Hypothalamo-pituitary-adrenal cortical responses to low-dose physostigmine and arginine vasopressin administration: sex differences between major depressives and matched control subjects

Drug Design Targeting the Muscarinic Receptors and the Implications in Central Nervous System Disorders

There is substantial evidence that cholinergic system function impairment plays a significant role in many central nervous system (CNS) disorders. During the past three decades, muscarinic receptors (mAChRs) have been implicated in various pathologies and have been prominent targets of drug-design efforts. However, due to the high sequence homology of the orthosteric binding site, many drug candidates resulted in limited clinical success. Although several advances in treating peripheral pathologies have been achieved, targeting CNS pathologies remains challenging for researchers. Nevertheless, significant progress has been made in recent years to develop functionally selective orthosteric and allosteric ligands targeting the mAChRs with limited side effect profiles. This review highlights past efforts and focuses on recent advances in drug design targeting these receptors for Alzheimer’s disease (AD), schizophrenia (SZ), and depression.

Associations among gonadal hormone, triglycerides and cognitive decline in female patients with major depressive disorders

BACKGROUND

Cognitive impairment has been identified as a core feature of depression. Serum triglycerides (TG), gonadal hormone and sex difference were shown to influence cognitive performance. The purpose of this study was to investigate the associations among serum TG, gonadal hormone, sex difference and cognitive performance in patients with major depressive disorders (MDD).

METHODS

The enrolled 183 patients (male/female = 80/103) meeting DSM-IV criteria for MDD were divided into high TG group (patients-HTG) and normal TG group (patients-NTG) according to TG level. Serum TG, estradiol (E2) and testosterone (T) levels were measured by the glycerokinase peroxidase-peroxidase and chemiluminescence methods. Cognition was assessed by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). The study was conducted between August 2016 and January 2020.

RESULTS

In female, patients-HTG had lower immediate memory, language, attention, delayed memory and RBANS total scores than patients-NTG after adjusting for covariates. There were significant differences in serum E2 and T levels between patients-HTG and patients-NTG in female after controlling for covariates. In female patients-HTG, serum E2 level was positively associated with immediate memory, delayed memory and RBANS total scores, and serum T level was positively related to immediate memory, language and RBANS total scores. These findings were not seen in male patients.

CONCLUSIONS

Our data suggested that patients-HTG exhibited poorer cognitive function compared with patients-NTG in female. Moreover, the decline in serum gonadal hormone level might contribute to the high TG development of female MDD, and was further implicated in their cognitive decline.

Pharmacological evidence of a cholinergic contribution to elevated impulsivity and risky decision-making caused by adding win-paired cues to a rat gambling task

BACKGROUND

Pairing rewards with sensory stimulation, in the form of auditory and visual cues, increases risky decision-making in both rats and humans. Understanding the neurobiological basis of this effect could help explain why electronic gambling machines are so addictive, and inform treatment development for compulsive gambling and gaming. Numerous studies implicate the dopamine system in mediating the motivational influence of reward-paired cues; recent data suggest the cholinergic system also plays a critical role. Previous work also indicates that cholinergic drugs alter decision-making under uncertainty.

AIMS

We investigated whether the addition of reward-concurrent cues to the rat gambling task (crGT) altered the effects of peripherally administered cholinergic compounds.

METHODS

Muscarinic and nicotinic agonists and antagonists were administered to 16 male, Long-Evans rats trained on the crGT. Measures of optimal/risky decision-making and motor impulsivity were the main dependent variables of interest.

RESULTS

The muscarinic receptor antagonist scopolamine improved decision-making overall, decreasing selection of one of the risky options while increasing choice of the more advantageous options. The muscarinic agonist oxotremorine increased choice latency but did not significantly affect option preference. Neither the nicotinic antagonist mecamylamine nor the agonist nicotine affected choice patterns, but mecamylamine decreased premature responding, an index of motor impulsivity.

CONCLUSIONS

These results contrast sharply from those obtained previously using the uncued rGT, and suggest that the deleterious effects of win-paired cues on decision-making and impulse control may result from elevated cholinergic tone.

Role of insulin-like growth factor 1, sex and corticosteroid hormones in male major depressive disorder

BACKGROUND

Hormones of the hypothalamic-pituitary-gonadal (HPG), hypothalamic-pituitary-adrenal (HPA), and hypothalamic-pituitary-somatotropic (HPS) axes are potentially involved in major depressive disorder (MDD), but these hormones have not been simultaneously investigated in male patients with MDD. We investigated the association between male MDD symptoms and estradiol, testosterone, cortisol, dehydroepiandrosterone sulfate (DHEAS), and insulin-like growth factor 1 (IGF1).

METHODS

Serum estradiol, testosterone, cortisol, DHEAS, and IGF1 levels were measured in 54 male patients with MDD and 37 male controls and were compared with clinical factors. We investigated the associations between hormone levels and Hamilton Depression Rating Scale (HAM-D) scores. The correlations among hormones were also investigated.

RESULTS

Patients had significantly lower estradiol levels than controls (22.4 ± 8.4 pg/mL vs. 26.1 ± 8.5 pg/mL, P = 0.040). Serum estradiol levels were negatively correlated with HAM-D scores (P = 0.000094) and positively correlated with Global Assessment of Functioning scores (P = 0.000299). IGF1 levels and the cortisol:DHEAS ratio were higher in patients than in controls (IGF1: 171.5 ± 61.8 ng/mL vs. 144.1 ± 39.2 ng/mL, P = 0.011; cortisol:DHEAS ratio: 0.07 ± 0.05 vs. 0.04 ± 0.02, P = 0.001). DHEAS levels were lower in patients than in controls (227.9 ± 108.4 μg/dL vs. 307.4 ± 131.2 μg/dL, P = 0.002). IGF1, cortisol:DHEAS ratio, and DHEAS were not significantly correlated with HAM-D scores. Cortisol and testosterone levels were not significantly different between patients and controls. Serum estradiol levels were positively correlated with DHEAS levels (P = 0.00062) in patients, but were not significantly correlated with DHEAS levels in controls.

CONCLUSION

Estradiol may affect the pathogenesis and severity of patients with MDD in men, and other hormones, such as those in the HPA and HPS axes, may also be involved in male MDD. Additionally, a correlation between estradiol and DHEAS may affect the pathology of MDD in men.

