Effect of chronic treatment with ladostigil (TV-3326) on anxiogenic and depressive-like behaviour and on activity of the hypothalamic-pituitary-adrenal axis in male and female prenatally stressed rats

Key Enzymes of the Serotonergic System - Tryptophan Hydroxylase 2 and Monoamine Oxidase A - In the Brain of Rats Selectively Bred for a Reaction toward Humans: Effects of Benzopentathiepin TC-2153

At the Institute of Cytology and Genetics (Novosibirsk, Russia) for over 85 generations, gray rats have been selected for high aggression toward humans (aggressive rats) or its complete absence (tame rats). Aggressive rats are an interesting model for studying fear-induced aggression. Benzopentathiepin TC-2153 exerts an antiaggressive effect on aggressive rats and affects the serotonergic system: an important regulator of aggression. The aim of this study was to investigate effects of TC-2153 on key serotonergic-system enzymes - tryptophan hydroxylase 2 (TPH2) and monoamine oxidase A (MAOA) - in the brain of aggressive and tame rats. Either TC-2153 (10 or 20 mg/kg) or vehicle was administered once intraperitoneally to aggressive and tame male rats. TPH2 and MAOA enzymatic activities and mRNA and protein levels were assessed. The selection for high aggression resulted in upregulation of Tph2 mRNA in the midbrain, of the TPH2 protein in the hippocampus, and of proteins TPH2 and MAOA in the hypothalamus, as compared to tame rats. MAO enzymatic activity was higher in the midbrain and hippocampus of aggressive rats while TPH2 activity did not differ between the strains. The single TC-2153 administration decreased TPH2 and MAO activity in the hypothalamus and midbrain, respectively. The drug affected MAOA protein levels in the hypothalamus: upregulated them in aggressive rats and downregulated them in tame ones. Thus, this study shows profound differences in the expression and activity of key serotonergic system enzymes in the brain of rats selectively bred for either highly aggressive behavior toward humans or its absence, and the effects of benzopentathiepin TC-2153 on these enzymes may point to mechanisms of its antiaggressive action.

Sargassum horneri Extract Attenuates Depressive-like Behaviors in Mice Treated with Stress Hormone

Sargassum horneri, a brown seaweed, is known for its various health benefits; however, there are no reports on its effects on depression. This study aimed to investigate the antidepressant effects of S. horneri ethanol extract (SHE) in mice injected with corticosterone (CORT) and to elucidate the underlying molecular mechanisms. Behavioral tests were conducted, and corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and CORT levels were measured. A fluorometric monoamine oxidase (MAO) enzyme inhibition assay was performed. Neurotransmitters like serotonin, dopamine, and norepinephrine levels were determined. Moreover, the ERK-CREB-BDNF signaling pathway in the prefrontal cortex and hippocampus was evaluated. Behavioral tests revealed that SHE has antidepressant effects by reducing immobility time and increasing time spent in open arms. Serum CRH, ACTH, and CORT levels decreased in the mice treated with SHE, as did the glucocorticoid-receptor expression in their brain tissues. SHE inhibited MAO-A and MAO-B activities. In addition, SHE increased levels of neurotransmitters. Furthermore, SHE activated the ERK-CREB-BDNF pathway in the prefrontal cortex and hippocampus. These findings suggest that SHE has antidepressant effects in CORT-injected mice, via the regulation of the hypothalamic-pituitary-adrenal axis and monoaminergic pathway, and through activation of the ERK-CREB-BDNF signaling pathway. Thus, our study suggests that SHE may act as a natural antidepressant.

Sex Differences in Depression-Like Behaviors in Adult Mice Depend on Endophenotype and Strain

Depression affects women nearly twice as frequently as men. In contrast, rodent models of depression have shown inconsistent results regarding sex bias, often reporting more depression-like behaviors in males. This sex discrepancy in rodents modeling depression may rely on differences in the baseline activity of males and females in depression-related behavioral tests. We previously showed that the baseline despair and anhedonia behaviors, major endophenotypes of depression, are not sex biased in young adolescent wild-type mice of C57BL/6N, DBA/2, and FVB/N strains. Since the prevalence of depression in women peaks in their reproductive years, we here investigated sex differences of the baseline depression-like behaviors in adult mice using these three strains. Similar to the results in young mice, no difference was found between adult male and female mice in behavioral tests measuring despair in both tail suspension and forced swim tests, and anhedonia in the sucrose preference test. We then extended our study and tested apathy, another endophenotype of depression, using the splash test. Adult male and female mice showed significantly different results in the baseline apathy-like behaviors depending on the investigated strain. This study dissects the complex sex effects of different depression endophenotypes, stresses the importance of considering strain, and puts forward a hypothesis of the inconsistency of results between different laboratories investigating rodent models of depression.

Role of Monoamine Oxidase Activity in Alzheimer's Disease: An Insight into the Therapeutic Potential of Inhibitors

Despite not being utilized as considerably as other antidepressants in the therapy of depression, the monoamine oxidase inhibitors (MAOIs) proceed to hold a place in neurodegeneration and to have a somewhat broad spectrum in respect of the treatment of neurological and psychiatric conditions. Preclinical and clinical studies on MAOIs have been developing in recent times, especially on account of rousing discoveries manifesting that these drugs possess neuroprotective activities. The altered brain levels of monoamine neurotransmitters due to monoamine oxidase (MAO) are directly associated with various neuropsychiatric conditions like Alzheimer’s disease (AD). Activated MAO induces the amyloid-beta (Aβ) deposition via abnormal cleavage of the amyloid precursor protein (APP). Additionally, activated MAO contributes to the generation of neurofibrillary tangles and cognitive impairment due to neuronal loss. No matter the attention of researchers on the participation of MAOIs in neuroprotection has been on monoamine oxidase-B (MAO-B) inhibitors, there is a developing frame of proof indicating that monoamine oxidase-A (MAO-A) inhibitors may also play a role in neuroprotection. The therapeutic potential of MAOIs alongside the complete understanding of the enzyme’s physiology may lead to the future advancement of these drugs.

