Oxytocin and vasopressin agonists and antagonists as research tools and potential therapeutics

We recently reviewed the status of peptide and nonpeptide agonists and antagonists for the V(1a), V(1b) and V(2) receptors for arginine vasopressin (AVP) and the oxytocin receptor for oxytocin (OT). In the present review, we update the status of peptides and nonpeptides as: (i) research tools and (ii) therapeutic agents. We also present our recent findings on the design of fluorescent ligands for V(1b) receptor localisation and for OT receptor dimerisation. We note the exciting discoveries regarding two novel naturally occurring analogues of OT. Recent reports of a selective VP V(1a) agonist and a selective OT agonist point to the continued therapeutic potential of peptides in this field. To date, only two nonpeptides, the V(2) /V(1a) antagonist, conivaptan and the V(2) antagonist tolvaptan have received Food and Drug Administration approval for clinical use. The development of nonpeptide AVP V(1a), V(1b) and V(2) antagonists and OT agonists and antagonists has recently been abandoned by Merck, Sanofi and Pfizer. A promising OT antagonist, Retosiban, developed at Glaxo SmithKline is currently in a Phase II clinical trial for the prevention of premature labour. A number of the nonpeptide ligands that were not successful in clinical trials are proving to be valuable as research tools. Peptide agonists and antagonists continue to be very widely used as research tools in this field. In this regard, we present receptor data on some of the most widely used peptide and nonpeptide ligands, as a guide for their use, especially with regard to receptor selectivity and species differences.     

Topiramate and metabolic acidosis in infants and toddlers

PURPOSE: Topiramate (TPM) inhibits carbonic anhydrase, with metabolic acidosis as a possible side effect, although this has been reported in only two adult cases. We investigated the acid-base metabolism in infants and toddlers treated with TPM. METHODS: Nine infants and toddlers aged 5 months to 2.3 years (median, 6 months) were treated with TPM at maximal doses of 8.2-26 mg/kg/day (median, 11 mg/kg/day). The maximal TPM dose was achieved after 8-35 days (median, 17 days). TPM was given in addition to other antiepileptic drugs (AEDs) in five cases and as a sole AED in four patients with refractory epilepsy resistant to multiple AEDs. The diagnoses were infantile spasms (n = 5), epilepsia partialis continua (n = 1), infantile epileptic encephalopathy (n = 1), and Lennox-Gastaut syndrome (n = 2). RESULTS: The blood gases were normal before treatment with TPM in all nine children. Metabolic acidosis developed in eight children after 8-26 days (median, 14 days) of TPM treatment with a minimum of serum bicarbonate between 15 to 18 mM (median, 17 mM), a minimal base excess between -6.2 and -11.2 mM (median, -7.9 mM), and pH between 7.22 and 7.40 (median, 7.35). Four of nine children showed clinical signs of hyperventilation and received oral sodium bicarbonate (1-2 mmol/kg), while TPM was still effective. CONCLUSIONS: Because metabolic acidosis developed in eight of the nine infants and toddlers taking TPM, we would suggest that the acid-base metabolism be monitored in young children who receive TPM.     

Monoamines and seizures: microdialysis findings in locus ceruleus and amygdala before and during amygdala kindling

We used microdialysis to determine extracellular concentrations of norepinephrine (NE), dopamine (DA) and serotonin (5-HT) before and during a 1-day amygdala kindling paradigm. Subjects were young cats (<1 year old; n=8; 6 female, 2 male). Consecutive 5-min samples (2 microl/min infusion rate) were obtained from left amygdala and ipsilateral locus ceruleus complex (LC) under 3 experimental conditions lasting 1-h each (n=12 samples per cat per condition): (1) just before amygdala stimulation (baseline), (2) during focal afterdischarge (AD) and (3) during generalized AD. ADs were elicited by electrical stimulation applied to establish thresholds immediately before dialysate collection as well as during each sample collected in focal vs. generalized AD conditions. Sample concentrations were time-adjusted to correspond with sleep vs. waking state and/or focal vs. generalized ADs. Seizure activity was indexed by AD threshold (mA) and duration (s) as well as number and duration of specific clinically evident (behavioral) seizure manifestations. Main results were: (1) Lower baseline concentrations (fmoles per sample) of NE, DA and 5-HT correlated with subsequent increases in duration of focal and generalized AD as well as number of behavioral seizure correlates. (2) When compared to baseline levels, NE, DA and 5-HT concentrations significantly increased only in amygdala during focal AD and in both amygdala and LC during generalized AD. (3) NE and 5-HT concentrations were higher than DA at both collection sites and were selectively associated with increased wakefulness throughout the study.     