The antidepressant efficacy of the muscarinic antagonist scopolamine: Past findings and future directions

Scopolamine is a nonselective muscarinic antagonist that has shown relatively rapid antidepressant effects, although to date the results are from limited clinical studies. Scopolamine reportedly has downstream signaling effects thought to be linked to neuroplasticity within glutamatergic synapses and consequent antidepressant action. In psychiatry, clinically validated pathways are unusual and thus merit further research in an effort develop more effect medicines for patients with mood disorders. Thus, we are faced with a unique opportunity to build on the clinical observation associated with scopolamine through reverse translation to identify of targets that retain the clinical efficacy while reducing the side effect profile. This chapter reviews the clinical antidepressant findings with scopolamine, including discussion of differential response across patient subgroups, as well as a review of biomarkers that predict clinical outcome. The preclinical data associated with scopolamine also are reviewed and convey a vision for narrowing in on the therapeutic muscarinic receptor subtype(s) that support the antidepressant effects to guide the development of next generation antimuscarinic drug targets for depression.

Hormones of the hypothalamic-pituitary-gonadal (HPG) axis in male depressive disorders - A systematic review and meta-analysis

Sexual dysfunctions are common in men with depression. As the hypothalamic-pituitary-gonadal (HPG) axis is a crucial regulator of sexual function, and also affects mood and cognition, the following question arises: Is the HPG axis altered in depressed men when compared to healthy controls? To answer this question, PubMed and PsycINFO were searched. Inclusion criteria for the systematic review and meta-analysis were: (1) case-control study including male patients with a depressive disorder and (2) assessment of follicle-stimulating hormone (FSH), luteinising hormone (LH), oestradiol, or testosterone. Seventeen studies were identified. Follicle-stimulating hormone and LH did not differ between patients and controls. By contrast, in patients, oestradiol was marginally increased (g = 0.52, 95% CI [-0.01, 1.04]; Z = 1.92, p = .055) and testosterone was significantly decreased (g = -0.45, 95% CI [-0.80, -0.10]; Z = -2.53, p = .012). Depressed men may be characterised by diminished testosterone and potentially elevated oestradiol, which beyond contributing to sexual dysfunction, could impact mood and cognition.

Cholinergic regulation of mood: from basic and clinical studies to emerging therapeutics

Mood disorders are highly prevalent and are the leading cause of disability worldwide. The neurobiological mechanisms underlying depression remain poorly understood, although theories regarding dysfunction within various neurotransmitter systems have been postulated. Over 50 years ago, clinical studies suggested that increases in central acetylcholine could lead to depressed mood. Evidence has continued to accumulate suggesting that the cholinergic system has a important role in mood regulation. In particular, the finding that the antimuscarinic agent, scopolamine, exerts fast-onset and sustained antidepressant effects in depressed humans has led to a renewal of interest in the cholinergic system as an important player in the neurochemistry of major depression and bipolar disorder. Here, we synthesize current knowledge regarding the modulation of mood by the central cholinergic system, drawing upon studies from human postmortem brain, neuroimaging, and drug challenge investigations, as well as animal model studies. First, we describe an illustrative series of early discoveries which suggest a role for acetylcholine in the pathophysiology of mood disorders. Then, we discuss more recent studies conducted in humans and/or animals which have identified roles for both acetylcholinergic muscarinic and nicotinic receptors in different mood states, and as targets for novel therapies.

MECHANISMS IN ENDOCRINOLOGY: Anorexia nervosa and endocrinology: a clinical update

Anorexia nervosa is a syndrome, that is collections of symptoms, which is not defined by its etiology. The severe cases are intractable. The syndrome is associated with multiple, profound endocrine alterations which may be adaptive, reactive or etiologic. Adaptive changes potentially may be inappropriate in clinical settings such as inpatient intensive re-nutrition or in a setting with somatic comorbidity. Electrolyte levels must be closely monitored during the refeeding process, and the need for weight gain must be balanced against potentially fatal refeeding complications. An important focus of clinical research should be to identify biomarkers associated with different stages of weight loss and re-nutrition combined with psychometric data. Besides well-established peripheral endocrine actions, several hormones also are released directly to different brain areas, where they may exert behavioral and psychogenic actions that could offer therapeutic targets. We need reliable biomarkers for predicting outcome and to ensure safe re-nutrition, however, first of all we need them to explore the metabolism in anorexia nervosa to open new avenues with therapeutic targets. A breakthrough in our understanding and treatment of this whimsical disease remains. Considering this, the aim of the present review is to provide an updated overview of the many endocrine changes in a clinical perspective.

Neurophysiological Changes Associated with Antidepressant Response to Ketamine Not Observed in a Negative Trial of Scopolamine in Major Depressive Disorder

Background

This randomized, placebo-controlled, crossover trial examined the antidepressant efficacy of the muscarinic antagonist scopolamine in major depressive disorder subjects with more severe and refractory forms of major depressive disorder relative to previous reports.

Methods

Participants included 23 medication-free major depressive disorder subjects (12 F/11 M, 20-55 years) currently experiencing a major depressive episode. Subjects had scored ≥20 on the Montgomery-Asberg Depression Rating Scale. Following a single-blind, placebo lead-in, participants were randomized to receive 2 counterbalanced blocks of 3 i.v. infusions of scopolamine (4 μg/kg) and placebo in a double-blind manner. The primary and secondary outcomes were the Montgomery-Asberg Depression Rating Scale and the Hamilton Anxiety Rating Scale, respectively. Magnetoencephalography and plasma brain-derived neurotrophic factor concentrations were obtained prior to and after each treatment phase.

Results

As assessed by both the Montgomery-Asberg Depression Rating Scale and Hamilton Anxiety Rating Scale, scopolamine had no significant antidepressant or anxiolytic effects relative to placebo. No significant drug vs placebo effects were seen in magnetoencephalography gamma power or brain-derived neurotrophic factor plasma concentrations, and brain-derived neurotrophic factor changes did not correlate with change in Montgomery-Asberg Depression Rating Scale score in response to scopolamine.

Conclusions

These results do not support the efficacy of scopolamine for more severe or refractory forms of depression. No pre- to post-infusion changes in plasma brain-derived neurotrophic factor were detected, and magnetoencephalography gamma power changed only in the placebo lead-in, suggesting that these biomarker measures were not affected by scopolamine in this cohort. While difficult to interpret given the lack of antidepressant response, the findings suggest that the neurobiological effects of ketamine and scopolamine are at least partly distinct.

