Drug metabolic enzyme genotype-phenotype discrepancy: High phenoconversion rate in patients treated with antidepressants

Cytochromes from the P450 family (CYP) play a central role in the primary metabolism of frequently prescribed antidepressants, potentially affecting their efficacy and tolerance. There are however important differences in the drug metabolic capacities of each individual resulting from a combination of intrinsic and environmental factors. This variability can present an important risk for patients and increases the difficulty of drug prescription in clinical practice. Pharmacogenetic studies have uncovered a number of alleles defining the intrinsic metabolizer status, however, additional factors affecting cytochrome activity can modify this activity and result in a phenoconversion. The present study investigates the discrepancy between the genetically predicted and actually measured activities for the six most important liver cytochromes (CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6 and CYP3A4) in a cohort of patients under antidepressant treatment, previously shown to have a high proportion of patients with low metabolizing activities. We now performed the genetic characterization of this cohort to determine the extent of the genetic versus environmental contribution in these decreased activities. For all enzyme tested, we observed an important rate of phenoconversion, affecting between 33 % and 65 % of the patients, as well as a significant (p < 1E-06) global reduction in the effective but not predicted activities of CYP2D6, CYP2C9 and CYP2C19 compared to the general population. Our results highlight the advantages of phenotyping versus genotyping as well as the increased risk of treatment failure or adverse effect occurrence in a polymedicated population.

Using admixture analysis to examine birth-cohort effects on age at onset of bipolar disorder

OBJECTIVE

It is suggested that age at onset (AAO) of bipolar I disorder (BP-I) is decreasing. We tested for a birth-cohort effect on AAO using admixture analysis.

METHOD

A clinical sample of 3896 BP-I cases was analysed using two approaches: (i) in a subsample with untruncated AAO × birth year distribution (n = 1865), we compared the best-fitting model for the observed AAO in patients born ≤1960 and >1960, (ii) to control for potential confounders, two separate subsamples born ≤1960 and >1960 were matched for age at interview (n = 250), and a further admixture analysis was undertaken.

RESULTS

The two approaches indicated that the proportion of cases in the early AAO category was significantly greater in cases born >1960; manic onsets were also more frequent in the early onset BP-I cases born >1960.

CONCLUSION

The decrease in AAO of BP-I in recent birth-cohorts appears to be associated with an increase in the proportion of cases in the early onset subgroup; not with a decrease in the mean AAO in each putative subgroup. This could indicate temporal changes in exposure to risk factors for mania.

Borderline personality disorder and childhood maltreatment: a genome-wide methylation analysis

Early life adversity plays a critical role in the emergence of borderline personality disorder (BPD) and this could occur through epigenetic programming. In this perspective, we aimed to determine whether childhood maltreatment could durably modify epigenetic processes by the means of a whole-genome methylation scan of BPD subjects. Using the Illumina Infinium® HumanMethylation450 BeadChip, global methylation status of DNA extracted from peripheral blood leucocytes was correlated to the severity of childhood maltreatment in 96 BPD subjects suffering from a high level of child adversity and 93 subjects suffering from major depressive disorder (MDD) and reporting a low rate of child maltreatment. Several CpGs within or near the following genes (IL17RA, miR124-3, KCNQ2, EFNB1, OCA2, MFAP2, RPH3AL, WDR60, CST9L, EP400, A2ML1, NT5DC2, FAM163A and SPSB2) were found to be differently methylated, either in BPD compared with MDD or in relation to the severity of childhood maltreatment. A highly relevant biological result was observed for cg04927004 close to miR124-3 that was significantly associated with BPD and severity of childhood maltreatment. miR124-3 codes for a microRNA (miRNA) targeting several genes previously found to be associated with BPD such as NR3C1. Our results highlight the potentially important role played by miRNAs in the etiology of neuropsychiatric disorders such as BPD and the usefulness of using methylome-wide association studies to uncover such candidate genes. Moreover, they offer new understanding of the impact of maltreatments on biological processes leading to diseases and may ultimately result in the identification of relevant biomarkers.

[Hyperthymic and cyclothymic temperaments: attenuated forms of bipolar disorder?]

A temperament is described as a temporally stable dimension, biologically determined. Several temperaments have been described (hyperthymic, depressive, cyclothymic, irritable and anxious) and could represent premorbid characteristics of an affective disorder. Some temperaments could thus correspond to chronic sub-affective states expressed as attenuated forms of mood disorder. Several studies suggest that a large proportion of bipolar patients have a hyperthymic or cyclothymic temperament. Moreover, temperaments seem to influence the clinical caracteristics of bipolar disorders. Future investigations will evaluate whether temperaments represent a predisposing factor, an attenuated form of bipolar disorders or a distinct entity.

[Bipolar disorder and attention deficit/hyperactivity disorder in adults: differential diagnosis or comorbidity]

Attention deficit/hyperactivity disorder (ADHD) can sometimes coexist with bipolar disorder (BD). Despite controversies about the coexistence of the two disorders, recent clinical as well as biological studies support the concept of comorbid adult ADHD and BD. Although there is some overlapping symptomatology between both disorders, ADHD can be diagnosed in patients suffering from with BD after a detailed clinical evaluation. Clinicians should be particularly attentive to specific symptoms in order to treat adequately both disorders since untreated ADHD comorbidity with BD is associated with poor clinical and socio-professional outcome.

Mindfulness-based cognitive therapy for bipolar disorder: a feasibility trial

BACKGROUND

The present open study investigates the feasibility of Mindfulness-based cognitive therapy (MBCT) in groups solely composed of bipolar patients of various subtypes. MBCT has been mostly evaluated with remitted unipolar depressed patients and little is known about this treatment in bipolar disorder.

METHODS

Bipolar outpatients (type I, II and NOS) were included and evaluated for depressive and hypomanic symptoms, as well as mindfulness skills before and after MBCT. Patients' expectations before the program, perceived benefit after completion and frequency of mindfulness practice were also recorded.

RESULTS

Of 23 included patients, 15 attended at least four MBCT sessions. Most participants reported having durably, moderately to very much benefited from the program, although mindfulness practice decreased over time. Whereas no significant increase of mindfulness skills was detected during the trial, change of mindfulness skills was significantly associated with change of depressive symptoms between pre- and post-MBCT assessments.

CONCLUSIONS

MBCT is feasible and well perceived among bipolar patients. Larger and randomized controlled studies are required to further evaluate its efficacy, in particular regarding depressive and (hypo)manic relapse prevention. The mediating role of mindfulness on clinical outcome needs further examination and efforts should be provided to enhance the persistence of meditation practice with time.

Self- and clinician-rated Montgomery-Asberg Depression Rating Scale: evaluation in clinical practice

BACKGROUND

Time- and cost-effective self-rating scales of depressive symptoms are particularly valuable for frequent use in large-scale effectiveness trials. The aim of the present study was to examine the psychometric properties of the French version of the self-rated Montgomery-Asberg Depression Rating Scale (MADRS-S) and determine whether it might complement the MADRS in monitoring depression severity and change over time in routine clinical practice.

