European Neuropsychopharmacology (v.13, #5)
Editorial Board (IFC).
D2 dopamine receptor gene polymorphism: paroxetine and social functioning in posttraumatic stress disorder by Bruce R. Lawford; Ross McD. Young,; Ernest P. Noble; Burnett Kann; Leanne Arnold; John Rowell; Terry L. Ritchie (313-320).
This study examined whether allelic status of the D2 dopamine receptor (DRD2) gene was associated with response to a selective serotonin reuptake inhibitor, paroxetine, in the treatment of posttraumatic stress disorder (PTSD). Sixty-three Caucasian war veterans with combat-related PTSD were treated with paroxetine for 8 weeks. Patients were assessed at baseline and at follow-up using the General Health Questionnaire-28 (GHQ). TaqI A DRD2 alleles were determined by PCR. Before paroxetine treatment, patients with the DRD2 A1+ allele (A1A2 genotype) compared to those with the A1− allele (A2A2 genotype) had higher total GHQ psychopathological scores (P=0.040) and higher GHQ subscale scores for anxiety/insomnia (0.046), social dysfunction (P=0.033) and depression (P=0.011). In an intention-to-treat analysis, paroxetine was associated with significant improvement in total GHQ scores (P=0.014) and in the factor scores of social dysfunction (P=0.033), anxiety (P=0.009) and depression (P=0.026). Furthermore, there was a significant allele by time interaction on the social dysfunction scale, with A1+ allelic patients showing significant improvement in social functioning compared to A1− allelic patients (P=0.031), an effect independent of changes in depression or anxiety. This suggests changes in social functioning induced by paroxetine may be, in part, mediated via D2 dopamine receptors. The DRD2 A1 allele may prove to be a useful marker to assist clinicians in predicting which patients with PTSD are likely to obtain improvements in social functioning with paroxetine treatment.
Keywords: D2 dopamine receptor gene; A1 allele; PTSD; Paroxetine; Social functioning; Intention-to-treat;
Ginkgo biloba normalises stress-elevated alterations in brain catecholamines, serotonin and plasma corticosterone levels by Zahoor Ahmad Shah; Pragya Sharma; S.B Vohora (321-325).
Stress and depression and associated mental health problems have increased tremendously in modern times. The search for effective and safe alternatives from natural sources especially plant products should, therefore, continue. Forced immobilization is one of the best explored models of stress in rats and the role of corticosterone, serotonin and catecholamines, i.e. norepinephrine (NE), dopamine (DA) is well documented. Numerous studies have shown that Ginkgo biloba has antioxidant and neuroprotective properties and utility in cerebrovascular insufficiency and impaired cerebral performance. We investigated the effect of G. biloba on whole brain catecholamine, serotonin and plasma corticosterone levels following 1, 2 and 4 h restraint stress using HPLC and also plasma corticosterone using luminescence spectrophotometry. G. biloba extract (14 mg/kg p.o.) restored restraint stress-induced elevation in whole brain levels of catecholamines (NE, DA), 5-HT and plasma corticosterone to near normal levels. Further studies are warranted to explore the clinical potential of this encouraging lead in the management of stress and to elucidate the mechanisms involved.
Keywords: Stress; Ginkgo biloba; Catecholamine; Serotonin; Corticosterone;
Brain neurosteroid changes after paroxetine administration in mice by Allon Nechmad; Rachel Maayan; Baruch Spivak; Edward Ramadan; Michael Poyurovsky; Abraham Weizman (327-332).
Although it is known that selective serotonin reuptake inhibitors (SSRIs), as other antidepressants, elevate mood only after 3–4 weeks of treatment, the mechanism responsible for this delay is not understood. SSRIs have been demonstrated to alter the levels of neurosteroids such as allopregnanolone (THP) which possess anxiolytic and mood-elevating properties. We compared the effect of 9 and 21 days i.p. administration of paroxetine, a potent SSRI, on the synthesis of THP and its precursor, 5α-dihydroprogesterone (DHP), in the mouse cortex, hypothalamus and olfactory bulb. Cortex, olfactory bulb and hypothalamus synthesized levels of DHP were significantly raised after 9 days of paroxetine administration, whereas a significant rise in the THP synthesized level was observed only after 21 days of treatment. Peripheral synthesis of DHP, measured by the level in serum, significantly increased after 9 days, but reverted to normal values after 21 days. No increase was detected in serum THP levels either after 9 or 21 days treatment. Differences in peripheral and brain synthesis indicates independence in brain synthesis. The data indicate that paroxetine administration differentially increases [3H]DHP and [3H]THP content, depending on the duration of the treatment. Our results suggest that brain THP may be involved in the antidepressive and anxiolytic activity of paroxetine.
