Increasing leptin precedes craving and relapse during pharmacological abstinence maintenance treatment of alcoholism

The appetite regulating peptide leptin has recently been associated with craving for alcohol and lifetime ethanol intake. However, effects of anti-craving drugs on leptin have not been studied until now. The objective of our study was to test the hypothesis whether leptin plasma concentration in abstinent alcohol addicts during treatment with naltrexone vs. acamprosate is associated with abstinence duration and craving for alcohol. Leptin plasma concentration was measured in 160 recently detoxified alcohol addicts during a double-blind, placebo-controlled relapse prevention trial with naltrexone vs. acamprosate vs. naltrexone plus acamprosate. During placebo treatment, increasing leptin plasma concentration was observed, whereas during combined treatment with naltrexone and acamprosate, leptin decreased significantly. The change from baseline of leptin plasma levels after weeks 4, 8 and 12 was inversely correlated with duration of abstinence and, after 4 weeks, positively correlated with self-rated craving. In summary, the study presents first evidence for an association of increasing leptin plasma concentrations with relapse to renewed alcohol intake in detoxified alcoholics. Moreover, there are hints for an interaction between pharmacological anti-craving treatment, plasma concentration of leptin, and abstinence duration.

A neuroendocrinological hypothesis on gender effects of naltrexone in relapse prevention treatment

The ability of naltrexone to increase hypothalamo-pituitary-adrenocortical (HPA)-axis activity was recently reported to be associated with its effects on the reduction of craving for alcohol. We now present data showing naltrexone to be more efficacious in female alcoholics. Since HPA-axis might be interpreted as a key mechanism of action that could explain the observed gender differences in the abstinence maintenance treatment of alcohol addiction.

Suppression of the HPA axis stress-response: implications for relapse

This article presents the proceedings of a symposium held at the meeting of the International Society for Biomedical Research on Alcoholism (ISBRA) in Mannheim, Germany, in October 2004. This symposium explored the potential role of hypothalamic-pituitary-adrenal (HPA) axis dysregulation upon relapse. HPA axis stimulation induces the release of the glucocorticoid cortisol, a compound with profound effects upon behavior and emotion. Altered stress-responses of the HPA axis in abstinent alcohol-dependent subjects, therefore, may influence their affective and behavioral regulation, thus impacting their potential for relapse. Bryon Adinoff began the symposium with a review of HPA axis dysfunction in alcohol-dependent subjects, including recent studies from his lab demonstrating an attenuated glucocorticoid response to both endogenous and exogenous stimulation in one-month abstinent men. Klaus Junghanns presented his work demonstrating that a blunted ACTH or cortisol response to subjective stressors (social stressor or alcohol exposure) is predictive of a return to early drinking. The final two presenters examined the interaction between naltrexone and HPA responsiveness in alcohol-dependent or at-risk subjects, as naltrexone induces an increase in ACTH and cortisol. Falk Kiefer discussed the relationship between basal HPA axis responsivity and clinical outcome following treatment with naltrexone or acamprosate. Plasma ACTH significantly decreased over the course of the study in the placebo group, but not the medication groups [corrected] Lower basal concentrations of ACTH and cortisol were associated with quicker relapse in the placebo group only. Suchitra Krishnan-Sarin described her preliminary work, in which family-history positive (FH+) and family history negative (FH-) subjects were administered naltrexone, followed by an assessment of alcohol-induced craving. The cortisol response to alcohol was significantly and inversely related to craving in the FH+, but not the FH-, subjects. Alterations in HPA axis responsivity may therefore have a negative impact upon clinical outcome in alcohol-dependent subjects, and disinhibition of the axis with medication may have therapeutic potential.

Adjunctive use of reboxetine in schizophrenia

BACKGROUND

Schizophrenia is frequently complicated by depressive or negative symptoms that respond only moderately to treatment with antipsychotic drugs. Reboxetine is a novel antidepressant, which inhibits the reuptake of norepinephrine. We sought to study the efficacy and tolerability of the adjunctive use of reboxetine in a cohort of schizophrenic patients with prominent depressive or negative symptoms.

METHODS

Sixteen schizophrenic inpatients were recruited for this study. All subjects received 4-8 mg of reboxetine/day while the antipsychotic medication (typical antipsychotics = 4; atypical antipsychotics = 12) was continued. All subjects underwent a standardized assessment including PANSS, CGI, HAMD, and CDSS before and after treatment with reboxetine (mean 26 +/- 17 d).

RESULTS

All subjects tolerated treatment with reboxetine. Adverse effects were mild and did not require discontinuation of reboxetine. All clinical scores (PANSS 93.1 vs. 63.1; CGI 5.4 vs. 4.1; HAMD 20.4 vs. 8.1; CDSS 12.5 vs. 4.6) improved significantly under adjunctive treatment with reboxetine (all P < 0.01).

CONCLUSION

The adjunctive use of reboxetine in schizophrenic patients was safe and well-tolerated. Our results suggest that the adjunctive use of reboxetine may be an effective treatment for depressive and negative symptoms in schizophrenia.

Pharmacological relapse prevention of alcoholism: clinical predictors of outcome

OBJECTIVE

The efficacy of pharmacological relapse prevention in alcoholism with acamprosate and naltrexone has been supported by several controlled trials. It remains uncertain whether any differential indication for treatment exists.

METHODS

We evaluated outcome data of a controlled trial on acamprosate and naltrexone in patients with low vs. high baseline somatic distress, depression and anxiety (Symptom Checklist-90, SCL-90), low vs. high baseline craving, and according to typological differentiation as proposed by Cloninger and Lesch. These variables have previously been suggested to be predictors of outcome.

RESULTS

Comparing the course of abstinence rates, acamprosate was mainly efficacious in patients with low baseline somatic distress, whereas naltrexone was effective especially in patients with high baseline depression. Baseline craving showed no predictive value. Pharmacological treatment was efficacious in type II alcoholics according to Cloninger. Applying Lesch's typological differentiation, acamprosate was shown to be mainly effective in type I, whereas naltrexone revealed best treatment effects in type III and IV.

CONCLUSION

The study supports the hypothesis that different subgroups of alcohol dependent subjects might benefit from a differential treatment with either naltrexone or acamprosate. Baseline psychopathology and especially typological differentiation might be useful in matching patients to distinct pharmacotherapeutic interventions. .