METHODS

Sixty-three adult outpatients with a current depressive episode completed the MADRS-S and were interviewed with the MADRS on two occasions, within a 1-month interval.

RESULTS

All patients readily accepted the MADRS-S. It showed good to excellent internal consistency (Cronbach's alpha 0.85 at Time 1; 0.94 at Time 2). Its factor structure revealed that a single component explained a large proportion of variability (47.0% at Time 1; 68.8% at Time 2). Concurrent validity of the self- and clinician-rated versions was good (Pearson's correlation coefficients for total scores 0.81 at Time 1; 0.91 at Time 2). The MADRS-S was sensitive to change over the 4-week observation period (correlation of 0.71 between change scores on self- and clinician-rated instruments).

LIMITATIONS

Generalizability is restricted to outpatients with moderate to severe depression, and the MADRS-S ability to measure treatment effects needs to be examined.

CONCLUSIONS

The present study indicates that the MADRS-S displays favourable psychometric properties and suggests that it might be a valid complement to the MADRS, both in research settings and clinical practice.

[Psychiatry]

Methods of brain stimulation such as transcranial magnetic stimulation, deep brain stimulation and vagus nerve stimulation may have a place in the treatment of depression or severe anxiety disorders resistant to conventional treatments. Several advances in chronotherapy as well as developments in treatment protocols have helped to prolong the antidepressant effect of sleep deprivation. The clinical applications of these methods in depressive episodes and especially in bipolar depression are discussed. The complete remission of a depressive episode and the maintenance of therapeutic benefit beyond the mere reduction of symptoms, have become important issues. The persistence of residual depressive symptoms is associated with increased risk of relapse: their recognition and treatment are illustrated in this article.

Effects of ovariectomy in prepubertal goats

The objectives of this study were to determine the effects of ovariectomy on mammary gland development in prepubertal goats and to validate this model to study mammogenesis in young dairy ruminants. In this experiment, 3 months of aged goats were ovariectomized (ovx) while shammed goats played as surgery controls (sham). Thereafter, sham and ovx goats were slaughtered at 7 months of age to provide tissue for the assays. Results demonstrated that proliferation of mammary of mammary epithelial cells was significantly lower in ovariectomized goats compared to control goats. In ovx animal, epithelium structures were completely overstretched and epithelial ducts were undeveloped with limited branching whereas control animals had classical complex arborescent units with multiple round ductules and limited stroma. Concerning ERalpha (estrogen receptor alpha), PR (progesterone receptor) and P450 (aromatase) expression, results showed number of ERalpha, PR and P450 positive cells was higher in shammed goats compared to ovariectomized goats. All this results suggested that goat mammogenesis and ovarian control are similar to prepubertal heifers and that young goats are a good model to study mammary gland development in ruminants. In conclusion, we demonstrated that ovariectomy of prepubertal goats decreased proliferation of mammary epithelial cells with a profound alteration of cell adhesion molecules.

Frequency of dysphoria and mixed states

BACKGROUND

Mixed states are a complex entity in the field of mood disorders. Dysphoria has been advocated as an important clinical dimension of mixed states. The objective of this work is to study the frequency of dysphoria within a population of patients with DSM-IV major depressive and/or manic episodes and to determine if it may help establish diagnostic criteria for subthreshold cases of depressive or manic mixed states.

SAMPLING AND METHODS

A total of 165 patients were assessed using the Mini International Neuropsychiatric Interview complemented by a section defining dysphoria as a constellation of 3 among 4 symptoms (inner tension, irritability, aggressive behavior and hostility).

RESULTS

When classifying patients according to the number of symptoms of the opposite polarity, changes in the frequency of dysphoria revealed a clear contrast between the 2 opposite manic and depressive poles and the full mixed state (DSM-IV definition). The frequency of dysphoria was 17.5% in pure depression, 22.7% in pure mania and 73.3% in full mixed state. Two threshold effects were identified: (1) the frequency of dysphoria increased from 17.5 to 61.1% (p = 0.002) when the number of manic symptoms in DSM-IV depressed patients increased from 0 to 1, and (2) dysphoria increased from 14.3 to 69.2% (p = 0.057) when the number of depressive symptoms increased from 2 to 3 in DSM-IV manic patients.

CONCLUSION

Dysphoria is strongly but not necessarily associated with mixed states. When used as a clinical marker for mixed states, dysphoria confirms the modern delimitations of sub-threshold mixed states by specifying the required number of symptoms of the opposite polarity (which could be lower for depressive mixed states than for manic mixed states). The study has limitations related to the inclusion of patients who are not drug-free, to the definition of dysphoria and to the sample size.

Phenomenology of mixed states: a principal component analysis study

OBJECTIVES

To contribute to the definition of external and internal limits of mixed states and study the place of dysphoric symptoms in the psychopathology of mixed states.

METHODS

One hundred and sixty-five inpatients with major mood episodes were diagnosed as presenting with either pure depression, mixed depression (depression plus at least three manic symptoms), full mixed state (full depression and full mania), mixed mania (mania plus at least three depressive symptoms) or pure mania, using an adapted version of the Mini International Neuropsychiatric Interview (DSM-IV version). They were evaluated using a 33-item inventory of depressive, manic and mixed affective signs and symptoms.

RESULTS

Principal component analysis without rotation yielded three components that together explained 43.6% of the variance. The first component (24.3% of the variance) contrasted typical depressive symptoms with typical euphoric, manic symptoms. The second component, labeled 'dysphoria', (13.8%) had strong positive loadings for irritability, distressing sensitivity to light and noise, impulsivity and inner tension. The third component (5.5%) included symptoms of insomnia. Median scores for the first component significantly decreased from the pure depression group to the pure mania group. For the dysphoria component, scores were highest among patients with full mixed states and decreased towards both patients with pure depression and those with pure mania.

CONCLUSIONS

Principal component analysis revealed that dysphoria represents an important dimension of mixed states.

The EACN scale for oil classification revisited thanks to fish diagrams

The phase behavior of C(10)E(4)-oil-water systems at constant o/w ratio and variable temperature (fish diagram) has been investigated for several homologous oil families. The temperature T( *) and surfactant concentration C( *) at the critical point were determined for 10 n-alkanes varying from C(6) to C(28) as well as for a series of alkylcyclohexanes and alkylbenzenes. On the basis of T( *), equivalent alkane carbon numbers (EACN) were assigned to nonlinear alkanes, alkylbenzenes, and alkylcyclohexanes. The consistency of the method was shown by corroborating that the EACN values of oils previously investigated with other C(i)E(j) (dibutyl ether, squalane, isopropyl myristate, and dodecylbenzene) are the same when determined with C(10)E(4). The fact that two oils of different nature but with the same EACN (i.e., the same T( *)) do not exhibit the same C( *) is discussed in terms of monomeric solubility of the surfactant in the oil (CMC(oil)).