Serotonin-related rodent models of early-life exposure relevant for neurodevelopmental vulnerability to psychiatric disorders

Mental disorders including depression and anxiety are continuously rising their prevalence across the globe. Early-life experience of individuals emerges as a main risk factor contributing to the developmental vulnerability to psychiatric disorders. That is, perturbing environmental conditions during neurodevelopmental stages can have detrimental effects on adult mood and emotional responses. However, the possible maladaptive neural mechanisms contributing to such psychopathological phenomenon still remain poorly understood. In this review, we explore preclinical rodent models of developmental vulnerability to psychiatric disorders, focusing on the impact of early-life environmental perturbations on behavioral aspects relevant to stress-related and psychiatric disorders. We limit our analysis to well-established models in which alterations in the serotonin (5-HT) system appear to have a crucial role in the pathophysiological mechanisms. We analyze long-term behavioral outcomes produced by early-life exposures to stress and psychotropic drugs such as the selective 5-HT reuptake inhibitor (SSRI) antidepressants or the anticonvulsant valproic acid (VPA). We perform a comparative analysis, identifying differences and commonalities in the behavioral effects produced in these models. Furthermore, this review discusses recent advances on neurodevelopmental substrates engaged in these behavioral effects, emphasizing the possible existence of maladaptive mechanisms that could be shared by the different models.

Repurposing Cholinesterase Inhibitors as Antidepressants? Dose and Stress-Sensitivity May Be Critical to Opening Possibilities

When stress becomes chronic it can trigger lasting brain and behavioral changes including Major Depressive Disorder (MDD). There is conflicting evidence regarding whether acetylcholinesterase inhibitors (AChEIs) may have antidepressant properties. In a recent publication, we demonstrated a strong dose-dependency of the effect of AChEIs on antidepressant-related behavior in the mouse forced swim test: whereas the AChEI donepezil indeed promotes depression-like behavior at a high dose, it has antidepressant-like properties at lower doses in the same experiment. Our data therefore suggest a Janus-faced dose-response curve for donepezil in depression-related behavior. In this review, we investigate the mood-related properties of AChEIs in greater detail, focusing on both human and rodent studies. In fact, while there have been many studies showing pro-depressant activity by AChEIs and this is a major concept in the field, a variety of other studies in both humans and rodents show antidepressant effects. Our study was one of the first to systematically vary dose to include very low concentrations while measuring behavioral effects, potentially explaining the apparent disparate findings in the field. The possibility of antidepressant roles for AChEIs in rodents may provide hope for new depression treatments. Importantly, MDD is a psychosocial stress-linked disorder, and in rodents, stress is a major experimental manipulation for studying depression mechanisms, so an important future direction will be to determine the extent to which these depression-related effects are stress-sensitive. In sum, gaining a greater understanding of the potentially therapeutic mood-related effects of low dose AChEIs, both in rodent models and in human subjects, should be a prioritized topic in ongoing translational research.

Alterations in the autonomic nerve activities of prenatal autism model mice treated with valproic acid at different developmental stages

Autism spectrum disorder (ASD) is characterized by impairment of social communication, repetitive behavior and restrictive interest. The risk of ASD is strongly associated with the prenatal period; for instance, the administration of valproic acid (VPA) to pregnant mothers increases risk of ASD in the child. Patients with ASD often exhibit an alteration in the autonomic nervous system. In this study, we assessed the autonomic nervous activity at each prenatal developmental stage of model mice of ASD treated with VPA, to clarify the relationship between timing of exposure and ASD symptoms. The assessment of the autonomic nervous activity was performed based on the analysis of electrocardiography data collected from fetal and adult mice. Interestingly, VPA model mouse fetuses exhibited a significantly lower activity of the sympathetic nervous system. In contrast, sympathetic nervous activity at P0 was significantly higher. In adult VPA model mice, the parasympathetic activity of female VPA mice was suppressed. Moreover, female VPA mice showed reduced the parasympathetic activity after exposure to restraint stress. These results suggest that the autonomic nervous activity of VPA model mice was altered from the fetal stage, and that the assessment of autonomic nervous activities at an early developmental stage could be useful for the understanding of ASD.

A comprehensive review of monoamine oxidase inhibitors as Anti-Alzheimer's disease agents: A review

Monoamine oxidases (MAO-A and MAO-B) are mammalian flavoenzyme, which catalyze the oxidative deamination of several neurotransmitters like norepinephrine, dopamine, tyramine, serotonin, and some other amines. The oxidative deamination produces several harmful side products like ammonia, peroxides, and aldehydes during the biochemical reaction. The concentration of biochemical neurotransmitter alteration in the brain by MAO is directly related with several neurological disorders like Alzheimer's disease and Parkinson's disease (PD). Activated MAO also contributes to the amyloid beta (Aβ) aggregation by two successive cleft β-secretase and γ-secretase of amyloid precursor protein (APP). Additionally, activated MAO is also involved in aggregation of neurofibrillary tangles and cognitive destruction through the cholinergic neuronal damage and disorder of the cholinergic system. MAO inhibition has general anti-Alzheimer's disease effect as a consequence of oxidative stress reduction prompted by MAO enzymes. In this review, we outlined and addressed recent understanding on MAO enzymes such as their structure, physiological function, catalytic mechanism, and possible therapeutic goals in AD. In addition, it also highlights the current development and discovery of potential MAO inhibitors (MAOIs) from various chemical scaffolds.

Prenatal Maternal Distress: A Risk Factor for Child Anxiety?

The deleterious association between various types of prenatal maternal psychological distress (PNMS, anxiety, depression, psychological distress, stress) and childhood anxiety symptomatology (internalizing behaviors, anxiety symptoms) has been established using both retrospective and prospective longitudinal studies across varied demographic cohorts and throughout development. Yet, the existing literature cannot claim maternal distress during pregnancy to be a specific risk factor for anxiety symptomatology, as studies utilizing such observational designs are unable to adequately account for confounding of potential genetic factors and the postnatal environment. In this review, we examine studies that attempt to minimize such confounding and thus disentangle the unique intrauterine exposure effect of varying types of PNMS on childhood anxiety symptomatology. Such methodologies include paternal versus maternal comparison studies, sibling comparisons, prenatal cross-fostering designs and timing of exposure studies (including disaster studies). Of the identified studies, findings indicate that prenatal maternal distress is likely to constitute a risk factor for anxiety symptomatology, although more studies are needed to replicate current findings in order to determine whether there are clear differences in effects across specific types of PNMS and for specific subpopulations. We review the methodological limitations and strengths of the literature prior to exploring avenues of future research and implications for theory and clinical practice.