The endocrine manifestations of anorexia nervosa: mechanisms and management

Anorexia nervosa is a psychiatric disorder characterized by altered body image, persistent food restriction and low body weight, and is associated with global endocrine dysregulation in both adolescent girls and women. Dysfunction of the hypothalamic-pituitary axis includes hypogonadotropic hypogonadism with relative oestrogen and androgen deficiency, growth hormone resistance, hypercortisolaemia, non-thyroidal illness syndrome, hyponatraemia and hypooxytocinaemia. Serum levels of leptin, an anorexigenic adipokine, are suppressed and levels of ghrelin, an orexigenic gut peptide, are elevated in women with anorexia nervosa; however, levels of peptide YY, an anorexigenic gut peptide, are paradoxically elevated. Although most, but not all, of these endocrine disturbances are adaptive to the low energy state of chronic starvation and reverse with treatment of the eating disorder, many contribute to impaired skeletal integrity, as well as neuropsychiatric comorbidities, in individuals with anorexia nervosa. Although 5-15% of patients with anorexia nervosa are men, only limited data exist regarding the endocrine impact of the disease in adolescent boys and men. Further research is needed to understand the endocrine determinants of bone loss and neuropsychiatric comorbidities in anorexia nervosa in both women and men, as well as to formulate optimal treatment strategies.

The Role of Muscarinic Receptors in the Pathophysiology of Mood Disorders: A Potential Novel Treatment?

The central cholinergic system has been implicated in the pathophysiology of mood disorders. An imbalance in central cholinergic neurotransmitter activity has been proposed to contribute to the manic and depressive episodes typical of these disorders. Neuropharmacological studies into the effects of cholinergic agonists and antagonists on mood state have provided considerable support for this hypothesis. Furthermore, recent clinical studies have shown that the pan-CHRM antagonist, scopolamine, produces rapid-acting antidepressant effects in individuals with either major depressive disorder (MDD) or bipolar disorder (BPD), such as bipolar depression, contrasting the delayed therapeutic response of conventional mood stabilisers and antidepressants. This review presents recent data from neuroimaging, post-mortem and genetic studies supporting the involvement of muscarinic cholinergic receptors (CHRMs), particularly CHRM2, in the pathophysiology of MDD and BPD. Thus, novel drugs that selectively target CHRMs with negligible effects in the peripheral nervous system might produce more rapid and robust clinical improvement in patients with BPD and MDD.

Peripheral oxytocin and vasopressin: Biomarkers of psychiatric disorders? A comprehensive systematic review and preliminary meta-analysis

A large array of studies have investigated peripheral oxytocin (OT) and vasopressin (ADH) as potential biomarkers of psychiatric disorders, with highly conflicting and heterogenous findings. We searched Web of KnowledgeSM and Scopus® for English original articles investigating OT and/or ADH levels in different biological fluids (plasma/serum, saliva, urine and cerebrospinal fluid) across several psychiatric disorders. Sixty-four studies were included. We conducted 19 preliminary meta-analyses addressing OT alterations in plasma/serum, saliva, urine and cerebrospinal fluid of 7 psychiatric disorders and ADH alterations in plasma/serum, saliva, urine and cerebrospinal fluid of 6 psychiatric disorders compared to controls. Hedge's g was used as effect size measure, together with heterogeneity analyses, test of publication biases and quality control. None of them (except serum OT in anorexia nervosa) revealed significant differences. There is no convincing evidence that peripheral ADH or OT might be reliable biomarkers in psychiatric disorders. However, the lack of significant results was associated with high methodological heterogeneity, low quality of the studies, small sample size, and scarce reliability of the methods used in previous studies, which need to be validated and standardized.

Elevated Hippocampal Cholinergic Neurostimulating Peptide precursor protein (HCNP-pp) mRNA in the amygdala in major depression

The amygdala is innervated by the cholinergic system and is involved in major depressive disorder (MDD). Evidence suggests a hyper-activate cholinergic system in MDD. Hippocampal Cholinergic Neurostimulating Peptide (HCNP) regulates acetylcholine synthesis. The aim of the present work was to investigate expression levels of HCNP-precursor protein (HCNP-pp) mRNA and other cholinergic-related genes in the postmortem amygdala of MDD patients and matched controls (females: N = 16 pairs; males: N = 12 pairs), and in the mouse unpredictable chronic mild stress (UCMS) model that induced elevated anxiety-/depressive-like behaviors (females: N = 6 pairs; males: N = 6 pairs). Results indicate an up-regulation of HCNP-pp mRNA in the amygdala of women with MDD (p < 0.0001), but not males, and of UCMS-exposed mice (males and females; p = 0.037). HCNP-pp protein levels were investigated in the human female cohort, but no difference was found. There were no differences in gene expression of acetylcholinesterase (AChE), muscarinic (mAChRs) or nicotinic receptors (nAChRs) between MDD subjects and controls or UCMS and control mice, except for an up-regulation of AChE in UCMS-exposed mice (males and females; p = 0.044). Exploratory analyses revealed a baseline expression difference of cholinergic signaling-related genes between women and men (p < 0.0001). In conclusion, elevated amygdala HCNP-pp expression may contribute to mechanisms of MDD in women, potentially independently from regulating the cholinergic system. The differential expression of genes between women and men could also contribute to the increased vulnerability of females to develop MDD.

Antidepressant effects of the muscarinic cholinergic receptor antagonist scopolamine: a review

The muscarinic cholinergic receptor system has been implicated in the pathophysiology of depression, with physiological evidence indicating this system is overactive or hyperresponsive in depression and with genetic evidence showing that variation in genes coding for receptors within this system are associated with higher risk for depression. In studies aimed at assessing whether a reduction in muscarinic cholinergic receptor function would improve depressive symptoms, the muscarinic receptor antagonist scopolamine manifested antidepressant effects that were robust and rapid relative to conventional pharmacotherapies. Here, we review the data from a series of randomized, double-blind, placebo-controlled studies involving subjects with unipolar or bipolar depression treated with parenteral doses of scopolamine. The onset and duration of the antidepressant response are considered in light of scopolamine's pharmacokinetic properties and an emerging literature that characterizes scopolamine's effects on neurobiological systems beyond the cholinergic system that appear relevant to the neurobiology of mood disorders. Scopolamine infused at 4.0 μg/kg intravenously produced robust antidepressant effects versus placebo, which were evident within 3 days after the initial infusion. Placebo-adjusted remission rates were 56% and 45% for the initial and subsequent replication studies, respectively. While effective in male and female subjects, the change in depression ratings was greater in female subjects. Clinical improvement persisted more than 2 weeks following the final infusion. The timing and persistence of the antidepressant response to scopolamine suggest a mechanism beyond that of direct muscarinic cholinergic antagonism. These temporal relationships suggest that scopolamine-induced changes in gene expression and synaptic plasticity may confer the therapeutic mechanism.