[Psychiatry]

Introduced this year on the Swiss market, duloxetine (Cymbalta) is a new antidepressant which inhibits the reuptake of noradrenaline and serotonin. Clinical studies have shown its efficacy in depression as well as in neuropathic pains (60-120 mg/day) with a good tolerability. In this paper are also included short reviews about the two large American studies developed by the National Institute of Mental Health in the fields of the treatment for depression (STAR-D) and of the antipsychotic treatments for schizophrenia (CATIE study). Its also reviews two questions of present interest: the use of the second generation antipsychotics for the treatment of bipolar depression and the concept of bipolar disorders in children.

A stepwise drug treatment algorithm to obtain complete remission in depression: a Geneva study

QUESTIONS UNDER STUDY/PRINCIPLES

We describe the proportion of severely depressed outpatients reaching complete remission at the different stages of a drug treatment algorithm. We compare several treatment options for SSRI (selective serotonin reuptake inhibitor) non-responders and test the feasibility of the algorithm in clinical conditions.

METHODS

Patients with severe depressive disorders (ICD-10; MADRS > or = 25) admitted to an academic outpatient clinic were enrolled in this algorithm-guided sequential treatment protocol (starting with an SSRI and ending with a tricyclic, lithium, triodothyronine combination). The general principle of the algorithm was to boost the drug therapy in the event of non-response.

RESULTS

135 patients entered the study and 131 were eligible for analysis. From this group, 86 patients dropped out (65.6%), 40 reached complete remission (30.5%) and 5 patients did not reach remission at all (3.8%). In the 117 patients to whom a last observation carried forward approach was applied, the median improvement of the MADRS score was 48.0% (range -20.7%-100%), with 48.7% of patients considered responders, 23.1% partial responders and 28.2% non-responders. Median retention time was 8 weeks (range 2-34).

CONCLUSIONS

This algorithm-guided antidepressant treatment was acceptable for clinicians and resulted in an elevated final response rate among study completers. However, the dropout rate was high, mainly due to treatment interruption or non-observance.

A stepwise drug treatment algorithm to obtain complete remission in depression: a Geneva study

QUESTIONS UNDER STUDY/PRINCIPLES

We describe the proportion of severely depressed outpatients reaching complete remission at the different stages of a drug treatment algorithm. We compare several treatment options for SSRI (selective serotonin reuptake inhibitor) non-responders and test the feasibility of the algorithm in clinical conditions.

METHODS

Patients with severe depressive disorders (ICD-10; MADRS > or = 25) admitted to an academic outpatient clinic were enrolled in this algorithm-guided sequential treatment protocol (starting with an SSRI and ending with a tricyclic, lithium, triodothyronine combination). The general principle of the algorithm was to boost the drug therapy in the event of non-response.

RESULTS

135 patients entered the study and 131 were eligible for analysis. From this group, 86 patients dropped out (65.6%), 40 reached complete remission (30.5%) and 5 patients did not reach remission at all (3.8%). In the 117 patients to whom a last observation carried forward approach was applied, the median improvement of the MADRS score was 48.0% (range -20.7%-100%), with 48.7% of patients considered responders, 23.1% partial responders and 28.2% non-responders. Median retention time was 8 weeks (range 2-34).

CONCLUSIONS

This algorithm-guided antidepressant treatment was acceptable for clinicians and resulted in an elevated final response rate among study completers. However, the dropout rate was high, mainly due to treatment interruption or non-observance.

Olanzapine plasma level in relation to antimanic effect in the acute therapy of manic states

The aim of this study was to evaluate internal as well as external validity of the two most frequently used mania scales, the Young Mania Rating Scale (YMRS) and the Bech-Rafaelsen Mania Scale (MAS), in patients with DSM-IV mania. Mokken analysis was used to evaluate internal validity in which a coefficient of homogeneity of 0.40 or higher indicates that the total score is a sufficient statistic. The external validity was evaluated by plasma-level relationship of olanzapine. In total, 20 patients with DSM-IV mania were analysed, and the coefficient of homogeneity was acceptable for the MAS, but not for the YMRS. In a subgroup of females who over 2 weeks had received a fixed dose of 20 mg olanzapine daily, a significant association was found between MAS scores and plasma levels, but this association was not obtained with the YMRS. In conclusion, the MAS was found superior to the YMRS in regard to both internal and external validity.

[Psychiatry]

The main innovation of the year 2004 was the introduction of a new, second-generation antipsychotic drug with a new mechanism of action (partial dopamine agonist), encouraging first clinical results, and an advantageous clinical tolerance profile. Additionally, three new galenic forms are presented: an oral, extended-release form of methylphenidate that could be useful in the treatment of attention-deficit/hyperactivity disorders; an intramuscular depot form of a second-generation antipsychotic drug (risperidone) with the advantage of improving adherence; and an intramuscular form of a second generation antipsychotic (olanzapine) that is valuable in emergency situations. Finally, we will briefly give an update on the advantages of lamotrigine in bipolar depression.

Antidepressant-induced mania, rapid cycling and the serotonin transporter gene polymorphism

The genes involved in the serotonin system are major candidates in association studies on affective disorders and responses to antidepressants. We studied a functional polymorphism of the serotonin transporter (5-HTT) gene (a 44 bp insertion/deletion in the 5-HTT-linked polymorphic region (5-HTTLPR)) and lifetime history of antidepressant-induced mania (AIM) in a population of 305 patients with bipolar affective disorder. AIM was defined using a broad definition and a restrictive definition. No association was found between the "s" allele of the 5-HTTLPR and AIM for either definition. However, we found an association between the 5-HTTLPR and lifetime history of rapid cycling in a subsample of patients (for allele and genotype distributions: exact probability, p=0.0009 and chi(2)=9.4; df=1; p=0.002, respectively). These results may help to explain the conflicting association results obtained with the 5-HTT gene polymorphism, in particular with AIM. Indeed, the precise phenotype associated with the 5-HTT gene is unclear. The association between the "s" allele and rapid cycling may provide further evidence for an association between the 5-HTTLPR "s" allele and a pattern of affective instability.