The Face of Pain - A Pilot Study to Validate the Measurement of Facial Pain Expression with an Improved EMG Method

OBJECTIVE: The purpose of this pilot study was to establish the validity of an improved facial electromyogram (EMG) method for the measurement of facial pain expression.

BACKGROUND: Darwin defined pain in connection with fear as a simultaneous occurrence of eye staring, brow contraction and teeth chattering. Prkachin was the first to use the video-based Facial Action Coding System to measure facial expressions while using four different types of pain triggers, identifying a group of facial muscles around the eyes.

METHOD: The activity of nine facial muscles in 10 healthy male subjects was analyzed. Pain was induced through a laser system with a randomized sequence of different intensities. Muscle activity was measured with a new, highly sensitive and selective facial EMG.

RESULTS: The results indicate two groups of muscles as key for pain expression. These results are in concordance with Darwin's definition. As in Prkachin's findings, one muscle group is assembled around the orbicularis oculi muscle, initiating eye staring. The second group consists of the mentalis and depressor anguli oris muscles, which trigger mouth movements.

CONCLUSIONS: The results demonstrate the validity of the facial EMG method for measuring facial pain expression. Further studies with psychometric measurements, a larger sample size and a female test group should be conducted.

Metyrapone as additive treatment in major depression: a double-blind and placebo-controlled trial

BACKGROUND

Inhibitors of steroid synthesis have been reported to exert antidepressive effects, according to preliminary findings.

OBJECTIVE

To test whether the addition of metyrapone to standard antidepressants induces a more rapid, more efficacious, and sustained treatment response in patients with major depression.

DESIGN

Double-blind, randomized, placebo-controlled trial.

SETTING

Hospitalized care.

PATIENTS

Sixty-three inpatients with a DSM-IV diagnosis of major depression and a baseline score 18 points or higher on the Hamilton Rating Scale for Depression.

INTERVENTIONS

Random allocation to 2 treatment groups receiving either placebo or metyrapone (1 g/d) for the first 3 weeks during a 5-week treatment with standard serotonergic antidepressants (nefazodone or fluvoxamine).

MAIN OUTCOME MEASURES

Primary outcome criteria were the number of responders and the time to onset of action. Responder rates were considered twice after 3 and 5 weeks with a definition of treatment response as 30% and 50% reduction, respectively, of baseline Hamilton Rating Scale for Depression scores. Onset of action was defined as the time point at which at least a 20% reduction of baseline Hamilton Rating Scale for Depression scores occurred.

RESULTS

Using intention-to-treat analysis, we found that a higher proportion of patients receiving metyrapone showed a positive treatment response at day 21 (23 of 33 patients) and at day 35 (19 of 33 patients) compared with placebo patients (day 21: 13 of 30 patients; Fisher exact P = .031; day 35: 10 of 30 patients; Fisher exact P = .047). The clinical course of patients treated with metyrapone showed an earlier onset of action (Kaplan-Meier analysis; log-rank test P<.006) beginning in the first week. The plasma concentrations of corticotropin and deoxycortisol were significantly higher during metyrapone treatment (multivariate analysis of covariance, P<.05), whereas cortisol remained largely unchanged. Metyrapone treatment was well tolerated without serious adverse effects.

CONCLUSIONS

Metyrapone is an effective adjunct in the treatment of major depression, accelerating the onset of antidepressant action. A better treatment outcome compared with standard treatment and a sustained antidepressive effect were observed.

Long-term effects of pharmacotherapy on relapse prevention in alcohol dependence

BACKGROUND

There is growing evidence that pharmacological treatment with two of the best validated anticraving drugs, acamprosate and naltrexone, is efficacious in promoting abstinence in recently detoxified alcohol-dependent subjects.

OBJECTIVE

The stability of effects after termination of treatment remains to be answered, especially when combining both the drugs.

METHOD

After detoxification, 160 alcohol-dependent subjects participated in a randomized, double-blind, placebo-controlled trial. Patients received naltrexone or acamprosate or a combination of naltrexone and acamprosate or placebo for 12 weeks. Patients were assessed weekly by interview, self-report, questionnaires and laboratory screening. Additionally, follow-up evaluation based on telephone interview of participants, general practitioners and relatives was conducted 12 weeks after terminating the medication.

RESULTS

At week 12, the proportion of subjects relapsing to heavy drinking was significantly lower in the group with combined medication compared with both placebo and acamprosate (P < 0.05). No difference was detectable between acamprosate and naltrexone, both of which were superior to placebo (P < 0.05). Relapse rates were 28% (combined medication), 35% (naltrexone), 50% (acamprosate) and 75% (placebo). After follow-up (week 24), combined medication led to relapse rates significantly lower than placebo, but not lower than acamprosate. Again, both naltrexone and acamprosate were superior to placebo. Relapse rates were 80% (placebo), 54% (acamprosate), 53% (naltrexone) and 34% (combined medication).

CONCLUSIONS

The results of this study highlight the stability of effects of pharmacotherapy on relapse prevention in alcohol dependence.

Combined therapy: what does acamprosate and naltrexone combination tell us?

AIMS

Relapse prevention treatment with both acamprosate and naltrexone has been shown to be efficacious in the treatment of alcoholism. Whereas both compounds act pharmacologically differently, there is up to now only limited evidence as to whether combined treatment is efficacious and pharmacologically safe. It remains to be answered whether data justify the combination of both drugs in clinical practice.

METHODS

Review of the three pre-clinical and four clinical studies that have been published to date on either combined tolerability or efficacy.

RESULTS

Data available up to now show no occurrence of severe adverse events during combined treatment. Diarrhoea and nausea were shown to be the most significant side-effects. Whereas pre-clinical studies regarding efficacy of combined treatment are not yet conclusive, clinical data show the superiority of combined treatment compared with both placebo and acamprosate monotherapy. The synergistic effect of combined treatment remained after 12 weeks of drug-free follow-up.

CONCLUSIONS

The combination of acamprosate with naltrexone in a clinical sample seems to be efficacious and safe. Numerous alcohol dependent patients could benefit, particularly those that responded insufficiently on monotherapeutic treatment with either acamprosate or naltrexone.

