Psychoneuroendocrinology of depression. Hypothalamic-pituitary-adrenal axis

Role of drug efflux transporters in the brain for drug disposition and treatment of brain diseases

The blood-brain barrier (BBB) serves as a protective mechanism for the brain by preventing entry of potentially harmful substances from free access to the central nervous system (CNS). Tight junctions present between the brain microvessel endothelial cells form a diffusion barrier, which selectively excludes most blood-borne substances from entering the brain. Astrocytic end-feet tightly ensheath the vessel wall and appear to be critical for the induction and maintenance of the barrier properties of the brain capillary endothelial cells. Because of these properties, the BBB only allows entry of lipophilic compounds with low molecular weights by passive diffusion. However, many lipophilic drugs show negligible brain uptake. They are substrates for drug efflux transporters such as P-glycoprotein (Pgp), multidrug resistance proteins (MRPs) or organic anion transporting polypeptides (OATPs) that are expressed at brain capillary endothelial cells and/or astrocytic end-feet and are key elements of the molecular machinery that confers the special permeability properties to the BBB. The combined action of these carrier systems results in rapid efflux of xenobiotics from the CNS. The objective of this review is to summarize transporter characteristics (cellular localization, specificity, regulation, and potential inhibition) for drug efflux transport systems identified in the BBB and blood-cerebrospinal fluid (CSF) barrier. A variety of experimental approaches available to ascertain or predict the impact of efflux transport on brain access of therapeutic drugs also are described and critically discussed. The potential impact of efflux transport on the pharmacodynamics of agents acting in the CNS is illustrated. Furthermore, the current knowledge about drug efflux transporters as a major determinant of multidrug resistance of brain diseases such as epilepsy is reviewed. Finally, we summarize strategies for modulating or by-passing drug efflux transporters at the BBB as novel therapeutic approaches to drug-resistant brain diseases.

Corticotropin-releasing factor-binding protein, stress and major depression

Major depressive disorder (MDD) is characterized by a dysregulation of the stress response system. A corticotropin-releasing factor (CRF) hyperdrive is a consistent and well-documented finding. CRF-binding protein (CRF-BP) may play a role in the pathogenesis of MDD. CRF-BP reduces the availability of CRF by binding free CRF and inhibits CRF function at the pituitary level. Moreover, CRF-BP expression increases in the pituitary and amygdala in response to acute stress, providing an additional feedback mechanism to maintain the homeostasis of the stress response. There are different regulatory elements of the expression of CRF-BP gene that are implicated in the pathophysiology of MDD, including CRF, glucocorticoids, cytokines and estrogens. A specific haplotype within the CRF-BP gene has been associated with MDD, but confirmation of this finding is necessary. Currently, the possible role of CRF-BP in the pathophysiology of conditions that have been associated with a hypofunction of the CRF system and immune dysfunctions is unclear. Implications of the function of CRF-BP for therapeutic strategies in MDD are being discussed. An important advantage of ligands that target CRF-BP is that concentrations of free CRF can be altered without acting directly on the transmission of CRF through its receptor.

Dissecting the genetic effect of the CRH system on anxiety and stress-related behaviour

Corticotropin-releasing hormone (CRH) plays a central role in the adaptation of the body to stress. CRH integrates the endocrine, autonomic and behavioural responses to stress acting as a secretagogue within the line of the hypothalamic pituitary adrenocortical (HPA) system and as a neurotransmitter modulating synaptic transmission in the central nervous system. Accumulating evidence suggests that the neuroendocrine and behavioural symptoms observed in patients suffering from major depression are at least in part linked to a hyperactivity of the CRH system. Genetic modifications of the CRH system by conventional and conditional gene targeting strategies in the mouse allowed us to study the endogenous mechanisms underlying HPA system regulation and CRH-related neuronal circuitries involved in pathways mediating anxiety and stress-related behaviour.

Stress and Depression

Improved methods of assessment and research design have established a robust and causal association between stressful life events and major depressive episodes. The chapter reviews these developments briefly and attempts to identify gaps in the field and new directions in recent research. There are notable shortcomings in several important topics: measurement and evaluation of chronic stress and depression; exploration of potentially different processes of stress and depression associated with first-onset versus recurrent episodes; possible gender differences in exposure and reactivity to stressors; testing kindling/sensitization processes; longitudinal tests of diathesis-stress models; and understanding biological stress processes associated with naturally occurring stress and depressive outcomes. There is growing interest in moving away from unidirectional models of the stress-depression association, toward recognition of the effects of contexts and personal characteristics on the occurrence of stressors, and on the likelihood of progressive and dynamic relationships between stress and depression over time-including effects of childhood and lifetime stress exposure on later reactivity to stress.

Single and repeated stress-induced modulation of phospholipase C catalytic activity and expression: role in LH behavior

PI-PLC, a critical enzyme of the phosphoinositide (PI) signaling pathway, mediates many physiological functions in the brain, including cellular plasticity. Stress-induced learned helplessness (LH) in animals serves as a model of behavioral depression. Recently, we observed that repeated stress prolongs the duration of LH behavior in rats, enabling us to compare neurobiologic abnormalities in acute and chronic depression. Here we examine whether LH behavior is associated with alterations in phospholipase C (PLC), and whether repetition of inescapable shock has similar or dissimilar effects on PLC to those of the single-stress paradigm. Rats were exposed to inescapable shock either once on day 1, or twice, on days 1 and 7. Rats were tested for escape latency on days 2 and 4 after day 1 inescapable shock or on days 2, 8, and 14 after day 1 and 7 inescapable shock. PI-PLC activity and mRNA and protein expression of three different PLC isozymes were determined in the frontal cortex and hippocampus. Higher escape latencies were observed in LH rats tested on day 2 after single inescapable shock and on day 14 after repeated inescapable shock. Single inescapable shock reduced PI-PLC activity in the frontal cortex and hippocampus of LH rats. On the other hand, repeated inescapable shock not only reduced PI-PLC activity in these brain areas of LH rats but also selectively decreased the expression of PLC beta1 and PLC gamma1 isozymes. Our results suggest different responsiveness at the level of PI-PLC after single vs repeated stress, and that reductions in PLC may be critical in the pathophysiology of depression and other stress-related disorders.

Effect of bupropion on nocturnal urinary free cortisol and its association with antidepressant response

The study examined the relationship between pre-treatment nocturnal hypothalamic-pituitary-adrenal (HPA) activity, as reflected by nocturnal urinary free cortisol (NUFC) response to a single-dose of sustained-release bupropion, and the antidepressant effect of the drug. NUFC changes in response to treatment with bupropion also were assessed. NUFC was measured in 20 patients with unipolar major depressive disorder before and after initiating treatment with sustained-release bupropion. Prior to treatment, subjects were studied on two separate sessions, one week apart. On the morning of each session, the participants received bupropion (150 mg, PO) or placebo using a randomized, double-blind procedure. Following the second session, subjects then received open-label treatment with bupropion for 8 weeks. NUFC sampling was repeated at the end of treatment. There was a significant interaction between NUFC concentration in response to single-dose bupropion and its antidepressant effect. Treatment non-responders showed a significant increase in NUFC in response to a single-dose of bupropion, whereas responders showed no such change. In addition, the NUFC response to bupropion challenge correlated significantly with the change in depression ratings as a result of treatment. In contrast to many other antidepressants, treatment with bupropion for 8 weeks did not reduce HPA activity in either responders or non-responders. These findings suggest that the NUFC response to a test-dose of bupropion might be helpful in predicting its antidepressant effect. One possible mechanism for the association between the NUFC response to acute bupropion challenge and antidepressant efficacy might be linked through dopaminergic and/or noradrenergic mechanisms.

