesting the importance of intracellular 5-HT in regulating osteoclast differentiation. Reserpine also modestly enhanced the expression of the osteoclast marker TRACP in the absence of RANKL. CONCLUSIONS: Taken together, these data suggest that the 5-HT system plays an important role in bone homeostasis through effects on osteoclast differentiation and implies that commonly used antidepressive agents may affect bone mass.

Effects of CYP2C19 genotype and CYP2C9 on Fluoxetine ( Prozac ) N-demethylation in human liver microsomes.

AIM: The present study was designed to define the kinetic behavior of Fluoxetine ( Prozac ) N-demethylation in human liver microsomes and to identify the isoforms of cytochrome P-450 (CYP) involved in this metabolic pathway. METHODS: The kinetics of Ne formation of norFluoxetine ( Prozac ) was determined in human liver microsomes from six genotyped CYP2C19 extensive metabolizers (EM). The correlation studies between the Fluoxetine ( Prozac ) N-demethylase activity and various CYP enzyme activities were performed. Selective inhibitors or chemical probes of various cytochrome P-450 isoforms were also employed. RESULTS: The kinetics of norFluoxetine ( Prozac ) formation in all liver microsomes were fitted by a single-enzyme Michaelis-Menten equation (mean Km=32 micromol/L+/-7 micromol/L). Significant correlations were found between N-demethylation of Fluoxetine ( Prozac ) at both 25 micromol/L and 100 micromol/L and 3-hydroxylation of tolbutamide at 250 micromol/L (r1=0.821, P1=0.001; r2=0.668, P2=0.013), respectively, and S-mephenytoin 4'-hydroxylase activity (r=0.717, P=0.006) at high substrate concentration of 100 micromol/L. S-mephenytoin (SMP) (a CYP2C19 substrate) at high concentration and sulfaphenazole (SUL) (a selective inhibitor of CYP2C9) substantially inhibited norFluoxetine ( Prozac ) formation. The reaction was minimally inhibited by coincubation with chemical probe, inhibitor of CYP3A4 (triacetyloleandomycin, TAO). The inhibition of Fluoxetine ( Prozac ) N-demethylation at high substrate concentration (100 micromol/L) was greater in PM livers than in EM livers (73 % vs 45 %, P < 0.01) when the microsomes were precoincubated with SUL plus TAO. CONCLUSION: Cytochrome P-450 CYP2C9 is likely to be a major CYP isoform catalyzing Fluoxetine ( Prozac ) N-demethylation in human liver microsomes at a substrate concentration close to the therapeutic level, while polymorphic CYP2C19 may play a more important role in this metabolic pathway at high substrate concentration.

Regulation of central corticosteroid receptors following short-term activation of serotonin transmission by 5-hydroxy-L-tryptophan or Fluoxetine ( Prozac ).

Alterations of the hypothalamic-pituitary-adrenal (HPA) axis function characterized by a decreased negative feedback capacity are often associated with affective disorders and are corrected by treatment with antidepressant drugs. To gain a better understanding of the effects of the antidepressant drug Fluoxetine ( Prozac ), a specific serotonin (5-HT) reuptake inhibitor, on central corticosteroid receptors, the effects of short-term activation of serotonin transmission on central corticosteroid receptor expression were analysed in adrenalectomized (ADX) rats either supplemented or not with corticosterone. Serotonin transmission was stimulated either by a single injection of the 5-HT precursor, 5-hydroxy-L-tryptophan (5-HTP), or by a 2-day treatment with Fluoxetine ( Prozac ). In ADX rats, administration of 5-HTP decreased hippocampal mineralocorticoid (MR) and glucocorticoid (GR) receptor numbers 24 h later, while their respective mRNAs were unchanged and these effects of 5-HTP were mediated by 5-HT2 receptors. In the hypothalamus, GR mRNAs and binding sites decreased 3 h and 24 h after 5-HTP, respectively. By contrast, Fluoxetine ( Prozac ) treatment increased hippocampal MR and GR mRNAs and MR binding sites while GR number remained unchanged. In ADX rats supplemented with corticosterone, 5-HTP and Fluoxetine ( Prozac ) treatment had the same effects on corticosteroid receptors compared to those observed in non supplemented ADX rats: 5-HTP decreased hippocampal MR and GR and hypothalamic GR while Fluoxetine ( Prozac ) treatment increased hippocampal MR. These results show that short-term stimulation of 5-HT transmission by 5-HTP decreases hippocampal and hypothalamic corticosteroid receptor numbers through a corticosterone-independent mechanism. It is hypothesized that the delayed maximal increase in extracellular 5-HT contents after Fluoxetine ( Prozac ) treatment, due to negative feedback regulations induced by the activation of 5-HT1A and 5-HT1B autoreceptors, is not the primary cause for the delayed normalization of corticosteroid receptor numbers that regulates the HPA axis functioning.