Maternal temperature exposure impairs emotional and cognitive responses and triggers dysregulation of neurodevelopment genes in fish

Fish are sensitive to temperature, but the intergenerational consequences of maternal exposure to high temperature on offspring behavioural plasticity and underlying mechanisms are unknown. Here we show that a thermal maternal stress induces impaired emotional and cognitive responses in offspring rainbow trout (Oncorhynchus mykiss). Thermal stress in mothers triggered the inhibition of locomotor fear-related responses upon exposure to a novel environment and decreased spatial learning abilities in progeny. Impaired behavioural phenotypes were associated with the dysregulation of several genes known to play major roles in neurodevelopment, including auts2 (autism susceptibility candidate 2), a key gene for neurodevelopment, more specifically neuronal migration and neurite extension, and critical for the acquisition of neurocognitive function. In addition, our analysis revealed the dysregulation of another neurodevelopment gene (dpysl5) as well as genes associated with human cognitive disorders (arv1, plp2). We observed major differences in maternal mRNA abundance in the eggs following maternal exposure to high temperature indicating that some of the observed intergenerational effects are mediated by maternally-inherited mRNAs accumulated in the egg. Together, our observations shed new light on the intergenerational determinism of fish behaviour and associated underlying mechanisms. They also stress the importance of maternal history on fish behavioural plasticity.

Placental glucocorticoid receptor and 11β-hydroxysteroid dehydrogenase-2 recruitment indicates impact of prenatal adversity upon postnatal development in mice

Prenatal stress may increase concentrations of maternal glucocorticoids, which restrict fetal growth, with variable impact upon postnatal development. Among key regulators of stress hormone effects are the glucocorticoid receptor (GR) and 11β-hydroxysteroid dehydrogenase-2 (11βHSD2), the enzyme that inactivates glucocorticoid. This study utilized mice selectively bred for social dominance (Dom) or submissiveness (Sub), respectively exhibiting resilience or sensitivity to stress, to test whether stress-induced alterations in placental GR and 11βHSD2 protein expression may mediate divergent effects of prenatal adversity upon postnatal development. Pregnant Dom and Sub dams underwent prenatal restraint stress (PRS) for 45 min on gestational days (GD) 15-17. PRS induced a similar spike in serum corticosterone concentrations of dams from each strain on GD15 (p < .001, n = 8), and impaired fetal growth (p < .01, n = 5 litters), although Dom placentae were larger than Sub placentae (p < .01). Among placentae from Dom dams, PRS elevated protein contents of both GR (p < .05, n = 5 litters) and 11βHSD2 (p < .01) on GD19. In contrast, GR contents were reduced among placentae from PRS-exposed Sub mice (p < .01), without changes in 11βHSD2 content. Correspondingly, Dom PRS pup growth recovered by PND14, yet Sub PRS pups remained underweight into adolescence (p < .0001, n = 40 pups). Thus, prenatal stress more strongly increased placental GR and 11βHSD2 levels among Dom mice than in Subs. Increased GR may improve placental function and up-regulate 11βHSD2 expression, protecting fetuses from effects of prenatal stress upon postnatal development. Placental recruitment of GR and 11βHSD2 are potential markers of stress-induced developmental disorders, in accordance with maternal resilience or sensitivity to stress.

Impact of social separation during pregnancy on the manifestation of defensive behaviors related to generalized anxiety and panic throughout offspring development

The multiple insecurities, anatomical, physiological and psychological changes arising from the gestational period can generate an overload of stress in the mother and cause disturbances in the offspring, affecting it throughout its development. The existing analysis linking prenatal stress and offspring’s anxiety have divergent results, being limited as to gestational week, type of stressor and age of progeny’s assessment. Social separation has been described as a stressor that causes increase in anxiety. Thus, the present study evaluated the effects of social separation applied in one of the three gestational weeks of rat dams on the manifestation of the defensive behaviors related to generalized anxiety disorder and panic in the Elevated T Maze of the male progeny in three stages of development (1, 3 or 6 months of life). It was found, in the offspring of grouped (control) dams, increased behaviors associated with generalized anxiety disorder and a reduction of panic-like behaviors throughout development. For animals whose dams were socially separated during pregnancy, the most critical period of exposure was the 2^nd gestational week, which affected the acquisition of aversive memory, demonstrated by the impairment on learning of avoidances of the offspring in all ages evaluated. Stressor exposure in this week also increased the avoidances, related to generalized anxiety of progeny in the 1^st month and decreased escapes, related to panic in the 3^rd month of life and, at the age of 6 months old, an inverse situation, with the reduction of the defensive behaviors associated to generalized anxiety disorder. The results show that, when assessing effects of prenatal stress on the manifestation of anxiety, not only the period of exposure is important, but also the age of offspring assessed.

Perinatal inflammation and adult psychopathology: From preclinical models to humans

Perinatal environment plays a crucial role in brain development and determines its function through life. Epidemiological studies and clinical reports link perinatal exposure to infection and/or immune activation to various psychiatric disorders. In addition, accumulating evidence from animal models shows that perinatal inflammation can affect various behaviors relevant to psychiatric disorders such as schizophrenia, autism, anxiety and depression. Remarkably, the effects on behavior and brain function do not always depend on the type of inflammatory stimulus or the perinatal age targeted, so diverse inflammatory events can have similar consequences on the brain. Moreover, other perinatal environmental factors that affect behavior (e.g. diet and stress) also elicit inflammatory responses. Understanding the interplay between perinatal environment and inflammation on brain development is required to identify the mechanisms through which perinatal inflammation affect brain function in the adult animal. Evidence for the role of the peripheral immune system and glia on perinatal programming of behavior is discussed in this review, along with recent evidence for the role of epigenetic mechanisms affecting gene expression in the brain.

M30 Antagonizes Indoleamine 2,3-Dioxygenase Activation and Neurodegeneration Induced by Corticosterone in the Hippocampus

Monoamine oxidases (MAO), downstream targets of glucocorticoid, maintain the turnover and homeostasis of monoamine neurotransmitters; yet, its pathophysiological role in monoamine deficiency, oxidative stress and neuroinflammation remains controversial. Protective effects of M30, a brain selective MAO inhibitor with iron-chelating antioxidant properties, have been shown in models of neurodegenerative diseases. This study aims to examine the neuroprotective mechanism of M30 against depressive-like behavior induced by corticosterone (CORT). Sprague-Dawley rats were given CORT subcutaneous injections with or without concomitant M30 administration for two weeks. CORT-treated rats exhibited depressive-like behavior with significant elevated levels of MAO activities, serotonin turnover, oxidative stress, neuroinflammation and apoptosis in the hippocampus with significant losses of synaptic proteins when compared to the control. The expression and activity of cytokine-responsive indoleamine 2,3-dioxygenase (IDO-1), a catabolic enzyme of serotonin and tryptophan, was significantly increased in the CORT-treated group with lowered levels of serotonin. Besides, CORT markedly reduced dendritic length and spine density. Remarkably, M30 administration neutralized the aberrant changes in the hippocampus and prevented the induction of depressive-like behavior induced by CORT. Our results suggest that M30 is neuroprotective against CORT-induced depression targeting elevated MAO activities that cause oxidative stress and neuroinflammation, resulting in IDO-1 activation, serotonin deficiency and neurodegeneration.

