Clinical practice. Irritable bowel syndrome

A 28-year-old woman presents with a 7-month history of recurrent, crampy pain in the left lower abdominal quadrant, bloating with abdominal distention, and frequent, loose stools. She reports having had similar but milder symptoms since childhood. She spends long times in the bathroom because she is worried about uncontrollable discomfort and fecal soiling if she does not completely empty her bowels before leaving the house. She feels anxious and fatigued and is frustrated that her previous physician did not seem to take her distress seriously. Physical examination is unremarkable except for tenderness over the left lower quadrant. How should her case be evaluated and treated?

Stereotypic behaviour in the deer mouse: pharmacological validation and relevance for obsessive compulsive disorder

Stereotypy is an important manifestation of obsessive compulsive disorder (OCD). OCD involves disturbed serotonin and dopamine pathways, and demonstrates a selective response to serotonin reuptake inhibitors (SRI), with limited to no response to noradrenaline reuptake inhibitors (NRI). Deer mice (Peromyscus maniculatus bairdii) engage in various spontaneous stereotypic behaviours, including somersaulting, jumping and pattern running, and has to date not been explored for possible relevance for OCD. We studied the population diversity of spontaneous stereotypy in these animals, followed by assessing behavioural response to chronic high and low dose SRI (viz. fluoxetine) and NRI (viz. desipramine) treatment (both 10 mg/kg; 20 mg/kg x 21 days). We also studied behavioural responses to the 5-HT(2A/C) agonist, meta-chlorophenylpiperazine (mCPP) and the D2 agonist, quinpirole (2 mg/kg and 5 mg/kg respectively x 4 days). Deer mice showed a distinct separation into high and low stereotypic behaviour populations, with high and low dose fluoxetine, but not desipramine, significantly reducing stereotypic behaviour in both populations. A significant attenuation of stereotypy was also observed in both groups following quinpirole or mCPP challenge. In its response to drug treatment, spontaneous stereotypic behaviour in deer mice demonstrates predictive validity for OCD. States of spontaneous stereotypy are attenuated by 5-HT(2A/C) and dopamine D2 receptor agonists.

Oral treatment with desipramine improves breathing and life span in Rett syndrome mouse model

Rett syndrome is a neurodevelopmental disease due to Mecp2 gene mutations that is associated to complex neurological symptoms, with bioaminergic deficits and life-threatening apneas related to sudden and unexpected death. In male mice, Mecp2-deficiency similarly induces medullary bioaminergic deficits, severe apneas and short life span. Here, we show that long-term oral treatment of Mecp2-deficient male mice with desipramine, an old drug of clinical use known to block norepinephrine uptake and to strengthen its synaptic effects, significantly alleviates their breathing symptoms and prolongs their life span. Although these mouse results identify desipramine as the first oral pharmacological treatment potentially able to alleviate breathing symptoms of Rett syndrome, we recommend further studies of desipramine effects in Mecp2-deficient mice before attempting any clinical trials in Rett patients.

A cost-utility comparison of four first-line medications in painful diabetic neuropathy

BACKGROUND

Painful diabetic neuropathy is common and adversely affects patients' quality of life and function. Several treatment options exist, but their relative efficacy and value are unknown.

OBJECTIVE

To determine the relative efficacy, costs and cost effectiveness of the first-line treatment options for painful diabetic neuropathy.

METHODS

Published and unpublished clinical trial and cross-sectional data were incorporated into a decision analytic model to estimate the net health and cost consequences of treatment for painful diabetic peripheral neuropathy over 3-month (base case), 1-month and 6-month timeframes. Efficacy was measured in QALYs, and costs were measured in $US, year 2006 values, using a US third-party payer perspective. The patients included in the model were outpatients with moderate to severe pain associated with diabetic peripheral neuropathy and no contraindications to treatment with tricyclic antidepressants. Four medications were compared: desipramine 100 mg/day, gabapentin 2400 mg/day, pregabalin 300 mg/day and duloxetine 60 mg/day.