The prominent role of stimulus processing: cholinergic function and dysfunction in cognition

PURPOSE OF REVIEW

The present review develops a framework from which to understand the role of the cholinergic system in healthy cognition and in cognitive dysfunction. Traditionally, the cholinergic system has been thought to have direct influence on cognitive processes such as working memory and attention. Although the influence of cholinergic function on stimulus processing has been long appreciated, the notion that cholinergic effects on stimulus processing is the mechanism by which acetylcholine influences cognitive processes has only more recently been considered.

RECENT FINDINGS

Literature supporting the hypothesis that cholinergic modulation influences cognitive functions through stimulus processing mechanisms has been growing for over a decade. Recent conceptualizations of the developing literature have argued for a new interpretation to an old and developing literature.

SUMMARY

The argument that cholinergic function modulates cognitive processes by direct effects on basic stimulus processing extends to cognitive dysfunction in neuropathological conditions including dementia and mood disorders. Memory and attention deficits observed in these and other conditions can be understood by evaluating the impact of cholinergic dysfunction on stimulus processing, rather than on the cognitive function in general.

Uncoupling protein 2 knockout exacerbates depression-like behaviors in mice via enhancing inflammatory response

Mitochondrial uncoupling protein 2 (UCP2) has been recognized as an important protein to regulate reactive oxygen species (ROS) production. The absence of UCP2 has the potential to promote ROS accumulation and thereby induces oxidative damages and inflammatory response. Increasing evidence strongly reveals that depression is accompanied by oxidative stress, so the present study was to investigate the impacts of UCP2 on the etiology of depression. Wild-type and UCP2 knockout mice were used to establish chronic mild stress (CMS)-induced anhedonia model of depression. The results showed that CMS led to more severe depressive responses in UCP2 knockout mice, characterized by exacerbated depression-like behaviors, increased corticosterone level and significant loss of weight. Moreover, CMS resulted in a higher mortality in UCP2 knockout mice. Our further study showed that UCP2 knockout enhanced CMS-induced activation of nuclear factor κB (NF-κB) p65 and increased mRNA expression of tumor necrosis factor alpha (TNF-α) in hypothalamus. And the levels of TNF-α of serum and spleen in UCP2 knockout mice are remarkably enhanced by CMS, even under basal conditions. Therefore, our findings suggest that UCP2 knockout-induced inflammation may contribute to the development of depressive symptoms.

Scopolamine produces larger antidepressant and antianxiety effects in women than in men

Some antidepressant agents generate differential benefit based on gender. Blocking cholinergic muscarinic receptors using scopolamine produces robust and rapid antidepressant effects in males and females combined. This study evaluated if males and females differ in the antidepressant response magnitude following scopolamine administration. A total of 52 male and female outpatients meeting criteria for recurrent major depressive or bipolar disorder participated in a double-blind, randomized, placebo-controlled, crossover clinical trial involving seven i.v. infusions of placebo or scopolamine (4 μg/kg). Following a single-blind placebo lead-in, participants entered either a placebo-block/scopolamine-block or a scopolamine-block/placebo-block sequence. Each block included three sessions. Clinical ratings were acquired before each infusion and included the Montgomery-Asberg Depression Rating Scale (MADRS) and the Hamilton Anxiety Rating Scale (HAM-A). A treatment group × block interaction (F=21.0, p<0.001) was observed in MADRS scores across gender, and the reduction was significant by the evaluation following the first scopolamine administration (F=8.4, p=0.006). The treatment group × block interaction was also significant in males (F=3.8, p=0.043) and females (F=35.6, p<0.001) separately. A block × gender interaction (F=7.4, p=0.009) indicated that the response magnitude was larger in women. The treatment × block interaction was significant for the HAM-A across gender (F=12.0, p<0.001), and was significant for females (F=24.9, p<0.001) but not for males (F=1.3, p=0.30). When comparing the baseline block to study end, the block × gender interaction (F=12.6, p=0.001) showed that the antianxiety response was greater in women. Men and women show a rapid antidepressant response following scopolamine, but the magnitude of response is larger in women than in men.

Brain structural and functional abnormalities in mood disorders: implications for neurocircuitry models of depression

The neural networks that putatively modulate aspects of normal emotional behavior have been implicated in the pathophysiology of mood disorders by converging evidence from neuroimaging, neuropathological and lesion analysis studies. These networks involve the medial prefrontal cortex (MPFC) and closely related areas in the medial and caudolateral orbital cortex (medial prefrontal network), amygdala, hippocampus, and ventromedial parts of the basal ganglia, where alterations in grey matter volume and neurophysiological activity are found in cases with recurrent depressive episodes. Such findings hold major implications for models of the neurocircuits that underlie depression. In particular evidence from lesion analysis studies suggests that the MPFC and related limbic and striato-pallido-thalamic structures organize emotional expression. The MPFC is part of a larger "default system" of cortical areas that include the dorsal PFC, mid- and posterior cingulate cortex, anterior temporal cortex, and entorhinal and parahippocampal cortex, which has been implicated in self-referential functions. Dysfunction within and between structures in this circuit may induce disturbances in emotional behavior and other cognitive aspects of depressive syndromes in humans. Further, because the MPFC and related limbic structures provide forebrain modulation over visceral control structures in the hypothalamus and brainstem, their dysfunction can account for the disturbances in autonomic regulation and neuroendocrine responses that are associated with mood disorders. This paper discusses these systems together with the neurochemical systems that impinge on them and form the basis for most pharmacological therapies.