Neuroendocrine pathways of addictive behaviour

Alcohol intake is known to modulate plasma concentrations of neuroendocrine peptides. However, recent results suggest that the endocrine system may not only respond passively to alcohol intake but that, vice versa, it also actively modulates alcohol intake behaviour. The most coherent body of data concerns the hypothalamo-pituitary-adrenocortical (HPA) axis, with low corticotrophin-releasing hormone (CRH) being associated with more intense craving and increased probability of relapse after acute detoxification. Leptin, beta-endorphin and atrial natriuretic peptide (ANP), which indirectly regulate the HPA system, also may modulate the intensity of craving or the intensity of the alcohol withdrawal syndrome. Although most of the currently available data demonstrate association rather than causality between neuroendocrine changes and alcohol-related behaviours, they do provide testable hypotheses and open up perspectives of treating alcohol dependence via manipulation of the neuroendocrine axis.

[Advances in the treatment of alcohol dependence: pharmacological relapse prevention]

The development and successful clinical examination of relapse preventing medications (so-called anti-craving substances) opens up completely new perspectives in the treatment of alcohol-dependent patients. This is especially important for the general practitioners since despite of improved psychosocial treatment of alcohol-dependent patients relapse rates after detoxification remain high. Since a few years, new medications reducing the relapse risk are available. In Germany acamprosate presently is the most important medication used for this indication. Compared with placebo treatment, approximatly twice as many patients remain abstinent under acamprosate one year after detoxification. The administration of the medication starts immediately after detoxification and supports the patient during the first months, when the relapse risk is especially high. The medical treatment, however, is not a replacement for a psychosocial treatment of the alcohol dependence, but should be accompanied by counselling and the attendance in self help groups.

Sleep Endocrine Effects of the 11-β-Hydroxysteroiddehydrogenase Inhibitor Metyrapone

STUDY OBJECTIVES

Besides regulating hormone secretion, steroids also modulate sleep architecture in specific ways. To simulate a state of altered glucocorticoid- and mineralocorticoid-receptor occupation, we administered metyrapone, an 11-beta-hydroxylase inhibitor, that blocks adrenal cortisol synthesis and inhibits the 11-beta-hydroxysteroiddehydrogenase type-1 enzyme in the central nervous system and investigated endocrine changes and the sleep electroencephalogram.

DESIGN

Each volunteer spent 4 nights in the sleep laboratory, the first of which served to habituate the subject to the conditions in the laboratory. The volunteers underwent 3 trial conditions in random order and in a single-blind design receiving 2 doses of metyrapone (4.5 g or 6.0 g) or placebo on the day before the sleep electroencephalogram recordings.

SETTING

Sleep laboratory.

PARTICIPANTS

8 healthy male volunteers.

MEASUREMENTS AND RESULTS

The corticotropin secretion was significantly enhanced by metyrapone, while the cortisol secretion remained largely unchanged. Growth hormone, progesterone, and dehydroepiandrosterone concentrations were also significantly increased by both doses. Metyrapone induced a pronounced reduction in slow-wave sleep and had slight but nonlinear effects upon rapid eye movement sleep. Parameters of sleep quality were not different between groups.

CONCLUSIONS

Metyrapone induces pronounced effects on hormonal secretion and the sleep electroencephalogram. These results are in part comparable to those from experiments with the administration of corticotropin-releasing hormone and with experiments that deplete mineralocorticoid receptors. The findings may be explained by altered steroid synthesis proximal to the enzyme block. Metyrapone exerts not only effects upon adrenocortical steroid synthesis, but also important extra-adrenal effects on central corticosteroid metabolism.

Ecotoxicological and chemical characterization of selected treatment process effluents of municipal sewage treatment plant

The triolein-containing semipermeable membrane devices (SPMDs) were deployed for 4 weeks in a sewage treatment plant in Beijing, China, to sample and concentrate priority hydrophobic organic pollutants in a sewage treatment process. The chemical analyses and ecotoxicities of the residuals of SPMDs dialysate were examined. The data from the chemical analyses by gas chromatography-mass spectrometry selected ion monitoring mode indicated the lower removal for polychlorinated biphenyls (PCB) congeners and polycyclic aromatic hydrocarbons (PAHs) coincided with the persistence of them in the environment. The acute toxicity examined by bioluminescence test with Vibrio fischeri revealed approximately only 20% decrease in the overall toxicity of the influent after the activate sludge treatment process. The ethoxy resorufin-O-deethylase (EROD) induction with a micro-EROD assay in vitro using H4-IIE rat hepatoma cell cultures demonstrated the presence of persistent organics in influent and sequency effluents. Results obtained suggested that integration of the SPMD technique and chemical analyses and bioassay might be a valuable approach for the risk assessment of hydrophobic organic pollutants in water ecosystem. It revealed the necessity for organic pollutants monitoring and ecotoxicities examining of sewage treatment plants.

Angiogenic capacity of endothelial cells in islets of Langerhans

Transplantation of pancreatic islets reconstitutes glucose homeostasis in diabetes mellitus. Before transplantation, islets are disrupted from the surrounding blood vessels by the isolation procedure, with the grafted tissue being subject to ischemic damage. The survival of transplanted islets is assumed to depend on effective revascularization. Perfusion studies suggest that newly formed microvessels supplying the graft with nutrients are exclusively rebuilt by the host. It is generally not known whether isolated islets contain endothelial cells (EC), which potentially participate in the revascularization process. Therefore, we tried to detect immature EC in isolated islets by transformation with polyoma middle T antigen. Endothelioma cells were generated, implicating the presence of de-differentiated EC within isolated islets. When embedded in a fibrin gel, the islets developed cellular cords consisting of EC, whereas FGF-2 and VEGF stimulated the formation of cord-like structures. Furthermore, we studied the presence of donor EC in islet grafts by using transgenic mice with an EC lineage-specific promotor-LacZ reporter construct (Tie-2LacZ). Following islet transplantation, Tie-2LacZ-positive EC of both donor and recipient were identified in the vicinity of or within the graft up to 3 wk after transplantation. In conclusion, EC and/or their progenitors with angiogenic capacity reside within isolated islets of different species, and their proliferative potential can be stimulated by various inducers. These graft-related endothelia persist after islet transplantation and are integrated within newly formed microvessels.