RESULTS

Desipramine and duloxetine were both more effective and less expensive than gabapentin and pregabalin in the base-case analysis and through a wide range of sensitivity analyses. Duloxetine offered borderline value compared with desipramine in the base case ($US47,700 per QALY), but not when incorporating baseline-observation-carried-forward analyses of the clinical trial data ($US867,000 per QALY). The results were also sensitive to the probability of obtaining pain relief with duloxetine.

CONCLUSIONS

Desipramine (100 mg/day) and duloxetine (60 mg/day) appear to be more cost effective than gabapentin or pregabalin for treating painful diabetic neuropathy. The estimated value of duloxetine relative to desipramine depends on the assumptions made in the statistical analyses of clinical trial data.

[Multivariate study of the Open Field Drink Test using undernourished rats and desipramine as an antipanic drug]

Approach-avoidance animal models are useful as initial screens for drugs affecting anxiety, but the components of anxiety assessed by these models remain poorly defined. Complex models of evaluation allow more complete inferences than those which are obtained when only one behavior is evaluated. Previous studies demonstrate that the tricyclic-antidepressant desipramine exerts a selective anticonflict effect on adult rats submitted to a protein deprivation schedule at perinatal age, in parameters of spontaneous behavior (elevated plus-maze) and conditioned intake (Geller Seifter). These deprived rats show alterations in noradrenergic neurotransmission that resembled the generalized activation of noradrenergic system displayed by patients suffering from panic attacks. The desipramine anticonflict activity was evaluated by a test of ethological conflict: the Open Field Drink Test, without discarding any behavior a priori under a multivaried approach. This approach has not been considered in previous studies with the open field and antipanic drugs. Considering the four variables selected by factorial analysis, desipramine (10 mg/kg/day) administered IP during just 7 days produced a significant diet x drug interaction which was consistent with previous studies. That interaction was independent of the effects of both treatments on weight or intake and was expressed, on deprived rats, as a decrease in all the behaviors, except for the time of drinking, with respect to the control rats, which displayed, in general, a decrease in all the behaviors except for the frequency of grooming.

Effect of citalopram in the modified forced swim test in rats

The present study examined the effect of citalopram (7.5 and 15 mg/kg) in the modified forced swim test (FST) in Wistar rats, in comparison to the effect of desipramine at the same doses. The citalopram at both doses increased swimming behavior, at the cost of climbing and immobility. The administration of desipramine increased climbing behavior while immobility counts were decreased. The modified FST is indeed more sensitive than the conventional FST in describing precisely the behavioral effects of antidepressant drugs, allowing to roughly estimate the contribution of individual neurotransmitter system to the mechanism of action of the studied drug.

A Cost-Effectiveness Comparison of Desipramine, Gabapentin, and Pregabalin for Treating Postherpetic Neuralgia

OBJECTIVES

To compare the net health effects and costs resulting from treatment with different first-line postherpetic neuralgia (PHN) medications.

DESIGN

Cost-utility analysis using published literature.

PARTICIPANTS

Hypothetical cohort of patients aged 60 to 80 with PHN.

INTERVENTIONS

Desipramine 100 mg/d, gabapentin 1,800 mg/d, and pregabalin 450 mg/d.

MEASUREMENTS

A decision model was designed to describe possible treatment outcomes, including different combinations of analgesia and side effects, during the first 3 months of therapy for moderate to severe PHN. The main outcome was cost per quality-adjusted life-year (QALY) gained. Costs were estimated using the perspective of a third-party payer. Multivariate, univariate, and probabilistic sensitivity analyses were performed, and the time frame of the model was varied to 1-month and 6-month horizons.

RESULTS

Desipramine was more effective and less expensive than gabapentin or pregabalin (dominant) under all conditions tested. Gabapentin was more effective than pregabalin but at an incremental cost of $216,000/QALY. Below $140/month, gabapentin became more cost-effective than pregabalin at a threshold of $50,000/QALY, and below $115/month gabapentin dominated pregabalin.