Transgenerational transmission of pregestational and prenatal experience: maternal adversity, enrichment, and underlying epigenetic and environmental mechanisms

Transgenerational transmission refers to positive and negative adaptations in brain function and behavior that affect following generations. In this paper, empirical findings regarding the transgenerational transmission of maternal adversity during three critical periods - childhood, pregestational adulthood and pregnancy - will be reviewed in terms of pregnancy outcomes, maternal care, offspring behavior and development, and physiological functioning. Research on the transgenerational transmission of enrichment and the implications for interventions to ameliorate the consequences of adversity will also be presented. In the final section, underlying epigenetic and environmental mechanisms that have been proposed to explain how experience is transferred across generations through transgenerational transmission will be reviewed. Directions for future research are suggested throughout.

Prenatal stress programs neuroendocrine stress responses and affective behaviors in second generation rats in a sex-dependent manner

An adverse environment in early life is often associated with dysregulation of the hypothalamo-pituitary-adrenal (HPA) axis and higher rates of mood disorders in adulthood. In rats, exposure to social stress during pregnancy results in hyperactive HPA axis responses to stress in the adult offspring and heightened anxiety behavior in the males, but not the females. Here we tested whether, without further intervention, the effects of prenatal stress (PNS) in the first filial generation (F1) are transmitted to the F2 generation via the maternal line. F1 control and PNS female rats were mated with control males and housed under non-stress conditions throughout pregnancy. HPA axis responses to acute stress, anxiety- and depressive-like behavior were assessed in the adult F2 offspring. ACTH and corticosterone responses to an acute stressor were markedly enhanced in F2 PNS females compared with controls. This was associated with greater corticotropin releasing hormone (Crh) mRNA expression in the paraventricular nucleus and reduced hippocampal glucocorticoid (Gr) and mineralocorticoid receptor (Mr) mRNA expression. Conversely, in the F2 PNS males, HPA axis responses to acute stress were attenuated and hippocampal Gr mRNA expression was greater compared with controls. F2 PNS males exhibited heightened anxiety-like behavior (light-dark box and elevated plus maze) compared with F2 control males. Anxiety-like behavior did not differ between F2 control and PNS females during metestrus/diestrus, however at proestrus/estrus, F2 control females displayed a reduction in anxiety-like behavior, but this effect was not observed in the F2 PNS females. Heightened anxiety in the F2 PNS males was associated with greater Crh mRNA expression in the central nucleus of the amygdala compared with controls. Moreover, Crh receptor-1 (Crhr1) mRNA expression was significantly increased, whereas Crhr2 mRNA was significantly decreased in discrete regions of the amygdala in F2 PNS males compared with controls, with no differences in the F2 females. No differences in depressive-like behavior (sucrose preference or forced swim test) were observed in either sex. In conclusion, the effects of maternal stress during pregnancy on HPA axis regulation and anxiety-like behavior can be transmitted to future generations in a sex-dependent manner. These data have implications for human neuropsychiatric disorders with developmental origins.

Changes induced by prenatal stress in behavior and brain morphology: can they be prevented or reversed?

This chapter presents a critical analysis of the behavioral alterations reported in the offspring of women exposed to stress and/or depression during pregnancy and the neurochemical and structural changes underlying them. Among the alterations attributed to prenatal stress in humans and experimental rats of both sexes is impaired regulation of the hypothalamic-pituitary-adrenal (HPA) axis, anxiety and exaggerated fear of novelty, and decreased social interaction. Learning and attention deficits are more prevalent in boys and male rats. Fear of novelty and anxiety are associated with enlargement of the amygdala and its corticotropin-releasing factor content, and decreased socialization, with lower oxytocin activity in the amygdala. Learning deficits are associated with a decrease in neurogenesis, dendritic complexity, and spine number in the dorsal hippocampus. Fostering prenatally stressed (PS) pups onto control mothers prevents the dysregulation of the HPA axis and heightened anxiety, indicating a role for postnatal factors in their etiology. By contrast, learning impairment and decreased socialization are not affected by this fostering procedure and are therefore prenatally mediated.In spite of their widespread use in depressed pregnant women, selective serotonin reuptake inhibitor (SSRI) antidepressants do not normalize the behavior of their children. When administered during gestation to stressed rats, SSRIs do not reduce anxiety or learning deficits in their offspring. Moreover, when given to unstressed mothers, SSRIs induce anxiety in the offspring. The detrimental effect of SSRIs may result from inhibition of the serotonin transporter exposing the brain to excess amounts of 5-hydroxytryptamine (5-HT) at a critical time during fetal development.

Sex differences in animal models of psychiatric disorders

Psychiatric disorders are characterized by sex differences in their prevalence, symptomatology and treatment response. Animal models have been widely employed for the investigation of the neurobiology of such disorders and the discovery of new treatments. However, mostly male animals have been used in preclinical pharmacological studies. In this review, we highlight the need for the inclusion of both male and female animals in experimental studies aiming at gender-oriented prevention, diagnosis and treatment of psychiatric disorders. We present behavioural findings on sex differences from animal models of depression, anxiety, post-traumatic stress disorder, substance-related disorders, obsessive-compulsive disorder, schizophrenia, bipolar disorder and autism. Moreover, when available, we include studies conducted across different stages of the oestrous cycle. By inspection of the relevant literature, it is obvious that robust sex differences exist in models of all psychiatric disorders. However, many times results are conflicting, and no clear conclusion regarding the direction of sex differences and the effect of the oestrous cycle is drawn. Moreover, there is a lack of considerable amount of studies using psychiatric drugs in both male and female animals, in order to evaluate the differential response between the two sexes. Notably, while in most cases animal models successfully mimic drug response in both sexes, test parameters and treatment-sensitive behavioural indices are not always the same for male and female rodents. Thus, there is an increasing need to validate animal models for both sexes and use standard procedures across different laboratories.