Brain structural and functional abnormalities in mood disorders: implications for neurocircuitry models of depression

The neural networks that putatively modulate aspects of normal emotional behavior have been implicated in the pathophysiology of mood disorders by converging evidence from neuroimaging, neuropathological and lesion analysis studies. These networks involve the medial prefrontal cortex (MPFC) and closely related areas in the medial and caudolateral orbital cortex (medial prefrontal network), amygdala, hippocampus, and ventromedial parts of the basal ganglia, where alterations in grey matter volume and neurophysiological activity are found in cases with recurrent depressive episodes. Such findings hold major implications for models of the neurocircuits that underlie depression. In particular evidence from lesion analysis studies suggests that the MPFC and related limbic and striato-pallido-thalamic structures organize emotional expression. The MPFC is part of a larger "default system" of cortical areas that include the dorsal PFC, mid- and posterior cingulate cortex, anterior temporal cortex, and entorhinal and parahippocampal cortex, which has been implicated in self-referential functions. Dysfunction within and between structures in this circuit may induce disturbances in emotional behavior and other cognitive aspects of depressive syndromes in humans. Further, because the MPFC and related limbic structures provide forebrain modulation over visceral control structures in the hypothalamus and brainstem, their dysfunction can account for the disturbances in autonomic regulation and neuroendocrine responses that are associated with mood disorders. This paper discusses these systems together with the neurochemical systems that impinge on them and form the basis for most pharmacological therapies.

TC-5214 (S-(+)-mecamylamine): a neuronal nicotinic receptor modulator with antidepressant activity

Both clinical and preclinical data support a potential therapeutic benefit of modulating the activity of CNS neuronal nicotinic receptors (NNRs) to treat depression and anxiety disorders. Based on the notion that the depressive states involve hypercholinergic tone, we have examined the potential palliative role of NNR antagonism in these disorders, using TC-5214 (S-(+) enantiomer of mecamylamine), a noncompetitive NNR antagonist. TC-5214 demonstrated positive effects in a number of animal models of depression and anxiety. TC-5214 was active in the forced swim test in rats (minimum effective dose (MED)=3 mg/kg i.p.), a classical depression model. It was also active in the behavioral despair test in mice (0.1-3.0 mg/kg i.p.), another model of depression. In the social interaction paradigm in rats, a model of generalized anxiety disorder (GAD), TC-5214 was active at a dose of 0.05 mg/kg s.c. In the light/dark chamber paradigm in rats, a model of GAD and phobia, TC-5214 was also active at a dose of 0.05 mg/kg s.c. Although TC-5214 shows modest selectivity among NNR subtypes, the antidepressant and anxiolytic effects seen in these studies are likely attributable to antagonist effects at the alpha4beta2 NNRs. This is supported by the observation of similar effects with alpha4beta2-selective partial agonists such as cytisine and with alpha4beta2-selective antagonists such as TC-2216. TC-5214 was well tolerated in acute and chronic toxicity studies in mice, rats, and dogs, showed no mutagenicity and displayed safety pharmacology, pharmacokinetic and metabolic profiles appropriate for therapeutic development. Overall, the results support a novel nicotinic cholinergic antagonist mechanism for antidepressant and anxiolytic effects and highlight the potential of NNR antagonists such as TC-5214 as therapeutics for the treatment of anxiety and depression.

Drugs and HPA axis

This paper outlines the interferences of the most widely used drugs with hypothalamo-pituitary-adrenal function and the related laboratory parameters, with the purpose of providing practical help to clinicians during testing for hypo- or hypercortisolemic states.

Sex differences in the ACTH response to 24H metyrapone in depression

Increased hypothalamic-pituitary-adrenal (HPA) axis activation has been observed in major depression. Increased corticotropin-releasing hormone (CRH) is hypothesized to drive corticotropin (ACTH) secretion leading to increased ACTH and cortisol secretion throughout 24H. Contradicting data exist as to whether the increased drive is present throughout the day or is restricted to the late afternoon and evening. To determine if increased HPA axis activation occurs during a specific circadian phase or is found throughout the 24H, we studied 26 healthy drug-free depressed patients and 26 healthy age- and sex-matched control subjects under metyrapone inhibition of cortisol synthesis for 24H beginning at 4 PM. Blood was drawn every 10 min for 24H and assayed for ACTH and cortisol. Gender differences in response to metyrapone were seen in both patients and controls. Depressed women demonstrated increased ACTH concentrations between 4 PM and 10 PM compared to control women. Maximal ACTH response over time was identical between depressed and control women. Depressed men demonstrated significantly decreased ACTH secretion between 4 and 10 PM as well as decreased maximal ACTH response compared to control men or depressed women. These data support an increased evening CRH drive in depressed women, but overall decreased CRH drive in depressed men.

Antidepressant efficacy of the antimuscarinic drug scopolamine: a randomized, placebo-controlled clinical trial

CONTEXT

The need for improved therapeutic agents that more quickly and effectively treat depression is critical. In a pilot study we evaluated the role of the cholinergic system in cognitive symptoms of depression and unexpectedly observed rapid reductions in depression severity following the administration of the antimuscarinic drug scopolamine hydrobromide (4 microg/kg intravenously) compared with placebo (P = .002). Subsequently a clinical trial was designed to assess more specifically the antidepressant efficacy of scopolamine.

OBJECTIVE

To evaluate scopolamine as a potential antidepressant agent.

DESIGN

Two studies were conducted: a double-blind, placebo-controlled, dose-finding study followed by a double-blind, placebo-controlled, crossover clinical trial.

SETTING

The National Institute of Mental Health. Patients Currently depressed outpatients aged 18 to 50 years meeting DSM-IV criteria for recurrent major depressive disorder or bipolar disorder. Of 39 eligible patients, 19 were randomized and 18 completed the trial.

INTERVENTIONS

Multiple sessions including intravenous infusions of placebo or scopolamine hydrobromide (4 microg/kg). Individuals were randomized to a placebo/scopolamine or scopolamine/placebo sequence (series of 3 placebo sessions and series of 3 scopolamine sessions). Sessions occurred 3 to 5 days apart.

MAIN OUTCOME MEASURES

Psychiatric evaluations using the Montgomery-Asberg Depression Rating Scale and the Hamilton Anxiety Rating Scale were performed to assess antidepressant and antianxiety responses to scopolamine.

RESULTS

The placebo/scopolamine group showed no significant change during placebo infusion vs baseline; reductions in depression and anxiety rating scale scores (P<.001 for both) were observed after the administration of scopolamine compared with placebo. The scopolamine/placebo group also showed reductions in depression and anxiety rating scale scores (P<.001 for both) after the administration of scopolamine, relative to baseline, and these effects persisted as they received placebo. In both groups, improvement was significant at the first evaluation after scopolamine administration (P< or =.002).

CONCLUSION

Rapid, robust antidepressant responses to the antimuscarinic scopolamine occurred in currently depressed patients who predominantly had poor prognoses.