Fluoxetine ( Prozac ) pharmacokinetics and effect on CYP2C19 in young and elderly volunteers.

The objective of this study was to assess in both young and elderly volunteers the pharmacokinetics of Fluoxetine ( Prozac ) and norFluoxetine ( Prozac ) and effects on cytochrome P450 (CYP) 2C19. Male volunteers aged 18 to 40 years (N = 14) or older than 65 years (N = 16) received Fluoxetine ( Prozac ) 20 mg/day for 6 weeks and Fluoxetine ( Prozac ) 40 mg/day for an additional 6 weeks. Blood was drawn over a 24-hour period after the initial dose and after 6 weeks and 12 weeks to determine AUC0-24, Cmax, and tmax; weekly to evaluate predose levels (C0); and over a 3-week period after discontinuation to evaluate washout (t1/2). Mephenytoin was used to assess CYP2C19 activity before and after 6 weeks and 12 weeks of Fluoxetine ( Prozac ). Fluoxetine ( Prozac ) AUC0-24, C0, and Cmax did not differ in young and elderly subjects. The norFluoxetine ( Prozac ) C0 was 22% lower in elderly subjects (p < .05), with comparable decreases in AUC0-24 and Cmax. In the elderly volunteers, the t1/2 for Fluoxetine ( Prozac ) was 25% longer (5.0 vs. 4.0 days) and for norFluoxetine ( Prozac ) was 33% longer (20 vs. 15 days), although variability and sample size precluded statistical significance. Fluoxetine ( Prozac ) dosing inhibited CYP2C19 activity in both age groups, increasing the (S)- to (R)-mephenytoin ratio 3- to 4-fold (p < .01). The half-lives of Fluoxetine ( Prozac ) and norFluoxetine ( Prozac ) at 40 mg/day were longer than commonly reported in the literature and may be longer in elderly subjects. Fluoxetine ( Prozac ) substantially inhibited the metabolism of the CYP2C19 substrate (S)-mephenytoin.

A rapid HPLC-DAD method for the analysis of Fluoxetine ( Prozac ) and norFluoxetine ( Prozac ) in plasma from overdose patients.

There is a need for fast, simple and reliable analytical methods for the analysis of Fluoxetine ( Prozac ) and norFluoxetine ( Prozac ) in patients who voluntarily or involuntarily have taken an overdose of the drug. A new liquid chromatographic method with diode array detection is presented herein for the determination of Fluoxetine ( Prozac ) and its main active metabolite in human plasma for toxicological purposes. A mobile phase composed of acetonitrile and aqueous tetramethylammonium perchlorate allows to obtain the complete separation of the analytes on a C18 reversed phase column. The fast and accurate sample pre-treatment step is carried out by means of solid-phase extraction using hydrophilic-lipophilic balance cartridges and loading 100 microL of plasma only. This procedure gives satisfactory extraction yield values, as well as good plasma sample purification from matrix interference. Linearity was obtained in the 150-3000 ng/mL range for both analytes. Selectivity with respect to other psychotropic drugs was satisfactory. The method seems to be suitable for the analysis of Fluoxetine ( Prozac ) and its metabolite in human plasma for depressed patients in overdose.

Effects of Fluoxetine ( Prozac ) and norFluoxetine ( Prozac ) on 5-hydroxytryptamine metabolism in blood platelets and brain after administration to rats.