CONCLUSION

Desipramine appears to be more effective and less expensive than gabapentin or pregabalin for the treatment of older patients with PHN in whom it is not contraindicated. After its price falls, generic gabapentin will likely be more cost-effective than pregabalin.

Attenuation of estrous cycle-dependent marble burying in female rats by acute treatment with progesterone and antidepressants

Premenstrual dysphoric disorder (PMDD) is characterized by the recurrence of a cluster of physical and negative mood symptoms, especially irritability, appearing when estrogen and progesterone levels decrease during the late luteal phase of the menstrual cycle. The aim of the present study was to explore a new potential model of premenstrual irritability. It has been suggested that burying of harmless objects by rodents may reflect a form of impulsive or anxiety-like behavior. This study demonstrates changes in burying behavior during various phases of the estrous cycle in some but not all female rats. Burying behavior was found to be enhanced at metestrus and decreased at proestrus, characterized by low and high ovarian hormone levels, respectively. No habituation of the cycle-dependent burying was observed. Enhanced burying was not observed in reproductive senescent and ovariectomized females characterized by stable, low levels of ovarian hormones. Increased marble burying at metestrus was reversed by acute treatment with antidepressants fluoxetine, desipramine, nomifensine, the benzodiazepine agonist diazepam, and progesterone, while the neuroleptic chlorpromazine was without effect. Reversal of cycle-dependent burying was unrelated to the drugs' effects on locomotor activity. These results indicate that estrous cycle-dependent marble-burying behavior displayed by a subgroup of female rats might be a manifestation of ovarian hormone-dependent irritability. This manifestation may be used to elucidate the neuroendocrine mechanisms triggering premenstrual irritability, and the detailed mode of action of antidepressants when used for PMDD.

Characterization of health related quality of life (HRQOL) for patients with functional bowel disorder (FBD) and its response to treatment

BACKGROUND AND AIMS

Assessing health related quality of life (HRQOL) is becoming more important in research and clinical care. However, little information is available on the performance of HRQOL questionnaires for the functional bowel disorders (FBD). The aims of this study were to (a) understand the performance of the Sickness Impact Profile (SIP) and IBS-QOL for the functional bowel disorders at baseline and after treatment, (b) determine which HRQOL subscales best improve with treatment, (c) determine clinically meaningful improvement, and (d) determine the predictors of HRQOL at baseline and in response to treatment.

METHODS

Women with moderate to severe FBD were evaluated using both medical (desipramine vs placebo) and psychological (cognitive-behavioral therapy vs education) treatments. Clinical and psychosocial questionnaires along with the SIP and IBS-QOL were given at baseline and after 12-wk treatment.

RESULTS

(a) Patients with FBD experience functional limitations in social interactions, home management, and recreational activities, respond emotionally to the pain, feel helpless, out of control, depressed, and irritable, and perceive restrictions in lifestyle relating to toilet accessibility, and eating; (b) HRQOL is not different among the FBD diagnoses or IBS subgroups; (c) the IBS-QOL is more responsive to treatment than the SIP; (d) meaningful clinical improvement is 2.8 points for SIP and 14 for IBS-QOL; and (e) improvement is demonstrated primarily in psychosocial rather than physical domains. In addition, we found that expectation of benefit is greater for taking a pill over a psychological intervention, and the predictive effects of abuse history and pain on outcome is mediated by psychosocial factors.

CONCLUSIONS

The data support the value of the IBS-QOL over the SIP, and provide new information on the profile of impairment in FBD, and the ways in which medical and psychological treatments produce improvement in HRQOL.

Anti-inflammatory properties of desipramine and fluoxetine

Background

Antidepressants are heavily prescribed drugs and have been shown to affect inflammatory signals. We examined whether these have anti-inflammatory properties in animal models of septic shock and allergic asthma. We also analysed whether antidepressants act directly on peripheral cell types that participate in the inflammatory response in these diseases.