Involvement of NMDA receptors in alcohol-mediated behavior: mice with reduced affinity of the NMDA R1 glycine binding site display an attenuated sensitivity to ethanol

BACKGROUND

Ethanol antagonizes central effects of glutamate by inhibition of the N-methyl-D-aspartate (NMDA) receptor function. The co-agonist glycine has been shown to reverse alcohol-mediated effects. The aim of this study was to evaluate the influence of the glycine binding site of the NMDA receptor on the behavioral effects of alcohol by investigating mice with an 80% reduced affinity of the NMDA R1 subunit for glycine (Grin1(D481N)).

METHODS

Free-choice and forced alcohol intake was studied over a period of 52 days. Anxiolytic activity (elevated plus maze, open field) and motor coordination (rotarod) was tested after 3 days of forced alcohol intake and during ethanol withdrawal.

RESULTS

In contrast to wild-type mice, alcohol-associated anxiolysis and motor impairment was attenuated in Grin1(D481N) mice during intoxication. Free-choice alcohol intake did not differ between wild-type and Grin1(D481N) mice.

CONCLUSIONS

Our results give first evidence in vivo for a possible role of an altered NMDA-receptor complex with a hyposensitive glycine binding site for behavioral effects mediated by ethanol.

Die NALCAM-Studie: Wirksamkeit, Verträglichkeit, Outcome

Ziel: Vergleich der Effektivität und Verträglichkeit von Naltrexon und Acamprosat in der Rückfallprophylaxe bei Alkoholabhängigkeit. </P><P>Methodik: Doppelblinde, placebo-kontrollierte Studie. Einschluss von 160 Patienten nach stationärem Alkoholentzug. Behandlung mit Naltrexon, Acamprosat, Naltrexon plus Acamprosat vs. Placebo im Rahmen eines ambulanten Therapieprogramms. Analyse der Behandlungseffekte nach 12 Wochen und im Follow-up. </P><P>Ergebnisse: Naltrexon, Acamprosat und Kombinationsmedikation waren der Placebobehandlung in der Verlängerung der Abstinenzzeit bei hoher Verträglichkeit signifikant überlegen. Die Kombinationsbehandlung zeigte eine höhere Wirksamkeit als die Acamprosat-Monotherapie. Die positiven Behandlungseffekte blieben im Follow-up erhalten. </P><P>Schlussfolgerung: Die Ergebnisse belegen eine Wirksamkeit und Stabilität der pharmakotherapeutischen Rückfallprophylaxe und deuten auf additive Effekte von Naltrexon und Acamprosat in der Abstinenzerhaltungstherapie hin.

Comparing and combining naltrexone and acamprosate in relapse prevention of alcoholism: a double-blind, placebo-controlled study

BACKGROUND

Naltrexone and acamprosate have been shown to be effective in relapse prevention of alcoholism via different pharmacologic mechanisms. Since it remains uncertain whether both substances are equally efficient and whether a combination of both drugs potentiates the efficacy, we conducted the first published controlled study comparing and combining both compounds.

METHODS

After detoxification, 160 patients with alcoholism participated in a randomized, double-blind, placebo-controlled protocol. Patients received naltrexone, acamprosate, naltrexone plus acamprosate, or placebo for 12 weeks. Patients were assessed weekly by interview, self-report, questionnaires, and laboratory screening. Time to first drink, time to relapse, and the cumulative abstinence time were the primary outcome measures.

RESULTS

Naltrexone, acamprosate, and the combined medication were significantly more effective than placebo. Comparing the course of nonrelapse rates between naltrexone and acamprosate, the naltrexone group showed a tendency for a better outcome regarding time to first drink and time to relapse. The combined medication was most effective with significantly lower relapse rates than placebo and acamprosate but not naltrexone.

CONCLUSIONS

The results of this study support the efficacy of pharmacotherapeutic strategies in the relapse prevention of alcoholism. Naltrexone and acamprosate, especially in combination, considerably enhance the potential of relapse prevention.

Is withdrawal-induced anxiety in alcoholism based on beta-endorphin deficiency?

RATIONALE

Associations between several psychopathological alterations and lowered beta-endorphin(beta E) plasma levels have already been stated in former studies. However, whereas single measures during static conditions generally failed in linking beta E levels with psychopathology, dynamic changes of beta E in particular have been shown to be associated with spells of anxiety and depression. During alcohol withdrawal, a decreased secretion of beta E with a delayed normalization has been reported, but up to now only few data became available regarding the interaction of plasma beta E and psychopathological parameters.

OBJECTIVES

The aim of our study was to test the hypothesis whether beta E during acute alcohol withdrawal is associated with anxiety, depression, and craving.

METHODS

We observed self-rated anxiety, depression, and craving during alcohol withdrawal and assessed beta E levels (RIA) in a consecutive sample of 60 alcoholics on day 1 and day 14 after onset of withdrawal, and in 30 healthy volunteers. To control for mutual interactions of beta E and the pituitary-adrenocortical hormone secretion, plasma corticotropin (ACTH) and cortisol were also determined.

RESULTS

In accordance with prior studies, beta E was significantly lowered on day 1 and day 14 of alcohol withdrawal relative to controls. Plasma levels of ACTH correlated significantly with beta E in alcoholics at both time points and in controls, without differing significantly between the groups. Self-rated anxiety, depression, and alcohol craving decreased significantly between day 1 and day 14. Levels of beta E were inversely correlated with anxiety day 1 (r=-0.58) and day 14 (r=-0.71). Partial correlation coefficients controlling for ACTH plasma levels revealed that this correlation was largely independent from ACTH. In addition, a significant inverse relationship was found between beta E and craving on day 14 (r=-0.28). No association appeared between beta E and depression.

CONCLUSIONS

Our results give first evidence that lowered beta E during alcohol withdrawal may contribute to anxiety as a common disturbance during this state.

Alcohol intake, tumour necrosis factor-alpha, leptin and craving: factors of a possibly vicious circle?

AIMS

Since the appetite-regulating peptide leptin was recently found to be highly correlated with both craving for alcohol and lifetime ethanol intake, the aim of our study was to test the hypothesis whether tumour necrosis factor-alpha (TNF-alpha) might be the factor that links alcohol intake with elevated leptin levels.