Enhanced cortisol suppression to dexamethasone associated with Gulf War deployment

OBJECTIVE

To examine whether PTSD or post-deployment health symptoms in veterans of the first Gulf War (Operation Desert Shield/Storm) are associated with enhanced suppression of the pituitary-adrenal axis to low-dose dexamethasone (DEX).

METHOD

Plasma cortisol and lymphocyte glucocorticoid receptor (GR) number were measured at 08:00 h on two consecutive days, before and after administration of 0.5mg of DEX at 23:00 h in 42 male Gulf War veterans (14 without psychiatric illness, 16 with PTSD only, and 12 with both PTSD and MDD) and 12 healthy male veterans not deployed to the Gulf War or another war zone.

RESULTS

In the absence of group differences in basal cortisol levels or GR number, Gulf War veterans without psychiatric illness and Gulf War veterans with PTSD only had significantly greater cortisol suppression to DEX than non-deployed veterans and Gulf War veterans with both PTSD and MDD. Gulf War deployment was associated with significantly greater cortisol suppression to DEX controlling for weight, smoking status, PTSD, and MDD; PTSD was not associated with response to DEX. Among Gulf War veterans musculoskeletal symptoms were significantly associated with cortisol suppression and those who reported taking anti-nerve gas pills (i.e., pyridostigmine bromide) during the war had significantly greater DEX-induced cortisol suppression than those who did not.

CONCLUSIONS

The data demonstrate that alterations in neuroendocrine function are associated with deployment to the Gulf War and post-deployment musculoskeletal symptoms, but not PTSD. Additional studies are needed to examine the relationship of enhanced glucocorticoid responsivity to deployment exposures and chronic unexplained medical symptoms in Gulf War veterans.

Adrenal cortical responses to low- and high-dose ACTH(1-24) administration in major depressives vs. matched controls

Increased hypothalamo-pituitary-adrenocortical (HPA) axis activity occurs in 30-50% of patients with major depression. This includes normal-to-increased adrenal cortical hormone (cortisol) secretion in spite of reduced corticotropin (ACTH) stimulation. A possible explanation is increased adrenal responsiveness to ACTH. Supporting this possibility is the finding of increased adrenal volume, which reverts to normal with successful treatment. Eight female and six male patients with major depression, and eight female and six male individually matched controls, underwent two test sessions 5-7 days apart. On the first day, a low ACTH(1-24) dose (0.014 microg/kg i.v.), equivalent to 1 microg in a 70-kg individual, was given. On the second day, a supramaximal stimulating dose (250 microg i.v.) was given. Serial blood samples were analyzed for immunoreactive (IR-)ACTH, ACTH(1-39), and cortisol. There were no significant sex or patient-control differences in IR-ACTH areas under the curve (AUCs) following low-dose ACTH(1-24), and the correlation between patient and matched control AUCs was +0.71, indicating good correspondence in the amount of circulating ACTH(1-24) available for adrenal stimulation. There were no significant sex or patient-control differences in cortisol response and no significant interaction between dose and subject group, indicating that patients did not differ from controls in their cortisol responses to either low- or high-dose ACTH(1-24). These findings do not indicate increased adrenal cortical responsiveness in patients with major depression. Neurochemical/neurohormonal and neural stimulatory factors other than ACTH might be responsible for the increased adrenal gland size and cortisol secretion, in spite of reduced pituitary ACTH secretion, that has been reported in this illness.

Growth Hormone Responses to Low-Dose Physostigmine in Elderly vs. Young Women and Men

BACKGROUND

Growth hormone (GH) secretion is a sensitive measure of CNS cholinergic neurotransmission, and GH decreases considerably with age. Cholinesterase inhibitors, which increase acetylcholine concentrations, have been used in elderly subjects to investigate the neuroendocrine effects of aging and Alzheimer's disease. However, there have been only a few studies of a potential sex difference in GH responses to cholinesterase inhibitors in elderly subjects, with mixed results.

OBJECTIVE

We therefore administered low-dose physostigmine (PHYSO), a cholinesterase inhibitor, to normal, non-hormone-replaced, elderly women and men, to ascertain a potential sex difference in GH response. We hypothesized: (1) elderly women and men would have similar hormone responses, because of relatively low circulating estrogen in the women, and (2) the elderly women would have significantly lower baseline GH and GH responses to cholinergic challenge than the young women we studied previously.

METHODS

Normal elderly women and men > or =65 years of age meeting stringent inclusion and exclusion criteria were studied on three test days, 4-7 days apart, by serial blood sampling for several hours for baseline GH, followed by administration of low-dose PHYSO (first and third days) or saline (second day) at 18:00 h. Frequent blood sampling was continued for several hours. Plasma GH and hypothalamo-pituitary-adrenal cortical hormones were measured in each sample.

RESULTS

PHYSO administration produced no side effects in about half the elderly subjects and mild side effects in the other half, with no significant female-male differences and no significant relationship between the presence or absence of side effects and GH response. PHYSO significantly increased GH compared to saline, to a similar degree in the elderly women and men. The elderly women had a significantly greater GH response to PHYSO than did the young women, whereas GH responses were similar in the elderly and young men.

CONCLUSIONS

These results indicate similar GH responses to low-dose PHYSO in elderly women compared to elderly men, and a significantly greater GH response in elderly women compared to young women. A likely mechanism is increased sensitivity of central cholinergic systems that inhibit somatostatin and/or enhance GHRH release from the hypothalamus.

Pituitary-adrenal responses to cholinergic stimulation and acute mild stress are differentially elevated in male and female M(2) muscarinic receptor knockout mice

Adrenocorticotrophic hormone (ACTH) and corticosterone responses to cholinergic stimulation are greater in male rats and mice than in females. To explore the role of M(2) muscarinic receptors in this sex difference, we administered the nonselective muscarinic agonist, oxotremorine, the acetylcholinesterase inhibitor, physostigmine, and saline (a mild stressor) to male and female M(2) receptor knockout (KO) and wild-type (WT) mice of the same genetic background. Because M(2) receptors function primarily as presynaptic autoreceptors, we hypothesized that their absence in M(2) KO mice would increase the sensitivity of hormone responses to cholinergic stimulation in these groups. Both male and female M(2) KO mice were significantly more responsive to the stress of saline injection than were their WT counterparts. Oxotremorine and physostigmine increased ACTH and corticosterone in all four groups, but to a significantly greater degree in KO males compared to WT males, KO females, and WT females. The increase in ACTH also was significantly greater in WT males compared to WT females. By contrast, the increase in corticosterone was significantly more in females compared to males, independent of genotype. Following pretreatment with the nonselective muscarinic antagonist, scopolamine, ACTH and corticosterone responses to oxotremorine and to saline in the M(2) KO mice were comparable with those of their WT counterparts. These findings suggest that the M(2) muscarinic receptor subtype influences male and female pituitary-adrenal responses following stimulation by both mild stress and cholinergic drugs. The M(2) receptor appears to regulate ACTH responses to cholinergic stimulation in males but not in females; however, other muscarinic receptors may be involved because corticosterone responses were higher in females compared to males. Because ACTH and corticosterone responses were greater in male and female M(2) KO mice, the M(2) receptor appears to dampen the stress response.