Methods

The antidepressants desipramine and fluoxetine were compared in vivo to the glucocorticoid prednisolone, an anti-inflammatory drug of reference. In a murine model of lipopolysaccharides (LPS)-induced septic shock, animals received the drugs either before or after injection of LPS. Circulating levels of tumour necrosis factor (TNF)-α and mortality rate were measured. In ovalbumin-sensitized rats, the effect of drug treatment on lung inflammation was assessed by counting leukocytes in bronchoalveolar lavages. Bronchial hyperreactivity was measured using barometric plethysmography. In vitro production of TNF-α and Regulated upon Activation, Normal T cell Expressed and presumably Secreted (RANTES) from activated monocytes and lung epithelial cells, respectively, was analysed by immunoassays. Reporter gene assays were used to measure the effect of antidepressants on the activity of nuclear factor-κB and activator protein-1 which are involved in the control of TNF-α and RANTES expression.

Results

In the septic shock model, all three drugs given preventively markedly decreased circulating levels of TNF-α and mortality (50% mortality in fluoxetine treated group, 30% in desipramine and prednisolone treated groups versus 90% in controls). In the curative trial, antidepressants had no statistically significant effect, while prednisolone still decreased mortality (60% mortality versus 95% in controls). In ovalbumin-sensitized rats, the three drugs decreased lung inflammation, albeit to different degrees. Prednisolone and fluoxetine reduced the number of macrophages, lymphocytes, neutrophils and eosinophils, while desipramine diminished only the number of macrophages and lymphocytes. However, antidepressants as opposed to prednisolone did not attenuate bronchial hyperreactivity. In vitro, desipramine and fluoxetine dose-dependently inhibited the release of TNF-α from LPS-treated monocytes. In lung epithelial cells, these compounds decreased TNF-α-induced RANTES expression as well as the activity of nuclear factor-κB and activator protein-1.

Conclusion

Desipramine and fluoxetine reduce the inflammatory reaction in two animal models of human diseases. These antidepressants act directly on relevant peripheral cell types to decrease expression of inflammatory mediators probably by affecting their gene transcription. Clinical implications of these observations are discussed.

[Working memory disturbances in patients with major depression after ECT treatment]

INTRODUCTION

Electroconvulsive therapy (ECT) is the most effective treatment in a variety of psychiatric syndromes (especially mood disorders). However one of its adverse effects is neurocognitive dysfunction. Declarative memory impairment after ECT is unquestionable and well investigated. There are only few ambiguous studies focused on nondeclarative and immediate memory changes during ECT.

METHOD

A study of immediate (working) memory changes in depressed patients treated with ECT (n=10; bitemporal ECT 3 times a week) or imipramine or desipramine (150-250 mg/day; n=10) was conducted in patients who fulfilled DSM-IV criteria for major unipolar depression. Hamilton Depression Rating Scale (HDRS) and Beck's Depression Inventory (BDI) were used to assess the efficacy of antidepressant therapy. Cognitive functions were assessed with neuropsychological tests: Stroop A and B, TMT (Trial Making) A and B. The patients' status was evaluated 1 day before the treatment and 1 day, 2 weeks, 1 month and 6 months after the first ECT procedure.

RESULTS

1 day after first ECT treatment, patient's working memory was slightly impaired, but this was not statistically significant. Both groups showed statistically significant improvement in working memory I month after start of treatment. However there were statistically significant differences between ECT and pharmacologically treated groups at the first month of therapy.

CONCLUSION

ECT treatment only temporally affects working memory function. The improvement of function may be a result of clinical recovery from depressant symptomatology.

