Blockage of melanocortin-4 receptors by intranasal HS014 attenuates single prolonged stress-triggered changes in several brain regions

The Melanocortin System: A Promising Target for the Development of New Antidepressant Drugs

Major depression is one of the most prevalent mental disorders, causing significant human suffering and socioeconomic loss. Since conventional antidepressants are not sufficiently effective, there is an urgent need to develop new antidepressant medications. Despite marked advances in the neurobiology of depression, the etiology and pathophysiology of this disease remain poorly understood. Classical and newer hypotheses of depression suggest that an imbalance of brain monoamines, dysregulation of the hypothalamic-pituitary-adrenal axis (HPAA) and immune system, or impaired hippocampal neurogenesis and neurotrophic factors pathways are cause of depression. It is assumed that conventional antidepressants improve these closely related disturbances. The purpose of this review was to discuss the possibility of affecting these disturbances by targeting the melanocortin system, which includes adrenocorticotropic hormone-activated receptors and their peptide ligands (melanocortins). The melanocortin system is involved in the regulation of various processes in the brain and periphery. Melanocortins, including peripherally administered non-corticotropic agonists, regulate HPAA activity, exhibit anti-inflammatory effects, stimulate the levels of neurotrophic factors, and enhance hippocampal neurogenesis and neurotransmission. Therefore, endogenous melanocortins and their analogs are able to complexly affect the functioning of those body’s systems that are closely related to depression and the effects of antidepressants, thereby demonstrating a promising antidepressant potential.

Increased intrinsic and synaptic excitability of hypothalamic POMC neurons underlies chronic stress-induced behavioral deficits

Chronic stress exposure induces maladaptive behavioral responses and increases susceptibility to neuropsychiatric conditions. However, specific neuronal populations and circuits that are highly sensitive to stress and trigger maladaptive behavioral responses remain to be identified. Here we investigate the patterns of spontaneous activity of proopiomelanocortin (POMC) neurons in the arcuate nucleus (ARC) of the hypothalamus following exposure to chronic unpredictable stress (CUS) for 10 days, a stress paradigm used to induce behavioral deficits such as anhedonia and behavioral despair [1, 2]. CUS exposure increased spontaneous firing of POMC neurons in both male and female mice, attributable to reduced GABA-mediated synaptic inhibition and increased intrinsic neuronal excitability. While acute activation of POMC neurons failed to induce behavioral changes in non-stressed mice of both sexes, subacute (3 days) and chronic (10 days) repeated activation of POMC neurons was sufficient to induce anhedonia and behavioral despair in males but not females under non-stress conditions. Acute activation of POMC neurons promoted susceptibility to subthreshold unpredictable stress in both male and female mice. Conversely, acute inhibition of POMC neurons was sufficient to reverse CUS-induced anhedonia and behavioral despair in both sexes. Collectively, these results indicate that chronic stress induces both synaptic and intrinsic plasticity of POMC neurons, leading to neuronal hyperactivity. Our findings suggest that POMC neuron dysfunction drives chronic stress-related behavioral deficits.

Comorbidity between Alzheimer's disease and major depression: a behavioural and transcriptomic characterization study in mice

BACKGROUND

Major depression (MD) is the most prevalent psychiatric disease in the population and is considered a prodromal stage of the Alzheimer's disease (AD). Despite both diseases having a robust genetic component, the common transcriptomic signature remains unknown.

METHODS

We investigated the cognitive and emotional behavioural responses in 3- and 6-month-old APP/PSEN1-Tg mice, before β-amyloid plaques were detected. We studied the genetic and pathway deregulation in the prefrontal cortex, striatum, hippocampus and amygdala of mice at both ages, using transcriptomic and functional data analysis.

RESULTS

We found that depressive-like and anxiety-like behaviours, as well as memory impairments, are already present at 3-month-old APP/PSEN1-Tg mutant mice together with the deregulation of several genes, such as Ciart, Grin3b, Nr1d1 and Mc4r, and other genes including components of the circadian rhythms, electron transport chain and neurotransmission in all brain areas. Extending these results to human data performing GSEA analysis using DisGeNET database, it provides translational support for common deregulated gene sets related to MD and AD.

CONCLUSIONS

The present study sheds light on the shared genetic bases between MD and AD, based on a comprehensive characterization from the behavioural to transcriptomic level. These findings suggest that late MD could be an early manifestation of AD.