The effects of intraperitoneal administration of Fluoxetine ( Prozac ) (2.5, 5, 10 or 20 mg kg(-1)) and norFluoxetine ( Prozac ) (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 ( Prozac ). Plasma 5-HT concentrations decreased significantly (48%) compared with control group results 3 h after administration of a single dose of Fluoxetine ( Prozac ) (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 ( Prozac ) or norFluoxetine ( Prozac ). 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 ( Prozac ) or norFluoxetine ( Prozac ). There was a good correlation between plasma and brain levels of Fluoxetine ( Prozac ) (0.962) and norFluoxetine ( Prozac ) (0.957). The results suggest that Fluoxetine ( Prozac ) and norFluoxetine ( Prozac ) lead to reduced levels of 5-HT in platelets and of 5-HIAA in the brain. Like the parent drug, norFluoxetine ( Prozac ) is a potent and selective inhibitor of 5-HT uptake.

Correlations for serotonin levels and measures of mood in a nonclinical sample.

The Beck Depression Inventory is frequently used to detect depression and its severity because depression is a prevalent mood disorder and is commonly treated by prescription of selective serotonin-reuptake inhibitors such as Prozac. The importance of serotonin (5-HT) in the treatment of major depression is evident but the nature of this involvement is unclear. In this study, the characteristics of platelets are employed as a peripheral model of the neuron to estimate central serotonergic activity, which is a consequence of numerous factors including 5-HT2 receptor sensitivity. The greater the sensitivity of the platelet serotonin receptors, the lower the concentration of serotonin required to mobilise a particular amount of calcium from internal stores through serotonin stimulation. Hence, Platelet 5-HT2 receptor sensitivity is inferred from the concentration of serotonin that is required to produce half maximal intracellular calcium mobilisation (EC50). In the present study, the correlation of -.422 between scores on the Beck Depression Inventory and EC50 in a sample of 49 university students was significant, implying that mood is significantly related to 5-HT2 receptor sensitivity, such that increases in depressed mood are accompanied by increases in 5-HT2 receptor sensitivity.

Chronic Fluoxetine ( Prozac ) treatment upregulates 5-HT uptake sites and 5-HT2 receptors in rat brain: an autoradiographic study.

This study was undertaken to investigate the effect of chronic treatment with Fluoxetine ( Prozac ), a selective serotonin uptake inhibitor used widely in the treatment of depression, on the distribution and density of 5-HT uptake sites, 5-HT2 receptors, and vesicular amine uptake sites in rat brain. Fluoxetine ( Prozac ) (10 mg/kg i.p.) was administered daily for 21 days. The density of 5-HT uptake sites labelled by Paroxetine ( Paxil ), 5-HT2 receptors labelled by ketanserin in presence of tetrabenazine and vesicular amine uptake sites labelled by ketanserin in the presence of mianserin were measured by quantitative autoradiography in 22 areas of rat brain, using coronal tissue sections. Chronic administration of Fluoxetine ( Prozac ) produced significant increases in the density of 5-HT uptake sites in layers of frontoparietal cortex (by 32-43%), of striate cortex (by 55%), in CA1 field of hippocampus (by 111%) and in superior colliculus (by 20%). Fluoxetine ( Prozac ) treatment also resulted in upregulation of 5-HT2 receptors in layers of frontoparietal cortex (31-38%) and in CA2-3 fields of hippocampus (by 39%). The density of tetrabenazine-sensitive vesicular amine uptake sites in the caudate-putamen was also significantly increased (by 66%). The observed alterations in 5-HT uptake site and 5-HT2 receptor densities are likely a part of adaptive neuronal changes that occur after chronic administration of Fluoxetine ( Prozac ) and may be related to the antidepressant effect of the drug.

Males and females respond differently to controllability and antidepressant treatment.

