Effect of intranasal administration of neuropeptide Y and single prolonged stress on food consumption and body weight in male rats

Transcriptome profiles associated with resilience and susceptibility to single prolonged stress in the locus coeruleus and nucleus accumbens in male sprague-dawley rats

Although most people are subjected to traumatic stress at least once in their lifetime, only a subset develop long-lasting, stress-triggered neuropsychiatric disorders, such as PTSD. Here we examined different transcriptome profiles within the locus coeruleus (LC) and nucleus accumbens (NAc) that may contribute to stress susceptibility. Sprague Dawley male rats were exposed to the single prolonged stress (SPS) model for PTSD. Two weeks later they were tested for their anxiety/avoidance behavior on the Elevated Plus Maze (EPM) and were divided into high and low anxiety-like subgroups. RNA (n = 5 per group) was subsequently isolated from LC and NAc and subjected to RNAseq. Transcriptome analysis was used to identify differentially-expressed genes (DEGs) which differed by at least 50 % with significance of 0.01. The LC had more than six times the number of DEGs than the NAc. Only one DEG was regulated similarly in both locations. Many of the DEGs in the LC were associated with morphological changes, including regulation of actin cytoskeleton, growth factor activity, regulation of cell size, brain development and memory, with KEGG pathway of regulation of actin cytoskeleton. The DEGs in the NAc were primarily related to DNA repair and synthesis, and differential regulation of cytokine production. The analysis identified MTPN (myotrophin) and NR3C1 (glucocorticoid receptor) as important upstream regulators of stress susceptibility in the LC. Overall the study provides new insight into molecular pathways in the LC and NAc that are associated with anxiety-like behavior triggered by stress susceptibility or resilience.

Intranasal Peptide Therapeutics: A Promising Avenue for Overcoming the Challenges of Traditional CNS Drug Development

The central nervous system (CNS) has, among all organ systems in the human body, the highest failure rate of traditional small-molecule drug development, ranging from 80-100% depending on the area of disease research. This has led to widespread abandonment by the pharmaceutical industry of research and development for CNS disorders, despite increased diagnoses of neurodegenerative disorders and the continued lack of adequate treatment options for brain injuries, stroke, neurodevelopmental disorders, and neuropsychiatric illness. However, new approaches, concurrent with the development of sophisticated bioinformatic and genomic tools, are being used to explore peptide-based therapeutics to manipulate endogenous pathways and targets, including "undruggable" intracellular protein-protein interactions (PPIs). The development of peptide-based therapeutics was previously rejected due to systemic off-target effects and poor bioavailability arising from traditional oral and systemic delivery methods. However, targeted nose-to-brain, or intranasal (IN), approaches have begun to emerge that allow CNS-specific delivery of therapeutics via the trigeminal and olfactory nerve pathways, laying the foundation for improved alternatives to systemic drug delivery. Here we review a dozen promising IN peptide therapeutics in preclinical and clinical development for neurodegenerative (Alzheimer's, Parkinson's), neuropsychiatric (depression, PTSD, schizophrenia), and neurodevelopmental disorders (autism), with insulin, NAP (davunetide), IGF-1, PACAP, NPY, oxytocin, and GLP-1 agonists prominent among them.

Antidepressant Effect of Neuropeptide Y in Models of Acute and Chronic Stress

The search for potential effective antidepressants with minimal side effects is necessary. Peptides are possible applicants for this role. We investigated the antidepressant effect of neuropeptide Y (NY), alone and in combination with clomipramine, in models of acute and chronic stress induced by ultrasound of variable frequencies. Rats were divided into the following groups: the control group, stress group, and stress groups with intranasal administration of NY (100 μg/kg) or clomipramine (7.5 mg/kg), or their combination. Rat behavior was evaluated using a sucrose preference test and forced swimming test in an acute stress model, and a sucrose preference test, forced swimming test, social interaction test, open field test, and Morris water maze test in a chronic stress model. The results of our experiment demonstrated a protective effect of intranasal NY in a model of acute stress, which was comparable to the antidepressant effect of clomipramine. When the same dose was chronically administered, NY also demonstrated an antidepressant action, although expressed in a lesser degree than clomipramine. The combination of NY and clomipramine was much less effective in the chronic stress paradigm compared to the separated drug administration, but was just as effective in the acute stress paradigm. Until now, there was no convincing evidence for the efficacy of the chronic administration of neuropeptide Y; we demonstrated its effectiveness in the animal model of depressive-like behavior. However, our hypothesis that neuropeptide Y can enhance the effect of a classical antidepressant was not confirmed.