METHODS

TNF-alpha, leptin, and alcohol craving were assessed in male alcohol addicts at the onset of alcohol withdrawal and in matched controls.

RESULTS

Increased leptin plasma levels in alcohol addicts correlated significantly with an enhanced secretion of TNF-alpha, which was itself related to the duration of alcohol misuse.

CONCLUSIONS

Since leptin was shown to be associated with alcohol craving, a possible vicious circle is suggested, including the components: alcohol intake, increase of TNF-alpha, enhanced leptin secretion, enhanced alcohol craving, and consecutively increased alcohol intake.

Involvement of plasma atrial natriuretic peptide in protracted alcohol withdrawal

OBJECTIVE

Atrial natriuretic peptide (ANP) has been shown to inhibit the effects of corticotrophin releasing hormone, corticotrophin and cortisol, and to influence affective and anxiety symptoms in man. We tested the hypothesis of whether ANP is associated with endocrine and psychopathological disturbances during acute alcohol withdrawal.

METHOD

ANP and cortisol plasma concentrations were studied in alcoholics during in-patient detoxification and in healthy controls. Additionally, craving, depressive mood and anxiety were assessed.

RESULTS

Although mean ANP levels increased significantly in alcoholics between days 1 and 14, they remained diminished compared to controls. Separating a subgroup of alcoholics with a decrease of ANP levels during withdrawal, these individuals revealed significantly elevated scores for mean and maximum craving and a trend to an elevated self-rated anxiety on day 14.

CONCLUSION

We suggest that a dysregulation of ANP plasma levels during alcohol withdrawal may contribute to symptoms of protracted withdrawal such as craving and anxiety.

Synergistic regulation of immunoreceptor signaling by SLP-76-related adaptor Clnk and serine/threonine protein kinase HPK-1

Recently, the identification of Clnk, a third member of the SLP-76 family of adaptors expressed exclusively in cytokine-stimulated hemopoietic cells, has been reported by us and by others. Like SLP-76 and Blnk, Clnk was shown to act as a positive regulator of immunoreceptor signaling. Interestingly, however, it did not detectably associate with known binding partners of SLP-76, including Vav, Nck, and GADS. In contrast, it became complexed in activated T cells and myeloid cells with an as yet unknown tyrosine-phosphorylated polypeptide of approximately 92 kDa (p92). In order to understand better the function of Clnk, we sought to identify the Clnk-associated p92. Using a yeast two-hybrid screen and cotransfection experiments with Cos-1 cells, evidence was adduced that p92 is HPK-1, a serine/threonine-specific protein kinase expressed in hemopoietic cells. Further studies showed that Clnk and HPK-1 were also associated in hemopoietic cells and that their interaction was augmented by immunoreceptor stimulation. A much weaker association was detected between HPK-1 and SLP-76. Transient transfections in Jurkat T cells revealed that Clnk and HPK-1 cooperated to increase immunoreceptor-mediated activation of the interleukin 2 (IL-2) promoter. Moreover, the ability of Clnk to stimulate IL-2 promoter activity could be blocked by expression of a kinase-defective version of HPK-1. Lastly we found that in spite of the differential ability of Clnk and SLP-76 to bind cellular proteins, Clnk was apt at rescuing immunoreceptor signaling in a Jurkat T-cell variant lacking SLP-76. Taken together, these results show that Clnk physically and functionally interacts with HPK-1 in hemopoietic cells. Moreover, they suggest that Clnk is capable of functionally substituting for SLP-76 in immunoreceptor signaling, albeit by using a distinct set of intracellular effectors.

Caspase-mediated cleavage of hematopoietic progenitor kinase 1 (HPK1) converts an activator of NFkappaB into an inhibitor of NFkappaB

Hematopoietic progenitor kinase 1 (HPK1), a mammalian Ste20-related protein kinase, is a potent stimulator of the stress-activated protein kinases (SAPKs/JNKs). Here we report activation of NFkappaB transcription factors by HPK1 that was independent of SAPK/JNK activation. Overexpression of a dominant-negative SEK1 significantly inhibited SAPK/JNK activation, whereas NFkappaB stimulation by HPK1 remained unaffected. Furthermore, activation of NFkappaB required the presence of full-length, kinase-active HPK1, whereas the isolated kinase domain of HPK1 was sufficient for activation of SAPK/JNK. We also demonstrate that overexpression of a dominant-negative IKKbeta blocks HPK1-mediated NFkappaB activation suggesting that HPK1 acts upstream of the IkappaB kinase complex. In apoptotic myeloid progenitor cells HPK1 was cleaved at a DDVD motif resulting in the release of the kinase domain and a C-terminal part. Although expression of the isolated HPK1 kinase domain led to SAPK/JNK activation, the C-terminal part inhibited NFkappaB activation. This dominant-negative effect was not only restricted to HPK1-mediated but also to NIK- and tumor necrosis factor alpha-mediated NFkappaB activation, suggesting an impairment of the IkappaB kinase complex. Thus HPK1 activates both the SAPK/JNK and NFkappaB pathway in hematopoietic cells but is converted into an inhibitor of NFkappaB activation in apoptotic cells.

Leptin: a modulator of alcohol craving?

BACKGROUND

Leptin has been shown to regulate food intake and energy expenditure. Because leptin acts via regulation of appetite, we studied the hypothesis that suggests leptin modulates craving for alcohol as well.

METHODS

We studied leptin plasma concentrations (RIA) both in alcoholic subjects during inpatient detoxification (day 1: n = 78, day 14: n = 60) and in healthy control subjects (n = 30). To rule out interference with the activation of the HPA axis during alcohol withdrawal, we also evaluated cortisol plasma levels (RIA).

RESULTS

We found plasma leptin and cortisol elevated at onset of withdrawal, decreasing significantly up to day 14. Leptin (and the body-mass corrected ratio leptin/BMI) was highly correlated with self-rated craving. No correlations of craving with cortisol and BMI were observed.

CONCLUSIONS

We suggest that leptin may modulate withdrawal-induced craving in alcoholic subjects.

Free-choice alcohol consumption in mice after application of the appetite regulating peptide leptin

BACKGROUND

Leptin has been shown to regulate food intake and energy expenditure. Very recently, associations of elevated leptin plasma levels during alcohol withdrawal with alcohol craving have been observed in humans. Therefore, we tested the hypothesis that the application of exogenous leptin modulates voluntary alcohol consumption in mice.