Neuropeptides at the crossroad of fear and hunger: a special focus on neuropeptide Y

Survival in a natural environment forces an individual into constantly adapting purposive behavior. Specified interoceptive neurons monitor metabolic and physiological balance and activate dedicated brain circuits to satisfy essential needs, such as hunger, thirst, thermoregulation, fear, or anxiety. Neuropeptides are multifaceted, central components within such life‐sustaining programs. For instance, nutritional depletion results in a drop in glucose levels, release of hormones, and activation of hypothalamic and brainstem neurons. These neurons, in turn, release several neuropeptides that increase food‐seeking behavior and promote food intake. Similarly, internal and external threats activate neuronal pathways of avoidance and defensive behavior. Interestingly, specific nuclei of the hypothalamus and extended amygdala are activated by both hunger and fear. Here, we introduce the relevant neuropeptides and describe their function in feeding and emotional‐affective behaviors. We further highlight specific pathways and microcircuits, where neuropeptides may interact to identify prevailing homeostatic needs and direct respective compensatory behaviors. A specific focus will be on neuropeptide Y, since it is known for its pivotal role in metabolic and emotional pathways. We hypothesize that the orexigenic and anorexigenic properties of specific neuropeptides are related to their ability to inhibit fear and anxiety.

Single prolonged stress PTSD model triggers progressive severity of anxiety, altered gene expression in locus coeruleus and hypothalamus and effected sensitivity to NPY

PTSD is heterogeneous disorder that can be long lasting and often has delayed onset following exposure to a traumatic event. Therefore, it is important to take a staging approach to evaluate progression of biological mechanisms of the disease. Here, we begin to evaluate the temporal trajectory of changes following exposure to traumatic stressors in the SPS rat PTSD model. The percent of animals displaying severe anxiety on EPM increased from 17.5% at one week to 57.1% two weeks after SPS stressors, indicating delayed onset or progressive worsening of the symptoms. The LC displayed prolonged activation, and dysbalance of the CRH/NPY systems, with enhanced CRHR1 gene expression, coupled with reduced mRNAs for NPY and Y2R. In the mediobasal hypothalamus, increased CRH mRNA levels were sustained, but there was a flip in alterations of HPA regulatory molecules, GR and FKBP5 and Y5 receptor at two weeks compared to one week. Two weeks after SPS, intranasal NPY at 300 µg/rat, but not 150 µg which was effective after one week, reversed SPS triggered elevated anxiety. It also reversed SPS elicited depressive/despair symptoms and hyperarousal. Overall, the results reveal time-dependent progression in development of anxiety symptoms and molecular impairments in gene expression for CRH and NPY systems in LC and mediobasal hypothalamus by SPS. With longer time afterwards only a higher dose of NPY was effective in reversing behavioral impairments triggered by SPS, indicating that therapeutic approaches should be adjusted according to the degree of biological progression of the disorder.

Potential of Intranasal Neuropeptide Y (NPY) and/or Melanocortin 4 Receptor (MC4R) Antagonists for Preventing or Treating PTSD

There is a great need for effective treatment options for post-traumatic stress disorder (PTSD). Neuropeptide Y (NPY) is associated with resilience to traumatic stress. MC4R antagonists, such as HS014, also reduce response to stress. Both regulate stress-responsive systems - the hypothalamic-pituitary-axis (HPA) and the noradrenergic nervous system and their associated behaviors. Therefore, we examined if their intranasal delivery to brain could attenuate development of PTSD-related symptoms in single prolonged stress (SPS) rodent PTSD model. Three regimens were used: (1) prophylactic treatment 30 min before SPS stressors, (2) early intervention right after SPS stressors, (3) therapeutic treatment when PTSD behaviors are manifested 1 wk or more after the traumatic stress. NPY delivered by regimen 1 or 2 prevented SPS-triggered elevation in anxiety, depressive-like behavior, and hyperarousal and reduced dysregulation of HPA axis. Hypothalamic CRH mRNA and GR in ventral hippocampus were significantly induced in vehicle- but not NPY-treated group. NPY also prevented hypersensitivity of LC/NE system to novel mild stressor and induction of CRH in amygdala. Some of these impairments were also reduced with HS014, alone or together with NPY. When given after symptoms were manifested (regiment 3), NPY attenuated anxiety and depressive behaviors. This demonstrates strong preclinical proof of concept for intranasal NPY, and perhaps MC4R antagonists, for non-invasive early pharmacological interventions for PTSD and comorbid disorders and possibly also as therapeutic strategy.