Keywords: Allopregnanolone; Anxiety; Depression; Neurosteroids; Paroxetine; 5α/KWD; Dihydroprogesterone;
CSF taurine level is influenced by plasma cholesterol and the CYP2D6 phenotype by Conny Nordin; Marja-Liisa Dahl; Thomas Eklundh; Mats Eriksson; Stefan Sjöberg (333-335).
Eight healthy male volunteers, lumbar-punctured before and during simvastatin treatment, were phenotyped for CYP2D6 analysis of the debrisoquine metabolic ratio (the ratio between the urinary recovery of debrisoquine and its 4-hydroxy metabolite) after a single oral dose of debrisoquine. The mean cerebrospinal fluid concentrations of cholesterol and taurine did not differ before and during treatment. During (but not before) treatment taurine in the CSF correlated with the debrisoquine metabolic ratio (r=−0.93; P=0.0007) Our results might indicate an influence of CYP2D6 on the level of taurine in the CSF that was secondary to the change in plasma cholesterol.
Keywords: Taurine; Cholesterol; CSF; CYP2D6;
Effects of serotonin 5-HT1/2 receptor agonists in a limited-access operant food intake paradigm in the rat by J. De Vry; R. Schreiber; A. Daschke; K.R. Jentzsch (337-345).
Hypophagic effects of serotonergic drugs have mostly been investigated in free-feeding paradigms and are generally ascribed to drug-induced acceleration of satiety, or to behavioral disruption. The present study investigated the hypophagic effects of various 5-HT1/2 receptor agonists in an operant paradigm. Because of its limited duration (10-min session) the procedure was considered to be relatively insensitive to satiety processes. The behavioral specificity of the hypophagic effect was assessed by additional testing of the compounds in a locomotor activity assay. Male Wistar rats, maintained at about 80% of their free-feeding weights, were trained to acquire stable operant responding in daily fixed ratio:10 food-reinforced sessions; after which they were tested once a week with a 5-HT receptor agonist. Each compound dose-dependently suppressed the number of earned pellets after i.p. administration: DOI (5-HT2A/2C receptor agonist; ED50: 0.36 mg/kg), TFMPP (5-HT1B/2C/2A; 0.37 mg/kg), m-CPP (5-HT2C/1B/2A; 0.54 mg/kg), ORG 37684 (5-HT2C/2A; 0.85 mg/kg), CP-94,253 (5-HT1B; 2.09 mg/kg), BW 723C86 (5-HT2B; 6.26 mg/kg) and ipsapirone (5-HT1A; 10.17 mg/kg). When tested at the dose equivalent to the ED50 value in the operant paradigm, only ORG 37684 and DOI weakly suppressed activity counts in a locomotor activity assay; suggesting that the inhibition of operant food intake obtained with the other compounds at these doses is not a direct consequence of unconditioned motor effects. It is suggested that the hypophagic effect induced by relatively low doses of CP-94,253, TFMPP and m-CPP, and by moderate doses of ipsapirone and BW 723C86, is partly due to a drug-induced suppression of appetite. Although the exact contribution of the diverse 5-HT1/2 receptor subtypes to appetite control remains to be studied in more detail, it is hypothesized that activation of 5-HT1B and/or 5-HT2C receptors attenuates appetite.
Keywords: Appetite; BW 723C86; CP-94,253; DOI; Ingestive behavior; Ipsapirone; m-CPP; ORG 37684; Satiety; TFMPP;
Effects of coaching by community pharmacists on psychological symptoms of antidepressant users; a randomised controlled trial by Oscar H Brook; Hein P.J Van Hout; Hugo Nieuwenhuysea; Marten De Haan (347-354).
Background: Community pharmacists strive to deliver pharmaceutical care to patients. At the moment, coaching of depressive primary care patients on taking their antidepressants (ADs) is not yet part of their standard care package. Aims: To investigate the effects of coaching by community pharmacists on psychological symptoms. Method: A randomised controlled trial with a 6-month follow-up. Outcomes: psychological symptoms with the Hopkins Symptom Checklist (SCL). Intention-to-treat (ITT) was performed with (1) last observation carried forward and (2) with group mean imputation (GMI). Results: Analyses with LOCF and GMI resulted in different findings. The LOCF method revealed that at the 6-month follow-up, the intervention patients were less depressed and less anxious than the controls. The intervention was particularly effective in patients with lower levels of education who received pharmacist’s coaching. However, ITT with the GMI method showed no differences in psychological symptoms. Differences between LOCF and GMI were explained by the selective attrition in the intervention arm (attrition intervention patients had lower initial SCL-item scores on depression and anxiety than the completers) and by the higher attrition rate in controls. Conclusions: Our study indicates that the interpretation of the effects of an intervention on psychological symptoms can differ substantially by the way missing values are imputed. If both LOCF and GMI produce significant differences, efficacy can be concluded. If not, the effects based on ITT analyses with LOCF are based on artefacts. We recommend that positive intervention effects should only be reported when findings with LOCF and GMI are in accordance.