Efficacy of noradrenergic and serotonergic antidepressants in chronic back pain: a preliminary concentration-controlled trial

OBJECTIVE

Although antidepressants are widely prescribed as analgesics in chronic back pain, their clinical pharmacology is not well established. Norepinephrine transporter blockade seems to be essential for analgesia, but optimal concentrations are unknown. Fixed-dose studies of serotonin reuptake inhibitors are generally negative, but such studies cannot be interpreted clearly because efficacy might be detected if concentration-response relationships were known. We evaluated (1) the feasibility of conducting a controlled-concentration study of a norepinephrine (desipramine) and a serotonin reuptake (fluoxetine) inhibitor and (2) the relationship between achieved concentrations and analgesic response.

METHODS

This single-center, 12-week, double-blind, prospective, controlled-concentration study randomized 121 chronic back pain patients without major depression to active placebo (benztropine mesylate) or to predetermined low, medium, or high concentrations of desipramine (targets were 50, 110, and 150 ng/mL, respectively) or fluoxetine (targets were 100, 200, and 400 ng/mL, respectively). Of these, 83 completed the trial: 38 withdrew primarily due to side effects.

RESULTS

Manipulation check revealed significant overlap of assigned and achieved concentrations related to drug intolerability. Completers' analysis of achieved concentrations revealed reduction in pain intensity was significantly greater for low-concentration desipramine (<60 ng/mL, mean Descriptor Differential Scale [DDS], 4.5) compared with placebo (DDS 6.2), higher concentrations of desipramine (>60 ng/mL, DDS 7.9), and all concentrations of fluoxetine (P < 0.05, DDS 7.1). Significant improvement in everyday function mirrored findings for pain intensity.

CONCLUSIONS

Preliminary evidence for a low-concentration "therapeutic window" for noradrenergic analgesia may warrant additional study.

Treatment with desipramine improves breathing and survival in a mouse model for Rett syndrome

Rett syndrome (RS) is a severe X-linked neurological disorder in which most patients have mutations in the methyl-CpG binding protein2 (MECP2) gene. No effective treatment exists. We previously showed that the Mecp2-deficient mice, a mouse model of RS, have highly variable respiratory rhythm and frequent apneas due to reduced norepinephrine (NE) content, and a drastic decrease of tyrosine hydroxylase (TH)-expressing neurons in the medulla. We showed here that treating these mice with desipramine (DMI), which specifically inhibits NE reuptake, significantly improved their respiratory rhythm during several weeks. In addition, the treatment significantly extended their lifespan. At the cellular level, we showed that the reduced number of TH-expressing neurons before treatment in the mutant animals was not due to apoptosis. Conversely, we found that DMI treatment increased the number of TH-expressing neurons in the mutant brainstem to reach wild-type levels. We showed that this increase was not due to cellular proliferation. We propose that the Mecp2-deficient TH-expressing neurons lose their ability to synthesize TH at some point during their postnatal development. Our results suggest that a pharmacological stimulation of the noradrenergic system could be a promising approach for the treatment of the respiratory dysfunction which causes a significant proportion of death in RS patients.

Desipramine prevents the sustained increase in corticotropin-releasing hormone-like immunoreactivity induced by repeated immobilization stress in the rat central extended amygdala

Clinical and experimental studies have shown that the activation of corticotropin-releasing hormone (CRH) and noradrenergic systems mediate stress-induced anxiety. Repeated immobilization stress (RIS) has been shown to induce long-lasting anxiety behavior and changes in noradrenaline turnover. The present work was aimed at studying the effect of RIS on the in situ expression of CRH-LI in the central extended amygdala and paraventricular nucleus of the hypothalamus (PVN). Our results showed that RIS for 15 days induces a significant increase of CRH-LI expression in the central extended amygdala. The increase in CRH-LI expression in the central extended amygdala was sustained even after a 25-day stress-free period. The concomitant administration of desipramine (DMI), a specific noradrenaline uptake inhibitor, fully prevented the RIS-induced increase in CRH expression. RIS also induced an increase of CRH-LI expression in the PVN that was prevented by the concomitant DMI administration. In contrast to the sustained effect observed in the central extended amygdala, the RIS-induced increase of CRH-LI expression in the PVN was nonlasting. DMI administration also prevented the RIS-induced increase of adrenal gland weight. The present findings showing that RIS induces a sustained increase of CRH expression in the central extended amygdala suggest that the repeated activation of CRH neurons and CRH receptors in the central extended amygdala may underlie the long-lasting anxiety behavior induced by RIS. Further studies should address the mechanisms involved in the effect of DMI and its eventual relevance in the therapeutic actions of DMI.