Gonadal steroid modulation of the limbic-hypothalamic- pituitary-adrenal (LHPA) axis is influenced by social status in female rhesus monkeys

Chronic stress can have a deleterious effect on the re-productive axis that, for females, is manifested in an increased incidence of infertility. However, gonadal steroids may, in turn, affect a female's response to stress as measured by activity within the limbic-hypothalamic-pituitary-adrenal (LHPA) axis. What is not clear is whether a history of exposure to stress modifies the effect of gonadal steroids on LHPA responsivity. Rhesus monkeys present a unique opportunity to assess LHPA responsivity when housed socially in groups. Under these situations, monkeys exhibit a rich network of affiliation and have established social status hierarchies. Previous work indicates that socially subordinate macaque females are hypercortisolemic due to diminished gluco-corticoid negative feedback. The present study tested the hypothesis that estradiol (E2) would decrease gluco-corticoid negative feedback, assessed from a dexamethasone (DEX) suppression test, and increase the response to corticotropin releasing factor (CRF) and that these effects would be attenuated by co-treatment with P4. In addition, we also determined whether E2 and P4 would differentially affect LHPA responsiveness to pharmacological challenge in socially dominant compared with subordinate females. Endogenous gonadal hormone secretion in female rhesus monkeys (n = 7) was suppressed by continuous treatment with a sustained release formulation of the GnRH analog leuprolide acetate (Lupron Depot). The response to a combined DEX suppression-CRF stimulation test was assessed using a counterbalanced design during a placebo (control) treatment condition and during E2, P4, and E2 + P4 re-placement therapy. Females who were members of a large breeding group of 140 adults and juveniles of both sexes, were classified as dominant (n = 4) or subordinate (n = 3) based on the relative social dominance positions within the group. Plasma levels of cortisol were significantly higher during E2 replacement compared to the other treatment conditions following DEX suppression and stimulation with CRF.

The programming of individual differences in defensive responses and reproductive strategies in the rat through variations in maternal care

There are profound maternal effects on individual differences in defensive responses and reproductive strategies in species ranging literally from plants to insects to birds. Maternal effects commonly reflect the quality of the environment and are most likely mediated by the quality of the maternal provision (egg, propagule, etc.), which in turn determines growth rates and adult phenotype. In this paper, we review data from the rat that suggest comparable forms of maternal effects on both defensive responses to threat and reproductive behavior and which are mediated by variations in maternal behavior. Ultimately, we will need to contend with the reality that neural development, function and health are defined by social and economic influences.

Psychostimulant withdrawal as an inducing condition in animal models of depression

A large body of evidence indicates that the withdrawal from high doses of psychostimulant drugs in humans induces a transient syndrome, with symptoms that appear isomorphic to those of major depressive disorder. Pharmacological treatment strategies for psychostimulant withdrawal in humans have focused mainly on compounds with antidepressant properties. Animal models of psychostimulant withdrawal have been shown to demonstrate a wide range of deficits, including changes in homeostatic, affective and cognitive behaviors, as well as numerous physiological changes. Many of these behavioral and physiological sequelae parallel specific symptoms of major depressive disorder, and have been reversed by treatment with antidepressant drugs. These combined findings provide strong support for the use of psychostimulant withdrawal as an inducing condition in animal models of depression. In the current review we propound that the psychostimulant withdrawal model displays high levels of predictive and construct validity. Recent progress and limitations in the development of this model, as well as future directions for research, are evaluated and discussed.

Blood-brain barrier active efflux transporters: ATP-binding cassette gene family

The blood-brain barrier (BBB) contributes to brain homeostasis by protecting the brain from potentially harmful endogenous and exogenous substances. BBB active drug efflux transporters of the ATP-binding cassette (ABC) gene family are increasingly recognized as important determinants of drug distribution to, and elimination from, the CNS. The ABC efflux transporter P-glycoprotein (Pgp) has been demonstrated as a key element of the BBB that can actively transport a huge variety of lipophilic drugs out of the brain capillary endothelial cells that form the BBB. In addition to Pgp, other ABC efflux transporters such as members of the multidrug resistance protein (MRP) family and breast cancer resistance protein (BCRP) seem to contribute to BBB function. Consequences of ABC efflux transporters in the BBB include minimizing or avoiding neurotoxic adverse effects of drugs that otherwise would penetrate into the brain. However, ABC efflux transporters may also limit the central distribution of drugs that are beneficial to treat CNS diseases. Furthermore, neurological disorders such as epilepsy may be associated with overexpression of ABC efflux transporters at the BBB, resulting in pharmacoresistance to therapeutic medication. Therefore, modulation of ABC efflux transporters at the BBB forms a novel strategy to enhance the penetration of drugs into the brain and may yield new therapeutic options for drug-resistant CNS diseases.

Chronic stress attenuates GABAergic inhibition and alters gene expression of parvocellular neurons in rat hypothalamus

Chronic stress causes disinhibition of the hypothalamus-pituitary-adrenal axis. Consequently, the brain is overexposed to glucocorticoids which in humans may precipitate stress-related disorders, e.g. depression. The hypothalamus-pituitary-adrenal activity is strongly regulated by GABAergic input to parvocellular neurons in the hypothalamic paraventricular nucleus. We here report a reduced frequency of miniature inhibitory postsynaptic currents (mIPSCs) in parvocellular neurons of rats exposed to 3 weeks of unpredictable stress. The mIPSC amplitude and kinetic properties were unchanged, pointing to a presynaptic change caused by chronic stress. Because paired-pulse inhibition was unaffected by chronic stress, the number of functional GABAergic synaptic contacts rather than the release probability seems to be reduced after chronic stress. Linearly amplified RNA from postsynaptic cells was hybridized with multiple cDNA clones of interest, including most GABA(A) receptor subunits. In agreement with the electrophysiological observations, relative expression of the prevalent GABA(A)alpha1, alpha3, gamma1 and gamma2 receptor subunits, which largely contribute to the recorded responses, was not altered after chronic stress. However, expression of the extra-synaptic GABA(A)alpha5 subunit, earlier linked to depression in humans, and of the delta receptor subunit were found to be significantly changed. In conclusion, chronic stress leads to presynaptic functional alterations in GABAergic input to the paraventricular nucleus which could contribute to the observed disinhibition of the hypothalamus-pituitary-adrenal axis; additionally other aspects of GABAergic transmission may also be changed due to transcriptional regulation of specific receptor subunits in the parvocellular neurons.

Why is depression bad for the failing heart? A review of the mechanistic relationship between depression and heart failure

BACKGROUND

Depression is 4 to 5 times as common in heart failure (HF) patients as in the general population, might confer a higher risk of developing HF, and negatively affects prognosis in established HF.

METHODS AND RESULTS

A review was undertaken via Medline (1966-2003) and PsycINFO (1872-2003) searches using the subject headings "depressive disorder" and "heart failure, congestive." Our findings suggest that the link between depression and HF may be due to shared pathophysiology. Depression may augment catecholamine release, arrhythmias, elaboration of proinflammatory cytokines, and platelet activation--processes that may influence prognosis in HF. Depression is also associated with a higher risk of noncompliance and lower levels of social support, which have been shown to worsen prognosis in HF. The impact of pharmacologic or behavioral treatment for depression on physiologic parameters or clinical outcomes in HF remains unclear. Inherent difficulties in recognition of depression in the setting of HF may decrease the likelihood that depressed patients receive the treatment they need.