Functional connectivity in prenatally stressed rats with and without maternal treatment with ladostigil, a brain-selective monoamine oxidase inhibitor

Stress during pregnancy in humans is known to be a risk factor for neuropsychiatric disorders in the offspring. Prenatal stress in rats caused depressive-like behavior that was restored to that of controls by maternal treatment with ladostigil (8.5 mg/kg per day), a brain-selective monoamine oxidase (MAO) inhibitor that prevented increased anxiety-like behavior in stressed mothers. Ladostigil inhibited maternal striatal MAO-A and -B by 45-50% at the time the pups were weaned. Using resting state-functional connectivity magnetic resonance imaging on rat male offspring of control mothers, and mothers stressed during gestation with and without ladostigil treatment, we identified neuronal connections that differed between these groups. The percentage of significant connections within a predefined predominantly limbic network in control rats was 23.3 within the right and 22.0 within the left hemisphere. Prenatal stress disturbed hemispheric symmetry, resulting in 30.2 and 21.6%, significant connections in the right and left hemispheres, respectively, but this was fully restored in the maternal ladostigil group to 24.6% in both hemispheres. All connections that were modified in prenatally stressed rats and restored by maternal drug treatment were associated with the dopaminergic system. Specifically, we observed that restoration of the connections of the right nucleus accumbens shell with frontal areas, the cingulate, septum and motor and sensory cortices, and those of the right globus pallidus with the infra-limbic and the dentate gyrus, were most important for prevention of depressive-like behavior.

Prenatal stress and subsequent exposure to chronic mild stress in rats; interdependent effects on emotional behavior and the serotonergic system

Exposure to prenatal stress (PS) can predispose individuals to the development of psychopathology later in life. We examined the effects of unpredictable chronic mild stress (CMS) exposure during adolescence on a background of PS in male and female Sprague-Dawley rats. PS induced more anxiety-like behavior in the elevated zero maze in both sexes, an effect that was normalized by subsequent exposure to CMS. Moreover, PS was associated with increased depression-like behavior in the forced swim test in males only. Conversely, sucrose intake was increased in PS males, whilst being decreased in females when consecutively exposed to PS and CMS. Hypothalamo-pituitary-adrenal (HPA) axis reactivity was affected in males only, with higher stress-induced plasma corticosterone levels after PS. Markedly, CMS normalized the effects of PS on elevated zero maze behavior as well as basal and stress-induced plasma corticosterone secretion. At the neurochemical level, both PS and CMS induced various sex-specific alterations in serotonin (5-HT) and tryptophan hydroxylase 2 (TPH2) immunoreactivity in the dorsal raphe nucleus, hippocampus and prefrontal cortex with, in line with the behavioral observations, more profound effects in male offspring. In conclusion, these findings show that prenatal maternal stress in Sprague-Dawley rats induces various anxiety- and depression-related behavioral and neuroendocrine changes, as well as alterations in central 5-HT and TPH2 function, predominantly in male offspring. Moreover, CMS exposure partially normalized the effects of previous PS experience, suggesting that the outcome of developmental stress exposure largely depends on the environmental conditions later in life and vice versa.

Vulnerability versus resilience to prenatal stress in male and female rats; implications from gene expression profiles in the hippocampus and frontal cortex

Adverse life events during pregnancy may impact upon the developing fetus, predisposing prenatally stressed offspring to the development of psychopathology. In the present study, we examined the effects of prenatal restraint stress (PS) on anxiety- and depression-related behavior in both male and female adult Sprague-Dawley rats. In addition, gene expression profiles within the hippocampus and frontal cortex (FC) were examined in order to gain more insight into the molecular mechanisms that mediate the behavioral effects of PS exposure. PS significantly increased anxiety-related behavior in male, but not female offspring. Likewise, depression-related behavior was increased in male PS rats only. Further, male PS offspring showed increased basal plasma corticosterone levels in adulthood, whereas both PS males and females had lower stress-induced corticosterone levels when compared to controls. Microarray-based profiling of the hippocampus and FC showed distinct sex-dependent changes in gene expression after PS. Biological processes and/or signal transduction cascades affected by PS included glutamatergic and GABAergic neurotransmission, mitogen-activated protein kinase (MAPK) signaling, neurotrophic factor signaling, phosphodiesterase (PDE)/ cyclic nucleotide signaling, glycogen synthase kinase 3 (GSK3) signaling, and insulin signaling. Further, the data indicated that epigenetic regulation is affected differentially in male and female PS offspring. These sex-specific alterations may, at least in part, explain the behavioral differences observed between both sexes, i.e. relative vulnerability versus resilience to PS in male versus female rats, respectively. These data reveal novel potential targets for antidepressant and mood stabilizing drug treatments including PDE inhibitors and histone deacetylase (HDAC) inhibitors.

The involvement of ERK/CREB/Bcl-2 in depression-like behavior in prenatally stressed offspring rats

A number of studies reveal that prenatal stress (PS) may induce an increased vulnerability to depression in offspring. Some evidences indicate that extracellular signal-regulated kinase (ERK)-cyclic AMP responsive element binding protein (CREB) signal system may play an important role in the molecular mechanism of depression. In the present study, we examined the effects of prenatal restraint stress on depression-like behavior in one-month offspring Sprague-Dawley rats and expression of ERK2, CREB, B-cell lymphoma-2 (Bcl-2) mRNA in the hippocampus, prefrontal cortex and striatum to explore the potential role of ERK-CREB pathway in mediating the behavioral effects of PS exposure. Our findings demonstrated that PS increased immobility time in forced swimming test and decreased expression of ERK2, CREB, Bcl-2 mRNA in the hippocampus and prefrontal cortex of juvenile offspring rats except for CREB in hippocampus of male offspring. Changes induced by PS were partly prevented by MK-801, an N-methyl-D-aspartate (NMDA) receptor antagonist. These findings suggested that the ERK-CREB system might be related with the depression-like behavior in juvenile offspring rats subjected to PS, in which NMDA receptors might be involved.

Prenatal stress produces social behavior deficits and alters the number of oxytocin and vasopressin neurons in adult rats

The present study investigated the long-lasting effects of prenatal repeated restraint stress on social behavior and anxiety, as well as its repercussions on oxytocin (OT) and vasopressin (VP)-positive neurons of the paraventricular (PVN) and supraoptic (SON) nuclei from stressed pups in adulthood. Female Wistar rats were exposed to restraint stress in the last 7 days of pregnancy. At birth, pups were cross-fostered and assigned to the following groups: prenatally non-stressed offspring raised by prenatally non-stressed mothers (NS:NS), prenatally non-stressed offspring raised by prenatally stressed mothers (S:NS), prenatally stressed offspring raised by prenatally non-stressed mothers (NS:S), prenatally stressed offspring raised by prenatally stressed mothers (S:S). As adults, male prenatally stressed offspring raised both by stressed mothers (S:S group) and non-stressed ones (NS:S group) showed impaired social memory and interaction. In addition, when both adverse conditions coexisted (S:S group), increased anxiety-like behavior and aggressiveness was observed in association with a decrease in the number of OT-positive magnocellular neurons, VP-positive magnocellular and parvocellular neurons of the PVN. The NS:S group exhibited a reduction in the amount of VP-positive magnocellular neurons compared to the S:NS. Thus, the social behavior deficits observed in the S:S and NS:S groups may be only partially associated with these alterations to the peptidergic systems. No changes were shown in the OT and VP cellular composition of the SON nucleus. Nevertheless, it is clear that a special attention should be given to the gestational period, since stressful events during this time may be related to the emergence of behavioral impairments in adulthood.