Melanotan-II reverses autistic features in a maternal immune activation mouse model of autism

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder characterized by impaired social interactions, difficulty with communication, and repetitive behavior patterns. In humans affected by ASD, there is a male pre-disposition towards the condition with a male to female ratio of 4:1. In part due to the complex etiology of ASD including genetic and environmental interplay, there are currently no available medical therapies to improve the social deficits of ASD. Studies in rodent models and humans have shown promising therapeutic effects of oxytocin in modulating social adaptation. One pharmacological approach to stimulating oxytocinergic activity is the melanocortin receptor 4 agonist Melanotan-II (MT-II). Notably the effects of oxytocin on environmental rodent autism models has not been investigated to date. We used a maternal immune activation (MIA) mouse model of autism to assess the therapeutic potential of MT-II on autism-like features in adult male mice. The male MIA mice exhibited autism-like features including impaired social behavioral metrics, diminished vocal communication, and increased repetitive behaviors. Continuous administration of MT-II to male MIA mice over a seven-day course resulted in rescue of social behavioral metrics. Normal background C57 male mice treated with MT-II showed no significant alteration in social behavioral metrics. Additionally, there was no change in anxiety-like or repetitive behaviors following MT-II treatment of normal C57 mice, though there was significant weight loss following subacute treatment. These data demonstrate MT-II as an effective agent for improving autism-like behavioral deficits in the adult male MIA mouse model of autism.

Evaluating the Levels of Nesfatin-1 and Ghrelin Hormones in Patients with Moderate and Severe Major Depressive Disorders

OBJECTIVE

The goal of this study was to evaluate the importance of nesfatin-1, acylated and des-acylated ghrelin, which are known as energy regulatory hormones, in patients with moderate and severe major depression disorders (MDD).

METHODS

Thirty patients with a moderate degree of MDD and, 30 with a severe degree of MDD were used as participants in this study. Thirty subjects without depression were enrolled as a control group. The Hamilton Depression Rating Scale was used to classify the patients with MDD. Blood samples were taken after overnight fasting. The plasma nesfatin-1, acylated ghrelin and des-acylated ghrelin levels were measured using a commercially available enzyme-linked immunosorbent assay kit.

RESULTS

The nesfatin-1, the acylated ghrelin and the des-acylated ghrelin levels were found to be significantly higher in severe MDD (3.92±0.4 ng/mL; 88.56±4.1 pg/mL; 962.76±67 pg/mL) as compared to moderate MDD (2.91±0.5 ng/mL; 77.63±4.19 pg/mL; 631.16±35 pg/mL), or the control (1.01±0.3 ng/mL; 58.60±9.00 pg/mL; 543.13±62 pg/mL), respectively.

CONCLUSION

Although nesfatin-1 and ghrelin are known as adversely affecting the hormones involving the regulation of appetite and food intake, they all increase in depressive patients and are even associated with the severity of the disease. In clinical medicine, the evaluation of the role of nesfatin-1 and ghrelin in endocrine and neu-roendocrine regulation of major metabolic functions is an important key mechanism in solving numerous diseases associated with endocrine and neuroendocrine disturbance. Increased levels of nesfatin-1 and ghrelin may also be important criteria in describing the prognoses of the patients and the effectiveness of the treatments.

Adolescent Alcohol Exposure-Induced Changes in Alpha-Melanocyte Stimulating Hormone and Neuropeptide Y Pathways via Histone Acetylation in the Brain During Adulthood

Background

Adolescent intermittent ethanol exposure causes long-lasting alterations in brain epigenetic mechanisms. Melanocortin and neuropeptide Y signaling interact and are affected by ethanol exposure in the brain. Here, the persistent effects of adolescent intermittent ethanol on alpha-melanocyte stimulating hormone, melanocortin 4 receptor, and neuropeptide Y expression and their regulation by histone acetylation mechanisms were investigated in adulthood.

Methods

Male rats were exposed to adolescent intermittent ethanol (2 g/kg, i.p.) or volume-matched adolescent intermittent saline from postnatal days 28 to 41 and allowed to grow to postnatal day 92. Anxiety-like behaviors were measured by the elevated plus-maze test. Brain regions from adult rats were used to examine changes in alpha-melanocyte stimulating hormone, melanocortin 4 receptor, and neuropeptide Y expression and the histone acetylation status of their promoters.