CONCLUSIONS

Depression is common in HF, may contribute to the development of HF in susceptible populations, and is independently predictive of poor clinical outcomes. Pathophysiologic pathways and psychosocial issues that are shared between the 2 conditions might explain these observations and represent potential therapeutic targets. Vigilant attention to the recognition and treatment of depression in HF patients is warranted.

Cognition in mania and depression: psychological models and clinical implications

Affective disorders, including bipolar disorder and major depressive disorder, are highly prevalent throughout the world and are extremely disabling. Diagnostic and Statistical Manual criteria and psychological models strongly implicate cognitive dysfunctions as being integral to our understanding of these disorders. We review the findings from studies that have used neurocognitive tests and functional imaging techniques to explore abnormal cognition in affective disorders. In particular, we highlight the evidence for cognitive dysfunctions that persist into full clinical remission, and the recent trend toward the use of "hot" processing tasks, involving emotionally charged stimuli, as a means of differentiating between the cognitive underpinnings of mania and depression. The clinical relevance of these developments is discussed.

Stress, depression, the immune system, and cancer

The links between the psychological and physiological features of cancer risk and progression have been studied through psychoneuroimmunology. The persistent activation of the hypothalamic-pituitary-adrenal (HPA) axis in the chronic stress response and in depression probably impairs the immune response and contributes to the development and progression of some types of cancer. Here, we overview the evidence that various cellular and molecular immunological factors are compromised in chronic stress and depression and discuss the clinical implications of these factors in the initiation and progression of cancer. The consecutive stages of the multistep immune reactions are either inhibited or enhanced as a result of previous or parallel stress experiences, depending on the type and intensity of the stressor and on the animal species, strain, sex, or age. In general, both stressors and depression are associated with the decreased cytotoxic T-cell and natural-killer-cell activities that affect processes such as immune surveillance of tumours, and with the events that modulate development and accumulation of somatic mutations and genomic instability. A better understanding of the bidirectional communication between the neuroendocrine and immune systems could contribute to new clinical and treatment strategies.

Cortisol, hunger, and desire to binge eat following a cold stress test in obese women with binge eating disorder

OBJECTIVE

Increased basal cortisol levels have been found in bulimia nervosa. After stress, increased cortisol levels have been associated with increased food intake in healthy women. Therefore, we assessed cortisol, hunger, and desire to binge eat after a cold pressor test (CPT) among women with binge eating disorder (BED).

METHODS

Twenty-two obese (body mass index [BMI] = 36.7 +/- 6.5 SD) females (11 non-BED, 11 BED) completed the Zung depression scale and underwent the CPT, hand submerged in ice water for 2 minutes. Over 60 minutes, periodic ratings of hunger and desire to binge eat were obtained, just before blood draws for cortisol, as well as insulin. On a separate day, participants had a 1-mg oral dexamethasone suppression test (DST).

RESULTS

The BED group had higher depression scores than the non-BED (p = .04), but depression was not a significant covariate for the cortisol response or to DST. After controlling for contraceptive use (n = 3), the BED group had higher basal cortisol than the non-BED group (p = .03), but cortisol did not differ after DST (p = .40). The BED group had nearly significant greater cortisol AUC after the CPT (p = .057) after controlling for insulin AUC and contraceptive use (p = .057). The BED group also had greater AUC for hunger (p = .03) and desire to binge eat (p = .02) after the CPT.

CONCLUSION

These findings support our hypothesis of a hyperactive HPA-axis in BED, which may contribute to greater hunger and binge eating.

Impairment of inhibitory control of the hypothalamic pituitary adrenocortical system in epilepsy

Excess comorbidity between depression and epilepsy proposes common pathophysiological patterns in both disorders. Neuroendocrine abnormalities were often observed in depression as well as in epilepsy. Lack of inhibitory control of the hypothalamic pituitary adrenocortical (HPA) system is a core feature of depression; main relay stations of this system are located in the amygdala and hippocampus, which are key regions for both disorders. Therefore we explored the feedback mechanism of the HPA system in epilepsy. In order to control for the impact of depression we focused on epilepsies without depression. We compared patients with epilepsy (subdivided by medication with or without hepatic enzyme inducing antiepileptic medication) with 16 healthy controls and 16 patients with unipolar major depression but without epilepsy. We observed a lack of inhibitory control of the HPA system in patients with epilepsy, also in the absence of enzyme inducing medication. An impact of the temporal lobe location of the epileptic focus could not be observed. Thus, epilepsies share with depression the deficiencies in the feedback mechanism of the HPA system, proposing common pathophysiological features of up to now unknown nature.

Changes in cortisol and dehydroepiandrosterone in women victims of physical and psychological intimate partner violence

BACKGROUND

Although intimate partner violence (IPV) has a great impact on women's health, few studies have assessed the consequences on physiologic responses.

METHODS

Women abused by their intimate male partners either physically (n = 70) or psychologically (n = 46) were compared with nonabused control women (n = 46). Information about sociodemographic characteristics, smoking, pharmacologic treatment, lifetime history of victimization (childhood and adulthood), and mental health status (depression, anxiety, and posttraumatic stress disorder, PTSD) was obtained through structured interviews. Saliva samples were collected at 8 am and 8 pm for 4 consecutive days to determine morning and evening basal levels of cortisol and dehydroepiandrosterone (DHEA).

RESULTS

Women who were victims of IPV had more severe symptoms of depression, anxiety, and incidence of PTSD and higher levels of evening cortisol and morning and evening DHEA compared with control women. Intimate partner violence was the main factor predicting the alterations in hormonal levels after controlling for age, smoking, pharmacologic treatment, and lifetime history of victimization. Mental health status did not have a mediating effect on the impact of IPV on hormonal levels.

CONCLUSIONS

This study shows that both physical and psychological IPV have a significant impact on the endocrine systems of women.

Emerging experimental therapeutics for bipolar disorder: clues from the molecular pathophysiology

Bipolar affective disorder (manic-depressive illness) is a common, severe, chronic, and often life-threatening illness, associated with significant comorbidity. The recognition of the significant morbidity and mortality of patients with bipolar disorder, as well as the growing appreciation that a high percentage of patients respond poorly to existing treatments, has made the task of discovering new therapeutic agents, that are both efficacious and have few side effects increasingly more important. Most recent agents introduced into the pharmacopeia for the treatment of bipolar disorder have been anticonvulsants and atypical antipsychotics. We propose that novel treatments developed specifically for bipolar disorder will arise from (1) understanding more precisely the molecular mechanisms of treatments that are clearly efficacious or (2) developing medications based on the knowledge obtained of the underlying pathophysiology of bipolar disorder. Knowledge with regard to the underlying pathophysiology of bipolar disorder is increasing at a rapid pace, including alterations in intracellular signaling cascades as well as impairments of cellular plasticity and resilience in critical neuronal circuits. We propose that therapeutics designed to enhance cellular plasticity and resilience and that counter maladaptive stress-responsive systems may have considerable utility for the treatment of bipolar disorder. Therapeutic strategies designed to address cellular resilience and plasticity include the regulation of neurotrophic pathways, glucocorticoid signaling, phosphodiesterase activity, and glutamatergic throughput and mitochondrial function. While the task of developing novel medications for bipolar disorder is truly daunting, these and similar approaches will ultimately lead to better medications for the millions who suffer from this devastating illness.