BACKGROUND: Women are much more likely to suffer from stress-related mental illness than men; yet few, if any, animal models for such sex differences exist. Previously, we reported that exposure to an acute stressor enhances learning in male rats yet severely impairs learning in female rats. Here, we tested whether these opposite effects in males versus females could be prevented by establishing control over the stressor or by antidepressant treatment. METHODS: Learning was assessed using the hippocampal-dependent task of trace eyeblink conditioning. In the first experiment, groups of male and female rats were exposed to controllable or uncontrollable stress and trained. In a second experiment, they were exposed to an uncontrollable stressor after chronic treatment with the antidepressant Fluoxetine ( Prozac ) (Prozac). In a final experiment, females were exposed to uncontrollable stress after acute treatment with Fluoxetine ( Prozac ). RESULTS: Establishing control over the stressful experience eliminated the detrimental effect of stress on learning in females as well as the enhancing effect of stress in males. Moreover, chronic but not acute treatment with Fluoxetine ( Prozac ) prevented the learning deficit in females after exposure to stress. Treatment with Fluoxetine ( Prozac ) did not alter the male response to stress. CONCLUSIONS: These data indicate that males and females not only respond in opposite directions to the same stressful event but also respond differently to controllability and antidepressant treatments.

Chronic Fluoxetine ( Prozac ) treatment partly attenuates the long-term anxiety and depressive symptoms induced by MDMA ('Ecstasy') in rats.

Use of the drug 3,4-methylenedioxymethamphetamine (MDMA, 'Ecstasy') can have long-term adverse effects on emotion in both humans and laboratory animals. The present study examined whether chronic treatment with the antidepressant drug Fluoxetine ( Prozac ) could reverse such effects. Male Wistar rats were briefly exposed to MDMA (4 x 5 mg/kg over 4 h) or vehicle on 2 consecutive days. Approximately 9-12 weeks later, half of the rats received a dose of approximately 6 mg/kg/day Fluoxetine ( Prozac ) in their drinking water for a 5-week period. Fluoxetine ( Prozac ) administration reduced fluid intake and body weight in MDMA and vehicle pretreated rats. After several weeks of Fluoxetine ( Prozac ) treatment, rats were assessed on the social interaction test, the emergence test of anxiety and the forced swim model of depression. MDMA pretreated rats showed reduced social interaction, increased anxiety on the emergence test, and increased immobility and decreased active responses in the forced swim test. Fluoxetine ( Prozac ) treatment reversed MDMA-induced anxiety in the emergence test and depressive-like effects in the forced swim test, yet exhibited no effects on the social interaction test. MDMA pretreated rats had decreased 5-HT and 5-HIAA levels in limbic and cortical regions, and decreased density of serotonin transporter sites in the cortex. Fluoxetine ( Prozac ) treatment did not greatly affect 5-HT levels in MDMA pretreated rats, but significantly decreased 5-HIAA levels in all brain sites examined. Postmortem blood serum levels of Fluoxetine ( Prozac ) and norFluoxetine ( Prozac ) did not differ in MDMA and vehicle pretreated rats. These results indicate that Fluoxetine ( Prozac ) may provide a treatment option for some of the deleterious long-term effects resulting from MDMA exposure.

COMORBID CONDITIONS.