Results

Adolescent intermittent ethanol-exposed adult rats displayed anxiety-like behaviors and showed increased pro-opiomelanocortin mRNA levels in the hypothalamus and increased melanocortin 4 receptor mRNA levels in both the amygdala and hypothalamus compared with adolescent intermittent saline-exposed adult rats. The alpha-Melanocyte stimulating hormone and melanocortin 4 receptor protein levels were increased in the central and medial nucleus of the amygdala, paraventricular nucleus, and arcuate nucleus of the hypothalamus in adolescent intermittent ethanol-exposed compared with adolescent intermittent saline-exposed adult rats. Neuropeptide Y protein levels were decreased in the central and medial nucleus of the amygdala of adolescent intermittent ethanol-exposed compared with adolescent intermittent saline-exposed adult rats. Histone H3K9/14 acetylation was decreased in the neuropeptide Y promoter in the amygdala but increased in the melanocortin 4 receptor gene promoter in the amygdala and the melanocortin 4 receptor and pro-opiomelanocortin promoters in the hypothalamus of adolescent intermittent ethanol-exposed adult rats compared with controls.

Conclusions

Increased melanocortin and decreased neuropeptide Y activity due to changes in histone acetylation in emotional brain circuitry may play a role in adolescent intermittent ethanol-induced anxiety phenotypes in adulthood.

NPY1 Receptor Agonist Modulates Development of Depressive-Like Behavior and Gene Expression in Hypothalamus in SPS Rodent PTSD Model

Delivery of neuropeptide Y (NPY) to the brain by intranasal infusion soon after traumatic stress has shown therapeutic potential, and prevented development of many behavioral and neuroendocrine impairments in the single prolonged stress (SPS) animal model of PTSD. Therefore, we examined whether the Y1R preferring agonist [Leu³¹Pro³⁴]NPY is sufficient to prevent development of SPS induced depressive-like behavioral changes, and hypothalamic gene expression as obtained with intranasal NPY intervention. Male Sprague-Dawely rats were given intranasal infusion of either NPY (150 μg/rat), a low (68 μg /rat), or high (132 μg/rat) dose of [Leu³¹Pro³⁴]NPY or vehicle immediately following the last SPS stressor, left undisturbed for 1 week and then tested for depressive-like behavior together with naïve unstressed controls. Vehicle treated animals had elevated immobility forced swim test (FST) and reduced sucrose preference, which were not observed in animals given NPY or the higher dose of [Leu³¹Pro³⁴]NPY. This dose of [Leu³¹Pro³⁴]NPY, like NPY, also prevented the SPS-elicited induction of CRF mRNA in the mediobasal hypothalamus. However, [Leu³¹Pro³⁴]NPY did not prevent, but rather enhanced, the SPS-triggered induction of GR and FKBP5 mRNA levels in the mediobasal hypothalamus. Thus, [Leu³¹Pro³⁴]NPY may be as effective as NPY and displays therapeutic potential for preventing development of depressive-like behaviors and dysregulation of the CRF/HPA system in PTSD. However, due to its different effects compared to NPY on GR and FKBP5 a broader agonist, such as NPY, may be more desirable.

Effect of Melanotan-II on Brain Fos Immunoreactivity and Oxytocin Neuronal Activity and Secretion in Rats

Melanocortins stimulate the central oxytocin systems that are involved in regulating social behaviours. Alterations in central oxytocin have been linked to neurological disorders such as autism, and melanocortins have been proposed for therapeutic treatment. In the present study, we investigated how systemic administration of melanotan-II (MT-II), a melanocortin agonist, affects oxytocin neuronal activity and secretion in rats. The results obtained show that i.v., but not intranasal, administration of MT-II markedly induced Fos expression in magnocellular neurones of the supraoptic (SON) and paraventricular nuclei (PVN) of the hypothalamus, and this response was attenuated by prior i.c.v. administration of the melanocortin antagonist, SHU-9119. Electrophysiological recordings from identified magnocellular neurones of the SON showed that i.v. administration of MT-II increased the firing rate in oxytocin neurones but did not trigger somatodendritic oxytocin release within the SON as measured by microdialysis. Our data suggest that, after i.v., but not intranasal, administration of MT-II, the activity of magnocellular neurones of the SON is increased. Because previous studies showed that SON oxytocin neurones are inhibited in response to direct application of melanocortin agonists, the actions of i.v. MT-II are likely to be mediated at least partly indirectly, possibly by activation of inputs from the caudal brainstem, where MT-II also increased Fos expression.