Decreased platelet nitric oxide synthase activity and plasma nitric oxide metabolites in major depressive disorder

BACKGROUND

Major depression (MD) has been associated with increased cardiovascular mortality in patients with coronary heart disease (CHD) and has been described as an independent risk factor for the development of CHD in healthy subjects; however, the mechanism of the association between MD and CHD remains to be determined. Nitric oxide (NO) plays a major role in cardiovascular regulation, and decreased NO production has been associated with several cardiovascular risk factors. We hypothesized that in patients with MD, NO production by both platelets and the endothelium would be reduced when compared with healthy control subjects (HCs).

METHODS

Blood samples were obtained from 15 subjects with MD and 16 HCs with no known history of cardiovascular illness. Plasma NO metabolite (NOx) levels were analyzed by chemiluminescence. Platelet endothelial NO synthase (eNOS) activity was examined through the conversion of l-[(14)C]arginine to l-[(14)C]citrulline.

RESULTS

The levels of both plasma NOx and platelet eNOS activity were significantly lower in subjects with MD compared with HCs.

CONCLUSIONS

These data suggest that decreased NO production by the vascular wall and platelets might contribute to the increased CHD risk observed in patients with MD.

Early Experience and Sex Interact to Influence Limbic-Hypothalamic-Pituitary-Adrenal-Axis Function After Acute Alcohol Administration in Rhesus Macaques (Macaca mulatta)

BACKGROUND

Studies in rodents demonstrate sex differences in neuroendocrine stress axis activity after treatment with alcohol. In abstinent alcoholics, atypical depressives, and individuals with posttraumatic stress disorder, limbic-hypothalamic-pituitary-adrenal (LHPA)-axis activity is often blunted; among females in these patient populations, however, resistance to glucocorticoid feedback and increased pituitary reactivity is observed. Early parental loss is a major life stressor and is a risk factor for both affective disturbances and LHPA-axis abnormalities later in life. We wanted to determine whether sex and early life parental absence would interact to influence alcohol-induced alterations in LHPA-axis activity after exposure to ethanol in macaques.

METHODS

Animals were reared with their mothers in social groups (MR, n = 94) or without adults in peer-only groups (PR, n = 79). At 5 years of age, they received an intravenous infusion of alcohol (2-2.2 g/kg), and the effects of alcohol, sex, and rearing condition on ACTH and cortisol levels were analyzed by ANOVA.

RESULTS

Peer-reared females had higher ACTH levels than did PR males, MR females, and MR males after alcohol infusion. Alcohol-induced cortisol levels were not affected by sex and rearing condition.

CONCLUSIONS

These findings suggest that there are sex differences in glucocorticoid negative feedback, pituitary responsivity, or release of ACTH secretagogues among individuals exposed to early life stress and emphasize the importance of considering sex effects when studying LHPA-axis dysregulation in alcoholism and other stress-related neuropsychiatric disorders.

Limbic-frontal circuitry in major depression: a path modeling metanalysis

This paper reports the results of an across lab metanalysis of effective connectivity in major depression (MDD). Using FDG PET data and Structural Equation Modeling, a formal depression model was created to explicitly test current theories of limbic-cortical dysfunction in MDD and to characterize at the path level potential sources of baseline variability reported in this patient population. A 7-region model consisting of lateral prefrontal cortex (latF9), anterior thalamus (aTh), anterior cingulate (Cg24), subgenual cingulate (Cg25), orbital frontal cortex (OF11), hippocampus (Hc), and medial frontal cortex (mF10) was tested in scans of 119 depressed patients and 42 healthy control subjects acquired during three separate studies at two different institutions. A single model, based on previous theory and supported by anatomical connectivity literature, was stable for the three groups of depressed patients. Within the context of this model, path differences among groups as a function of treatment response characteristics were also identified. First, limbic-cortical connections (latF9-Cg25-OF11-Hc) differentiated drug treatment responders from nonresponders. Second, nonresponders showed additional abnormalities in limbic-subcortical pathways (aTh-Cg24-Cg25-OF11-Hc). Lastly, more limited limbic-cortical (Hc-latF9) and cortical-cortical (OF11-mF10) path differences differentiated responders to cognitive behavioral therapy (CBT) from responders to pharmacotherapy. We conclude that the creation of such models is a first step toward full characterization of the depression phenotype at the neural systems level, with implications for the future development of brain-based algorithms to determine optimal treatment selection for individual patients.

The effects of repeated intra-amygdala CRF injections on rat behavior and HPA axis function after stress

Patients diagnosed with certain anxiety disorders or depression show symptoms of a dysregulated HPA-axis secondary to increased release of corticotropin releasing factor (CRF). Male Wistar rats were injected with CRF (100 ng/microL) in the basolateral amygdala (BLA) for 5 days. Measurement of behavior was performed on the elevated plus maze and open field test. Behavioral and neuroendocrine response to restraint stress was also evaluated. Chronic treatment of CRF resulted in a significant increase in grooming after restraint stress in the Open Field test. Basal plasma corticosterone concentrations were significantly lower in the CRF-injected rats. These animals also showed greater and longer increase in corticosterone levels following the restraint stress than controls, but had comparable ACTH responses to restraint stress. Our results indicate that chronic administration of CRF into the basolateral amygdala may promote stress-induced grooming behavior in rats. In addition the data suggests that increased CRF in the amygdala may contribute to the dysregulation of corticosterone secretion. These findings may have important implications for patients suffering from psychiatric illnesses such as posttraumatic stress disorder and depression that are characterized by abnormalities in cortisol release.

Brain region and dose effects of an olanzapine/fluoxetine combination on extracellular monoamine concentrations in the rat

Clinical studies of patients with treatment-resistant depression have shown that combined treatment with fluoxetine and olanzapine rapidly and significantly improved depressive symptoms. The present study used in vivo microdialysis to investigate the brain regional and dose effects of these drugs on extracellular monoamine concentrations in the rat prefrontal cortex, hypothalamus, nucleus accumbens and striatum. In the prefrontal cortex, the olanzapine/fluoxetine combination (3/10 mg/kg, respectively) increased catecholamine concentrations to a significantly greater extent than either drug alone (dopamine mean+/-S.E.M. percent of baseline: olanzapine (120 +/- 12.4), fluoxetine (123 +/- 6.2), combination (185 +/- 8.8); norepinephrine: olanzapine (124 +/- 7.2), fluoxetine (126 +/- 5.0), combination (215 +/- 15.8)). The combination also increased serotonin concentrations to 156 +/- 11.0% of baseline, but to a lesser extent than fluoxetine alone (210 +/- 14.5%). Similar synergistic effects of the combination were observed in the hypothalamus, but not in the other regions studied. The dose response effects of the drugs alone and in combination were complex, but larger doses of the combinations produced greater monoamine concentration increases than smaller dose combinations. The effects of the olanzapine/fluoxetine combination are meaningful in prefrontal cortex and hypothalamus due to their hypothesized role in the etiology and pharmacotherapy of depression. The wide-ranging neurochemical effects of this drug combination may make it particularly useful as a treatment for complex, resistant depressions.