Staud R, Price DD, Robinson ME, Mauderli AP, Vierck CJ. Maintenance of windup of second pain requires less frequent stimulation in fibromyalgia patients compared to normal controls. Pain. 2004;110:689-696. Many chronic pain syndromes, including fibromyalgia (FM), show evidence of central nervous system hyperexcitability related to central sensitization. Windup (WU) of second pain reflects increased excitability of spinal cord neurons that is related to central sensitization. Psychophysical testing can help characterize this important central nervous system phenomenon because of the parallels between electrophysiological WU and WU of second pain. Animal experiments have shown that once WU has been established, only low frequency tonic nociceptive input is required to maintain the sensitized state of dorsal horn neurons (WU-maintenance or WU-M). The stimulus frequency necessary to maintain the hyperexcitability of spinal cord neurons can provide a measure of central sensitization. Because central sensitization plays an important role in many chronic pain syndromes including FM, we compared WU-M in 72 normal controls (NC) and 104 FM subjects. WU of second pain was produced by a train of 0.7-second duration thermal pulses applied to the glabrous surface of the hands at a frequency of 0.3 Hz. Enhanced second pain associated with WU could, thereafter, be maintained in FM but not NC subjects for up to 120 seconds by stimuli delivered at 0.16 and 0.08 Hz (WU-M stimuli). These two frequencies of stimulation do not produce WU when delivered alone. Thus, unlike NC subjects, FM subjects showed enhanced second pain during WU-M stimuli at very low stimulus frequencies, indicating central sensitization. Increased WU sensitivity, enhanced WU-M, and increased WU-related aftersensations help account for persistent pain conditions in FM subjects. In addition to WU, WU-M appears to be a useful tool to study mechanisms of pain in patients with characteristics of central sensitization. Comment: Interesting study as we become more and more concerned with central senitization in primary headache patients.-Stewart J. Tepper, MD Jick H, Kaye JA, Jick SS. antidepressants and the risk of suicidal behaviors. JAMA. 2004;292:338-343. Background: The relation between the use of antidepressants, especially selective serotonin reuptake inhibitors (SSRIs), and suicidal ideation and behaviors has received considerable public attention recently. The use of such drugs among teenagers has been of particular concern. Objective: To estimate the relative risks (RRs) of nonfatal suicidal behavior in patients starting treatment with one of three antidepressant drugs compared with patients starting treatment with dothiepin. Design and Setting: Matched case-control study of patients treated in UK general practices using the UK General Practice Research Database for 1993-1999.Participants: The base population included 159,810 users of the four antidepressant drugs. Participants could have used only one of these antidepressants and had to have received at least one prescription for the study antidepressant within 90 days before their index date (the date of suicidal behavior or ideation for cases and the same date for matched controls). Main Outcome Measures: Frequency of first-time exposure to Amitriptyline ( Elavil ), Fluoxetine ( Prozac ), Paroxetine ( Paxil ), and dothiepin of patients with a recorded diagnosis of first-time nonfatal suicidal behavior or suicide compared with comparable patients who did not exhibit suicidal behavior. Results: After controlling for age, sex, calendar time, and time from first antidepressant prescription to the onset of suicidal behavior, the relative risks for newly diagnosed nonfatal suicidal behavior in 555 cases and 2062 controls were 0.83 (95% confidence interval, [CI] 0.61-1.13) for Amitriptyline ( Elavil ), 1.16 (95% CI, 0.90-1.50) for Fluoxetine ( Prozac ), and 1.29 (95% CI, 0.97-1.70) for Paroxetine ( Paxil ) compared with those using dothiepin. The RR for suicidal behavior among patients first prescribed an antidepressant within 1 to 9 days before their index date was 4.07 (95% CI, 2.89-5.74) compared with patients who were first prescribed an antidepressant 90 days or more before their index date. Time since first antidepressant prescription was not, however, a confounder of the relation between specific antidepressants and suicidal behavior since its relation to suicidal behavior was not materially different among users of the four study drugs. Similarly for fatal suicide, the RR among patients who were first prescribed an antidepressant within 1 to 9 days before their index date was 38 (95% CI, 6.2-231) compared with those who were first prescribed an antidepressant 90 days or more before their index date. There were no significant associations between the use of a particular study antidepressant and the risk of suicide. Conclusions: The risk of suicidal behavior after starting antidepressant treatment is similar among users of Amitriptyline ( Elavil ), Fluoxetine ( Prozac ), and Paroxetine ( Paxil ) compared with the risk among users of dothiepin. The risk of suicidal behavior is increased in the first month after starting antidepressants, especially during the first 1 to 9 days. A possible small increase in risk (bordering statistical significance) among those starting the newest antidepressant, Paroxetine ( Paxil ), is of a magnitude that could readily be due to uncontrolled confounding by severity of depression. Based on limited information, we also conclude that there is no substantial difference in effect of the four drugs on people aged 10 to 19 years. Comment: This is an interesting study by the Boston collaborative group trying to unravel whether any of the antidepressants used in young people to treat a first attack of depressive illness were more likely to be linked to suicidal behavior. This was carried out using the UK General Practice Database which allows record linkage between diagnosis, treatment, and outcomes. As a primary care practitioner who contributes data to the GPRD, I am concerned that this study does not have the statistical power to exclude the possibility of an association. The authors rightly acknowledge the limited data upon which their conclusion is based. Moreover, the GPRD data base does not allow for the severity of depression to be categorized, hence the statement that "the possible small increase in risk (bordering statistical significance) among those starting the newest antidepressant, Paroxetine ( Paxil ), is of a magnitude that could readily be due to uncontrolled confounding by severity of depression" cannot be excluded using the GPRD.