Gastrodin reversed the traumatic stress-induced depressed-like symptoms in rats

Exposure to severe stress can lead to the development of neuropsychiatric disorders such as depression and post-traumatic stress disorder (PTSD) in at-risk individuals. Gastrodin (GAS), a primary constituent of an Oriental herbal medicine, has been shown to effectively treat various mood disorders. Thus, the present study aimed to determine whether GAS would ameliorate stress-associated depression-like behaviors in a rat model of single prolonged stress (SPS)-induced PTSD. Following the SPS procedure, rats received intraperitoneal administration of GAS (20, 50, or 100 mg/kg) once daily for 2 weeks. Subsequently, the rats performed the forced swimming test, and norepinephrine (NE) levels in the hippocampus were measured. Daily GAS (100 mg/kg) significantly reversed depression-like behaviors and restored SPS-induced increases in hippocampal NE concentrations as well as tyrosine hydroxylase expression in the locus coeruleus. Furthermore, the administration of GAS attenuated SPS-induced decreases in the hypothalamic expression of neuropeptide Y and the hippocampal mRNA expression of brain-derived neurotrophic factor. These findings indicate that GAS possesses antidepressant effects in the PTSD and may be an effective herbal preparation for the treatment of PTSD.

Interactions with the MC4R rs17782313 variant, mental stress and energy intake and the risk of obesity in Genome Epidemiology Study

Background

The melanocortin-4 receptor (MC4R) regulates metabolism by modulating eating behavior and MC4R variants (rs17782313 and rs571312) are associated with obesity in Asians and Caucasians. However, the impact of their interactions with nutritional and lifestyle factors on obesity are poorly described. Therefore, we investigated the interaction of MC4R variants and dietary patterns on the risk of obesity in Korean middle-aged adults.

Methods

Data collected included, genetic variations, anthropometric and biochemical measurements, dietary and lifestyle habits, and food intake. Data were obtained from the 8830 adults aged 40–69 years in the Ansung and Ansan cohort of the Korean Genome Epidemiology Study.

Results

The MC4R rs18882313 minor allele had a higher frequency in the obese group (P < 0.01). MC4R genotypes were not associated with differences in daily energy and macronutrient intakes. However, the intakes of processed foods and fat (as percentages of energy) were significantly higher and intake of fruits were significantly lower in subjects with MC4R minor alleles (P < 0.05). Interestingly, there was a positive interaction between MC4R variants and mental stress levels that were associated with the risk of obesity after adjusting for age, gender, residence area, daily energy intake, smoking status and physical activity (interaction P = 0.0384). Only in subjects with high stress were MC4R minor alleles associated with higher BMIs after adjusting for confounders. The association was present without modulating energy and nutrient intake. In the group with energy intakes higher than estimated energy requirement (EER), subjects with MC4R minor alleles had higher BMIs than those with the major alleles (P < 0.001).

Conclusions

The interactions of mental stress and energy intakes with the MC4R minor allele genotype might be associated with increased risk of obesity in Korean adults. This research might identify subjects with a specific MC4R minor alleles as a human subset of people with a low metabolic tolerance for excessive energy intake, especially when under stress.

D-TRP(8)-γMSH Prevents the Effects of Endotoxin in Rat Skeletal Muscle Cells through TNFα/NF-KB Signalling Pathway

Sepsis induces anorexia and muscle wasting secondary to an increase in muscle proteolysis. Melanocyte stimulating hormones (MSH) is a family of peptides that have potent anti-inflammatory effects. Melanocortin receptor-3 (MC3-R) has been reported as the predominant anti-inflammatory receptor for melanocortins. The aim of this work was to analyse whether activation of MC3-R, by administration of its agonist D-Trp(8)-γMSH, is able to modify the response of skeletal muscle to inflammation induced by lipopolysaccharide endotoxin (LPS) or TNFα. Adult male rats were injected with 250 μg/kg LPS and/or 500 μg/kg D-Trp(8)-γMSH 17:00 h and at 8:00 h the following day, and euthanized 4 hours afterwards. D-Trp(8)-γMSH decreased LPS-induced anorexia and prevented the stimulatory effect of LPS on hypothalamic IL-1β, COX-2 and CRH as well as on serum ACTH and corticosterone. Serum IGF-I and its expression in liver and gastrocnemius were decreased in rats injected with LPS, but not in those that also received D-Trp(8)-γMSH. However, D-Trp(8)-γMSH was unable to modify the effect of LPS on IGFBP-3. In the gastrocnemius D-Trp(8)-γMSH blocked LPS-induced decrease in pAkt, pmTOR, MHC I and MCH II, as well as the increase in pNF-κB(p65), FoxO1, FoxO3, LC3b, Bnip-3, Gabarap1, atrogin-1, MuRF1 and in LC3a/b lipidation. In L6 myotube cultures, D-Trp(8)-γMSH was able to prevent TNFα-induced increase of NF-κB(p65) phosphorylation and decrease of Akt phosphorylation as well as of IGF-I and MHC I expression. These data suggest that MC3-R activation prevents the effect of endotoxin on skeletal wasting by modifying inflammation, corticosterone and IGF-I responses and also by directly acting on muscle cells through the TNFα/NF-κB(p65) pathway.