Vulnerability for apoptosis in the limbic system after myocardial infarction in rats: a possible model for human postinfarct major depression

OBJECTIVE

Major depressive disorder occurs in 15%-30% of patients who have had a myocardial infarction (MI), but the neurobiological mechanisms involved are not well understood. Previously, we found early intracellular signalling changes in the limbic system after acute MI in rats. The aim of the present study was to test the presence of behavioural deficits compatible with animal models of depression after acute MI in rats and to verify whether this is associated with apoptosis vulnerability markers.

METHODS

Occlusion of the left-anterior descending artery was induced for 40 minutes under anesthesia in adult male Sprague-Dawley rats. Control sham rats underwent the same surgical procedure without occlusion. After surgery, subgroups of MI and sham rats were treated with desipramine, 10 mg/kg, intraperitoneally for 14 days. All rats were tested on measures of behavioural depression 14 days after surgery with a sucrose preference test, a forced swimming test, and a memory test (Morris water maze [MWM]). The rats were sacrificed, and the MI size was determined; apoptosis was estimated in the prefrontal cortex, hypothalamus, amygdala and hippocampus by measuring Bax:Bcl-2 ratio and caspase-3 activity.

RESULTS

Untreated MI rats drank significantly less sucrose and swam significantly less than sham rats. No difference was found on the MWM. Behavioural depression was prevented by desipramine. Bax:Bcl-2 ratio was significantly increased in the prefrontal cortex and hypothalamus of MI rats, compared with sham rats; caspase-3 activity showed no difference between the 2 groups. Bax:Bcl-2 ratio in the prefrontal cortex was correlated with swim time in the forced swim test.

CONCLUSION

Behavioural impairment and limbic apoptotic events observed after a myocardial infarct are consistent with a model of human post-MI depression.

Analgesic effects of serotonergic, noradrenergic or dual reuptake inhibitors in the carrageenan test in rats: Evidence for synergism between serotonergic and noradrenergic reuptake inhibition

The efficacy of antidepressant drugs with serotonergic, noradrenergic, or dual reuptake inhibition was evaluated in reversing carrageenan-induced thermal hyperalgesia and mechanical allodynia in rats. Duloxetine (1-30mg/kg, i.p.), a balanced serotonergic-noradrenergic reuptake inhibitor (SNRI), was equiefficacious and more potent than the SNRI venlafaxine (3-100mg/kg, i.p.) in reversing both thermal hyperalgesia and mechanical allodynia induced by carrageenan. In addition, the selective noradrenergic reuptake inhibitors (NRIs) thionisoxetine (0.03-10mg/kg, i.p.) and desipramine (1-30mg/kg, i.p.) also produced complete reversals of carrageenan-induced thermal hyperalgesia. However, only thionisoxetine exhibited a greater than 80% reversal of the carrageenan-induced mechanical allodynia. In contrast, the selective serotonergic reuptake inhibitors (SSRIs) paroxetine, sertraline, and fluoxetine (0.3-10mg/kg i.p.) had little or no effect in the carrageenan model. In order to understand whether the observed enhanced effectiveness of the dual SNRIs was due to a possible synergism between serotonergic and noradrenergic reuptake inhibition, the effects of the NRI thionisoxetine alone and in combination with an inactive dose of the SSRI fluoxetine were determined. In the presence of fluoxetine, the potency of thionisoxetine in reversing carrageenan-induced hyperalgesia and allodynia was significantly increased by approximately 100-fold and brain concentrations of thionisoxetine were increased by 1.1- to 5-fold. The present data indicate fluoxetine pharmacodynamically potentiated the analgesic effects of thionisoxetine over and above a metabolic interaction between these two drugs. The present findings thus indicate that, in the carrageenan model, dual serotonergic-noradrenergic reuptake inhibition by dual SNRIs, or SSRI-NRI combinations, produces synergistic analgesic efficacy.