METHODS

Sixteen mice (129/Sv x C57BL/6J) were habituated to ethanol consumption over a time period of 3 months. After a basal 2-week free-choice drinking phase, mice were separated into two groups (n = 8) according to weight and alcohol consumption. They received recombinant leptin (1 mg/kg) versus saline intraperitoneally daily for 10 days. After 4 days of free-choice consumption of ethanol (16% v/v) versus water, ethanol was withdrawn at day 4 and replaced at day 6 to test the occurrence of an alcohol deprivation effects. Fluid intake was evaluated by controlling the weight of the drinking tubes daily.

RESULTS

Free-choice ethanol consumption after withdrawal was significantly elevated in mice after intraperitoneal injection of 1 mg/kg leptin (alcohol deprivation effect), but not during basal drinking.

CONCLUSION

We suggest that leptin may enhance motivation for alcohol consumption in habituated mice after alcohol withdrawal.

Activation of guanylate cyclase by natriuretic peptides in mouse pituitary AtT20 cells is influenced by phosphorylation of ANP

The discovery of free and membrane-bound ectokinases raises the question whether phosphorylation is another mechanism to modulate the action of distinct neuropeptides. Atrial-natriuretic-peptide (ANP) which is widespread found in the central nervous system (CNS) and involved in the modulation of stress reactions and emotional states like anxiety contains a recognition-motif for cAMP-dependent protein kinase A. We investigated the effect of phosphorylation of ANP and C-type natriuretic peptide (CNP), a related peptide without phosphorylation site, on their ability to activate their receptors in mouse pituitary AtT20 cells by measuring the formation of cyclic guanosinmonophosphate (cGMP). Phosphorylation with protein kinase A inactivated ANP. Coincubation experiments adding adenosintriphosphate (ATP), ATP-analogues or inhibitors of protein kinases to the medium pointed to the presence of an intrinsic protein kinase A like ectokinase-activity on AtT20 cells. The activity of CNP was unaffected in these experiments. Phosphorylation by ectokinases may be a physiological mechanism to regulate the biological activity of ANP in different tissues, such as pituitary and CNS.

Comparison of the effects of endothelin-1 and -3 on secretion of pituitary hormones in healthy male volunteers

The investigation was conducted to study the effects of endothelin-1 (ET-1) and endothelin-3 (ET-3) on adrenocorticotropin (ACTH), cortisol and prolactin release in man. The design was a prospective placebo controlled double-blind study, including 7 healthy males studied on three occasions. After infusion of either 20 ng/min x kg ET-1, ET-3 or normal saline, venous blood samples were drawn 12 times for determination of ACTH, cortisol and prolactin during the pre- within- and postinfusion period. ET-1 infusion induced a significant increase of plasma ACTH (p< 0.009) and prolactin (p<0.0001) whereas cortisol levels increased without reaching significance (p<0.074). Infusion of ET-3 induced no changes in plasma levels of ACTH, cortisol or prolactin. The parallel increase of ACTH and prolactin induced by infusion of ET-1 could indicate an involvement of corticotropin-releasing hormone (CRH) in mediating the ET-1 effect on the HPA-axis in man. Whether this supports a possible role of ET-1 as a modulator of the hypothalamo-pituitary-adrenal (HPA) axis remains to be clarified.

Alpha-helical-corticotropin-releasing hormone reverses anxiogenic effects of C-type natriuretic peptide in rats

Previously we have shown that atrial natriuretic peptide (ANP) has anxiolytic-like properties after intraperitoneal, intracerebroventricular and intraamygdala infusion in rats. Since C-type natriuretic peptide (CNP) exerts endocrine and behavioral effects opposing those of ANP, we characterized the behavioral properties of CNP after icv infusion in rats by their performance in the elevated plus maze with and without the corticotropin-releasing hormone (CRH) antagonist alpha-helical-CRH (alpha-CRH). Low CNP doses of 0.05 microg icv or 0.1 microg icv did not significantly influence the behavior of rats in the plus maze. At higher doses (0.5 microg, 2 microg, 5 microg icv) CNP had distinct anxiogenic properties. Our hypothesis that corticotropin-releasing hormone (CRH) is involved, which elicits anxiety-like behavior, was examined by icv coadministration of alpha-CRH, an antagonist at CRH-1 and CRH-2-receptors. Icv alpha-CRH alone had no intrinsic anxiolytic properties at a dose of 25 microg. The anxiogenic effects of 2 microg CNP icv seen in the plus maze were entirely blocked by alpha-CRH. Directly after exposition ACTH and corticosterone levels did not differ between the groups, but after 30 min ACTH levels were significantly higher in the CNP-treated group compared to alpha-CRH/CNP-treated animals. Corticosterone was found significantly lowered in the alpha-CRH/saline group compared to the CNP treated group but not compared to saline controls. Our data suggest opposing effects of CNP and ANP on anxiety-related behavior and neuroendocrine regulation in rats, which appear to be mediated via different receptor occupation and brain regions, and by a CRH-dependent mechanism.

Harman and norharman plasma levels in weaned alcoholics: correlations with depression and tobacco smoking

Based on the hypothesis that β-carbolines are involved in the pathogenesis of alcohol-related mood disturbance, harman and norharman levels were assayed in the blood plasma of alcoholics and correlated to the Hamilton Depression (HAM-D) scores after 3 and 5 weeks post-admission. Tobacco smoking was co-evaluated since it is known to influence β-carboline levels. After a 3-week period, plasma harman but not norharman was increased in depressed alcoholics and positively related to the HAM-D sum-score (r = 0.47; p < 0.04) and to tobacco smoking (r = 0.56; p < 0.02). Since no correlation between depression and smoking was found, these data could account for the higher incidence of depressive symptoms in withdrawn alcoholics with increased harman levels. The partial correlations support this hypothesis.