[Translation and validation of a French version of the Young Mania Rating Scale (YMRS)]

Both the Young Mania Rating Scale (YMRS) and the Mania Assessment Scale (MAS) have been widely used during the last decade for the evaluation of severity of mania in clinical trials. For both scales good inter-rater reliability, validity and sensitivity to change have been reported. The French version of the MAS has been validated. To our know-ledge, the YMRS has not yet been translated into French and validated. The main objective of the present study was to validate a French version of the YMRS and to test its use in manic patients entering a study on the effectiveness of valproic acid and olanzapine combination. After translating the items in French, we tested this version of the YMRS on two samples of psychiatric patients recruited in a ward of adult inpatients (18 to 65 Years old) at the Department of Psychiatry, Geneva University Hospital. The first sample included 18 (hypo) manic inpatients (10 males, 8 females). Mean age was 37.0 (standard deviation 10.1). Interviews were video taped and assessed by three different judges on both scales (YMRS and MAS). The second sample included 20 inpatients (5 males, 15 females) who provided written informed consent to enter a study on the association of valproic acid and olanzapine in the treatment of mania. Mean age was 40.0 (standard deviation 11.3). Patients were followed over four weeks and assessed on both scales (YMRS and MAS) every seven days (day 0, 7, 14, 21 and 28). On day 7, patients were assessed during a joint interview by two of three judges who independently administered both scales in permuted order. On days 0, 14, 21 and 28, patients were evaluated by one of the same three raters. Inter-rater reliability was assessed by comparing item scores and total scores assigned by different judges with intra-class correlation coefficient ICC (2,1). Three judges were considered for patients in sample 1. Two judges were considered for patients in sample 2 (day 7 assessment). Concurrent validity with the MAS was analysed in sample 2 on days 0, 7, 14, 21 and 28 using Spearman rank-order correlation coefficient. Sensitivity to change was assessed in sample 2 by comparing total score at inclusion and at last observation using Wilcoxon signed ranks test. For both the MAS and YMRS, intraindividual change was calculated as the difference between total scores at inclusion and discharge (last observation carried forward approach). The relationship between changes on the two scales was analysed through Spearman correlation coefficient. Significance level was set to 0.05 for each test. Ranges of YMRS total scores were 2 to 32 in sample 1 and 1 to 28 in sample 2, indicating symptom severity from euthymic to moderately manic. Inter-rater reliability was very good for the total scores in both samples, both for the MAS and the YMRS (ICC>0.89). When considering YMRS individual items, correlation coefficient varied from 0.61 to 0.96 in the first sample. In the second sample, 9 of 11 items displayed values above 0.63. The remaining two items, increased motor activity and energy and Language-thought disorder, presented modest inter-rater reliability (ICC=0.54 and 0.50 respectively). This was largely attributable to a single patient, who was perceived very differently by the two judges (scores 0-2 for increased motor activity and energy; 1-4 for Language-thought disorder). When this patient was excluded, intra-class correlation coefficients were above 0.69 for both items. Overall, inter-rater reliability of the YMRS items was in the same range as for the MAS items (0.61-0.96 vs 0.61-0.93 in sample 1; 0.50-0.93 vs 0.54-0.83 in sample 2). Correlation between the two instruments was very high and statistically significant at each weekly assessment (rs>0.91, p<0.001) except for day 21 which displayed a somewhat lower correlation (rs=0.75, p<0.01). This latter result was attributed to a reduced spread of values and number of patients on day 21. YMRS and MAS total scores as a function of time in patients receiving combined treatment with olanzapine and valproic acid (sample 2) show that for both at for both scales, total scores significantly decreased from day 0 to last observation (Wilcoxon signed ranks test, p<0.001), with median decrease of 18 points both on the YMRS (range 9-32) and MAS (range 10-33). Median relative decrease was 67% for the YMRS and 69% for the MAS. When analysing the relationship between intraindividual changes on the YMRS and MAS, highly significant correlation was observed (Spearman rs=0.93, p<0.001), showing that the two scales were virtually interchangeable in assessing treatment efficacy. In conclusion, the YMRS is a simple and easy-to-use instrument for measuring severity of manic symptoms The newly translated French version was satisfactory in terms of inter-rater reliability, concurrent validity with the MAS, and sensitivity to change in patients receiving treatment for manic symptoms. This should allow its future use for international comparison studies.

A theoretical reappraisal of mixed states: dysphoria as a third dimension

Mixed states are heterogeneous clinical entities difficult to define precisely. The stringent actual DSM IV criteria are unsatisfactory for current clinical use. Many frequently encountered mixed patients benefit without an accurate diagnosis from biological therapeutic interventions such as the introduction of mood stabilizers. We propose a brief review of the definition and characteristics of mixed states and propose a new approach to the typology of mixed states. Based on recent literature data, we add to the depressive and manic syndrome the concept of dysphoria as a third dimension. Integrating this three dimensional approach with recent factor analysis, we describe in addition to the DSM IV mixed state (type I) two new subtypes of mixed states (type IIM and IID). This new typology can give the clinician a more accurate understanding of the complex and polymorphous reality of mixed states and help him make more specific therapeutic interventions. These subtypes of mixed states will need validation through prospective clinical studies. Biological differences, differential outcome over time, and differential response to treatment will be important validation criteria.

Possible induction of mania and hypomania by olanzapine or risperidone: a critical review of reported cases

BACKGROUND

Risperidone and olanzapine are atypical antipsychotics that are now widely used in clinical practice.

METHOD

A MEDLINE search (1966-1999) showed that, following the introduction of these agents in recent years, 26 cases of induced hypomanic and manic syndromes have been reported during standard olanzapine (N = 10) or risperidone (N = 16) treatment.

RESULTS

A critical analysis of these case reports reveals that the effects on mood were sometimes insufficiently documented and that in about half of them (N = 16) evidence is highly suggestive of a causative role of risperidone or olanzapine in the induction of (hypo)manic symptomatology.

CONCLUSION

Despite limitations, the available literature confirms intriguing effects of these 2 antipsychotics on mood. The risk factors as well as the mechanisms of action underlying these effects remain to be clarified.

Hypomania-like syndrome induced by olanzapine

We report a female patient with a diagnosis of a not otherwise specified psychotic disorder (DSM-IV) who developed hypomania shortly after the introduction of olanzapine treatment.

Pineal nitric oxide synthase, but not heme oxygenase, mRNA is suppressed by continuous exposure to light

We have previously shown that exposure of rats to constant light (LL) induced a decrease in NO synthase (NOS) activity in the pineal gland. We report here that the use of the sensitive technique of RT-PCR has demonstrated that mRNA for neuronal NOS is present in the pineal, and that it is photoneurally regulated. There was a marked decrease in pineal neuronal NOS mRNA levels in continuous light conditions, similar to the changes seen in NOS enzyme activity. Inducible NOS was not present in the pineal, and there was evidence that the photoregulatable form was not endothelial NOS. The mRNA for two isoforms of heme oxygenase, the enzyme responsible for the generation of the putative neuromodulator carbon monoxide, was also present in the pineal, but neither isoform was photoregulated. Using immunodetection, it was not possible to identify the presence of NOS protein, other than to a minimal extent, even though NOS activity was clearly present. NADPH-diaphorase staining and in situ hybridization were carried out in an attempt to identify the precise location of neuronal NOS message. A strong NADPH-diaphorase reaction was present in sympathetic nerve fibers of the pineal, but pinealocytes showed no or only very weak labelling. In situ hybridization was also unable to identify neuronal NOS message in pinealocytes. These data thus also suggest the possible presence of a pineal-specific NOS isoenzyme.