Inhibition of nonexocytotic norepinephrine release by desipramine reduces myocardial infarction size

During myocardial ischemia, a substantial accumulation of norepinephrine occurs in the ischemic zone due to a local nonexocytotic release of norepinephrine. Norepinephrine release is driven by the neuronal monoamine transporter (NET), which reverses its usual transmembrane transport direction. We investigated whether this local accumulation of norepinephrine contributes to irreversible myocardial injury in an in vivo model of myocardial infarction. Male, anaesthetized Wistar rats were subjected to 30 min coronary occlusion and subsequent 120 min reperfusion. Five minutes prior to coronary occlusion, the NET inhibitor desipramine was administered intravenously. Infarct size (IS) was determined by TTC-staining and was related to the area at risk (AAR). The influence of desipramine on cardiac norepinephrine release was investigated in isolated perfused hearts with 30 min of regional ischemia. Norepinephrine was measured in the effluent from the hearts by HPLC and electrochemical detection. Desipramine (0.1–0.8 mg/kg) dose-dependently reduced infarct size (IS/AAR) from 0.54 to 0.21 and suppressed postischemic norepinephrine release from 245 to 108 pg/mL. In summary, the data indicate that nonexocytotic release of norepinephrine in myocardial ischemia exaggerates acute ischemic damage, because suppression of ischemia-induced release of norepinephrine by the tricyclic antidepressant desipramine effectively reduces infarct size in an in vivo model of myocardial ischemia.

Phosphodiesterase genes are associated with susceptibility to major depression and antidepressant treatment response

Cyclic nucleotide phosphodiesterases (PDEs) constitute a family of enzymes that degrade cAMP and cGMP. Intracellular cyclic nucleotide levels increase in response to extracellular stimulation by hormones, neurotransmitters, or growth factors and are down-regulated through hydrolysis catalyzed by PDEs, which are therefore candidate therapeutic targets. cAMP is a second messenger implicated in learning, memory, and mood, and cGMP modulates nervous system processes that are controlled by the nitric oxide (NO)/cGMP pathway. To investigate an association between genes encoding PDEs and susceptibility to major depressive disorder (MDD), we genotyped SNPs in 21 genes of this superfamily in 284 depressed Mexican Americans who participated in a prospective, double-blind, pharmacogenetic study of antidepressant response, and 331 matched controls. Polymorphisms in PDE9A and PDE11A were found to be associated with the diagnosis of MDD. Our data are also suggestive of the association between SNPs in other PDE genes and MDD. Remission on antidepressants was significantly associated with polymorphisms in PDE1A and PDE11A. Thus, we found significant associations with both the diagnosis of MDD and remission in response to antidepressants with SNPs in the PDE11A gene. We show here that PDE11A haplotype GAACC is significantly associated with MDD. We conclude that PDE11A has a role in the pathophysiology of MDD. This study identifies a potential CNS role for the PDE11 family. The hypothesis that drugs affecting PDE function, particularly cGMP-related PDEs, represent a treatment strategy for major depression should therefore be tested.