Congenital iodine deficiency and hypothyroidism impair LTP and decrease C-fos and C-jun expression in rat hippocampus

Iodine is essential for the synthesis of triiodothyronine (T(3)) and thyroxine (T(4)). Iodine deficiency leads to inadequate thyroid hormone. Thyroid hormones deficiency during brain development affects cognitive functions, such as attention, learning, and memory. However, the mechanism underlying these deficits is unclear. To investigate the role of iodine deficiency and hypothyroidism in synaptic plasticity, this study examined the induction of long-term synaptic plasticity (LTP) and expression of immediate early (IEA) gene proteins in rat hippocampus following congenital iodine deficiency or hypothyroidism. Through gestation and lactation, iodine-deficient or hypothyroid dam rats were administered with either iodine-deficient diet or methimazole-added drinking water. Exposure was terminated on postnatal day (PN) 30. In hippocampus of pup rats, the induction of LTP in area CA1 was determined on PN60 and the expression of c-fos and c-jun proteins was examined on PN20, PN30 and PN60. Compared to control pups, both treated groups have shown: (1) significantly lower concentrations of serum FT(3) and FT(4), (2) much smaller population spike (PS) amplitude (p<0.01) and field-excitatory postsynaptic potential (f-EPSP) slope induced by high-frequency stimulation (HFS) (P<0.01), and (3) significantly lower integrated optical density (IOD) total of c-fos and c-jun expression (P<0.05 or P<0.01). In summary, iodine deficiency and hypothyroidism during critical periods of brain development impair LTP induction and decrease the expression of c-fos and c-jun proteins in hippocampus.     

Three-dimensional volumetric analysis and reconstruction of amygdala and hippocampal head, body and tail

Volumetric changes in the amygdala and hippocampus are relevant to many disorders, but their close proximity makes it difficult to separate these structures by magnetic resonance imaging, leading many volumetric protocols to exclude problematic slices from analysis, or to analyze the amygdalo-hippocampal complex conjointly. The hippocampus tail is also often excluded, because of the difficulty in separating it from the thalamus. We have developed a reliable protocol for volumetric analysis and 3-D reconstruction of the amygdala and hippocampus (as a whole and in its anatomical parts). Twenty volunteers from clinical and healthy populations were recruited. T1-weighted images were acquired at 1.5 Tesla with native spatial resolution of 1.5 mm x 1.0 mm x 1.0 mm. Volumetric analyses were performed blind to diagnosis, using the interactive software package DISPLAY. Inter-rater (intrarater) intraclass correlations for the method were: 0.95 (0.88) for hippocampus tail, 0.83 (0.93) for hippocampus body, 0.95 (0.92) for hippocampus head, 0.96 (0.86) for total hippocampus and 0.86 (0.94) for amygdala. Volumes (mean+/-S.D.) corrected for intracranial volume for this mixed group were for the hippocampal tail: 0.325+/-0.087 cm(3); hippocampal body: 0.662+/-0.120 cm(3); hippocampal head: 1.23+/-0.174 cm(3); total hippocampus: 2.218+/-0.217 cm(3), and amygdala: 0.808+/-0.185 cm(3). In conclusion, the study demonstrates that the amygdala and hippocampal parts can be quantified reliably.     

Pain and numbness in the arms and hands and carpal tunnel syndrome diagnosis

We studied the frequency and localization of pain and numbness in patients with carpal tunnel syndrome (CTS), in comparison with individuals of the general population, matched for sex and age, and we determined the sensitivity and the specificity of these symptoms for the CTS diagnosis. Pain was a common symptom in the two groups of patients. Numbness occurred more frequently in CTS group (p<0.05). In CTS patients, pain complaints were present in neck (42.8%), arms (36.8%) and hands (82.8%). Among controls, pain was more common in head (11.4%), trunk (37.1%), legs (22.8%). In our casuistics, in relation to the CTS diagnosis, the presence of pain and numbness have low sensitivity and high specificity when they occur in the arms, and high sensitivity and specificity when they occur in the hands.     