Effects of chronic maternal stress on hypothalamo-pituitary-adrenal (HPA) function and behavior: no reversal by environmental enrichment

Maternal stress during pregnancy is linked to increased risk for impaired behavioral and emotional development and affective disorders in children. In animal models, acute periods of prenatal or postnatal stress have profound effects on HPA function and behavior in adult offspring. However, few animal studies have determined the impact of chronic exposure to stress throughout the perinatal period. The objective of this study was to determine the effects of chronic maternal stress (CMS) during the 2nd half of pregnancy and nursing on HPA function, locomotor behavior and prepulse inhibition in adult guinea pig offspring, as well as to determine whether environmental enrichment (EE) could reverse the effects of CMS. Guinea pigs were exposed to a random combination of variable stressors every other day over the 2nd half of gestation and from postnatal day (pnd) 1 until weaning (pnd25). Following weaning, offspring were housed in either standard conditions or EE. In both adult male and female offspring, there was no effect of CMS on basal or activated HPA function. CMS significantly increased locomotor activity in an open-field in male offspring, though no effect was observed in females. In female offspring, CMS disrupted PPI; however there was no effect on male PPI. EE had a number of effects on HPA function and behavior but in most cases these were independent of the influence of CMS. EE significantly elevated basal cortisol levels in male offspring at pnd70, whereas in female offspring, EE interacted with CMS to elevate basal cortisol levels from pnd35 to pnd70. In female offspring, EE decreased locomotor activity. In males, EE enhanced PPI; however in female offspring EE disrupted PPI. In conclusion, while CMS had minimal effects on HPA function, there were significant long-term sex-specific effects on behavior. EE did not reverse the effects observed as a result of CMS, but rather modified HPA function and behavior independently of CMS. Further, there was significant interaction of CMS with EE that resulted in elevation of basal HPA function in female offspring. These data, combined with previous studies from our laboratory, suggest that acute phases of maternal stress in late pregnancy may have greater long-term effects on HPA function and related behaviors than prolonged chronic maternal stress.

Sex-dependent changes induced by prenatal stress in cortical and hippocampal morphology and behaviour in rats: an update

Recent prospective studies have shown that gestational stress in humans is more likely to cause cognitive and emotional problems in the offspring if it occurs during weeks 12-20 of pregnancy. There are also suggestions that such problems may be gender dependent. This review describes recent studies that found sex differences in the behaviour and brain morphology of rats stressed prenatally during the equivalent period of neuronal development in humans. Learning deficits are more prevalent in males and anxious behaviour in females but their appearance depends also on the timing and intensity of the stress and the age when the offspring were tested. Cognitive deficits and anxiety are linked to a sex-dependent reduction in neurogenesis and in measures of dendritic morphology in the prefrontal cortex and hippocampal formation. Maternal adrenalectomy prior to the stress prevents the anxiety in both sexes and learning deficits in males. Corticosterone administration to the dam to mimic levels induced by stress reinstates only the anxiety, indicating that it arises from foetal exposure to corticosterone from the maternal circulation. Learning deficits in males may result from a combination of a reduction in testosterone and in aromatase activity, together with the action of other adrenal hormones.

Neuroendocrine control of maternal stress responses and fetal programming by stress in pregnancy

The major changes in highly dynamic neuroendocrine systems that are essential for establishing and maintaining pregnancy are outlined from studies on rodents. These changes optimise the internal environment to provide the life support system for the placenta, embryo and fetus. These include automatic prevention of further pregnancy, blood volume expansion, increased appetite and energy storage. The brain regulates these changes, in response to steroid (estrogens, progesterone) and peptide (lactogens, relaxin) hormone signals. Activation of inhibitory endogenous opioid mechanisms in the brain in late pregnancy restrains premature secretion of oxytocin, and attenuates hypothalamo-pituitary-adrenal (HPA) responses to stress. This opioid mechanism is activated by allopregnanolone, a neuroactive progesterone metabolite. The significance of reduced HPA axis responses in shifting maternal metabolic balance, and in protecting the fetuses from adverse programming of HPA axis stress responsiveness and anxious behaviour in later life is critically discussed. Experimental studies showing sex-dependent fetal programming by maternal stress or glucocorticoid exposure in late pregnancy are reviewed. The possibility of over-writing programming in offspring through neurosteroid administration is discussed. The impact of maternal stress on placental function is considered in the context of reconciling studies that show offspring programming by stress in very early or late pregnancy produce similar phenotypes in the offspring.

Corticosterone mediates some but not other behavioural changes induced by prenatal stress in rats

The effect of daily varied stress from days 13-21 of gestation in Wistar rats was investigated by tests of learning and memory and anxiogenic behaviour in the 60-day-old offspring of both sexes. Prenatal stress decreased the anogenital distance in males at 1 day of age. Anxiogenic behaviour in the elevated plus maze was seen in prenatally-stressed rats of both genders. There was no significant gender difference in the rate of spatial learning in the Morris water maze but prenatal stress only slowed that of males. In the object recognition test with an inter-trial interval of 40 min, females but not males, discriminated between a familiar and novel object. Prenatal stress did not affect object discrimination in females but feminised that in males. Maternal adrenalectomy with replacement of basal corticosterone levels in the drinking fluid prevented all of the above effects of prenatal stress in the offspring. To mimic the peak corticosterone levels and time course of elevation in response to stress, corticosterone (3 mg/kg) was injected twice (0 and 30 min) on days 13-16 and once on days 17-20 of gestation to adrenalectomised mothers. This treatment re-instated anxiogenic behaviour similar to that induced by prenatal stress, indicating that it is mediated by exposure of the foetal brain to raised levels of corticosterone. However, steroid administration to adrenalectomised dams did not decrease anogenital distance, feminise object recognition memory or slow spatial learning in their male offspring. The findings indicate that other adrenal hormones are necessary to induce these effects of prenatal stress.