Intranasal Delivery of Galanin 2 and Neuropeptide Y1 Agonists Enhanced Spatial Memory Performance and Neuronal Precursor Cells Proliferation in the Dorsal Hippocampus in Rats

A need for new therapeutic approaches are necessary for dementia conditions and memory deficits of different origins, such as Alzheimer's disease. There is complex pathophysiological mechanisms involved, affecting adult hippocampal neurogenesis, in which neuropeptides and its neurogenesis regulation seem to participate. Neuropeptide Y(NPY) Y1 receptor (Y1R) and galanin (GAL) receptor 2 (GALR2) interact in brain regions responsible for learning and memory processes, emphasizing the hippocampus. Moreover, a significant challenge for treatments involving peptide drugs is bypassing the blood-brain barrier. The current study assesses the sustained memory performance induced by GALR2 and NPYY1R agonists intranasal coadministration and their neurochemical hippocampal correlates. Memory retrieval was conducted in the object-in-place task together with in situ proximity ligation assay (PLA) to manifest the formation of GALR2/Y1R heteroreceptor complexes and their dynamics under the different treatments. We evaluated cell proliferation through a 5-Bromo-2’-deoxyuridine (BrdU) expression study within the dentate gyrus of the dorsal hippocampus. The GalR2 agonist M1145 was demonstrated to act with the Y1R agonist to improve memory retrieval at 24 hours in the object-in-place task. Our data show that the intranasal administration is a feasible technique for directly delivering Galanin or Neuropeptide Y compounds into CNS. Moreover, we observed the ability of the co-agonist treatment to enhance the cell proliferation in the DG of the dorsal hippocampus through 5- Bromo-2’-deoxyuridine (BrdU) expression analysis at 24 hours. The understanding of the cellular mechanisms was achieved by analyzing the GALR2/Y1R heteroreceptor complexes upon agonist coactivation of their two types of receptor protomers in Doublecortin-expressing neuroblasts. Our results may provide the basis for developing heterobivalent agonist pharmacophores, targeting GALR2-Y1R heterocomplexes. It involves especially the neuronal precursor cells of the dentate gyrus in the dorsal hippocampus for the novel treatment of neurodegenerative pathologies as in the Alzheimer’s disease.

Neuropeptide Y (NPY) intranasal delivery alleviates Machado-Joseph disease

Machado–Joseph disease (MJD) is the most common dominantly-inherited ataxia worldwide with no effective treatment to prevent, stop or alleviate its progression. Neuropeptide Y (NPY) is a neuroprotective agent widely expressed in the mammalian brain. Our previous work showed that NPY overexpression mediated by stereotaxically-injected viral vectors mitigates motor deficits and neuropathology in MJD mouse models. To pursue a less invasive translational approach, we investigated whether intranasal administration of NPY would alleviate cerebellar neuropathology and motor and balance impairments in a severe MJD transgenic mouse model. For that, a NPY solution was administered into mice nostrils 5 days a week. Upon 8 weeks of treatment, we observed a mitigation of motor and balance impairments through the analysis of mice behavioral tests (rotarod, beam walking, pole and swimming tests). This was in line with a reduction of cerebellar pathology, evidenced by a preservation of cerebellar granular layer and of Purkinje cells and reduction of mutant ataxin-3 aggregate numbers. Furthermore, intranasal administration of NPY did not alter body weight gain, food intake, amount of body fat nor cholesterol or triglycerides levels. Our findings support the translational potential of intranasal infusion of NPY as a pharmacological intervention in MJD.