Imaging brain signal transduction and metabolism via arachidonic and docosahexaenoic acid in animals and humans

The polyunsaturated fatty acids (PUFAs), arachidonic acid (AA, 20:4n-6) and docosahexaenoic acid (DHA, 22:6n-3), important second messengers in brain, are released from membrane phospholipid following receptor-mediated activation of specific phospholipase A(2) (PLA(2)) enzymes. We developed an in vivo method in rodents using quantitative autoradiography to image PUFA incorporation into brain from plasma, and showed that their incorporation rates equal their rates of metabolic consumption by brain. Thus, quantitative imaging of unesterified plasma AA or DHA incorporation into brain can be used as a biomarker of brain PUFA metabolism and neurotransmission. We have employed our method to image and quantify effects of mood stabilizers on brain AA/DHA incorporation during neurotransmission by muscarinic M(1,3,5), serotonergic 5-HT(2A/2C), dopaminergic D(2)-like (D(2), D(3), D(4)) or glutamatergic N-methyl-d-aspartic acid (NMDA) receptors, and effects of inhibition of acetylcholinesterase, of selective serotonin and dopamine reuptake transporter inhibitors, of neuroinflammation (HIV-1 and lipopolysaccharide) and excitotoxicity, and in genetically modified rodents. The method has been extended for the use with positron emission tomography (PET), and can be employed to determine how human brain AA/DHA signaling and consumption are influenced by diet, aging, disease and genetics.     

Loneliness and stress-related inflammatory and neuroendocrine responses in older men and women

Loneliness is a predictor of mortality and increased cardiovascular morbidity. Inflammation is a potential pathway through which loneliness might impact health. The aim of the study was to investigate the relationship between loneliness and inflammatory interleukin-6 (IL-6), interleukin-1 receptor antagonist (IL-1Ra) and monocyte chemotactic protein-1 (MCP-1) responses to standardized mental stress. A secondary purpose was to evaluate whether individual variations in cortisol responses influenced the hypothesised relationship between loneliness and inflammation. Saliva samples and blood were taken from 524 healthy middle-aged men and women from the Whitehall II cohort at baseline, immediately after the stress tasks and 45min later. Loneliness was measured using the revised UCLA loneliness scale. Greater loneliness was associated with larger IL-6 (p=0.044) and IL-1Ra (p=0.006) responses to psychological stress and higher MCP-1 (p<0.001) levels in women, independently of age, grade of employment, body mass index and smoking status. No associations were observed in men. Cortisol responsivity was inversely related to loneliness in women, with the odds of being a cortisol responder decreasing with increased loneliness independently of covariates (p=0.008). The impact of loneliness on health in women may be mediated in part through dysregulation of inflammatory and neuroendocrine systems.     

Expression and regulation of cholecystokinin and cholecystokinin receptors in rat nodose and dorsal root ganglia

Cholecystokinin (CCK) is an important satiety factor, acting via the vagus nerve to influence central feeding centers. CCK binding sites have been demonstrated in the vagal sensory nodose ganglion and within the nerve proper. Using in situ hybridization, expression of the CCK(A) and (B) receptors (Rs), as well as of CCK itself, was studied in the normal nodose ganglion (NG), and after vagotomy, starvation and high-fat diet. CCK(A)-R mRNA expression in dorsal root ganglia (DRGs) was also explored. In the NG, 33% of the neuron profiles (NPs) contained CCK(A)-R mRNA and in 9% we observed CCK(B)-R mRNA. CCK mRNA was not found in normal NGs. Peripheral vagotomy decreased the number of CCK(A)-R mRNA-expressing NPs, dramatically increased the number of CCK(B)-R mRNA, and induced CCK mRNA and preproCCK-like immunoreactivity in nodose NPs. No significant differences in the number of NPs labelled for either mRNA species were detected following 48 h food deprivation or in rats fed a high-fat content diet. In DRGs, 10% of the NPs expressed CCK(A)-R mRNA, a number that was not affected by either axotomy or inflammation. This cell population was distinct from neurons expressing calcitonin gene-related peptide mRNA. These results demonstrate that the CCK(A)-R is expressed by both viscero- and somatosensory primary sensory neurons, supporting a role for this receptor as a mediator both of CCK-induced satiety and in sensory processing at the spinal level. The stimulation of CCK and CCK(B)-R gene expression following vagotomy suggests a possible involvement in the response to injury for these molecules.     