Chronic treatment with the antidepressant amitriptyline decreases CRF-R1 receptor mRNA levels in the rat amygdala

Using semi-quantitative in situ hybridization, corticotropin-releasing factor (CRF) and CRF receptor 1 (CRF-R1) mRNA levels were determined in the rat hypothalamus and amygdala after short-term (10 days) and chronic (4 weeks) treatment with the antidepressant amitriptyline. We found that chronic treatment with amitriptyline produced a significant decrease in CRF mRNA (to 33% of control) in the hypothalamic paraventricular nucleus (PVN). Short-term or chronic amitriptyline treatment had no effect on CRF-R1 mRNA levels in the PVN. However, after chronic treatment, there was a significant decrease of CRF-R1 mRNA levels in the lateral + basolateral (to 60% of control), and in the medial (to 70% of control) amygdala nuclei. These results suggest that the tricyclic antidepressant amitriptyline may exert part of its effects through modulation of hypothalamic CRF and of CRF-R1 gene expression in the amygdala.

Single stress induces long-lasting elevations in vasopressin mRNA levels in CRF hypophysiotrophic neurones, but repeated stress is required to modify AVP immunoreactivity

Repeated stress is known to induce an increased vasopressin (AVP) expression in paraventricular corticotrophin-releasing factor (CRF) neurones which is supposed to enhance the ACTH-releasing capacity of these cells. To test the hypothesis that a single stress is sufficient to produce these changes, we used quantitative in-situ hybridization analysis to measure steady state CRF and AVP mRNA. Moreover the colocalized AVP and CRF immunoreactive sites were assessed in the dense core vesicle compartment of CRF axon terminals in the external zone of the median eminence with quantitative immunoelectron microscopy. Acute immobilization produced a significant increase in the average AVP and CRF mRNA levels (145% and 65%, respectively, above control values) in the medial parvocellular subdivisions of the paraventricular nucleus (PVN), and these changes persisted for over 4 days after stress. In contrast to these changes in AVP mRNA levels, there were no concomitant changes in AVP immunostaining in CRF terminals and axons during the 4-day period. However, when immobilization stress was repeated daily, the number of CRF terminals containing AVP increased progressively. Moreover, the ratio of AVP and CRF immunoreactivity in the dense core vesicle compartment was increased. Taken together, these results provide evidence that single stress experience can cause long-lasting changes in AVP and CRF mRNA steady state expression that is not apparently accompanied by changes in peptide levels. They also suggest that repeated stress is required for developing progressive shifts in the neurohormone storage pattern of these neurones.

Mitogen-activated protein kinase (p38-, JNK-, ERK-) activation pattern induced by extracellular and intracellular singlet oxygen and UVA

Ultraviolet A (UVA; 320-400 nm) radiation in human skin fibroblasts induces a pattern of mitogen-activated protein kinase (MAPK) activation consisting of a rapid and transient induction of p38 and c-Jun-N-terminal kinase (JNK) activity but not extracellular signal-regulated kinases (ERK). UVA activation of p38 can be inhibited by the singlet oxygen (1O2) quenchers azide and imidazole, but not by the hydroxyl radical scavengers mannitol or dimethylsulfoxide, pointing to the involvement of 1O2. The same effect has been shown for JNK. Like UVA, 1O2 generated intracellularly upon photoexcitation of Rose Bengal activates p38 and JNK but not ERK. p38 and JNK activation was also elicited by chemiexcitation for the intracellular generation of 1O2 by the lipophilic 1,4-endoperoxide of N,N'-di(2,3-dihydroxypropyl)-1, 4-naphthalene dipropionamide. In contrast, extracellular generation of 1O2, by irradiation of Rose Bengal immobilized on agarose beads or by chemiexcitation employing the hydrophilic 1,4-endoperoxide of disodium 3,3'-(1,4-naphthylidene) dipropionate, was ineffective in activating p38 or JNK. These data suggest that the activation of p38 and JNK by 1O2 occurs only when the electronically excited molecule is generated intracellularly.

Inactivation of intracellular and non-enveloped viruses by a non-ionic naphthalene endoperoxide

Singlet oxygen (1O2, 1delta(g)) selectively oxidizes many biological targets, some of which, such as viruses, are located intracellularly under in vivo conditions. Considering the short lifetime of 1O2 in aqueous media, it is essential to generate this species in close proximity to the targets. Therefore, a water-soluble and non-ionic carrier of 1O2, DHPNO2, has been designed to convey 1O2 through lipid membranes. In contrast to the known anionic carrier NDPO2, which inactivates only extracellular enveloped viruses, the new compound exhibits virucidal activity on all types of viruses, enveloped (HIV) and non-enveloped (Poliovirus), extracellular and intracellular. HIV inactivation can also be achieved in the presence of red blood cells, suggesting the possible use of DHPNO2 in the decontamination of cellular blood products.

Ectopic expression of the CRF-binding protein: minor impact on HPA axis regulation but induction of sexually dimorphic weight gain

Corticotrophin-releasing factor (CRF) and urocortin possess a high-affinity binding protein. Although the CRF binding protein (BP) can sequester these ligands and inhibit their activity, the endogenous activity of this protein is not understood. Therefore, transgenic mouse lines that over-express the CRF-BP were created. The transgene was constructed by ligating rat CRF-BP cDNA (1.1 kb) between a mouse metallothionein-I promoter (1.8 kb) and a nonfunctional human growth hormone gene sequence (2.1 kb) in a modified pBR322 plasmid and microinjecting the transgene into C57BL/6 x SJL hybrid ova. The transgene was expressed in 50% in both male and female progeny. All transgenic lines were maintained by crossing transgenic animals with wild-type C57BL/6 mates. Reverse-transcriptase (RT) PCR of the CRF-BP transgene showed that it is widely expressed not only in the brain and pituitary, but also peripheral tissues including the liver, kidney and spleen. Transgenic animals of both sexes showed significant increases in weight gain as established by analysis of variance; however, the weight gain profiles for each sex were distinct. High levels of circulating CRF-BP were detected in the transgenic animals, but the basal ACTH and corticosterone levels were not significantly decreased compared to wild-type littermates. The hypothalamopituitary-adrenal (HPA) axis was stimulated by systemic inflammation induced with lipopolysaccharide (LPS). An expected increase in transgene expression was observed and was accompanied by a significant attenuation of ACTH secretion at 3 h after LPS injection in the transgenic males but not the females. These data suggest that HPA axis regulation is significantly affected only with very high circulating levels of CRF-BP. Moreover, this work supports previous studies that implicate CRF and urocortin in the regulation of appetite and the binding protein expression may play a sexually dimorphic role in regulating this and other responses.