Interaction between environmental and genetic factors modulates schizophrenic endophenotypes in the Snap-25 mouse mutant blind-drunk

To understand the pathophysiology of neuropsychiatric disorders such as schizophrenia requires consideration of multiple genetic and non-genetic factors. However, very little is known about the consequences of combining models of synaptic dysfunction with controlled environmental manipulations. Therefore, to generate new insights into gene–environment interactions and complex behaviour, we examined the influence of variable prenatal stress (PNS) on two mouse lines with mutations in synaptosomal-associated protein of 25 kDa (Snap-25): the blind-drunk (Bdr) point mutant and heterozygous Snap-25 knockout mice. Neonatal development was analysed in addition to an assessment of adult behavioural phenotypes relevant to the psychotic, cognitive and negative aspects of schizophrenia. These data show that PNS influenced specific anxiety-related behaviour in all animals. In addition, sensorimotor gating deficits previously noted in Bdr mutants were markedly enhanced by PNS; significantly, these effects could be reversed with the application of anti-psychotic drugs. Moreover, social interaction abnormalities were observed only in Bdr animals from stressed dams but not in wild-type littermates or mutants from non-stressed mothers. These results show for the first time that combining a synaptic mouse point mutant with a controlled prenatal stressor paradigm produces both modified and previously unseen phenotypes, generating new insights into the interactions between genetics and the environment relevant to the study of psychiatric disease.

Multifunctional neuroprotective derivatives of rasagiline as anti-Alzheimer's disease drugs

The recent therapeutic approach in which drug candidates are designed to possess diverse pharmacological properties and act on multiple targets has stimulated the development of the multimodal drugs, ladostigil (TV3326) [(N-propargyl-(3R) aminoindan-5yl)-ethyl methyl carbamate] and the newly designed multifunctional antioxidant iron chelator, M-30 (5-[N-methyl-N-propargylaminomethyl]-8-hydroxyquinoline). Ladostigil combines, in a single molecule, the neuroprotective/neurorestorative effects of the novel anti-Parkinsonian drug and selective monoamine oxidase (MAO)-B inhibitor, rasagiline (Azilect, Teva Pharmaceutical Co.) with the cholinesterase (ChE) inhibitory activity of rivastigmine. A second derivative of rasagiline, M-30 was developed by amalgamating the propargyl moiety of rasagiline into the skeleton of our novel brain permeable neuroprotective iron chelator, VK-28. Preclinical experiments showed that both compounds have anti-Alzheimer's disease activities and thus, the clinical development is oriented toward treatment of this type of dementia. This review discusses the multimodal effects of two rasagiline-containing hybrid molecules, namely ladostigil and M-30, concerning their neuroprotective molecular mechanisms in vivo and in vitro, including regulation of amyloid precursor protein processing, activation of protein kinase C, and mitogen-activated protein kinase signaling pathways, inhibition of cell death markers and upregulation of neurotrophic factors. Altogether, these scientific findings make these multifunctional compounds potentially valuable drugs for the treatment of Alzheimer's disease.

Induction of neurotrophic factors GDNF and BDNF associated with the mechanism of neurorescue action of rasagiline and ladostigil: new insights and implications for therapy

Parkinson's disease (PD) and Alzheimer's disease (AD) are the most common neurodegenerative disorders, although there is no drug or therapeutic treatment to demonstrate disease-modifying effects. Previous work has proposed that neurodegeneration is linked to a lack of trophic support in those neurons and brain areas associated with PD and AD. Indeed, previous studies have found that neurotrophic factors (NTFs) support neuronal survival in various cellular and animal models of PD and AD. Thus, attention has begun to turn to the possibility of NTF neuroprotective-neurorescue therapies for these diseases, indicating that NTFs may be of significant clinical importance as exogenously supplied or endogenously induced elements that obliterate neuronal deficits and degeneration. We have recently reported that the anti-PD drug rasagiline, the anti-AD drug ladostigil, and their propargyl moiety, propargylamine, enhanced the expression levels of brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor, endogenous NTFs associated with activation of phosphatidylinositol 3-kinase, protein kinase, and mitogen-activated protein kinase cell signaling/survival pathways. These studies indicate that the induction of NTFs by rasagiline and ladostigil might suppress apoptosis and induce neurorescue in neurodegenerative disorders and may support the drugs' possible disease-modifying mechanism of action.

Effects of gestational stress: 1. Evaluation of maternal and juvenile offspring behavior

In both humans and animals, stress experienced during gestation is associated with physiological changes and disruptions in emotional function and cognitive ability in offspring; however, much less is known about the effects of such stress in mothers. In animal models, physical restraint is commonly employed to induce stress during gestation and results in elevated postpartum maternal anxiety and changes in maternal care. The purpose of the current study was to evaluate the consequences of restraint stress applied on gestation days 10 through 19 in mother rats and their juvenile offspring. Progeny were reared by birth mothers. Preterm anxiety was assessed in the elevated plus maze and maternal behavior in the retrieval test. Cognitive (T-maze) and anxiety measures (elevated plus maze and emergence) were applied to a subset of male and female offspring at 30-31 days of age. Weight and litter characteristics were also recorded. Mother rats exposed to stress during gestation had attenuated weight gain, elevated anxiety-like behavior, and reduced maternal care. Stressed mothers also had fewer pups and an elevated offspring mortality rate. The consequences of gestational stress in offspring were subtle and gender-dependent. Only juvenile females displayed marginal effects of gestational stress in the form of elevated anxiety-like behavior and attenuated weight gain. In the current study, although gestational stress had robust effects in the mother rat, these did not translate to similar changes in offspring behavior. The importance of focusing research on maternal responses to gestational stress is highlighted by these findings.

The long-term behavioural consequences of prenatal stress

Maternal distress during pregnancy increases plasma levels of cortisol and corticotrophin releasing hormone in the mother and foetus. These may contribute to insulin resistance and behaviour disorders in their offspring that include attention and learning deficits, generalized anxiety and depression. The changes in behaviour, with or independent of alterations in the function of the hypothalamic pituitary adrenal (HPA) axis, can be induced by prenatal stress in laboratory rodents and non-human primates. The appearance of such changes depends on the timing of the maternal stress, its intensity and duration, gender of the offspring and is associated with structural changes in the hippocampus, frontal cortex, amygdala and nucleus accumbens. The dysregulation of the HPA axis and behaviour changes can be prevented by maternal adrenalectomy. However, only the increased anxiety and alterations in HPA axis are re-instated by maternal injection of corticosterone.