Urinary 5-hydroxyindoleacetic acid and whole blood serotonin and tryptophan in autistic and normal subjects

Urinary 5-hydroxyindoleacetic acid (5-HIAA) excretion in two consecutive collection periods (5:00 PM-11:00 PM and 11:00 PM-8:00 AM) and whole blood serotonin (5-HT) and tryptophan (TRP) were measured in groups of unmedicated autistics (n = 16), medicated autistics (n = 20), and normal controls (n = 27). Whole blood 5-HT values were significantly higher in unmedicated autistics compared to normal controls. No significant differences were found in 5-HIAA excretion (microgram/mg creatinine, mean +/- SD) between unmedicated autistics (4.07 +/- 1.52) and normal controls (3.50 +/- 1.07), or between medicated (5.35 +/- 2.93) and drug-free autistic individuals. No correlations were found between 5-HT values and urinary 5-HIAA excretion. Urinary 5-HIAA (microgram/mg creatinine, mean +/- SD) was significantly greater in hyperserotonemic autistic subjects (4.88 +/- 0.87) compared to normal controls (3.50 +/- 1.07, total collection period; p = 0.002). The relevance of these findings to the possibility that increased gut production of 5-HT might cause the elevated whole blood 5-HT levels seen in autism is discussed.     

MAOA and MAOB polymorphisms and anger-related traits in suicidal participants and controls

MAOA and, to a lesser extent, MAOB polymorphisms have been related to aggression traits and suicidality. We aimed to investigate the role of MAOA and MAOB in suicidal versus non-suicidal participants and interactions between genetic variation and suicidal status on aggression and anger-related traits. The sample was composed of three groups: one group of suicide attempters (n = 171, males 35.1 %), one group of suicide completers (n = 90, males 57.8 %) and a healthy control group (n = 317, males 43.8 %). We examined the following markers: MAOA rs909525, rs6323, and rs2064070, and MAOB rs1799836. Anger traits were measured with the state-trait anger expression inventory (STAXI) and aggression traits with the questionnaire for measuring factors of aggression (FAF). Associations were separately examined for males and females. Variation in the three MAOA variants was associated with higher levels of anger expressed outwards (STAXI “anger-out” subscale) in male suicidal patients compared to controls (p < 0.001). In females, the C allele of rs6323 showed higher scores on the same subscale (“anger out”) (p = 0.002). Allele frequencies of the MAOA rs909525 were associated with suicidality (p < 0.007). Our findings show an association between genetic variation in three polymorphisms of the MAOA and anger traits in suicidal males and one replication for the functional variant rs6323 in females. This relationship was stronger than a direct genetic association with suicide status. Future studies incorporating endophenotypic measures of anger and aggression in suicidal participants are warranted.     

Sigma1 and sigma2 receptor binding affinity and selectivity of SA4503 and fluoroethyl SA4503

SA4503, a potent sigma(1) receptor agonist, is reported as having 103-fold higher affinity for sigma(1) (IC(50) = 17.4 nM) than sigma(2) (IC(50) = 1,784 nM) sites in guinea pig brain membranes. Modest structural changes appear to have major effects on sigma(1)/sigma(2) selectivity. The fluoroethyl analog, FE-SA4503, is described as having high primary affinity for sigma(2) sites (IC(50) = 2.11 nM) and a weaker interaction with sigma(1) sites (IC(50) = 6.48 nM). SA4503 and FE-SA4503 have been radiolabeled for PET studies, and both bind selectively to sigma(1) receptors in animal and human brain in vivo. We prepared SA4503 and FE-SA4503 as reference compounds for radioligand development efforts. In our hands, SA4503 is 14-fold selective for sigma(1) (K(i) = 4.6 nM) over sigma(2) (K(i) = 63.1 nM) sites in guinea pig brain homogenates. Further, FE-SA4503 exhibits the same 14-fold selectivity for sigma(1) (K(i) = 8.0 nM) over sigma(2) (K(i) = 113.2 nM) receptors. The main differences from previously reported values stem from sigma(2) affinity determinations. This protocol, displacement of [(3)H]DTG binding to sigma(2) sites using (+)-pentazocine (200 nM) to mask sigma(1) sites, was validated by the proper rank order of sigma(2) inhibitory potencies shown by a panel of additional ligands: ifenprodil > haloperidol > DTG > (+)-pentazocine. Robust Pearson correlation (r = 1.0, P = 0.002; slope = 0.97) was observed for our pK(i) values against those from a prior study by others. The findings have bearing on structure-activity relationships for this active series, and on conclusions that might be drawn from experiments relying upon defined sigma(1)/sigma(2) binding selectivity.     