Corticotropin releasing factor receptor 1-deficient mice display decreased anxiety, impaired stress response, and aberrant neuroendocrine development

Corticotropin releasing factor (CRF) is a major integrator of adaptive responses to stress. Two biochemically and pharmacologically distinct CRF receptor subtypes (CRFR1 and CRFR2) have been described. We have generated mice null for the CRFR1 gene to elucidate the specific developmental and physiological roles of CRF receptor mediated pathways. Behavioral analyses revealed that mice lacking CRFR1 displayed markedly reduced anxiety. Mutant mice also failed to exhibit the characteristic hormonal response to stress due to a disruption of the hypothalamic-pituitary-adrenal (HPA) axis. Homozygous mutant mice derived from crossing heterozygotes displayed low plasma corticosterone concentrations resulting from a marked agenesis of the zona fasciculata region of the adrenal gland. The offspring from homozygote crosses died within 48 hr after birth due to a pronounced lung dysplasia. The adrenal agenesis in mutant animals was attributed to insufficient adrenocorticotropic hormone (ACTH) production during the neonatal period and was rescued by ACTH replacement. These results suggest that CRFR1 plays an important role both in the development of a functional HPA axis and in mediating behavioral changes associated with anxiety.

Endotoxin decreases corticotropin-releasing factor receptor 1 messenger ribonucleic acid levels in the rat pituitary

Bacterial endotoxins produce profound activation of the hypothalamo-pituitary-adrenal axis, mediated by stimulation of hypothalamic CRF neurons. Although a number of studies have described direct pituitary actions of inflammatory mediators, the effects of inflammatory stimuli on the sensitivity of corticotropes to CRF remain to be elucidated. The aim of this study was to determine the effects of inflammatory stress on the CRF receptor 1 (CRF-R1) messenger RNA (mRNA) levels in the rat pituitary. The systemic injection of endotoxin [lipopolysaccharide (LPS); 50 microg/kg, i.v.] increased plasma concentrations of ACTH and corticosterone. Ribonuclease protection analysis of total RNA isolated from individual whole pituitaries indicated that LPS produced a significant decrease in CRF-R1 mRNA that was evident by 2 h after injection (to 57% of control) and more marked by 6 h (to 38% of control). To evaluate whether the decrease in CRF-R1 mRNA was dependent upon increased exposure to CRF and/or vasopressin (AVP), LPS was injected with an anti-CRF antiserum, a CRF receptor antagonist (Astressin), or anti-AVP antiserum. A strong inhibition of the ACTH response to LPS was produced by pretreatment with anti-CRF antiserum, Astressin, or anti-AVP antiserum. However, these treatments had no effect on the decrease in CRF-R1 mRNA produced by LPS, indicating that neither CRF nor AVP are obligatory mediators of this pituitary response. The hypothesis that LPS might have direct pituitary effects on CRF-R1 mRNA levels was tested in vitro. Indeed, decreases in CRF-R1 mRNA to 43% and 53% of the control level were observed in rat anterior pituitary cell cultures that were treated with either LPS itself or the inflammatory mediator interleukin-1beta, respectively. Collectively, these results show that CRF receptor mRNA levels in the pituitary of the rat are markedly reduced by systemic LPS treatment and that this decrease is not dependent upon increased exposure of the pituitary to CRF or AVP, but may involve direct effects within the pituitary of either LPS itself or ensuing cytokine production.

Functional N-methyl-D-aspartate receptors in O-2A glial precursor cells: a critical role in regulating polysialic acid-neural cell adhesion molecule expression and cell migration

The capacity for long-distance migration of the oligodendrocyte precursor cell, oligodendrocyte-type 2 astrocyte (O-2A), is essential for myelin formation. To study the molecular mechanisms that control this process, we used an in vitro migration assay that uses neurohypophysial explants. We provide evidence that O-2A cells in these preparations express functional N-methyl-D-aspartate (NMDA) receptors, most likely as homomeric complexes of the NR1 subunit. We show that NMDA evokes an increase in cytosolic Ca2+ that can be blocked by the NMDA receptor antagonist AP-5 and by Mg2+. Blocking the activity of these receptors dramatically diminished O-2A cell migration from explants. We also show that NMDA receptor activity is necessary for the expression by O-2A cells of the highly sialylated polysialic acid-neural cell adhesion molecule (PSA-NCAM) that is required for their migration. Thus, glutamate or glutamate receptor ligands may regulate O-2A cell migration by modulating expression of PSA-NCAM. These studies demonstrate how interactions between ionotropic receptors, intracellular signaling, and cell adhesion molecule expression influence cell surface properties, which in turn are critical determinants of cell migration.

Virucidal activity of pure singlet oxygen generated by thermolysis of a water-soluble naphthalene endoperoxide

Using the water-soluble naphthalene carrier of singlet oxygen NDPO2, we have shown that pure singlet oxygen is able to inactivate enveloped viruses (human immunodeficiency virus type 1, herpes simplex virus type 1, cytomegalovirus, vesicular stomatitis virus), but has no effect on non-enveloped viruses (adenovirus and poliovirus 1). These results are related to the experiments on photoinactivation of viruses by hydrophobic photosensitizers (merocyanine 540, hypericin, phthalocyanines, hematoporphyrin and benzoporphyrin derivatives) and they strengthen the hypothesis that singlet oxygen plays a predominant role in this process.

Application of factorial and Doehlert designs for optimization of pectate lyase production by a recombinant Escherichia coli

The expression of a recombinant pectate lyase from Bacteroides thetaiotaomicron strain 217 was studied in Escherichia coli strain HB101(pBT4). First, two sets of complete 2(4) factorial designs were used to evaluate the influences of casamino acids, glucose, magnesium, calcium, tetracycline, ampicillin, tryptophan and MOPS buffer on pectate lyase production in a basal medium. While casamino acids, glucose and magnesium were found to be the prevalent factors, the presence of tetracycline, ampicillin and MOPS buffer were necessary for the reproducibility of the process, probably by increasing the plasmid stability. Secondly, application of the Doehlert design, a response-surface methodology, allowed a good prediction of pectate lyase production according to the variation in glucose and magnesium concentrations. This optimization strategy allowed the production of biomass and recombinant pectate lyase respectively to be increased from 0.2 gl-1 to 1.9 gl-1 (dry weight) and from 10 units ml-1 to 210 units ml-1 within 24 h at 30 degrees C in shake flasks.

Expression of ionotropic glutamate receptor subunit mRNAs by paraventricular corticotropin-releasing factor (CRF) neurons

To determine whether paraventricular corticotropin-releasing factor (CRF) neurons express NMDA, AMPA or kainate-preferring glutamate receptors, we have colocalized, by in situ hybridization (ISH), transcripts of various glutamate receptor subunit genes with the CRF messenger RNA on doublet adjacent sections of the rat hypothalamus. We found that more than 70% of CRF-positive neurons contain the NMDA receptor subunit NR1 mRNA whereas NR2A and NR2B subunit mRNAs were not detectable in CRF cells. A significant proportion of identified CRF cells express AMPA receptor subunit GluRA (46%), GluRB (21%) as well as the kainate-preferring receptor subunit KA2 (31%) mRNAs. These results support the hypothesis that the excitatory transmitter glutamate may directly influence CRF neurons through NMDA as well as non-NMDA receptors.