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.

Effect of prenatal stress and gonadal hormone condition on depressive behaviors of female and male rats

Whether prenatal stress (PNS) and gonadal hormones may influence depressive behavior of rats in the forced swim test was investigated. In Experiment I, adult diestrous female rats had increased immobility, which is indicative of depression, but did not show any significant difference in the duration of struggling compared to intact adult males. In Experiment 2, the behavior of adult intact, castrated, or castrated dihydrotestosterone (DHT)- or estrogen (E2)-replaced offspring of dams that were restrained under lights for 45 min on gestational day 18 (PNS) or were not subjected to gestational stress (non-PNS, control condition) were compared. There were no effects of PNS, but DHT and E2 produced anti-depressant effects on behavior of male rats. Castration decreased struggling and increased immobility compared to intact rats. DHT or E2 replacement was able to partially reinstate struggling and immobility behavior but not to levels of intact males. In Experiment 3, behavior of PNS or control rats that were in proestrus or were ovariectomized and DHT, E2, or vehicle-replaced were compared. Ovariectomy decreased struggling and increased immobility compared to that of proestrous rats. E2 or DHT to control females increased anti-depressant struggling behavior compared to ovariectomized control or PNS rats administered vehicle, which demonstrated greater duration of struggling than did E2-primed, PNS rats. E2 or DHT administration decreased immobility of PNS and control females. These findings suggest that E2 and DHT have some anti-depressant effects but that modest PNS may alter E2's ability to alleviate some depressive behavior in female, but not male rats.

A neurodevelopmental model for anorexia nervosa

This paper integrates genetic and biological data on aetiological risk for anorexia nervosa (AN) with cognitive and psychosocial explanatory models. We have reviewed clinical and basic science data from each of these domains and then used a developmental perspective to formulate a multifactorial threshold model. By positioning interpersonal stress as a central component of this model, psychological, social and biological conceptualisations of AN can be used to generate a data driven, neurodevelopmental hypothesis for the aetiology of this complex disorder.

Plasma leptin suppression by arginine vasopressin in normal women and men

Leptin inhibits appetite by activating several neuroendocrine systems, including the hypothalamo-pituitary-adrenal cortical (HPA) axis. In turn, elevated glucocorticoids can increase circulating leptin. We therefore measured plasma leptin in 12 normal women and eight normal men administered low-dose physostigmine (PHYSO) and arginine vasopressin (AVP) to stimulate the HPA axis. The subjects underwent four test sessions 5-7 days apart: PHYSO (8 microg/kg IV), AVP (0.08 U/kg IM), PHYSO + AVP, and saline control. Serial blood samples were taken before and after pharmacologic challenge and analyzed for leptin, adrenocorticotropin (ACTH)1-39, cortisol, and AVP. Estradiol and testosterone also were measured at each test session. PHYSO and AVP produced no side effects in about half the subjects and predominantly mild side effects in the other half, with no significant female-male differences. Correlations between side effects (absent or present) after PHYSO or AVP and the corresponding leptin responses were nonsignificant. Baseline plasma leptin concentrations were significantly higher in the women than in the men (p < 0.003). Leptin concentrations following PHYSO remained unchanged from baseline, indicating that the short-lived ACTH and cortisol increases produced by PHYSO did not affect leptin secretion. In contrast, AVP administration, while also increasing ACTH and cortisol, suppressed leptin, to a significantly greater degree in the women than in the men (p = 0.01). This significant suppression of leptin by AVP has not been previously described; physiologically, it may be part of a negative feedback regulatory system between central leptin and its activation of the HPA axis, by inhibition of leptin production or acceleration of its clearance.

Sexual diergism of baseline plasma leptin and leptin suppression by arginine vasopressin in major depressives and matched controls

Leptin inhibits appetite by activating several neuroendocrine systems, including the hypothalamo-pituitary-adrenal cortical (HPA) axis. In turn, chronically elevated glucocorticoids increase circulating leptin. HPA axis hyperactivity occurs in 30-50% of patients with major depression, but the few prior reports of leptin measurements in this illness have shown inconsistent results. We, therefore, measured plasma leptin in 12 female and 8 male unipolar major depressives and 12 female and 8 male individually matched normal controls administered low-dose physostigmine (PHYSO) and arginine vasopressin (AVP) to stimulate the HPA axis. The subjects underwent four test sessions 5-7 days apart: PHYSO (8 microg/kg IV); AVP (0-08 U/kg IM); PHYSO+AVP; and saline control. Serial blood samples were taken before and after pharmacologic challenge and analyzed for leptin, ACTH(1-39), cortisol and AVP. Estradiol and testosterone also were measured at each test session. PHYSO and AVP produced no side effects in approximately half the subjects and predominantly mild side effects in the other half, with no significant patient-control differences. Correlations between side effects (absent or present) after PHYSO or AVP and the corresponding leptin responses were non-significant in all groups. Baseline plasma leptin concentrations (mean+/-S.D.) were significantly higher in the female patients compared to the female controls (22.5+/-13.9 ng/ml vs. 12.3+/-9.7 ng/ml), whereas they were similar in the male patients and the male controls (3.9+/-1.4 ng/ml vs. 3.6+/-2.0 ng/ml). Leptin concentrations following PHYSO remained unchanged from baseline, indicating that the short-lived ACTH and cortisol increases produced by PHYSO did not affect leptin secretion. In contrast, AVP administration, while also increasing ACTH and cortisol, significantly suppressed leptin, more so in the women than in the men. Baseline leptin and the leptin decrease after AVP were moderately positively correlated with the Hamilton Depression Scale 'somatization' factor in the female patients (r=0.50) and more strongly correlated with the 'mood-depression' factor in the male patients (r=0.81). These findings indicate a sexual diergism (functional sex difference) in plasma leptin measures between major depressives and matched normal controls.