Childhood trauma and anger in adults with and without depressive and anxiety disorders

Background

Childhood trauma (CT) is associated with severe sequelae, including stress-related mental health disorders that can perpetuate long into adulthood. A key mechanism in this relationship seems to be emotion regulation. We aimed to investigate (1) whether childhood trauma is associated with anger in adulthood, and, if so, (2) to explore which types of childhood trauma predominate in the prediction of anger in a cohort that included participants with and without current affective disorders.

Methods

In the Netherlands Study of Depression and Anxiety (NESDA), childhood trauma was assessed with a semi-structured Childhood Trauma Interview (CTI) at baseline, and analyzed in relation to anger as measured at a 4-year follow-up with the Spielberger Trait Anger Subscale (STAS), the Anger Attacks Questionnaire, and cluster B personality traits (i.e., borderline, antisocial) of the Personality Disorder Questionnaire 4 (PDQ-4), using analysis of covariance (ANCOVA) and multivariable logistic regression analyses. Post hoc analyses comprised cross-sectional regression analyses, using the Childhood Trauma Questionnaire-Short Form (CTQ-SF) also obtained at a 4-year follow-up.

Results

Participants (n = 2271) were on average 42.1 years (SD = 13.1), and 66.2% were female. Childhood trauma showed a dose–response association with all anger constructs. All types of childhood trauma were significantly associated with borderline personality traits, independently of depression and anxiety. Additionally, all types of childhood trauma except for sexual abuse were associated with higher levels of trait anger, and a higher prevalence of anger attacks and antisocial personality traits in adulthood. Cross-sectionally, the effect sizes were larger compared with the analyses with the childhood trauma measured 4 years prior to the anger measures.

Conclusions

Childhood trauma is linked with anger in adulthood, which could be of particular interest in the context of psychopathology. Focus on childhood traumatic experiences and adulthood anger may help to enhance the effectiveness of treatment for patients with depressive and anxiety disorders. Trauma-focused interventions should be implemented when appropriate.     

Relationship status and testosterone in North American heterosexual and non-heterosexual men and women: cross-sectional and longitudinal data

Previous research has found that single heterosexual (Het) men have higher salivary testosterone (T) concentrations than partnered Het men. Here, we used both longitudinal and cross-sectional analyses to examine a more diverse population (n = 258) that included Het and non-heterosexual (Non-Het) women and men. Results showed that, for Het men (but not Het women) and Non-Het women (but not Non-Het men), baseline T was significantly lower in partnered than unpartnered individuals. Longitudinal analyses indicated that changes in partnered status were not associated with changes in testosterone concentrations; instead, women and men with lower T at baseline were significantly more likely to be partnered at follow-up. These findings thus suggest that partnered status is associated with stable, trait-level T values, rather than current state. Furthermore, the observed effect is limited to individuals (male or female) who are oriented toward female partners. The results are discussed in terms of evolutionary trade-offs between single and multiple partners, and the possibility of female choice and/or disinterest.     

Non-suicidal self-injury and suicidal thoughts and behaviors in heterosexual and sexual minority young adults