CONCLUSION

Excess circulating maternal stress hormones alter the programming of foetal neurons, and together with genetic factors, the postnatal environment and quality of maternal attention, determine the behaviour of the offspring.

Prenatal stress does not alter innate novelty-seeking behavioral traits, but differentially affects individual differences in neuroendocrine stress responsivity

Exposure to stress during prenatal or early postnatal life can dramatically impact adult behavior and neuroendocrine function. We recently began to selectively breed Sprague-Dawley rats for high (high responder, HR) and low (low responder, LR) novelty-seeking behavior, a trait that predicts a variety of differences in emotional reactivity, including differences in neuroendocrine stress response, fear- and anxiety-like behavior, aggression, and propensity to self-administer drugs of abuse. We evaluated genetic-early environment interactions by exposing HR- and LR-bred animals to prenatal stress (PS) from pregnancy day 3-20, hypothesizing that PS exposure would differentially impact HR versus LR behavior and neuroendocrine reactivity. We evaluated novelty-induced locomotion, anxiety-like behavior, and corticosterone stress response in weanling (25-day-old) and adult HR-LR stressed and control males. Exposure to PS did not alter HR-LR differences in locomotion, but did impact anxiety-like behavior, specifically in LR animals. Surprisingly, LR animals exposed to PS exhibited less anxiety than LR controls. HR rats were not affected by PS, with both stress and control groups showing low levels of anxiety. PS differentially impacted neuroendocrine stress reactivity in young versus adult HR-LR animals, leading to an exaggerated corticosterone response in LR pups compared to LR controls, while HRs pups were unaffected. In contrast, exposure to PS produced an exaggerated stress response in HR adults, compared to HR controls, while LR animals were not significantly affected. These findings highlight how genetic predisposition may shape individual's response to early life stressors, and furthermore, show that a history of early life stress may differentially impact an organism at different points in life. Future work will explore neural mechanisms which underlie the different behavioral and neuroendocrine consequences of PS in HR versus LR animals.

Aminoindan and hydroxyaminoindan, metabolites of rasagiline and ladostigil, respectively, exert neuroprotective properties in vitro

The anti-Parkinson, selective irreversible monoamine oxidase B inhibitor drug, rasagiline (Azilect), recently approved by the US Food and Drug Administration, has been shown to possess neuroprotective-neurorescue activities in in vitro and in vivo models. Recent preliminary studies indicated the potential neuroprotective effect of the major metabolite of rasagiline, 1-(R)-aminoindan. In the current study, the neuroprotective properties of 1-(R)-aminoindan were assessed employing a cytotoxic model of human neuroblastoma SK-N-SH cells in high-density culture-induced neuronal death. We show that aminoindan (0.1-1 mumol/L) significantly reduced the apoptosis-associated phosphorylated protein, H2A.X (Ser139), decreased the cleavage of caspase 9 and caspase 3, while increasing the anti-apoptotic proteins, Bcl-2 and Bcl-xl. Protein kinase C (PKC) inhibitor, GF109203X, prevented the neuroprotection, indicating the involvement of PKC in aminoindan-induced cell survival. Aminoindan markedly elevated pPKC(pan) and specifically that of the pro-survival PKC isoform, PKCepsilon. Additionally, hydroxyaminoindan, a metabolite of a novel bifunctional drug, ladostigil [(N-propargyl-(3R) aminoindan-5yl)-ethyl methyl carbamate], combining cholinesterase and monoamine oxidase inhibitor activity, exerted similar neuroprotective properties. Aminoindan and hydroxyaminoindan also protected rat pheochromacytoma PC-12 cells against the neurotoxin, 6-hydroxydopamine. Our findings suggest that both metabolites may contribute to the overall neuroprotective activity of their respective parent compounds, further implicating rasagiline and ladostigil as potentially valuable drugs for treatment of a wide variety of neurodegenerative disorders of aging.

Maternal adrenal hormone secretion mediates behavioural alterations induced by prenatal stress in male and female rats

Prenatal stress in rats has been shown to impair the regulation of the hypothalamic pituitary adrenal (HPA) axis and predispose to anxiogenic and depressive-like behaviour. In a previous study, abolition of excess corticosterone (COR) release during stress by maternal adrenalectomy prevented the dysregulation of the HPA axis. In the present study, we determined whether excess maternal COR is also responsible for the alterations in offspring behaviour. Pregnant Wistar rats were adrenalectomized or sham-operated on day 11 of gestation and subjected once daily to mild restraint for 30 min on days 14-21 of gestation. An undisturbed group of pregnant females served as controls. All experiments were performed in male and female offspring. Pup weight and anogenital distance of males were measured after birth; anxiogenic behaviour was assessed in the elevated plus maze (EPM) at the age of 5 weeks and spatial memory in the Morris water maze in littermates at 3-4 months. Prenatally stressed (PS) males did not show a reduction in anogenital distance, and their increase in anxiogenic behaviour in the EPM was less than that in PS females. On the other hand, impairment of spatial learning was only seen in PS males. Both the anxiogenic behaviour of PS males and females and the learning deficit in males were completely abolished by adrenalectomy. These data show that excess stress-induced COR can alter the programming of the foetal brain and predispose it to alterations in behaviour that are gender specific.

The therapeutic potential of monoamine oxidase inhibitors

Monoamine oxidase inhibitors were among the first antidepressants to be discovered and have long been used as such. It now seems that many of these agents might have therapeutic value in several common neurodegenerative conditions, independently of their inhibition of monoamine oxidase activity. However, many claims and some counter-claims have been made about the physiological importance of these enzymes and the potential of their inhibitors. We evaluate these arguments in the light of what we know, and still have to learn, of the structure, function and genetics of the monoamine oxidases and the disparate actions of their inhibitors.

Ladostigil, a novel multifunctional drug for the treatment of dementia co-morbid with depression

Ladostigil is a novel drug that inhibits acetyl and butyrylcholinesterase, and monoamine oxidase (MAO) A and B selectively in the brain. It reverses memory deficits induced by chronic inhibition of cortical cytochrome oxidase in rats and has anxiolytic and antidepressant-like activity in prenatally-stressed rats. Ladostigil also prevents oxidative-nitrative stress induced in astrocytes in the hippocampal CA1 region following icv injection of STZ in rats which also impairs their episodic memory. The unique combination of ChE and MAO enzyme inhibition combined with neuroprotection makes ladostigil a potentially useful drug for the treatment of dementia in subjects that also have extrapyramidal dysfunction and depression.