The adaptor protein Gads (Grb2-related adaptor downstream of Shc) is implicated in coupling hemopoietic progenitor kinase-1 to the activated TCR

The hemopoietic-specific Gads (Grb2-related adaptor downstream of Shc) adaptor protein possesses amino- and carboxyl-terminal Src homology 3 (SH3) domains flanking a central SH2 domain and a unique region rich in glutamine and proline residues. Gads functions to couple the activated TCR to distal signaling events through its interactions with the leukocyte-specific signaling proteins SLP-76 (SH2 domain-containing leukocyte protein of 76 kDa) and LAT (linker for activated T cells). Expression library screening for additional Gads-interacting molecules identified the hemopoietic progenitor kinase-1 (HPK1), and we investigated the HPK1-Gads interaction within the DO11.10 murine T cell hybridoma system. Our results demonstrate that HPK1 inducibly associates with Gads and becomes tyrosine phosphorylated following TCR activation. HPK1 kinase activity is up-regulated in response to activation of the TCR and requires the presence of its proline-rich motifs. Mapping experiments have revealed that the carboxyl-terminal SH3 domain of Gads and the fourth proline-rich region of HPK1 are essential for their interaction. Deletion of the fourth proline-rich region of HPK1 or expression of a Gads SH2 mutant in T cells inhibits TCR-induced HPK1 tyrosine phosphorylation. Together, these data suggest that HPK1 is involved in signaling downstream from the TCR, and that SH2/SH3 domain-containing adaptor proteins, such as Gads, may function to recruit HPK1 to the activated TCR complex.

HPK1 is activated by lymphocyte antigen receptors and negatively regulates AP-1

The serine/threonine kinase HPK1 is a member of the germinal center kinase (GCK) family that has been implicated in the regulation of MAP kinase pathways. Here, we demonstrate the involvement of HPK1 in antigen receptor signaling. Engagement of the TCR or the BCR resulted in a marked induction of HPK1 catalytic activity. Subsequent analysis revealed that Src and Syk/ZAP-70 tyrosine kinases and the adaptor proteins LAT, SLP-76, BLNK, Grb2, and Grap are involved in HPK1 activation. Overexpression of HPK1 inhibited TCR activation of AP-1 and ERK2, whereas the kinase-inactive mutant of HPK1 potentiated these responses. Neither form of HPK1 affected PMA or v-Ras activation of AP-1 and ERK2. Thus, HPK1 is a negative regulator of the TCR-induced AP-1 response pathway.

Activation of hematopoietic progenitor kinase-1 by erythropoietin

Hematopoietic progenitor kinase-1 (HPK1), which is expressed predominantly in hematopoietic cells, was identified as a mammalian Ste20 homologue that, upon transfection, leads to activation of JNK/SAPK in nonhematopoietic cells. The JNK/SAPK pathway is activated by various environmental stresses and proinflammatory and hematopoietic cytokines. Upstream activators of HPK1 currently remain elusive, and its precise role in hematopoiesis has yet to be defined. We therefore examined the possible involvement of HPK1 in erythropoietin (Epo) and environmental stress-induced JNK/SAPK activation in the Epo-dependent FD-EPO cells and Epo-responsive SKT6 cells. We found that Epo, but not environmental stresses, induced rapid and transient activation of HPK1, whereas both induced activation of JNK/SAPK. A screen for HPK1 binding proteins identified the hematopoietic cell-specific protein 1 (HS1) as a potential HPK1 interaction partner. We found HPK1 constitutively associated with HS1 and that HS1 was tyrosine-phosphorylated in response to cellular stresses as well as Epo stimulation. Furthermore, antisense oligonucleotides to HPK1 suppressed Epo-dependent cell growth and Epo-induced erythroid differentiation. We therefore conclude that Epo induces activation of both HPK1 and HS1, whereas cellular stresses activate only HS1, and that the HPK1-JNK/SAPK pathway is involved in Epo-induced growth and differentiation signals.

DNA adduct formation in mammalian cell cultures by polycyclic aromatic hydrocarbons (PAH) and nitro-PAH in coke oven emission extract

Mammalian cells in culture were used to study the genotoxic potential of coke oven emissions constituting a complex mixture of chemicals. For this purpose, particle extracts and some polycyclic aromatic and nitroaromatic hydrocarbons (PAH and nitro-PAH) occurring in these mixtures were assayed for DNA adduct formation using the -postlabeling technique. In primary cultures of rat hepatocytes, benzo[a]pyrene (B[a]P), benz[a]anthracene (B[a]A) and benzo[b]fluoranthene (B[k]F) caused DNA adduct levels in the range of 1 adduct/108 nucleotides. 4-Nitropyrene (4-NP), 6-nitrochrysene (6-NC), 3-nitrofluoranthene (3-NF) caused DNA adduct levels that were by one to two orders of magnitude higher. The crude particle extract and its fractions differing in acidity and polarity induced the formation of DNA reactive material within diagonal radioactive zones (DRZ) on the autoradiograms. On a weight base, the neutral aromatic fraction contributed by more than 80% to the total adduct level in hepatocytes. To examine whether the PAH- and nitro-PAH-DNA derived adducts can be further differentiated, hepatocyte cultures were preincubated with 2,3,7,8-tetrachloro-p-dioxin (TCDD) to induce the activity of cytochrome P450 1A1. TCDD pretreatment strongly increased the levels of PAH-DNA adducts, whereas, the levels of nitro-PAH adducts were markedly decreased. NCI-H322 cells, a human lung tumor cell line derived from Clara cells, exhibited PAH-DNA adduct levels between 10 and 100, and nitro-PAH-DNA adducts at levels between 0.2 to about 30 adducts per 108 nucleotides, respectively. In contrast to hepatocytes, incubations with extractable organic matter (EOM) and the neutral aromatic EOM fraction displayed several distinct spots in the chromatograms of NCI-H322 cells. The major spot was assigned by cochromatography to be identical with the major DNA adduct formed by incubation with B[a]P alone. In V79NH cells, a Chinese hamster lung cell line expressing nitro-PAH activating enzymes, but virtually no cytochrome P450 activity, PAH-derived DNA adducts were not detectable. Nitro-PAH-derived DNA adducts, however, were formed at levels between 10 and 300 adducts/108 nucleotides. The slightly and the moderately polar EOM fraction caused the formation of distinct adduct spots suggesting the occurrence of nitro-PAH in these fractions. GC/MS analyses revealed the presence of twelve PAH in the aromatic fraction, at a total amount of about 10% (w/w), and of four nitro-PAH in the slightly polar and the acidic fraction amounting to about 0.2% (w/w). In conclusion, our results indicate that PAH and nitro-PAH contribute to the genotoxicity of coke oven emissions. Using DNA adduct analysis in rat hepatocytes (+/-pretreatment with TCDD) and in NCI-H322 and in V79NH cells offers a promising approach to determine the genotoxic activity of PAH and nitro-PAH in any complex environmental samples.