ObjectiveDespite consistently greater rates of non-suicidal self-injury (NSSI) and suicidal thoughts and behaviors (STBs; i.e., suicidal ideation, method/plan, and attempts) in lesbian, gay, and bisexual (LGB) individuals, prevalence, characteristics, and relations between these dangerous thoughts and behaviors are equivocal. The present study sought to examine and compare the rates of NSSI and STBs in a large sample of sexual minority and majority young adults.MethodsParticipants were 12,422 college students (ages 18–29; 57.3% female) who self-reported demographic characteristics, NSSI frequency, the number of NSSI forms used, the number of NSSI functions, as well as STB history (i.e., ideation, method/plan, and attempts). Each participant’s degree of SA was assessed via a 7-point scale (i.e., K0–K6) from Alfred Kinsey’s research of sexual attraction and sexual experiences. This scale was collapsed to create five categories of SA: exclusively other SA (K0), mostly other SA (K1/2), equally other and same SA (K3), mostly same SA (K4/5), and exclusively same SA (K6).ResultsConsistent with previous research, we found that being a sexual minority young adult was associated with significantly higher odds of STBs compared to being a heterosexual young adult. In addition, compared to the exclusively other SA group (K0), being in the mostly other SA group (K1/2), equally other and same SA group (K3), or mostly same SA group (K4/5) was associated with significantly higher odds of NSSI engagement. Among those with NSSI, we found that the number of NSSI forms was significantly associated with suicide attempts, but was not associated with either suicidal ideation or suicide method/plan in the mostly other SA group (K1/2) or in the equally other and same SA group (K3). We also found a significant curvilinear relation between NSSI frequency and STBs in the mostly other SA group (K1/2) and between NSSI frequency and suicide method/plan and attempt in the exclusively other SA group (K0). In addition, we revealed specificity with regard to the relation between the number of lifetime NSSI episodes and risk for STBs among the equally other and same SA (K3), mostly same SA (K4/5), and exclusively same SA (K6) groups.ConclusionOur findings suggest that among sexual minority young adults, equally other and same SA individuals may be at higher risk of NSSI and STBs than their sexual minority counterparts. In addition, these findings extend previous research by suggesting that the relations between NSSI frequency, number of forms, and number of functions and STBs might vary according to SA. A multi-theory based explanation is provided to explain the key findings and the study implications are discussed.     

Opiate and digitalis receptor assays distinguish between neuroexcitant and inactive organochlorines and between anesthetics and convulsants

Specific binding of [3H]naloxone to rat brain tissue in vitro was inhibited by the excitant organochlorinated insecticides (OCI), by ether (E) and octanol (OCT), and by the convulsant indoklon (IND) and its anesthetic isomer, isoindoklon (ISO). In the presence of 100 mM NaCl the inhibition of naloxone binding by E, OCT and ISO was greatly potentiated, whereas that by OCI and IND was attenuated. KCl (100 mM) was equally effective as NaCl on the action of anesthetics, but the effect of the excitant drugs was, in contrast to NaCl, unaffected by KCl. Specific binding of [3H]ouabain in the absence of Na, was depressed by anesthetics and enhanced by neuroexcitants. In the presence of NaCl, which by itself inhibits ouabain binding to brain, both anesthetics and excitants enhanced ouabain binding. DDE, a non-insecticidal analog of DDT, and the dimethyl derivative of the OCI, lindane, were inactive in the receptor assays. These observations point to a unique isolated system which responds consistently to anesthetic agents as a class and, in a different way, to neuroexcitant compounds.     