-David S. Millson, MD March J, Silva S, Petrycki S, Curry J, Wells K, Fairbank J, Burns B, Domino M, McNulty S, Vitiello B, Severe J, Treatment for Adolescents With Depression Study (TADS) Team. Fluoxetine ( Prozac ), cognitive-behavioral therapy, and their combination for adolescents with depression: treatment for Adolescents With Depression Study (TADS) randomized controlled trial. JAMA. 2004;292:807-820. Background: Initial treatment of major depressive disorder in adolescents may include cognitive-behavioral therapy (CBT) or a selective serotonin reuptake inhibitor (SSRI). However, little is known about their relative or combined effectiveness. Objective: To evaluate the effectiveness of four treatments among adolescents with major depressive disorder. Design, Setting, and Participants: Randomized controlled trial of a volunteer sample of 439 patients between the ages of 12 and 17 years with a primary Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, diagnosis of major depressive disorder. The trial was conducted at 13 US academic and community clinics between spring 2000 and summer 2003. Interventions: Twelve weeks of (1) Fluoxetine ( Prozac ) alone (10 to 40 mg/d), (2) CBT alone, (3) CBT with Fluoxetine ( Prozac ) (10 to 40 mg/d), or (4) placebo (equivalent to 10 to 40 mg/d). Placebo and Fluoxetine ( Prozac ) alone were administered double-blind; CBT alone and CBT with Fluoxetine ( Prozac ) were administered unblinded. Main Outcome Measures: Children's Depression Rating Scale-Revised total score and, for responder analysis, a (dichotomized) Clinical Global Impressions improvement score. Results: Compared with placebo, the combination of Fluoxetine ( Prozac ) with CBT was statistically significant (P= 0.001) on the Children's Depression Rating Scale-Revised. Compared with Fluoxetine ( Prozac ) alone (P= .02) and CBT alone (P= .01), treatment of Fluoxetine ( Prozac ) with CBT was superior. Fluoxetine ( Prozac ) alone is a superior treatment to CBT alone (P= .01). Rates of response for Fluoxetine ( Prozac ) with CBT were 71.0% (95% confidence interval [CI], 62%-80%); Fluoxetine ( Prozac ) alone, 60.6% (95% CI, 51%-70%); CBT alone, 43.2% (95% CI, 34%-52%); and placebo, 34.8% (95% CI, 26%-44%). On the Clinical Global Impressions improvement responder analysis, the two Fluoxetine ( Prozac )-containing conditions were statistically superior to CBT and to placebo. Clinically significant suicidal thinking, which was present in 29% of the sample at baseline, improved significantly in all four treatment groups. Fluoxetine ( Prozac ) with CBT showed the greatest reduction (P= .02). Seven (1.6%) of 439 patients attempted suicide; there were no completed suicides. Conclusion: The combination of Fluoxetine ( Prozac ) with CBT offered the most favorable tradeoff between benefit and risk for adolescents with major depressive disorder. Comment: The evidence is accumulating that the suicide risk may be up slightly due to the activating effects of the SSRIs when initially treating severe depression, especially in adolescents, though apparently less so with Fluoxetine ( Prozac ). The risk is reduced by having the patient simultaneously undergo Cognitive Behavioral Therapy (CBT). In headache management, we rarely have such severely depressed patients when we initiate therapy, but depression is co-morbid with migraine, and discussion of depression and mood is important before initiation of SSRI therapy.-Stewart J. Tepper, MD Hao Y, Creson T, Zhang L, Li P, Du F, Yuan P, Gould TD, Manji HK, Chen G. Mood stabilizer valproate promotes ERK pathway-dependent cortical neuronal growth and neurogenesis. J Neurosci. 2004;24:6590-6599. Manic-depressive illness has been conceptualized as a neurochemical illness. However, brain imaging and postmortem studies reveal gray-matter reductions, as well as neuronal and glial atrophy and loss in discrete brain regions of manic-depressive patients. The roles of such cerebral morphological deficits in the neuropathophysiology and therapeutic mechanisms of manic-depressive illness are unknown. Valproate (2-propylpentanoate) is a commonly used mood stabilizer. The ERK (extracellular signal-regulated kinase) pathway is used by neurotrophic factors to regulate neurogenesis, neurite outgrowth, and neuronal survival. We found that chronic treatment of rats with valproate increased levels of activated phospho-ERK44/42 in neurons of the anterior cingulate, a region in which we found valproate-induced increases in expression of an ERK pathway-regulated gene, bcl-2. Valproate time and concentration dependently increased activated phospho-ERK44/42 and phospho-RSK1 (ribosomal S6 kinase 1) levels in cultured cortical cells. These increases were attenuated by Raf and MEK (mitogen-activated protein kinase/ERK kinase) inhibitors. Although valproate affects the functions of GSK-3 (glycogen synthase kinase-3) and histone deacetylase (HDAC), its effects on the ERK pathway were not fully mimicked by selective inhibitors of GSK-3 or HDAC. Similar to neurotrophic factors, valproate enhanced ERK pathway-dependent cortical neuronal growth. Valproate also promoted neural stem cell proliferation-maturation (neurogenesis), demonstrated by bromodeoxyuridine (BrdU) incorporation and double staining of BrdU with nestin, Tuj1, or the neuronal nuclei marker NeuN (neuronal-specific nuclear protein). Chronic treatment with valproate enhanced neurogenesis in the dentate gyrus of the hippocampus. Together, these data demonstrate that valproate activates the ERK pathway and induces ERK pathway-mediated neurotrophic actions. This cascade of events provides a potential mechanism whereby mood stabilizers alleviate cerebral morphometric deficits associated with manic-depressive illness. Comment: Valproate has important structural effects on the brain in patients with bipolar illness, where underlying structural differences ("morphometic deficits") exist. Morphometic differences are also present in epilepsy patients, and it may not be a stretch to assume them in primary headache patients. So, the chronic effects of valproate are biochemical, electrical, and structural, and we are just beginning to understand them.-Stewart J. Tepper, MD.