Transgenerational Social Stress, Immune Factors, Hormones, and Social Behavior

A social signal transduction theory of depression has been proposed that states that exposure to social adversity alters the immune response and these changes mediate symptoms of depression such as anhedonia and impairments in social behavior The exposure of maternal rats to the chronic social stress (CSS) of a male intruder depresses maternal care and impairs social behavior in the F1 and F2 offspring of these dams. The objective of the present study was to characterize basal peripheral levels of several immune factors and related hormone levels in the adult F2 offspring of CSS exposed dams and assess whether changes in these factors are associated with previously reported deficits in allogrooming behavior. CSS decreased acid glycoprotein (α1AGP) and intercellular adhesion molecule-1 (ICAM-1) in F2 females, and increased granulocyte macrophage-colony stimulating factor (GM-CSF) in F2 males. There were also sex dependent changes in IL-18, tissue inhibitors of metalloproteinases 1 (TIMP-1), and vascular endothelial growth factor (VEGF). Progesterone was decreased and alpha melanocyte stimulating hormone (α-MSH) was increased in F2 males, and brain-derived neurotrophic factor (BDNF) was decreased in F2 females. Changes in α1AGP, GM-CSF, progesterone, and α-MSH were correlated with decreased allogrooming in the F2 offspring of stressed dams. These results support the hypothesis that transgenerational social stress affects both the immune system and social behavior, and also support previous studies on the adverse effects of early life stress on immune functioning and stress associated immunological disorders, including the increasing prevalence of asthma. The immune system may represent an important transgenerational etiological factor in disorders which involve social and/or early life stress associated changes in social behavior, such as depression, anxiety, and autism, as well as comorbid immune disorders. Future studies involving immune and/or endocrine assessments and manipulations will address specific questions of function and causation, and may identify novel preventative measures and treatments for the growing number of immune mediated disorders.

Comparative effects of intranasal neuropeptide Y and HS014 in preventing anxiety and depressive-like behavior elicited by single prolonged stress

Stress triggered neuropsychiatric disorders are a serious societal problem. Prophylactic treatment or early intervention has great potential in increasing resilience to traumatic stress and reducing its harmful impact. Previously, we demonstrated proof of concept that intranasal administration of neuropeptide Y (NPY) or the melanocortin receptor four (MC4R) antagonist, HS014, prior to single prolonged stress (SPS) rodent post-traumatic stress disorder (PTSD) model, can prevent or attenuate many PTSD associated impairments. Here, we compare effects of NPY or HS014 given 30 min before or immediately after SPS stressors on development of anxiety, depressive-like behavior and associated biochemical abnormalities. SPS triggered anxiety on elevated plus maze (EPM) was reduced by intranasal administration of 100 μg NPY and to even greater extent HS014 (3.5 ng or 100 μg). The SPS-elicited depressive-like behavior on forced swim test was prevented with 100 μg NPY or the high dose HS014. Combined administration of low HS014 and NPY, ineffective by themselves, prevented development of depressive-like behavior. Reductions in stress triggered activation of locus coeruleus/noradrenergic system and HPA axis were observed with both HS014 and NPY. In contrast to NPY which has been showed earlier, infusion of HS014 immediately after SPS did not prevent the development of anxiogenic behavior on EPM. However, HS014 given after SPS stressors effectively even at very low dose, prevented development of depressive-like behavior. Thus, both MC4R antagonist and NPY, alone or combined, have potential for prophylactic treatment against traumatic stress triggered anxiety or depressive-like behaviors, while NPY has more widespread potential for early intervention.