Chronic mild stress affects sucrose intake and sleep in rats

Depression in humans is associated with sleep abnormalities of three types: altered rapid eye movement (REM) sleep, fragmented sleep, and reduced delta sleep. In an animal model of depression, chronic exposure to mild stressors (CMS, e.g. periods of soiled cage, reversed light/dark cycle, grouped housing, food and/or water deprivation) causes behavioral and hormonal changes which, in humans, often are associated with depression. In the CMS model, a reduced sucrose intake has been defined as one of the core symptoms of depression, anhedonia, although this finding is not consistent among various laboratories. In the present study, we investigated if the CMS procedure, in our laboratory, would cause decreased sucrose intake and, also, give sleep changes similar to what is found in depressed patients. Exposure to CMS decreased sucrose intake in our rats. The largest effect was obtained after 2 weeks of the stress protocol. CMS rats spent more time in REM sleep and showed more fragmented sleep compared to their baseline recording, while there were no changes in the control rats. Increased sleep fragmentation in CMS rats was particularly evident by increased number of arousals, and increased REM sleep and slow-wave-sleep-1 (SWS-1) episodes. The duration of sleep stage episodes was decreased. The amount of slow-wave-sleep-2 (SWS-2) was not decreased, however SWS-2 in percent of total SWS was reduced. Correlation analysis showed that animals that had less consumption of sucrose spent more time in REM sleep and had increased number of REM sleep episodes. In this study, CMS appears to be a model of depression.

Workshop report: The effects of psychological variables on the progression of HIV-1 disease

The reciprocal interactions between the neuroendocrine, immune, and autonomic nervous systems are complicated, yet worthy of examination. A body of literature suggests that psychological factors such as stress, or psychiatric conditions such as major depression, may influence the immune system thereby altering host susceptibility to viral, or other types of infection. Alternately, in an attempt to limit infection and replication, the anti-viral host response, via innate and acquired immunity and subsequent release of pro-inflammatory cytokines and additional anti-viral mediators, may affect mood, cognition emotion, and possibly precipitate a psychiatric disorder. In order to address what is known regarding neuroendocrine-immune interactions in the context of HIV infection, the Center for Mental Health Research on AIDS convened a panel of scientists from diverse areas of expertise. Their primary charge was to examine whether stress-induced activation of the neuroendocrine system affects the immune system in a manner that negatively influences HIV disease progression, and whether HIV infection influences the central nervous system and behavior. The ensuing report summarizes their deliberations as they discussed the current body of information and identified outstanding critical questions in the areas of research. The group consensus was that the biological mediators of psychological status can play an important role in mediating HIV disease progression, particularly in subgroups of vulnerable patients; furthermore, they identified candidate biological mediators and mechanisms of disease progression. The Workgroup outlined the inherent challenges and limitations of such research and provided recommendations as to the future directions of research utilizing human, animal, and in vitro models of HIV-1 infection and stress.

Basal and dexamethasone suppressed salivary cortisol concentrations in a community sample of patients with posttraumatic stress disorder

BACKGROUND

Posttraumatic stress disorder (PTSD) has been associated with lower concentrations of cortisol and enhanced suppression of cortisol by dexamethasone, although discrepancies exist among reports. The objective of the study was to determine the pattern of cortisol responses in patients seeking treatment for PTSD resulting from a variety of traumatic experiences and to test whether cortisol responses are significantly related to childhood trauma, severity of symptoms, or length of time since trauma.

METHODS

Salivary cortisol was measured at 8 AM, 4 PM, and 10 PM on 2 consecutive days before and after a 10 PM dose of .5 mg dexamethasone in 17 psychotropic medication and substance-free subjects with PTSD and 17 matched control subjects.

RESULTS

Repeated-measures analysis of variance (ANOVA) of the baseline salivary cortisol concentrations demonstrated a significant effect for group with higher concentrations in the PTSD group but no significant differences in responses to dexamethasone. The presence of childhood abuse did not significantly affect salivary cortisol concentrations, and there was no correlation between predexamethasone cortisol and either the severity of PTSD symptoms or the time since the index trauma.

CONCLUSIONS

Neither low basal concentrations nor enhanced suppression of cortisol are consistent markers of a PTSD diagnosis.

Psychological stress and fibromyalgia: a review of the evidence suggesting a neuroendocrine link

The present review attempts to reconcile the dichotomy that exists in the literature in relation to fibromyalgia, in that it is considered either a somatic response to psychological stress or a distinct organically based syndrome. Specifically, the hypothesis explored is that the link between chronic stress and the subsequent development of fibromyalgia can be explained by one or more abnormalities in neuroendocrine function. There are several such abnormalities recognised that both occur as a result of chronic stress and are observed in fibromyalgia. Whether such abnormalities have an aetiologic role remains uncertain but should be testable by well-designed prospective studies.

Hypocortisolism and increased glucocorticoid sensitivity of pro-Inflammatory cytokine production in Bosnian war refugees with posttraumatic stress disorder

BACKGROUND

Posttraumatic stress disorder (PTSD) is associated with dysregulation of the hypothalamus pituitary adrenal (HPA) axis. Alterations include various responses to HPA axis stimulation, different basal hormone levels, and changes in glucocorticoid receptor (GR) numbers on lymphocytes. The functional significance of these latter changes remains elusive.

METHODS

Twelve Bosnian war refugees with PTSD and 13 control subjects were studied. On 2 consecutive days, they collected saliva samples after awakening and at 11, 15, and 20 hours. Glucocorticoid (GC) sensitivity was measured by dexamethasone (DEX) inhibition of lipopolysaccharide (LPS)-induced interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) production in whole blood.

RESULTS

The PTSD patients showed no cortisol response after awakening and had lower daytime cortisol levels (F = 14.57, p <.001). Less DEX was required for cytokine suppression in PTSD patients (IL-6: t = -2.82, p =.01; TNF-alpha: t = 5.03, p <.001), reflecting higher GC sensitivity of pro-inflammatory cytokine production. The LPS-stimulated production of IL-6, but not TNF-alpha, was markedly increased in patients (IL-6: F = 10.01, p <.004; TNF-alpha: F =.89, p =.34).

CONCLUSIONS

In refugees with PTSD, hypocortisolism is associated with increased GC sensitivity of immunologic tissues. Whether this pattern reflects an adaptive mechanism and whether this is sufficient to protect from detrimental effects of low cortisol remains to be investigated.

Rearing condition and rh5-HTTLPR interact to influence limbic-hypothalamic-pituitary-adrenal axis response to stress in infant macaques

BACKGROUND

In humans and macaques, a promoter polymorphism that decreases transcription of the serotonin transporter gene is associated with anxiety. Serotonin transporter gene disruption in rodents produces anxious animals with exaggerated limbic-hypothalamic-pituitary-adrenal (LHPA) responses to stress. We wanted to determine whether serotonin transporter gene promoter variation (rh-5HTTLPR) and rearing condition would interact to influence endocrine responses to stress in infant rhesus macaques.

METHODS

Animals were reared with their mothers (MR, n = 141) or in peer-only groups (PR, n = 67). At 6 months of age, adrenocorticotropic hormone (ACTH) and cortisol levels were determined at baseline and during separation stress. Serotonin transporter genotype (l/l and l/s) was determined with polymerase chain reaction followed by gel electrophoresis.

RESULTS

Cortisol levels increased during separation, and there was a main effect of rearing condition, with decreased cortisol levels among PR macaques. Animals with l/s rh5-HTTLPR genotypes had higher ACTH levels than did l/l animals. Adrenocorticotropic hormone levels increased during separation, and there was a separation x rearing x rh5-HTTLPR interaction, such that PR-l/s animals had higher ACTH levels during separation than did other animals studied.