Caffeine potentiates the formation of micronuclei caused by environmental chemical carcinogens in V79 Chinese hamster cells

The effect of caffeine on the genotoxicity of several carcinogenic compounds representing various classes of chemicals was investigated in a panel of V79 Chinese hamster cells genetically engineered to express cytochromes P4501A1 and P4501A2 and differing in their expression of N-acetyltransferases. The formation of micronuclei served as genetic endpoint. The results show that caffeine increases the number of micronuclei induced by 2-aminoanthracene several fold in the test cell lines. The lowest concentration of caffeine enhancing 2-aminoanthracene-induced genotoxicity was 100 nM. Caffeine also potentiated the genotoxicity of aflatoxin B1, 2-amino-3-methylimidazo[4,5-f]-quinoline. N-methyl-N-nitro-N-nitrosoguanidine, 1,6-dinitropyrene, and 7,8-diol-benzo[a]pyrene. Overall, caffeine lowered the effective genotoxic concentrations of these agents by a factor of about three. In contrast, the genotoxic effect of 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone is markedly decreased in the presence of caffeine. The results indicate that caffeine may modulate the genotoxicity of chemical carcinogens by different mechanisms.

The Syk protein tyrosine kinase is essential for Fcgamma receptor signaling in macrophages and neutrophils

The cytoplasmic protein tyrosine kinase Syk has two amino-terminal SH2 domains that engage phosphorylated immunoreceptor tyrosine-based activation motifs in the signaling subunits of immunoreceptors. Syk, in conjunction with Src family kinases, has been implicated in immunoreceptor signaling in both lymphoid and myeloid cells. We have investigated the role of Syk in Fcgamma receptor (FcgammaR)-dependent and -independent responses in bone marrow-derived macrophages and neutrophils by using mouse radiation chimeras reconstituted with fetal liver cells from Syk-/- embryos. Chimeric mice developed an abdominal hemorrhage starting 2 to 3 months after transplantation that was ultimately lethal. Syk-deficient neutrophils derived from the bone marrow were incapable of generating reactive oxygen intermediates in response to FcgammaR engagement but responded normally to tetradecanoyl phorbol acetate stimulation. Syk-deficient macrophages were defective in phagocytosis induced by FcgammaR but showed normal phagocytosis in response to complement. The tyrosine phosphorylation of multiple cellular polypeptides, including the FcgammaR gamma chain, as well as Erk2 activation, was compromised in Syk-/- macrophages after FcgammaR stimulation. In contrast, the induction of nitric oxide synthase in macrophages stimulated with lipopolysaccharide and gamma interferon was not dependent on Syk. Surprisingly, Syk-deficient macrophages were impaired in the ability to survive or proliferate on plastic petri dishes. Taken together, these results suggest that Syk has specific physiological roles in signaling from FcgammaRs in neutrophils and macrophages and raise the possibility that in vivo, Syk is involved in signaling events other than those mediated by immunoreceptors.

SH2/SH3 adaptor proteins can link tyrosine kinases to a Ste20-related protein kinase, HPK1

Ste20-related protein kinases have been implicated as regulating a range of cellular responses, including stress-activated protein kinase pathways and the control of cytoskeletal architecture. An important issue involves the identities of the upstream signals and regulators that might control the biological functions of mammalian Ste20-related protein kinases. HPK1 is a protein-serine/threonine kinase that possesses a Ste20-like kinase domain, and in transfected cells activates a protein kinase pathway leading to the stress-activated protein kinase SAPK/JNK. Here we have investigated candidate upstream regulators that might interact with HPK1. HPK1 possesses an N-terminal catalytic domain and an extended C-terminal tail with four proline-rich motifs. The SH3 domains of Grb2 bound in vitro to specific proline-rich motifs in the HPK1 tail and functioned synergistically to direct the stable binding of Grb2 to HPK1 in transfected Cos1 cells. Epidermal growth factor (EGF) stimulation did not affect the binding of Grb2 to HPK1 but induced recruitment of the Grb2.HPK1 complex to the autophosphorylated EGF receptor and to the Shc docking protein. Several activated receptor and cytoplasmic tyrosine kinases, including the EGF receptor, stimulated the tyrosine phosphorylation of the HPK1 serine/threonine kinase. These results suggest that HPK1, a mammalian Ste20-related protein-serine/threonine kinase, can potentially associate with protein-tyrosine kinases through interactions mediated by SH2/SH3 adaptors such as Grb2. Such interaction may provide a possible mechanism for cross-talk between distinct biochemical pathways following the activation of tyrosine kinases.

CD44 regulates hematopoietic progenitor distribution, granuloma formation, and tumorigenicity

CD44 is expressed in various isoforms on numerous cell types and tissues during embryogenesis and in the mature organism. CD44 may also be involved in tumor growth. To study the multiple roles of CD44, we abolished expression of all known isoforms of CD44 in mice by targeting exons encoding the invariant N-terminus region of the molecule. Surprisingly, mice were born in Mendelian ratio without any obvious developmental or neurological deficits. Hematological impairment was evidenced by altered tissue distribution of myeloid progenitors with increased levels of colony-forming unit-granulocyte-macrophage (CFU-GM) in bone marrow and reduced numbers of CFU-GM in spleen. Fetal liver colony-forming unit-spleen and granulocyte colony-stimulating factor mobilization assays, together with reduced CFU-GM in peripheral blood, suggested that progenitor egress from bone marrow was defective. In what was either a compensatory response to CD44 deficiency or an immunoregulatory defect, mice also developed exaggerated granuloma responses to Cryotosporidium parvum infection. Finally, tumor studies showed that SV40-transformed CD44-deficient fibroblasts were highly tumorigenic in nude mice, whereas reintroduction of CD44s expression into these fibroblasts resulted in a dramatic inhibition of tumor growth.