Keywords: Pharmaceutical care; Patient education; Pharmacist coaching; Depression;
Antinociceptive effects of tricyclic antidepressants and their noradrenergic metabolites by M.O Rojas-Corrales; J Casas; M.R Moreno-Brea; J Gibert-Rahola; J.A Micó (355-363).
This study evaluates the antinociceptive effect of several tricyclic antidepressants in four nociceptive tests which employ either thermal (hot plate and tail flick tests) or chemical (formalin and acetic acid tests) stimuli. Forced swimming test was also performed as a model of depression and an activity test was also performed. Mixed antidepressants in current clinical use: amitriptyline, imipramine and clorimipramine and their respective main secondary metabolites which preferentially inhibit noradrenaline reuptake: nortriptyline, desipramine and desmethylclorimipramine, were tested (2.5–20 mg/kg, i.p.) in mice. The results show a stronger antinociceptive effect in chemical tests induced by all the drugs, compared with thermal tests. The doses needed to produce antinociception were lower than those inducing an antidepressive effect, both effects being mutually independent. The overall results show that preferentially noradrenergic tricyclics induced an antinociceptive effect comparable with that of mixed tricyclics, indicating that noradrenaline reuptake plays an important role in tricyclic-induced antinociception.
Keywords: Tricyclics; Antidepressants; Pain; Antinociception; Noradrenaline; Serotonin;
Lack of association between the 5HT2A receptor polymorphism (T102C) and unipolar affective disorder in a multicentric European study by Pierre Oswald; Daniel Souery; Isabelle Massat; Jurgen Del-Favero; Sylvie Linotte; George Papadimitriou; Dimitris Dikeos; Radka Kaneva; Vibra Milanova; Lilijana Oruč; Sladana Ivezič; Alessandro Serretti; Roberta Lilli; Christine Van Broeckhoven; Julien Mendlewicz (365-368).
We report here a case-control association study with T102C polymorphism in the serotonin 2A receptor gene (HTR2A) in patients affected by unipolar affective disorder (UPAD) and in controls. A total of 284 subjects were genotyped (142 UPAD and 142 controls). All subjects were interviewed using standard diagnostic interviews and matched. A homogenous population of unipolar patients with suicidal attempt was identified. Conditional logistic regression was applied. No association of the HTR2A polymorphism was found in the overall sample of 142 UPAD-control pairs regarding allele and genotype frequencies (P=0.36 and P=0.52 respectively) and homo-heterozygote distributions (P=0.91). This study confirms, in a multicentric European sample, the earlier observations that the T102C HTR2A polymorphism is not associated with UPAD. Nevertheless, a type 2 statistical error cannot be excluded. Therefore, to exclude the implication of HTR2A in UPAD, this result must be replicated in larger samples and in other populations using the transmission disequilibrium test and different polymorphisms around HTR2A.
Keywords: Serotonin; 5HT2A receptor polymorphism; Unipolar affective disorder; Conditional logistic regression;
Behavioural changes after different stress paradigms: prepulse inhibition increased after physical, but not emotional stress by Femke T.A Pijlman; Arnoud H.J Herremans; Jan van de Kieft; Chris G Kruse; Jan M van Ree (369-380).
Physical (PS) and emotional (ES) stress have opposite long-term effects on open field behaviour, i.e., response to novelty. PS induced a long-term reduction in locomotor activity, while ES increased it. Additionally, sensitivity to rewarding stimuli was differentially affected by PS and ES. Whether the stress effects were specific for locomotor activity and reward or if these two stress treatments also have differential effects on other behaviours and brain functions is not known. In the present study, temperature regulation, sensory gating, learning capacity, locomotor activity and coping style were examined. PS consisted of a repeated mild foot shock treatment, which the ES animals witnessed. The tests pose additional challenges, to which all groups can respond differently depending on their previous experience. All tests were performed several days after the last stress treatment. Stress effects were specifically observed on locomotor activity, startle response and prepulse inhibition (PPI). The PS animals showed a potentiated inhibition of the startle when a prepulse (PPI) was used, although the initial startle response was already significantly lower than that of controls. ES animals did not differ from controls on PPI and startle. Additionally PS animals showed an initial decrease in activity, which turned into an increase when the tests continued. ES showed a constant increase in activity compared to controls. Stress effects on the tests for other brain processes and behaviour were not found. In addition, PS animals appeared to be less sensitive to the dopamine agonist apomorphine than control animal. In summary, physical and emotional stress induce differential changes on locomotor activity, startle response and PPI. Underlying mechanisms explaining the differences in stress effects are discussed, i.e., the role of the mesolimbic dopamine system and opioid systems.