CONCLUSIONS

These data demonstrate that serotonin transporter gene variation affects LHPA axis activity and that the influence of rh5-HTTLPR on hormonal responses during stress is modulated by early experience.

Combined DEX/CRH test among Japanese patients with major depression

There is compelling evidence for an important role of the hypothalamus-pituitary-adrenal (HPA) axis abnormalities in the pathophysiology of major depressive disorder. Growing evidence has suggested that the combined dexamethasone (DEX)/CRH test is much more sensitive than the conventional DEX suppression test in order to detect HPA axis abnormalities. However, little data is currently available on DEX/CRH results for Asian populations, which prompted us to examine the sensitivity of the DEX/CRH test among Japanese subjects with major depression. The DEX/CRH test was administered in 20 inpatients with major depressive episode and 30 healthy controls. Significantly increased cortisol responses were observed for the patients, compared to the controls. There was a substantial difference in the distribution of non-suppressor, intermediate suppressor, and suppressor, which were defined in terms of cortisol response, was observed between the patients and controls (10, 60, and 30% in the patients vs. 0, 27, and 73% in the controls, P<0.01). Responses of ACTH showed a trend in the same direction. Within the depressed patients, individuals with a history of attempted suicide, in particular, tended to have enhanced responses to the DEX/CRH test, compared to those without such a history. Our results confirmed that the DEX/CRH test is a sensitive test to detect HPA axis abnormalities among Japanese patients with major depression. In addition, a possible relationship between suicidal acts and enhanced HPA axis abnormalities was suggested.

Depressive symptoms and the risk of type 2 diabetes: the Atherosclerosis Risk in Communities study

OBJECTIVE

The goal of this study was to determine whether depressive symptoms predict type 2 diabetes.

RESEARCH DESIGN AND METHODS

We analyzed data on depressive symptoms (including recent fatigue, sleep disturbance, feelings of hopelessness, loss of libido, and increased irritability) in a longitudinal, biracial cohort study of 11,615 initially nondiabetic adults aged 48-67 years, who were subsequently followed for 6 years for the development of type 2 diabetes.

RESULTS

At baseline, depressive symptoms were positively associated with BMI, fasting insulin, systolic blood pressure, caloric intake, physical inactivity, and current smoking (all P < 0.05). In prospective analyses, after adjusting for age, race, sex, and education, individuals in the highest quartile of depressive symptoms had a 63% increased risk of developing diabetes compared with those in the lowest quartile (relative hazard [RH] 1.63, 95% CI 1.31-2.02). This relation persisted after adjustment for stress-associated lifestyle factors (smoking, physical activity, caloric intake, and adiposity) (1.28, 1.02-1.60) and metabolic covariates (fasting insulin and glucose, lipids, blood pressure, and adiposity) (1.38, 1.10-1.73).

CONCLUSIONS

In this cohort, depressive symptoms predicted incident type 2 diabetes. This relation is only partially explained by demographic, metabolic, and lifestyle factors. Possible neuroendocrine mediators of the stress-obesity-diabetes relationship require further evaluation in prospective cohort studies that use an established tool to assess depression and incorporate neurohormonal measurements.

Prepartum, postpartum, and chronic depression effects on newborns

In order to assess the effects of the onset and chronicity of maternal depression on neonatal physiology, eighty pregnant women were assessed for depression during mid-pregnancy (M gestational age = 25.9 weeks) and shortly after delivery. The women were classified as reporting depressive symptoms 1) only during the prepartum assessment; 2) only during the postpartum assessment; 3) during both the prepartum and postpartum assessments; or 4) reporting no depressive symptoms at either the prepartum or the postpartum assessment. Maternal mood and biochemistry were assessed during pregnancy, and the EEG and biochemical characteristics of their 1-week-old infants were assessed shortly after birth. As predicted, the newborns of the mothers with prepartum and postpartum depressive symptoms had elevated cortisol and norepinephrine levels, lower dopamine levels, and greater relative right frontal EEG asymmetry. The infants in the prepartum group also showed greater relative right frontal EEG asymmetry and higher norepinephrine levels. These data suggest that effects on newborn physiology depend more on prepartum than postpartum maternal depression but may also depend on the duration of the depressive symptoms.

Pituitary-adrenal responses to standard and low-dose dexamethasone suppression tests in adult survivors of child abuse

BACKGROUND

Previous studies indicate that adverse childhood events are associated with persistent changes in corticotropin-releasing factor neuronal systems. Our aim was to determine whether altered glucocorticoid feedback mediates the neuroendocrine sequelae of childhood trauma.

METHODS

Standard and low-dose dexamethasone suppression tests (DST) were performed in women with a history of child abuse (n=19), child abuse and major depression (n=16), major depression and no childhood trauma (n=10), and no history of mental illness or childhood trauma (n=19). Secondary analysis with posttraumatic stress disorder (PTSD) as the organizing diagnosis was also conducted.

RESULTS

In the low-dose DST, depressed women with a history of abuse exhibited greater cortisol suppression than any comparator group and greater corticotropin suppression than healthy volunteers or nondepressed abuse survivors. There were no differences between nondepressed abuse survivors and healthy volunteers in the low-dose DST or between any subject groups in the standard DST. The PTSD analysis produced similar results.

CONCLUSIONS

Cortisol supersuppression is evident in psychiatrically ill trauma survivors, but not in nondepressed abuse survivors, indicating that enhanced glucocorticoid feedback is not an invariable consequence of childhood trauma but is more related to the resultant psychiatric illness in traumatized individuals.

Urocortin expression in the Edinger-Westphal nucleus is down-regulated in transgenic mice over-expressing neuronal corticotropin-releasing factor

In recent years a large body of evidence has emerged linking chronic stress with increased vulnerability for depression and anxiety disorders. As corticotropin-releasing factor (CRF) is hypersecreted under these psychological conditions, we used our CRF-overexpressing (CRF-OE) mouse line to study underlying brain mechanisms possibly causing these disorders. Urocortin (Ucn), a recently discovered member of the CRF peptide family may play a role in the pathophysiology of stress-induced disorders. Stressors recruit Ucn-immunoreactive neurons in the Edinger-Westphal nucleus (E-WN), which is the major site of Ucn expression. Furthermore, E-WN Ucn mRNA levels are upregulated in CRF-deficient mice. Based on these findings, we hypothesized the down-regulation of E-WN Ucn in CRF-OE mice and consequently, altered responsiveness to stressful stimuli. Our results support this hypothesis as we found weaker immunohistochemical labeling with anti-Ucn and a six times weaker Ucn mRNA signal in E-WN in CRF-OE mice. Moreover, E-WN Ucn-expressing neurons mounted a response to acute challenge in CRF-OE mice too. From these results it is concluded that the CRF and E-WN Ucn neuronal systems work in concert in response to acute challenges, but are inversely regulated in their activities during chronic hyperactivity of the hypothalamo-pituitary-adrenal axis.