Adrenergic control of rat pineal NO synthase

We have previously shown that exposure of rats to constant light (LL) induced a decrease in NO synthase (NOS) activity in the pineal gland. We present here the evidence that chronic (5 days) norepinephrine (NE) or isoproterenol treatment prevents the effect of LL and enhances pineal NOS activity in LL animals. This effect of NE appears to be mediated by beta-adrenoceptors, because it was not mimicked by the alpha-agonist phenylephrine. Pineal NOS activity was reduced in 16-h light/8-h dark animals treated for 4 days with the beta-adrenergic antagonist propranolol but not with the alpha 1-antagonist prazosin, indicating again an involvement of beta-adrenergic receptor in the control of NOS. Treatment with adrenergic antagonists did not affect cortical NOS activity, suggesting that the control of NOS is different in these two tissues or that the pineal expresses a specific isoform of the enzyme. Taken together, these data suggest that NE controls NOS in the pineal gland through beta-adrenergic receptors. To our knowledge, this represent the first demonstration of a regulation of NOS by a neurotransmitter in the CNS, as assayed under Vmax conditions.

Isolation from bovine haemoglobin of a peptide that might be used as a potential hydrophobic photosensitizer carrier

The isolation of a peptic hydrolysate and of a pure peptide from bovine haemoglobin is described. These peptides were used to solubilize an insoluble photosensitizer in order to study their utilization as a carrier for photochemotherapy. Protoporphyrin IX was used as a model of an insoluble photosensitizer. Solubilization of protoporphyrin IX was first performed with the total haemoglobin hydrolysate, then with peptide fractions, and finally with a pure peptide isolated from this fraction by reversed-phase HPLC. The molecular mass and the primary structure of the pure peptide were determined by fast-atom-bombardment and tandem MS (molecular mass 1648 Da). The singlet oxygen quantum yield of the protoporphyrin IX-peptide complex was determined.

Stress-induced changes in messenger RNA levels of N-methyl-D-aspartate and AMPA receptor subunits in selected regions of the rat hippocampus and hypothalamus

The postsynaptic AMPA/kainate and N-methyl-D-aspartate-selective glutamate receptors are formed by several different subunits and the overall subunit composition of the receptor appears to determine its physiological and pharmacological properties. Although glutamatergic mechanisms have been implicated in various forms of hippocampal stress responses, the impact of stress on glutamate receptor subunit composition has not yet been elucidated. We have used cell-by-cell quantitative in situ hybridization to assess stress-induced changes in transcript levels of N-methyl-D-aspartate and AMPA receptor subunit genes in subdivisions of the rat hippocampus and hypothalamus that are implicated in the stress response. We found that 24 h after a single immobilization stress there was a significant increase in the cellular level of NR1 subunit messenger RNA (about 35-45% above control values) in hippocampal CA3 and CA1 pyramidal cells as well as in neurons of the hypothalamic supraoptic and paraventricular nuclei. Moreover, in the CA3 area we have detected a concomitant increase (50% above controls) in the level of NR2B subunit messenger RNA, while the expression of NR2A subunit gene did not change after stress. Stress induced a selective decrease in the level of AMPA receptor subunit glutamate receptor A messenger RNA in neurons of both the CA3 and CA1 areas (18 and 24%, respectively, below control values). These results suggest that the regulation of specific subunit messenger RNAs of the N-methyl-D-aspartate and AMPA receptors may be involved in altered hippocampal and hypothalamic responsiveness to glutamate and thus could play a critical role in stress-induced changes in their function.

Corticotropin-releasing factor and vasopressin mRNA levels in roman high- and low-avoidance rats: response to open-field exposure

Roman high- (RHA) and low- (RLA) avoidance rats are selected and bred for rapid versus non-acquisition of two-way, active avoidance behavior in a shuttle box. They also show a number of other behavioral differences which appear to be essentially related to emotional factors, the RLA rats being emotionally more sensitive. The ACTH secretory response to stressors is also augmented in RLA rats. We thus raised the question whether the expression of corticotropin-releasing factor (CRF) and vasopressin (VP), two neurohormones exerting a synergistic action on ACTH release from corticotropic cells, is different in the two strains. Steady-state mRNA levels were examined in the parvicellular neurons of the paraventricular nucleus under basal conditions and 4 h after a single 8-min exposure to an open-field stressor. In situ hybridization histochemistry with 35S-labeled oligonucleotide probes was followed by quantitative cell by cell autoradiography. When basal CRF and VP mRNA levels were compared in the two lines, we found that the RLA rats had a significantly higher VP-labeling density than the RHA rats. No difference was found for CRF mRNA. During open-field exposure, we observed behavioral differences paralleled by elevated corticosterone compatible with an increased emotional response in RLA rats. Open-field exposure produced a significant increase in CRF but not VP mRNA in both RHA and RLA rats (by 43 and 57%, respectively). These results suggest that differences in basal VP expression in CRF neurons may participate in the mechanisms underlying the hyperactivity of the hypothalamo-pituitary-adrenal (HPA) axis in the emotionally more sensitive RLA rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Photophysical and photobiological activities of a porphyrin peptide fraction derived from haemoglobin

In a previous study, we described the preparation of a porphyrin peptide hydrolysate from haemoglobin, its isolation and its analysis by high performance liquid chromatography (HPLC) and fast atom bombardment (FAB) mass spectrometry. The purpose of the present paper is to test the photosensitizing activity of this fraction. We determined the singlet oxygen quantum yield (phi delta) in order to quantify the efficiency of the porphyrin peptide fraction. The quantum yield is about phi(1O2)=0.06. An analysis of the phototoxic effect on tumour cells in culture was performed and compared with haematoporphyrin derivative (HpD), the only photosensitizer in clinical use at present. The phototoxicity of the porphyrin peptide fraction is weaker than that of HpD. However, for a porphyrin dose of 50 micrograms ml-1, the difference in phototoxicity is low, and in the absence of irradiation porphyrin peptides are less toxic than HpD. These results suggest that porphyrin peptides could be potent photosensitizers; moreover, they are of great interest since they allow the solubilization of hydrophobic porphyrins and could be applied in the future as insoluble photosensitizer carriers.