Keywords: Stress; Prepulse inhibition; Dopamine; Locomotor activity; Animal;
Toxic rise of clozapine plasma concentrations in relation to inflammation by Marie-Jeanne Haack; M.L.F.J. Bak; Rob Beurskens; Michael Maes; L.M.L Stolk; Philippe A.E.G. Delespaul (381-385).
Recently a small number of patients were observed in two psychiatric hospitals in the Netherlands with clozapine intoxications that complicate or mimic infections. These patients were on chronic medication and normally had stable clozapine blood plasma levels. This article presents four of these cases. Medline was searched for reports of similar cases. A hypothesis was formulated and tested by literature study. Immune modulatory and toxic effects of clozapine protein reactive metabolites or haptens, may play a role in the development of inflammation. Clozapine has a direct influence on different cytokines resembling an inflammatory reaction. Infection or inflammation could induce bioactivation of clozapine into its nitrenium ion that can exert a toxic reaction that induces apoptosis and gives rise to elevated cytokine levels. Clozapine can function as a hapten and induce an IgG, IgM or IgE mediated hypersensitivity reaction. The cytokines released during infection or inflammation downregulate the clozapine metabolism in the P450 system through CYP 1A2. Clozapine plasma levels should be monitored closely if an inflammatory or infectious process is suspected.
Keywords: Clozapine; P450 metabolism; Infection; Inflammation; Cytokines; Toxic;
Autoradiographic imaging of the serotonin transporter in the brain of rats and pigs using S-([18F]fluoromethyl)-(+)-McN5652 by Marion Kretzschmar; Peter Brust; Jörg Zessin; Paul Cumming; Ralf Bergmann; Bernd Johannsen (387-397).
The [18F]fluoromethyl analogue of (+)-McN5652 ([18F]FMe-McN) has recently been developed as a radioligand for imaging the neuronal serotonin transporter (SERT) with positron emission tomography (PET). We describe here the autoradiographic evaluation of [18F]FMe-McN in the brain of rats and pigs. Autoradiographic studies of [18F]FMe-McN performed on rat and pig brain in vitro showed a high accumulation of radioactivity in the regions rich in SERT, such as amygdala, hypothalamus, superficial gray layer of the superior colliculus, various nuclei of thalamus and substantia nigra. The binding of [18F]FMe-McN was reduced by citalopram, a highly selective inhibitor for SERT. Similar regional specific binding densities of [18F]FMe-McN were observed in both species. The regional distribution and specific binding of this radiotracer correlates well with the distribution and regional brain binding of [3H]citalopram. Region-to-cerebellum ratios of [18F]FMe-McN in vitro reached a maximum value of 20.6 in the rat and 14.5 in the pig. In addition, ex vivo autoradiography of the rat brain was performed 90 min after i.v. administration of [18F]FMe-McN. The highest regional uptake of [18F]FMe-McN was observed in the hypothalamic area, substantia nigra and amygdaloid area. There is a high correlation between the in vitro and in vivo binding. The region-to-cerebellum ratio in vivo reached a maximum value of 5.1 in the substantia nigra, the highest yet reported for an 18F-labelled SERT tracer in vivo in this region. Furthermore, the distribution volume of [18F]FMe-McN calculated from the PET data in various regions of the porcine brain is highly correlated with the SERT density as determined by in vitro autoradiography with [3H]citalopram. Thus, [18F]FMe-McN has a clear potential as a radiotracer for studies of the SERT distribution in man with PET.
Keywords: S-([18F]Fluoromethyl)-(+)-McN5652; Serotonin transporter; Positron emission tomography; [3H]Citalopram; Autoradiography; Swine brain;
Corrigendum to “Effects of 8-OH-DPAT on open field performance of young and aged rats prenatally exposed to diazepam: a tool to reveal 5-HT1A receptor function” by C. Cannizzaro; M. Martire; G. Provenzano; R. Monastero; M. Gagliano; F. Plescia; A. Mineo; E. Cannizzaro (399).