Growth hormone response to growth hormone-releasing hormone and clonidine in young monkeys: correlation with behavioral characteristics

Blunted growth hormone (GH) release in response to stimulation by a secretagogue has been widely reported in both children and adults with anxiety and depressive disorders. Blunted GH responsiveness appears to be a stable characteristic of an individual, suggesting that it may be useful as a biological marker that would allow early recognition of these disease processes. Another potential biological marker for anxiety disorders is the temperamental construct of behavioral inhibition. Children identified as being behaviorally inhibited early in life are more likely than less inhibited children to suffer from anxiety disorders later in life (Biederman et al. 1993; Hirshfeld et al. 1992). If blunted GH responsiveness to pharmacological challenge and behavioral inhibition are markers of anxiety and depressive disorders, then it would follow that they would coexist in a subset of individuals. However, such prospective studies in clinically normal young children are difficult to perform. Therefore, in this study, we examined GH responsiveness and temperament in a group of 38 young rhesus monkeys (ages 3-6 months). Monkeys received an intravenous dose of 10 microg/kg of growth hormone-releasing hormone (GHRH) and 5 microg/kg of clonidine, combined, to assess GH response to stimulation. Behavioral reactivity in a fearful situation was assessed using the Human Intruder Test developed by Kalin et al. (1991). This test measures response to a potentially threatening stimulus (a human stranger making direct eye contact). Results showed a population distribution of GH response to GHRH and clonidine ranging from 120 ng/mL/90 minutes to 3,000 ng/mL/90 minutes. There was no difference in GH response in males versus females or any significant effect of age on GH response. There was a significant correlation between GH responsiveness and the time spent reacting to the intruder in the Human Intruder Test. Monkeys with lower GH responsiveness reacted less to the intruder (p < 0.01). Additionally, when monkeys were classified based on their reactivity in the Human Intruder Test, behaviorally nonreactive monkeys had significantly lower GH responsiveness than behaviorally reactive monkeys (p < 0.005). These data provide evidence that there are inherent differences in GH responsiveness to stimulation in young rhesus monkeys and that low GH responsiveness is linked to low behavioral reactivity, which may be a form of behavioral inhibition. Further studies will be necessary to determine if the characteristics of low GH responsiveness and low behavioral reactivity predict an increased propensity to develop anxious or depressive behaviors over the course of the life span.

Signal transduction and genes-to-behaviors pathways in psychiatric diseases

Although psychiatric diseases are among the most common and destructive of all human illnesses, the molecular and cellular mechanisms underlying their complex origins remain to be elucidated. Dysfunction of critical intracellular signaling pathways is very likely to be involved. This conclusion is based on a number of observations, including the short- and long-term cellular effects of psychiatric drugs; the critical role signaling pathways play in neurotransmitter, neuropeptide, and neurohormone communication; and the fact that signaling pathways are principle regulators of the diverse array of behavioral symptoms experienced by patients. The genomics era has brought to psychiatry an abundance of genetic linkage and candidate gene findings. The difficult task--now under way--is to discern the functional relevance of these results. Recent evidence suggests the involvement of the ubiquitous protein phosphatase 2B (calcineurin), a critical regulator of many signal transduction pathways, as a schizophrenia susceptibility gene. It is likely that genetic findings in severe psychiatric disorders will continue to implicate direct and indirect modulation of critical intracellular signaling pathways.

Examining stress reactivity in neonates: relations between cortisol and behavior

The association between cortisol and behavioral reactivity to a medical heel stick and a neurobehavioral exam was examined in 100 healthy African American neonates, who have been underrepresented in this area of research. Using continuous measures, behavioral distress was associated with cortisol reactivity to both stressors. High levels of behavioral distress, however, were associated with cortisol reactivity only in response to the neurobehavioral exam. In contrast, low levels of behavioral distress were associated with cortisol reactivity only in response to the heel stick. The results highlight potentially important parameters for exploring the relation between biological and behavioral reactivity to stress such as the operationalization of behavioral distress and the context in which a stress response is elicited.

The corticotropin-releasing hormone binding protein is associated with major depression in a population from Northern Sweden

BACKGROUND

Recent research suggests that central corticotropin releasing hormone hyperdrive is an important neurobiological risk factor for developing major depression. The availability of free corticotropin releasing hormone in the central nervous system is tightly regulated by the expression of corticotropin releasing hormone binding protein. Therefore, the gene encoding for corticotropin releasing hormone binding protein is a functional candidate gene for major depression.

METHODS

We present a systematic study of single nucleotide polymorphisms in the corticotropin releasing hormone binding protein gene and their role in the liability for major depression. Seven single nucleotide polymorphisms were genotyped in a well-diagnosed sample of 89 patients with recurrent major depressions and matched controls.

RESULTS

Two single nucleotide polymorphisms within the corticotropin releasing hormone binding protein gene were significantly associated with the disease (p <.05). An expectation-maximization algorithm estimated a specific haplotype to have a frequency of 53% in patients and 35% in controls (p <.001).

CONCLUSIONS

The corticotropin releasing hormone binding protein gene is likely to be involved in the genetic vulnerability for major depression.

Glutamate and Depression

The past decade has seen a steady accumulation of evidence supporting a role for the excitatory amino acid (EAA) neurotransmitter, glutamate, and its receptors in depression and antidepressant activity. To date, evidence has emerged indicating that N-methyl-d-aspartate (NMDA) receptor antagonists, group I metabotropic glutamate receptor (mGluR1 and mGluR5) antagonists, as well as positive modulators of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors have antidepressant-like activity in a variety of preclinical models. Moreover, antidepressant-like activity can be produced not only by drugs modulating the glutamatergic synapse, but also by agents that affect subcellular signaling systems linked to EAA receptors (e.g., nitric oxide synthase). In view of the extensive colocalization of EAA and monoamine markers in nuclei such as the locus coeruleus and dorsal raphe, it is likely that an intimate relationship exists between regulation of monoaminergic and EAA neurotransmission and antidepressant effects. Further, there is also evidence implicating disturbances in glutamate metabolism, NMDA, and mGluR1,5 receptors in depression and suicidality. Finally, recent data indicate that a single intravenous dose of an NMDA receptor antagonist is sufficient to produce sustained relief from depressive symptoms. Taken together with the proposed role of neurotrophic factors in the neuroplastic responses to stressors and antidepressant treatments, these findings represent exciting and novel avenues to both understand depressive symptomatology and develop more effective antidepressants.

Influence of mirtazapine on urinary free cortisol excretion in depressed patients

Mirtazapine has been shown to acutely inhibit cortisol secretion in healthy subjects. In the present study, the impact of mirtazapine treatment on urinary free cortisol (UFC) excretion was investigated in depression. Twenty patients (six men, 14 women) suffering from major depression according to DSM-IV criteria were treated with mirtazapine for 3 weeks. The patients received 15 mg mirtazapine on day 0; 30 mg mirtazapine on day 1; and 45 mg mirtazapine per day from day 2 to the end of the study (day 21). UFC excretion was measured before treatment (day 1), at the beginning (day 0), after 1 week (day 7) and after 3 weeks (day 21) of treatment with mirtazapine. Urine samples were collected from 08:00 to 08:00 h the following day. On the days of urine sampling, the severity of depressive symptoms was assessed using the 21-item version of the Hamilton Rating Scale for Depression (21-HAMD). There was a significant reduction of UFC excretion during 3-week mirtazapine therapy, which was already obvious after the first day of treatment (day 0). However, there were no significant across-subjects correlations between UFC reduction and decrease in 21-HAMD sum scores. Apparently, the mirtazapine-induced rapid reduction of cortisol secretion in depressed patients is not necessarily correlated with a favorable therapeutic response.