Effects of norFluoxetine ( Prozac ) on the action potential and transmembrane ion currents in canine ventricular cardiomyocytes.

NorFluoxetine ( Prozac ) is the most important active metabolite of the widely used antidepressant compound Fluoxetine ( Prozac ). Although the cellular electrophysiological actions of Fluoxetine ( Prozac ) are well characterized in cardiac cells, little is known about the effects of its metabolite. In this study, therefore, the effects of norFluoxetine ( Prozac ) on action potential (AP) configuration and transmembrane ion currents were studied in isolated canine cardiomyocytes using the whole cell configuration of patch clamp techniques. Micromolar concentrations of norFluoxetine ( Prozac ) (1-10 microM) modified AP configuration: amplitude and duration of the AP and maximum velocity of depolarization were decreased in addition to depression of the plateau and elimination of the incisura of AP. Voltage clamp experiments revealed a concentration-dependent suppression of both L-type Ca(2+) current, I(Ca) (EC(50)=1.13+/-0.08 microM) and transient outward K(+) current, I(to) (EC(50)=1.19+/-0.17 microM) having Hill coefficients close to unity. The midpoint potential of the steady-state inactivation of I(Ca) was shifted from -20.9+/-0.75 mV to -27.7+/-1.35 mV by 3 microM norFluoxetine ( Prozac ) ( P<0.05, n=7). No such shift in the steady-state inactivation curve was observed in the case of I(to). Similarly, norFluoxetine ( Prozac ) caused no change in the steady-state current-voltage relationship of the membrane or in the density of the inward rectifier K(+) current, I(K1). All these effects of norFluoxetine ( Prozac ) developed rapidly and were fully reversible. Comparing present results with those obtained previously with Fluoxetine ( Prozac ), it can be concluded that norFluoxetine ( Prozac ) displays stronger suppression of cardiac ion channels than Fluoxetine ( Prozac ). Consequently, the majority of the cardiac side effects observed during Fluoxetine ( Prozac ) treatment are likely to be attributed to its metabolite norFluoxetine ( Prozac ).