Cannabis and schizophrenia: demographic and clinical correlates

The high prevalence of psychoactive substance abuse or dependence among schizophrenic patients has now been well established. Mueser et al. stressed the need to assess the abuse of specific classes of substances and analyse the data accordingly. The objective of this study was to compare the socio-demographic correlates and the clinical features in a group of schizophrenic patients with a lifetime cannabis abuse or dependence according to the DSM III-R with a group of schizophrenic patients who had never presented any abuse or dependence. SUBJECTS AND METHODS: The study included 124 subjects with diagnoses of schizophrenia or schizoaffective disorders according to the DSM III-R. Inclusion criteria for participation in the study were age 18 years or older and willingness to provide consent to participate in the study. The inpatients were evaluated when their condition was stabilised. Assessment tools were the psychoactive substance use disorder section of the Composite International Diagnostic Interview (CIDI), the Positive and Negative Syndrome Scale (PANSS), the Global Assessment of Functioning Scale (GAF). Subjects with cannabis abuse or dependence during their lifetime were compared with subjects without abuse or dependence, using chi(2) test for categorical variables and analyses of covariance (ANCOVA) for quantitative variables. RESULTS: Forty-nine subjects (42,6%) presented lifetime abuse or dependence on one or more substances. Since 19 patients with alcohol, stimulant, sedative or opiate abuse or dependence were excluded, the study finally included 96 subjects including a first group of schizophrenic patients with cannabis abuse (n=6) or dependence (n=24) and a second group without any psychoactive substance abuse (n=66). Thirteen (11.3%) patients presented cannabis abuse or dependence within the 6 months prior to the assessment. The mean SD age of onset of cannabis abuse or dependence was 19.6 +/- 3.0 years. Cannabis abuse/dependence preceded the first psychiatric treatment in 70% of the subjects (n=21). 83.3% of the schizophrenic patients with cannabis abuse or dependence were male (n=25) compared to 62.1% in the group without substance abuse (n=41) (chi(2)=4.32, df=1, p=0.04). Schizophrenic patients with cannabis abuse were significantly younger (mean age: 28.9 +/- 6.3 vs 37.0 +/- 12.7, ANCOVA, F=7.2, df=1,96 p=0.009). There was no significant difference between the two groups for marital status, (chi(2)=5.34, df=2, p=0.07), level of education, (chi(2)=0.93, df=2, p=0.62) professional status, (chi(2)=8.7, df=5, p=0.11), on PANSS total score (ANCOVA, F=0.42, df=1,93, p=0.52), GAF score (ANCOVA, F=0.06, df=1,92, p=0.80), mean number of hospitalizations (ANCOVA, F=3.25, df=1,85, p=0.08), mean age of first psychiatric contact (ANCOVA, F=0.74, df=1,93, p=0.39), and neuroleptic dosages (ANCOVA, F=0.03, df=1,90, p=0.87). In contrast, the total duration of hospitalization was significantly longer for the group with cannabis abuse. Patients with cannabis abuse were more likely to have an history of suicide attempts than subjects without substance abuse (chi(2)=11.52, df=1, p=0.0007). DISCUSSION: The prevalence rates for substance abuse and the socio-demographic characteristics of the population of our study are consistent with findings of previous studies. Male gender and age were significantly related to history of cannabis abuse or dependence. Cannabis abuse frequently preceded the onset of psychiatric treatment. However, both schizophrenia and substance abuse tend to develop gradually, with no clear demarcation for the onset of schizophrenia. The absence of any link between the scores for the subscales of the PANSS and cannabis abuse, both in our study and in some retrospective previous studies, is not suggestive of cannabis abuse as a self-medication of positive or negative symptoms of schizophrenia. Self-medication could concern other symptoms, such as cognitive deficits. In addition, the hypothesis of self-medication has especially been suggested in cocaine abuse or dependence. Some limitations to this study can be discussed. First, although the recruitment was systematic and done in a public mental health service, the patients of our study are not necessarily representative of all schizophrenic patients. Secondly, as in any retrospective study, the prevalence of lifetime substance abuse may have been under-estimated. Urinary toxicology tests may have been able to improve the sensitivity of the diagnosis of recent substance abuse, but structured interviews are more appropriate for the diagnosis of lifetime substance abuse in schizophrenic patients than urinary toxicology tests. CONCLUSION: The socio-demographic characteristics of cannabis abuse or dependence in schizophrenia are similar to those found in general population. Cannabis using schizophrenic patients were more likely to be younger and male than non users. The duration of hospitalization was significantly longer for the group with cannabis abuse. Prevalence of suicide attempts in schizophrenia is closely correlated to cannabis abuse.     

Physicochemical and biological properties of canine-prothrombin and thrombin

Canine prothrombin was purified by a combination of BaSO4 adsorption, elution of adsorbed prothrombin in 0.25 M sodium citrate, concentration of the eluate by (NH4) 2SO4 fractionation at 80 % saturation and DEAE cellulose chromatography. The prothrombin was pure by immunoelectrophoresis but some trace impurities were visible by SDS polyacrylamide gel electrophoresis (SDS PAGE). The molecular weight was 81,300 ± 850(SD) by SDS PAGE, the extinction coefficient was 13.8 ± 0.4(SD) for 10 mg per ml, and the specific activity was 1,200 ± 50 (SD) NIH units per mg prothrombin. Then, the activation behavior of prothrombin by activated Factor X in the presence of Factor V, phospholipids and Ca⁺⁺ was studied, and the molecular weight of each product was determined by SDS PAGE. The molecular weights for P2 (intermediate 1), Fa(fragment 1), P3(intermediate 2) and Fb(fragment 2) were 60,000, 28,540, 40,400 and 21,240, respectively. Next, thrombin was separated by the use of QAE-Sephadex A-50 chromatography. The molecular weight averaged 38,111 ± 500(SD), the extinction coefficient was 16.0 ± 0.2(SD) for 10 mg per ml and the specific activity was 2,000 ± 65(SD) NIH units per mg thrombin. Comparison of these results with previous studies of bovine material(Biochem. 11: 4502, 1972; J. Biol. Chem. 249: 594, 1974) showed that the results were generally similar. One peculiar finding with the canine material was that P2 appeared to consist of two polypeptide subunits. Further studies are required to elucidate its significance.     