Endocrine withdrawal syndromes

Hypersecretion of endogenous hormones or chronic administration of high doses of the same hormones induces varying degrees of tolerance and dependence. Elimination of hormone hypersecretion or discontinuation of hormone therapy may result in a mixed picture of two syndromes: a typical hormone deficiency syndrome and a generic withdrawal syndrome. Thus, hormones with completely different physiological effects may produce similar withdrawal syndromes, with symptoms and signs reminiscent of those observed with drugs of abuse, suggesting shared mechanisms. This review postulates a unified endocrine withdrawal syndrome, with changes in the hypothalamic-pituitary-adrenal axis and the central opioid peptide, in which noradrenergic and dopaminergic systems of the brain act as common links in its pathogenesis. Long-term adaptations to hormones may involve relatively persistent changes in molecular switches, including common intracellular signaling systems, from membrane receptors to transcription factors. The goals of therapy are to ease withdrawal symptoms and to expedite weaning of the patient from the hormonal excess state. Clinicians should resort to the fundamentals of tapering hormones down over time, even in the case of abrupt removal of a hormone-producing tumor. In addition, the prevention of stress and concurrent administration of antidepressants may ameliorate symptoms and signs of an endocrine withdrawal syndrome.

Depression and cardiovascular disease: mechanisms of interaction

This article explores the relationship between depression and cardiovascular disease from a mechanistic standpoint. Depression and cardiovascular disease are two of the most prevalent health problems in the United States and are the two leading causes of disability both in the United States and worldwide. Although depression is a known risk factor for the development of cardiovascular disease, as well as an independent predictor of poor prognosis following a cardiac event, the mechanistic relationship between the two remains unclear. Depression is associated with changes in an individual's health status that may influence the development and course of cardiovascular disease, including noncompliance with medical recommendations, as well as the presence of cardiovascular risk factors such as smoking and hypertension. In addition, depression is associated with physiologic changes, including nervous system activation, cardiac rhythm disturbances, systemic and localized inflammation, and hypercoagulability, that negatively influence the cardiovascular system. Further, stress may be an underlying trigger that leads to the development of both depression and cardiovascular disease. This article reviews seven potential mechanisms for the relationship between depression and cardiovascular disease and presents the available evidence surrounding each mechanism. Finally, future directions for research are discussed.

H3 receptor blockade by thioperamide enhances cognition in rats without inducing locomotor sensitization

RATIONALE

Attention deficit hyperactivity disorder (ADHD) is currently treated with psychomotor stimulants, including methylphenidate and amphetamine. Several adverse effects are associated with these drugs, however, such as agitation and abuse. H(3) receptor antagonists are under clinical investigation for ADHD.

OBJECTIVES

To investigate the potential of thioperamide, a prototypical H(3) receptor antagonist, to enhance learning and attention while inducing no effects on locomotor stimulation and sensitization, or alterations in ACTH levels.

METHODS

Thioperamide (1, 3, 10, 30 mg/kg) was administered prior to testing in a multi-trial, inhibitory avoidance response in rat pups (five trials separated by 1 min) to evaluate attention/cognition. Locomotor sensitization and cross-sensitization was assessed following administration of methylphenidate (3 mg/kg), cocaine (10 mg/kg), or thioperamide (1, 3, 10 mg/kg).

RESULTS

Thioperamide significantly enhanced performance of the five-trial inhibitory avoidance response with efficacy similar to that previously reported for methylphenidate. Administration of amphetamine, methylphenidate and cocaine produced significant locomotor sensitization, however. In contrast, thioperamide did not induce locomotor stimulation or sensitization, nor did it cross-sensitize to the stimulant effects of amphetamine or cocaine. The repeated administration of methylphenidate significantly elevated ACTH levels, while thioperamide did not affect this neuroendocrine endpoint.

CONCLUSIONS

H(3) receptor blockade may offer a safer alternative to psychomotor stimulants for the treatment of ADHD.

HPA axis and memory

The hormones of the hypothalamus-pituitary-adrenal (HPA) axis influence memory in situations of acute and chronic stress. The present review tries to summarize the current state of knowledge by describing the enhancing as well as the impairing effects of stress or glucocorticoid (GC) treatment documented in animals and humans. GCs secreted during the acquisition of a stressful task facilitate consolidation. However, acute stress (or GC treatment) unrelated to the task impairs performance. The effects of acute stress are additionally modulated by gender, age and the emotional valence of the learning material. Chronic stress in rodents has mostly impairing effects on memory and hippocampal integrity. However, other regions of the brain, such as the prefrontal cortex, are also sensitive to stress. In humans, similar observations have been reported in several patient populations as well as in older subjects. The potential to reverse these effects using behavioural or pharmacological approaches needs to be explored.

Effect of depression on stroke morbidity and mortality

OBJECTIVES

This narrative review examines the evidence and discusses the clinical relevance of depression as a risk factor for stroke morbidity and mortality. It also proposes recommendations for future research.

METHODS

We used the Medline computer database to search the relevant original studies published in English from January 1966 to December 2001. Our key words were as follows: depressive disorder, cerebrovascular disease, stroke, vascular risk factors, and mortality. Articles that investigated the relation between antecedent depression and subsequent stroke morbidity and mortality were collected and reviewed.

RESULTS

Since 1990, 8 prospective studies have been published. Among these 8 studies, 6 addressed depression and stroke morbidity, 1 investigated the association of depression with stroke morbidity and stroke mortality, and 1 investigated the association with stroke mortality only. Of 7 studies examining the independent effect of depression on stroke morbidity, 6 were positive. With regard to stroke mortality, 2 studies found an independent association between depression and specific stroke mortality. The contributions and methodological limitations of these studies are discussed.

CONCLUSIONS

Emerging data suggest an association between depressive symptoms and increased risk for stroke morbidity and mortality. More methodologically sound studies are needed to elucidate causal pathways that link depression and cerebrovascular disease. They are also needed to determine the effect of depression intervention on reducing the risk of cerebrovascular events. Information on author affiliations appears at the end of the article.

Depressive symptoms and the risk of type 2 diabetes mellitus in a US sample

OBJECTIVE

There is some evidence to suggest that individuals with depression are at an almost twofold increased risk of developing type 2 diabetes mellitus, but results are far from conclusive. Therefore, to determine if depressive symptoms increased the risk of type 2 diabetes, we conducted longitudinal analyses using data from the NHANES I Epidemiologic Follow-up Survey (NHEFS).

RESEARCH DESIGN AND METHODS

Participants included individuals who were white or African-American, did not report previous diagnosis of diabetes, and who completed the Centers for Epidemiologic Studies Depression (CES-D) questionnaire in the 1982-1984 study (n = 8870). Participants were followed up for incident-diagnosed diabetes through 1992 (mean follow-up 9.0 years).

RESULTS

There were 1444 (15.9%) participants with high depressive symptoms in the 1982-1984 study (CES-D score > or = 16). During follow-up, there were 465 incident cases of diabetes. Incidence of diabetes was 6.9/1000 person years among those with high depressive symptoms, 6.0/1000 person years among those with moderate symptoms, and 5.0/1000 person years among those with no symptoms. After adjusting for age, sex, and race, the relative hazard (RH) of diabetes among those with high depressive symptoms was 1.27 (95% CI: 0.93 to 1.73) compared to those without symptoms. Further adjustment for education and known diabetes risk factors (body mass index and physical activity) further attenuated the relationship (RH 1.11, 95% CI: 0.79 to 1.56).

CONCLUSIONS

There was no increased incidence of diabetes for those with high or moderate depressive symptoms compared to those with no depressive symptoms. These results do not support the etiologic relationship of depression predisposing individuals to diabetes.