Antidepressant treatment reduces Fos-like immunoreactivity induced by swim stress in different columns of the periaqueductal gray matter

Antidepressant treatment attenuates behavioral changes induced by uncontrollable stress. The periaqueductal gray matter (PAG) is proposed to be a brain site involved in the behavioral responses to uncontrollable stress and antidepressant effects. The main goal of the present study was to investigate the effect of antidepressant treatment on the pattern of neural activation of the PAG along its mediolateral and rostrocaudal subregions after a forced swim stress episode. Male Wistar rats were sub-acutely treated with desipramine (a selective noradrenaline re-uptake blocker, three injections of 10 mg/kg in 24 h) or clomipramine (a non-selective serotonin and noradrenaline re-uptake blocker, three injections of 10 mg/kg in 24 h) and submitted to the forced swimming test (FST). Two hours after the test their brain were removed for Fos immunohistochemistry. Fos-like immunoreactivity (FLI) in rostral, intermediate and caudal portions of dorsomedial (dmPAG), dorsolateral (dlPAG), lateral (lPAG) and ventrolateral (vlPAG) PAG were quantified by a computerized system. The FST session increased FLI in most parts of the PAG. Previous treatment with desipramine or clomipramine reduced FLI in all columns of the PAG. FLI in the PAG correlated positively with to the immobility time and negatively with to climbing behavior scored during the test. These results indicate that neurons in the PAG are activated by uncontrollable stress. Moreover, inhibitory action of antidepressants on this activity may be associated with the anti-immobility effects of these drugs in the FST.

Antidepressant-like and anxiolytic-like actions of the mGlu5 receptor antagonist MTEP, microinjected into lateral septal nuclei of male Wistar rats

This study describes the effects of intra-lateral septal infusions of different doses of the mGluR5 antagonist MTEP in the DRL-72 s paradigm and the elevated plus-maze test in rats, two behavioral models known to be sensitive to antidepressant-like and anxiolytic-like drug effects, respectively. Intra-lateral septal infusions of MTEP induced a dose-dependent (5.0 microg/microl, P<0.05; 10.0 microg/microl, P<0.05) increase in reinforced lever presses and a cohesive rightward shift of the inter-response time distribution (5.0 microg/microl, P<0.05; 10.0 microg/microl, P<0.05). These effects are indicative of antidepressant-like actions of the compound. Desipramine, a prototypical antidepressant drug, induced (5.0 microg/microl; P<0.05) similar effects. In the elevated plus-maze test, intra-lateral septal infusions of MTEP (5.0 microg/microl, P<0.05; 10.0 microg/microl, P<0.05) increased the exploration of the open arms without affecting locomotion. This anxiolytic-like effect was similar to that observed with the infusion of the benzodiazepine midazolam (10.0 microg/microl; P<0.05) in the same brain area. It is concluded that intra-lateral septal infusions of the mGlu5 receptor antagonist MTEP produced antidepressant-like actions or anxiolytic-like effects in male rats.

Antidepressant treatment of chronic tension-type headache: a comparison between fluoxetine and desipramine

Amitriptyline, which is a noradrenaline reuptake and 5-HT reuptake inhibitor, has an established role in the management of chronic tension-type headaches. In a single-blind study, patients with chronic tension-type headache were randomized to either fluoxetine 20 mg (a selective 5-HT reuptake inhibitor) or desipramine 75 mg (a selective noradrenaline reuptake inhibitor) and followed for 12 weeks to compare the effectiveness of the two drugs in improving headache, and to assess whether pain control is related to changes in depression. Patients were evaluated at weekly intervals on an analog pain-rating scale and at 4-weekly intervals on the Montgomery and Asberg Depression Rating Scale (MADRS), the MOS general health status questionnaire (SF36), the Hospital Anxiety and Depression Scale (HADS), and a side effects checklist. Eighteen patients were randomized to take fluoxetine and 19 to take desipramine. Of the 25 patients who completed the trial, 12 were on fluoxetine and 13 were on desipramine. There was no significant difference between the two groups at baseline nor in change of pain; reduction in use of analgesic medication; nor change in the HADS, MADRS, or SF36 scores at 12 weeks, but 72% of patients who completed the study improved, and this improvement almost exactly mirrored the improvement on the MADRS. The results from this trial are compatible with the notion that the beneficial effect of antidepressants in chronic tension-type headache is indirect, mediated by an effect on depression, and not more,dependent on serotonin reuptake inhibition than noradrenaline reuptake inhibition.