Clozapine and cocaine effects on dopamine and serotonin release in nucleus accumbens during psychostimulant behavior and withdrawal

There is an increasing awareness that a psychosis, similar to that of schizophrenic psychosis, can be derived from cocaine addiction. Thus, the prototypical atypical antipsychotic medication, clozapine, a 5-HT(2)/DA(2) antagonist, was studied for its effects on cocaine-induced dopamine (DA) and serotonin (5-HT) release in nucleus accumbens (NAcc) of behaving male Sprague-Dawley laboratory rats with In Vivo Microvoltammetry, while animals' locomotor (forward ambulations), an A(10) behavior, was monitored at the same time with infrared photobeams. Release mechanisms for monoamines were determined by using a depolarization blocker, gamma-butyrolactone (gammaBL). BRODERICK PROBE microelectrodes selectively detected release of DA and 5-HT within seconds and sequentially in A(10) nerve terminals, NAcc. Acute and subacute studies were performed for each treatment group. Acute studies are defined as single injection of drug(s) after a stable baseline of each monoamine and locomotor behavior has been achieved. Subacute studies are defined as 24-h follow-up studies on each monoamine and locomotor behavior, in the same animal at which time, no further drug was administered. Results showed that (1) acute administration of cocaine (10 mg/kg ip) (n=5) significantly increased both DA and 5-HT release above baseline (P<.001) while locomotion was also significantly increased above baseline (P<.001). In subacute studies, DA release decreased significantly below baseline (P<.001) and significant decreases in 5-HT release occurred at the 15-min mark and at each time point during the second part of the hour (P<.05); the maximum decrease in 5-HT was 40% below baseline. Locomotor behavior, on the other hand, increased significantly above baseline (P<.05). (2) Acute administration of clozapine/cocaine (20 and 10 mg/kg ip, respectively; n=6) produced a significant block of the cocaine-induced increase in DA (P<.001) and 5-HT release (P<.001). Cocaine-induced locomotion was blocked simultaneously with each monoamine by clozapine as well (P<.001). In subacute studies, DA release continued to be blocked presumably via clozapine by exhibiting a statistically significant decrease (P<.001), but 5-HT release increased significantly (P<.001), while cocaine-induced locomotor activity also continued to be antagonized by clozapine, i.e., locomotor activity exhibited no difference from baseline (P>.05). In summary, acute studies (a) support previous data from this laboratory and others that cocaine acts as a stimulant on the monoamines, DA and 5-HT and on locomotor behavior as well and (b) show that clozapine, 5-HT(2)/DA(2) antagonist, blocked enhanced DA, 5-HT and psychomotor stimulant behavior induced by cocaine. Subacute studies (a) suggest that withdrawal responses occurred in the cocaine group, based on recorded deficiencies in monoamine neurotransmitters (b) show that withdrawal effects in the cocaine group likely presynaptic, were distinguished from locomotor behavior, classically known to be mediated postsynaptically, and finally, (c) suggest that clozapine, with longer lived pharmacokinetic properties, reversed 5-HT cocaine-related withdrawal effects, but was unable to reverse DA cocaine-related withdrawal responses. Taken together with data from this laboratory, in which the 5-HT(2A/2C) antagonist, ketanserin, affected cocaine neurochemistry in much the same way as did clozapine, a mediation by either separate or combined 5-HT(2A/2C) receptors for these clozapine/cocaine interactions, is suggested. Further studies, designed to tease out the responses of selective 5-HT(2A) and 5-HT(2C) receptor compounds to cocaine and clozapine/cocaine, are underway.