Vasopressin as a target for antidepressant development: an assessment of the available evidence

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis is one of the key biological abnormalities described in major depressive disorder, occurring in 30-50% of depressed subjects. Corticotropin-releasing hormone (CRH) and vasopressin (AVP) are the main regulators of this stress system, with the two neuropeptides acting synergistically in bringing about adrenocorticotropin (ACTH) release from the anterior pituitary and cortisol from the adrenal gland. Based on the demonstration of elevated cerebrospinal fluid levels of CRH in depressives, and other evidence, it has been postulated that excess CRH and the resultant increased HPA forward drive form the basis of neuroendocrine dysregulation in depression. However, there is an accumulating body of evidence to support a significant role for AVP in the regulation of pituitary-adrenal activity in health and also in depressive disorder. This review, based on a Medline search from 1980 to 2001, focuses on the functional neuroanatomy, receptor pharmacology, VP synergism with CRH, and the data from clinical and pre-clinical studies that support an important role for AVP in the pathophysiology of major depression. We suggest that future antidepressants may target the vasopressinergic system.

Genome survey for susceptibility loci for recurrent, early-onset major depression: results at 10cM resolution

Recurrent (two or more episodes), early-onset (first episode at < or = 25 years) major depressive disorder (RE-MDD) is a strongly familial condition (lambda(first-degree relatives) = 8) whose malignant effects have a significant negative impact on the health and longevity of patients and their family members. The goal of this study was to identify candidate susceptibility loci that influence the development of RE-MDD. We completed a systematic survey of the human genome, conducted at an average resolution of 10 cM, for the identification of simple sequence tandem repeat polymorphisms (SSTRPs) that target susceptibility genes for RE-MDD by virtue of linkage disequilibrium. The efficiency of our association study was enhanced by genotyping pools of DNA from 100 adults with RE-MDD and 100 adult controls who had no personal or family history of mental disorders. Both groups included equal numbers of Caucasian men and women and were matched as closely as possible for age and ethnicity. Allelic associations with RE-MDD were observed for 19 of the 387 SSTRPs in the CHLC Human Screening Set/Weber Version 9. Sixteen of the 19 candidate susceptibility loci revealed significant allelic associations with RE-MDD in men (n = 7) or women (n = 9), but not in both sexes. Evidence for both risk and protective alleles was detected. Two of the candidate susceptibility loci reside within several Mb of loci previously reported-megabases to be linked to "comorbid alcoholism and depression" in families of individuals with alcoholism and to a broadly defined affected phenotype that included recurrent major depression in the families of patients with bipolar disorder. Although it has been suggested that the genes that influence risk for MDD in the two sexes may not be entirely the same, the results of our study suggest that sex specificity of susceptibility loci for RE-MDD may be the rule rather than the exception. The observed preponderance of sex-specific susceptibility loci for RE-MDD suggests that there may be important differences in the molecular pathophysiology of RE-MDD in men and women. Alternatively, our findings may reflect the existence of sex-specific differences in the molecular mechanisms that determine resilience to endogenous or environmental depressogenic stimuli.

Alterations induced by gestational stress in brain morphology and behaviour of the offspring

Retrospective studies in humans suggest that chronic maternal stress during pregnancy, associated with raised plasma levels of CRH, ACTH and cortisol may increase the likelihood of preterm birth, developmental delays and behavioural abnormalities in the children. In adulthood, it may contribute to the significant association between the incidence of schizophrenia, increased left or mixed handedness, reduction in cerebral asymmetry and anomalies in brain morphology. Our studies and others have shown that prenatal stress in rats can mimic these developmental and behavioural alterations. These rats show a reduced propensity for social interaction, increased anxiety in intimidating or novel situations and a reduction in cerebral asymmetry and dopamine turnover, consistent with those in schizophrenic humans. Prenatally-stressed (PS) rats also show behaviour consistent with depression, including a phase-shift in their circadian rhythm for corticosterone, sleep abnormalities, a hedonic deficit and greater acquisition of learned helplessness under appropriate conditions. These behavioural abnormalities are associated with impaired regulation of the hypothalamic-pituitary-adrenal axis response to stress and increased CRH activity. PS males may show demasculinisation and feminisation of their sexual behaviour. The developmental and behavioural abnormalities in PS offspring could occur through sensitisation of the foetal brain by maternal stress hormones to the action of glucocorticoid and CRH and to neurotransmitters affected by them. This may have long-lasting consequences and could explain the precipitation of depressive symptoms or schizophrenia by psychosocial stress in later life. The character of the behavioural abnormalities probably depends on the timing of the maternal stress in relation to development of the particular neuronal systems.

Sleep EEG, depression and gender

Despite clear evidence of an intimate connection between sleep, major depressive disorders (MDD) and gender, few studies have explored gender differences in either sleep or in wakefulness in patients as a means of better understanding the psychogenic components of MDD. Indeed, few sleep studies focus on characterising gender differences in any population. This paper will present a review of the literature on gender differences in sleep and depression. The theoretical and clinical implications of the findings will also be discussed. The premise of the present review is that there is an inherent increased vulnerability to depression in women that arises out of basic gender differences in brain organisation and state regulation, particularly in response to a "biological challenge" during sleep. It is argued that the inherent properties of organisation and regulation of sleep EEG in healthy men and women, elicited under challenge conditions, show gender-specific vulnerability to organisational abnormalities that model homeostatic abnormalities in depressed men and women and contribute to the genesis of depression. 2001 Harcourt Publishers Ltd

Donepezil and related cholinesterase inhibitors as mood and behavioral controlling agents

Acetylcholinesterase inhibitors (ChEIs) enhance neuronal transmission by increasing the availability of acetylcholine in muscarinic and nicotinic receptors. This effect is believed to be responsible for the beneficial and protective effects of ChEIs on cognition in patients with Alzheimer's disease (AD). Effects of ChEIs on mood and behavior have also been reported. Earlier observations were limited by the exclusive availability of intravenous forms of administration, the short half-life of the formulations, and the high frequency of peripheral side effects. The introduction, in recent years, of better tolerated and less invasive compounds has rekindled the interest in cholinergic central nervous system mechanisms and has given rise to studies in areas other than cognition. The ChEI donepezil has been involved in the largest number of studies and positive reports. Preliminary observations suggest the possible value of ChEIs in the management of behavioral dysregulation, apathy, irritability, psychosis, depression, mania, tics, and delirium and in the diagnosis of depression, panic, and personality disorders.