NK1 receptor expression by cholinergic interneurones in human striatum

Neurokinin-1 (NK1) receptor expression in human striatum was analysed using the polymerase chain reaction. To determine whether cholinergic interneurones express this receptor, in situ hybridization histochemistry was then applied to caudate nucleus and putamen. Radioactive oligonucleotide probes specific for choline acetyltransferase (ChAT) and NK1 receptor mRNA were used on adjacent cryostat sections. All of the 160 identified neurones positive for ChAT were also labelled for NK1 receptor. Moreover, in the caudate nucleus, NK1 receptor mRNA was detected in a population of large neurones that were not cholinergic. These results are consistent with the hypothesis that NK1 receptor-mediated mechanisms are involved in the function of cholinergic interneurones. This might be relevant to pharmacological or pathophysiological situations where substance P inputs are modified.

Stressor-specific increase of vasopressin mRNA in paraventricular hypophysiotrophic neurons

Cellular levels of vasopressin (VP) and corticotropin-releasing factor (CRF) RNA transcripts were determined in hypophysiotrophic neurons after open-field and immobilization stress using quantitative in situ hybridization. We found that 8 min open-field stress is sufficient to produce a significant up-regulation of CRF mRNA, without any concomitant changes in the level of VP mRNA. In contrast, 8 min immobilization stress resulted in an increased labeling density of both CRF and VP mRNAs. These results suggest that the level of CRF and VP transcripts in parvicellular hypophysiotrophic neurons is differentially regulated in a stressor-specific manner.

Up-regulation of vasopressin mRNA in paraventricular hypophysiotrophic neurons after acute immobilization stress

Cellular levels of vasopressin (VP) and corticotropin-releasing factor (CRF) mRNAs were determined in the rat hypothalamic paraventricular nucleus after acute immobilization stress. Messenger RNA levels were measured by in situ hybridization histochemistry using 35S-labeled synthetic DNA oligonucleotide probes and quantitative autoradiography. Analysis of histograms related to density values revealed that two hours after immobilization the average cellular VP and CRF mRNA levels were significantly increased (145 +/- 30.3 and 68 +/- 21.3%, respectively, above control values). Moreover, the number of VP-expressing parvicellular neurons was doubled in stressed rats relative to controls. These results indicate that single acute immobilization stress is sufficient to up-regulate VP as well as CRF mRNA production in the hypothalamic CRF-neurosecretory system.

Coexpression of dopamine D2 and substance P (neurokinin-1) receptor messenger RNAs by a subpopulation of cholinergic neurons in the rat striatum

Amongst different intrinsic and extrinsic inputs, cholinergic striatal interneurons receive afferents from the dopaminergic nigrostriatal projection and from local collaterals of striatonigral cells containing substance P. The following study demonstrates that both dopamine D2 and substance P (neurokinin-1) receptors are expressed by a large proportion of cholinergic interneurons. Using in situ hybridization on triplet adjacent sections with radioactive probes specific for choline acetyltransferase, substance P receptor, and D2 receptor long-splicing form messenger RNAs, we show that these interneurons can be divided into four subpopulations in terms of substance P and D2 receptor expression. A majority of these neurons coexpress both receptors (76%), while other minor subpopulations express either one (respectively, 16% and 2%) or none of them (6%). Our results also show that substance P receptor is expressed by striatal neurons that are not cholinergic. These findings are in agreement with the concept that striatal cholinergic interneurons are heterogeneous in terms of input-output connections and the type of receptors expressed. Moreover, the presence of substance P and D2 receptors on a majority of these neurons is relevant to a putative role of cholinergic interneurons in several conditions such as various neurodegenerative disorders or antipsychotic drug administration, where substance P and dopamine inputs are modified.

Stress-induced increase in vasopressin and corticotropin-releasing factor expression in hypophysiotrophic paraventricular neurons

The concerted action of CRF and vasopressin (VP) plays a critical role in regulating ACTH release from anterior pituitary cells. In this study, we have explored the expression of these neurohormones in hypophysiotropic paraventricular neurons after repeated exposure of rats to immobilization stress. Cell by cell quantitative in situ hybridization was used to evaluate the steady state level of mRNAs coding for VP and CRF. We found that 16 daily stress exposures resulted in a significant increase in the average cellular level of CRF and VP mRNAs (150% and 200% of control levels, respectively). Moreover, in the repeatedly stressed group, the number of VP-expressing parvicellular neurons was approximately doubled relative to the control value. Using quantitative immunoelectron microscopy, VP- and CRF-immunoreactive sites were assessed in the dense core vesicle compartment of CRF axon terminals in the external zone of the median eminence. We found that after repeated stress, the immunolabeling of VP was augmented, while that of CRF was slightly decreased. Concurrently, we observed a significant increase in the proportion of CRF nerve terminals that were VP positive (from 50% in controls to 90% in stressed animals). We conclude that the observed changes in CRF neurons may represent a physiological response to increased functional demand and may lead to alterations in the composition of the ACTH-releasing signal.

Interaction of singlet oxygen with DNA and biological consequences

To study the interaction of singlet oxygen (1O2) with DNA and the biological consequences of 1O2-induced DNA damage, we used the thermodissociable endoperoxide of 3,3'-(1,4 naphthalidene) dipropionate (NDPO2) as a generator of free 1O2 in reactions with (1) 2'-deoxynucleoside 3'-monophosphates (dNps), (2) an oligonucleotide (16-mer) having one deoxyguanine (dG), (3) native and denaturated rat kidney DNA and (4) single-stranded (ss) and double-stranded (ds) bacteriophage M13mp10 DNA. Using both anion exchange and reversed phase HPLC and 32P-postlabeling analyses, it was found that exposure of the various dNps to chemically generated 1O2 led to a detectable reaction with dGp and not with dAp, dCp, d5mCp or Tp. The reaction with dGp led to degradation of this nucleotide and the formation of a large number of reaction products, one of which could be identified as 7-hydro-8-oxo-2'-deoxyguanosine 3'-monophosphate (8-oxo-dGp). A second product could tentatively be identified as a formamido pyrimidine derivative of dGp (Fapy-dGp). When ss DNA, ds DNA or the oligonucleotide were exposed to 1O2, the formation of 8-oxo-dG could also be demonstrated. With the oligonucleotide, we found a so far unidentified reaction product. Under the same reaction conditions the yield of 8-oxo-dG was about 8-fold higher in ss DNA than in ds DNA. In ss DNA 8-oxo-dG seemed to be a more prominent product than in the case of reaction of 1O2 with free dGp. Reaction of 1O2 with ss or ds M13mp10 DNA led to biological inactivation of these DNAs, ss DNA being at least 100-fold more sensitive than ds DNA. It could be concluded that inactivation of the ss DNA must be largely due to 1O2-induced DNA lesions other than 8-oxo-dG. In agreement with the observed preferential reaction of 1O2 with dG most of the so far sequenced mutations, induced by 1O2 in a 144 bp mutation target sequence inserted in the lacZ alpha gene of ss or ds M13mp10 DNA, occurred at a G or G/C base pair respectively. A preference for G(C) to T(A) transversions can be observed for which 8-oxo-dG might have been responsible. In ss DNA a significant number of the mutations are characterized by the fact that a G is deleted.